CA1238226A - Dehydrated food products and method for making the same - Google Patents
Dehydrated food products and method for making the sameInfo
- Publication number
- CA1238226A CA1238226A CA000468565A CA468565A CA1238226A CA 1238226 A CA1238226 A CA 1238226A CA 000468565 A CA000468565 A CA 000468565A CA 468565 A CA468565 A CA 468565A CA 1238226 A CA1238226 A CA 1238226A
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- CA
- Canada
- Prior art keywords
- range
- dehydrated
- foodstuff
- product
- moisture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/02—Dehydrating; Subsequent reconstitution
- A23B7/024—Freeze-drying, i.e. cryodessication or lyophilisation
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L19/00—Products from fruits or vegetables; Preparation or treatment thereof
- A23L19/10—Products from fruits or vegetables; Preparation or treatment thereof of tuberous or like starch containing root crops
- A23L19/12—Products from fruits or vegetables; Preparation or treatment thereof of tuberous or like starch containing root crops of potatoes
- A23L19/14—Original non-roasted or non-fried potato pieces
Abstract
ABSTRACT
Foodstuffs which have been frozen are partially dehydrated in a gaseous medium having a dry bulb temperature higher than about 200° F and a wet bulb temperature higher than about 120° F prior to finish drying at a dry bulb temperature of less than about 180° F to a storage stable moisture content of less than 12% by total weight. Dehydrated products ranging in size from 1/16" thick slices to 3/4" dice produced by this dehydration process reconstitute in less than about 15 minutes with an amount of water equivalent to at least 85% of the previously removed moisture.
Foodstuffs which have been frozen are partially dehydrated in a gaseous medium having a dry bulb temperature higher than about 200° F and a wet bulb temperature higher than about 120° F prior to finish drying at a dry bulb temperature of less than about 180° F to a storage stable moisture content of less than 12% by total weight. Dehydrated products ranging in size from 1/16" thick slices to 3/4" dice produced by this dehydration process reconstitute in less than about 15 minutes with an amount of water equivalent to at least 85% of the previously removed moisture.
Description
~3~9S01 - 1 -_CKGROUND OF THE INVENTION
Field _ Invention The invention relates to a method for producing dehydrated vegetables capable of rapid reconstitution.
More particularly, the invention is directed to a sequence of cooking, freezing and dehydration steps carried out under controlled conditions so as to produce a product having a porous interior and exterior surface.
Description of the Prior Art Dehydration is one of the oldest methods for preserving food. Commercial production of dehydrated foods, however is a development o-f the twentieth century. During the last forty years many procedures have been developed in an attempt to produce dehydrated products which upon reconstitution resemble fresh food in taste, texture, and appearance. More recently there has keen a general concern for quick dehydrating products. Most of these efforts have resulted in unsatisfactory processes and products. A problem common to prior dehydration methods is a phenomenon referred to as case-hardening or the formation of a - horny, vitreous material primarily on the surface of the food. It has teen postulated that this may result from the collapse of the cellular structure of the vegetable which dehydrates into a dense mass of material of low dehydration characteristics.
Prior art methods for producing quick rewriting products include soaking the material in solutions of salt or leavening agents prior to dehydration ; subjecting food material to dehydration techniques which effect an expansion or puffing of the product and freeze-drying. U.S. Patent No. 2,705,697 dehydrates ; potato dice using a fluidized bed dryer to form tan-colored pieces hollow in the center with the sides puffed out much as are the sizes of a pillow. U.S.
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a Jo I En 6 ?3489S01 - 2 -Patent No 3,338,724 discloses the importance of soaking potato pieces in a salt solution prior to such dehydration to produce puffed potato products having a density of 0.15 to 0.20 gm/cc. U.S. Patent No.
3,438,792 freeze dries potatoes prior to finish drying in hot air to avoid case-hardening. U.S. Patent No.
3f644,129 is based on the discovery that minimizing the temperature at which potato pieces are blanched prior to such combined freeze drying-hot air drying is effective in improving the dehydration characteristics of the dehydrated product. U.S. Patent No. 3,573,070 discloses a process comprising freezing prior to combined freeze drying-hot air drying in an attempt to produce improved dehydrated products. U.S. Patent No 3,188,750 attempts to produce a dehydrated product possessing a high degree of biological integrity by first hot air drying raw material prior to freeze drying which is preferably followed by another hot air - drying. U.S. Patent No. 2,729,566 teaches that rapid ; 20 freezing followed by a slow thawing at a temperature within the range of 28F to 32F for at least 15 minutes prior to hot air dehydration is critical and that potato pieces being processed should not reach a temperature higher than about 130F during dehydration.
U.S. Patent No. 2,707,684, however, discloses that if potato pieces are rapidly frozen prior to dehydration, the final products will have a slow dehydration rate.
U.S. Patent No. 2,713,003 preconditions food products by freezing, throughout or superficially, prior to dehydrating. U.S. Patent No. 2,278,472 also freezes food prior to dehydration. U.S. Patent No. 3,359l123 is directed to rendering potatoes more amenable to freeze-thaw procedures by a controlled cooking procedure which avoids moisture pickup by the potato followed by dehydrating the product under such conditions so as to avoid any further gelatinization of . :: . . '. , , ' ', - ' .' . ' , , . , , - . -,. I, .. . , P3~89S01 - 3 -the potato pieces, for example by drying in air having a 20 to 40% relative humidity GOB. Patent No 1,084,714 dehydrates vegetables in a gas containing from about I to about 50~ by weight of water vapor at a temperature from 194F to 428F. U.S. Patent No.
3,973,047 is directed to reducing the level of micro-organisms in dehydrated vegetables by subjecting vegetables, partially dried to between 8 and 50%
moisture, to air having dry bulb/wet bulb temperatures, ranging from 200F dry bulb/130F wet bulb to about 140F dry bulb/120F wet bulb, which are sufficiently high to kill bacteria without causing significant dehydration, prior to finish drying to a final moisture content of less than about 8%.
The foregoing disclosures are representative of the attempts made to overcome the shortcomings of dehydrated food products as compared to freshly prepared foodstuff. The food industry has had to rely on similar procedures to prepare dehydrated vegetables over the years. Recently, cooking and eating habits have been influenced by a number of factors which reduce the time allocated for food preparation in households as well as in eating establishments. This has caused a need for good nutritious foods which can be prepared quickly and easily. A number of frozen entree, side dish, and complete dinners, in addition to canned products, have been available in the marketplace which attempt to satisfy the consumer's need for convenient foods. Notwithstanding numerous efforts to develop industrially produced and commercially acceptable dehydrated food products, there is a limited number of dehydrated vegetable products on the market.
Such vegetables are primarily used as flavoring in soups, stocks, casseroles, and the live. Moreover, dehydrated vegetables used in instant soups, i.e., having a reconstitution time of less than about 5-20 ;
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~3489S01 ( ~23~ 6 minutes, have been small in size in order to permit preparation within the prescribed time period.
Normally the vegetable piece size is no larger than about 1/8 inch in cross section Typically, the dehydrated products have been reduced to a powder.
Complaints about such products include that the dehydrated pieces reconstitute incompletely and are tough and chewy despite their small size. Larger vegetable pieces have only recently been used as ingredients in commercial mixes containing dehydrated vegetables, stock seasoning, and noodles. These mixes are used as starting materials for preparation of soup to which only water and meat need be added in the kitchen. Their recipe normally requires as long as 1-1/2 hours in preparation for consumption.
SUMMARY OF THE INVENTION
The present invention relates generally to the production of dehydrated food materials and preferably vegetables. More particularly the invention is directed to a process for dehydrating vegetable materials which are capable of quick dehydration in water to more closely resemble the taste, texture, and appearance of fresh vegetables than heretofore has been commercially achieved The` product of the instant invention exhibits reconstitution properties and characteristics which are not exhibited by dehydrated vegetables currently available in the market. The dehydrated product of the present invention is porous throughout its interior as well as on its exterior surface. It exhibits neither a shrunken appearance typical of conventionally dried vegetables nor an expanded or puffed shape often associated with food materials which have been subjected to the specialized techniques of previous attempts to manufacture quick dehydrating food products. Moreover, the quick dehydrating vegetable :
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P3489S01 i -- 5 -products of the present invention can be produced enlarger sizes than heretofore was thought possible for products for which there is a concern for dehydration time upon dehydration the product reconstitutes rapidly to a uniform degree. The resultant product does not exhibit objectionable firm, chewy, interiors and mushy exterior surfaces which tend to slough during reconstitution as is typically the case with conventionally dried products.
The products of the present invention have been found to be particularly useful as a mix for sauces, salads stews and soups which, in contrast to commercially available products requiring upwards of 90 minutes to reconstitute, can be essentially completely dehydrated in preparation for consumption in less than about 10 to I minutes.
It is believed that the advantages of the present invention are achieved by subjecting frozen foodstuff, from which essentially no moisture has been artificially removed, to dehydration in a gaseous medium having a dry bulb temperature higher than about 200F and a wet bulb temperature higher than about 120F, and dehydrating the foodstuff to a storage stable moisture content of less than about 12% by total Waco. ' It has been found to be preferable to at least partially dehydrate foodstuff by subjecting the same to a dry bulb temperature in the range of about 225 to 400F and a wet bulb temperature in the range of about 120 to 170F, fur a time sufficient to effect the removal of between about 10 to 99% by weight moisture from the foodstuff. Forced air streams having a velocity higher than about 300 PPM and preferably between about 350 to 2000 PPM to effect a fluidization of the product curing dehydration is a particularly suitable drying expedient for purposes of .
.
, - . , .
I
P34~9S01 ` - 6 -the present invention.
Finish drying partially dehydrated foodstuff to storage stable moisture content of less than about 12%
by total weight is accomplished in an atmosphere having a dry bulb temperature preferably of less than about 220 F, and more preferably between 120-185 F.
Particularly good results are achieved when temperatures between about 130 to 160 F cry bulb are used. Dehydrating foodstuff in accordance with the present invention to a storage stable moisture content less than about 12% by total weight is typically effected in less than about 6 hours total drying time, and preferably between about 3 to 5-1/2 hours.
Preliminary to partial dehydration the foodstuff is subjected to treatments with aqueous media at temperatures above about 120 F to preferably as high as about 212 F for up to 75 minutes to precook, and for between 3 to 75 minutes to cook, the foodstuff When pressurized steam is used, the product is subjected to temperature higher than 212 F. It is preferred to cool the foodstuff in water intermediate these steps.
Freezing the food material prior to partial dehydration contributes significantly to producing dehydrated products with the desired characteristics and can be accomplished preferably by exposing foodstuff to an atmosphere having a temperature between about -20 to +20 F for up to about 60 minutes or until the product is frozen throughout.
Foodstuff which is particularly suitable for purposes of the present invention include vegetable and fruit materials such as potatoes, sweet potatoes, carrots, parsnips, beets, beans, peas, peppers, onion, corn barley, rice, wheat, apples and bananas.
Particularly good results are achieved when potatoes, processed in accordance with the present ' ., - , :, , ' .. . . . . .
~3489S01 - 7 -invention, are partially dried in the gaseous medium having a dry bulb temperature in the range of about 250 to 350 F and preferably 300 F, and a wet bulb temperature in the range of 120 to 16~ F and preferably 140 F.
Among the many advantages realized by the practice of the present invention include the production of foodstuff, such as dehydrated vegetables, which rapidly dehydrate to replace at least 85% and preferably 90-95% of the previously removed moisture in less than about 15 minutes Another advantage of the present invention is that a process for dehydrating foodstuff is provided wherein the time required to reduce the moisture content of the foodstuff to a storage stable extent of less than about 12% by total weight is substantially reduced relative to the time required if conventional dehydration procedures were used.
A further advantage is that dehydrated vegetables having a minimum dimension as large as about 3/4 inch can be produced which are capable of such rapid dehydration.
It is, thus, an object of the present invention to produce a dehydrated food product which, when reconstituted, closely resembles the taste, texture and appearance of its fresh food counterpart.
Another object of the present invention is to produce dehydrated food products essentially devoid of a case-hardened interior.
And yet another object of the invention is to produce quick dehydrating vegetables having shapes and sizes varying from 1/16" slices to 3/4" dice, including 1/2" slices, 1/2" dice, 1/2" x 1/2" x 3/4"
strips and 1j2" x 3/4" x 3/4" strips.
I A further object of the present invention is to provide a method for dehydrating foodstuff to a storage ' -,. . .
- . . - - .
~3g89S01 - 8 -stable moisture content of less than about 12% by total weight in less than about 6 hours total drying lime.
till another object of the present invention is to provide a dehydrated food product which is substantially completely reconstituted by a process comprising dehydrating the dehydrated foodstuff in an aqueous medium to replace at least about 85% and preferably at least 90-95% of the moisture previously removed by the dehydration process.
lo An yet another object of the present invention is to produce dehydrated foodstuff having a storage stable moisture content of less than about 12~ by total weight, a Bull Index within the range of about 260-700 in addition to a Dehydration Ratio within the range of about 2.9-10.5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
_ _ Preliminary to carrying out the process of the present invention the foodstuff, which is preferably vegetable material, is normally cleaned of dirt and debris, peeled, and trimmed if necessary, prior to dividing into pieces if so desired.
While selected vegetable material such as grains and legumes can be processed whole, it is preferable to divide large vegetables such as potatoes and carrots into pus such as slices, dices, or strips. Although the invention is applicable to a variety of foodstuff and vegetables in particular, the best mode presently contemplated for carrying out the process shall be describe herein in full, clear, concise, and exact terms in connection with Russet Burbank potatoes. It should be recognized, however, that certain treatment parameters may vary depending on the size and the particular material being processed.
Potatoes were cut into large pieces having a size of about 1/2" x 3/4" x 3/4". The potatoes may also be cut into pieces having other shapes and sizes such ;
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I
as 3/8" dice, in addition to slices and strips. The potato pieces are then subjected to treatments comprising heating with steam or water having a temperature within the range of about 120F to 212F
and preferably between about 165F to 200F for between 3 to 75 minutes cooling in tap water to a temperature below about 80F, and cooking in steam or water having a temperature within the range of about 120F to 212F
and preferably between 165F to 200 for between 3 to 75 minutes. Particularly good results were achieved when 1/2" x 3/4" x 3/4" potato pieces were heated for 30 minutes in water having a temperature of about 170F, cooled in water having a temperature of about 60F for 10 minutes, and heated in water having a temperature of 180F for 30 minutes. Generally the nature of the raw material being processed will determine which of these treatments alone or in combination will be used. For potatoes superior results are achieved with this sequence of steps For selected frozen vegetables, however, such as green beans and corn, a blanch in water having a temperature in the range of about 1~0F to 200F or in atmospheric steam for less than about 3 to 15 minutes prior to partial drying produces good results. Among the advantages resulting from such procedures are the inactivation of enzymes, gelatinization of starch and strengthening of the cellular tissue to withstand subsequent processing.
Potatoes and other-vegetable material may also be treated with solutions containing agents to reduce discoloration and minimize stickiness of the product prior to the partial dehydration step without adversely affecting the quality of the finished product.
Although minimizing stickiness may be accomplished by surface drying the foodstuff, care must be taken to avoid removing significant amounts of natural moisture .
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P3g~95~1 - 10 -from the product prior to partial drying in accordance with the present invention Otherwise case-hardening is likely to occur and the quality of the product reconstituted from the finished dried state is adversely affected.
The moisture content of potato pieces are typically within the range of about 73 to 87~ by total weight prior to the removal of any moisture therefrom.
For example, the 1/2" x 3/4" x 3/4" Russet Burbank dice had a moisture content of about 81% by total weight prior to dehydration in accordance with the present invention. Typical moisture contents based on total weight of other vegetables before any dehydration occurs includes: carrots, about 90%; sweet potatoes, about 83~; bell peppers, about 81%; Red Pontiac potatoes, about 85%; White Rose potatoes, about 85~.
As is generally known, however, the natural moisture contents of all vegetables vary within ranges. The _ position of Foods; Raw, Processed and Prepared,_ _ _ _ _ Agricultural Handbook No. 8, Agricultural Research Service, USED., U.S. Government Printing Office, Washington, DO 20402 sets forth the moisture content ranges for a variety of food materials including those which can be processed in accordance with the present invention.
It has further been discovered that particularly good results were achieved when potato pieces as well as other vegetables are subjected to a freezing operation prior to any significant dehydration taking place. The potato pieces at essentially their natural moisture levels, except for moisture lost during storage and handling, were frozen. Although freezing may be carried out in a number of ways, immersion freezing in a refrigerated liquid or brine is least US preferred. While tunnel or blast freezing at temperatures between about -20 F to +20 F may be - -- . . -.' . . ' -' . : .
P3489so~ I
used, it is preferred to subject potatoes to cold air having a temperature of -20 F to 0 F in a freezing chamber such as a spiral freezer, for at least about 45, and preferably 60 to 120 minutes. Although freezing preliminary to partial drying is important to the process of the present invention, the particular manner by which the foodstuff it frozen is not critical It has been found that any expedient for freezing can be used with minimal affect on the characteristics of the final product if the frozen foodstuff is subsequently subjected to dehydration in an atmosphere having dry bulb-wet bulb temperatures as herein described.
The frozen foodstuff at essentially its natural moisture content is then subjected to a critical sequence of dehydration procedures directly from the frozen state. The foodstuff is first partially dried by exposure to hot air having a dry bulb temperature (OF
dry bulb) in excess of about 220F dry bulb, and a wet bulb temperature (OF wet bulb) of at least 120F wet bulb for a time period between about 3 to 20 minutes.
Forced air streams having a velocity as high as about 2000 PPM are used during partial dehydration with particularly good results. The fluidization effected by the forced air stream is beneficial in reducing the incidence of products sticking together as well as in promoting uniform exposure of product to the dehydrating medium. In general, this can be effected using air velocities of between about 350 to 2000 PPM depending on the size and weight of the food material being treated. The extent to which the ; moisture con-tent of the product is reduced by partial drying under such conditions depends on the natural moisture content of the foodstuff being processed. It has been found that at least about 10% by weight moisture, i.e., based essentially on the natural P3~9S01 - 12 -moisture content of the foodstuff, should be removed at this stage, although moisture removal to a greater extent can also be affected. Depending on the foodstuff being processed, for example barley as much as about 99% by weight moisture can be removed by dehydrating under such conditions. The following table lists vegetables processed in accordance with the present invention for purposes of Tables II and III
along with a range for the percent by weight moisture removed during this stage of processing.
table I
Vegetable By Weight Moisture Removed Russet Burbank Potatoes 42 - 77%
15 Red Pontiac Potatoes 56 - 62%
White Rose Potatoes 54 - 77%
Carrots 51 - 93%
Sweet Potatoes 37 - 83%
Bell Peppers lo - 52%
20 Barley 97 - 99%
Potato pieces having moisture contents within the range of about 73 - 87% by total weight may be partially dried to a moisture content in the range of about 5d-75~ by total weight by removing about 42 to 77% by weight moisture.
Forced air at velocities of between 850 to 1400 PPM having temperatures in the range ox about 250F
dry bulb/l35oF wet bulb to 350F dry bulb/150F wet bulb are particularly suitable for potatoes. A
superior end product was produced when the potato pieces were subjected to a forced air stream at 1200 PPM having a temperature of about 300 F dry Balboa F wet bulb for 8 minutes to remove about 52% by weight moisture thereby reducing the moisture content by total weight thereof to about 67%.
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~23~ 6 As used herein for purposes of the present invention the wet bulb and dry bulb temperatures are readings taken from thermometers at an elevation of about ~,500 feet above sea level As one can appreciate, wet bulb temperatures are elevation-dependent and, therefore, may vary from the disclosed ranges relative to changes in elevation without falling outside the scope of the present invention. Standard psychometric charts can be used to convert treatment parameters measured at an elevation of 4,500 feet above sea-level to those for other elevations at which the invention is practiced.
It has been found that dehydration under the foregoing conditions substantially eliminates case-hardening of the product which can result from conventional drying. Conventional hot-air drying progressively removes water first from the surface and, only when the exterior is substantially dry, from the interior of the potato. Case-hardening of the product ; 20 is to be avoided because such condition reduces and ultimately substantially inhibits the migration of water from the interior to the exterior ox the product.
Thus, dehydration to a storage-stable moisture level is extremely slow and scorching is a concern. The case-hardened surface also adversely affects dehydration characteristics. Because the surface is not porous but rather exhibits an impervious skin, prolonged soaking is required in order for water to reconstitute the interior of the product. Often this condition prevents complete dehydration within the prescribed time.
Incompletely dehydrated products exhibit firm, chewy centers, and surfaces which are prone to sloughing.
All of such characteristics are to be avoided.
The dehydration procedure of the present invention prevents case-hardening by promoting uniform moisture removal frown throughout the product. By uniformly ~34~9S01 - 14 -dehydrating the foodstuff, the natural passages provided by the interstitial spaces between the cells and the porous condition of the product affected by freezing does not become shrunken or clogged at the S surface. The moisture, therefore, can freely pass from the interior of the piece through the exterior surface to rapidly dehydrate the product Moreover, it has been found that case-hardening appears to be a concern primarily in the initial stages of drying, i.e., during removal of the first 10 to 25% by weight moisture from the product. If case-hardening is avoided during the initial stage of the dehydration operation using the partial drying technique of the present invention, dehydration can be completed using a preferred expedient therefore such as conventional hot air techniques as discussed below, without destroying the porous characteristics of the product provided by the treatments of the present invention. although porosity is an essential characteristic in the resultant product, excessive puffing or expansion of the product during dehydration is to be avoided because attendant cell rupture releases soluble solids such as starches and sugars contained within the cell. Upon subsequent reconstitution these solids are readily solubilized into and are leached from the food material being dehydrated. The nutritional value of the product is thus substantially reduced. Such products also tend to be brittle and break or slough during reconstitution.
It has been found that such objectionable features are avoided by subjecting foodstuff to the sequence of freezing followed by partial dehydration, in accordance with the present invention, which is believed to be responsible for the desired attributes of the products of the present invention.
The partially dehydrated potato pieces and other vegetables are finished dried. Due to the effects of .
~3~89S01 - 15 -prior treatments of partial drying at the aforementioned dry bulb-wet bulb temperatures and freezing, the potato pieces have beer sufficiently conditioned so that the particular expedient used for dehydration to a storage-stable moisture content is not a major concern. It has been discovered that exposing the potatoes and other vegetables to a hot atmosphere until a storage-stable moisture content is achieved produces an end product with suitable characteristics.
For example, hot air dehydration of the product in a stationary or fluidized bed, preferably at temperatures below about 180F, to storage stable moisture contents of less than about 12% by total weight, result with particularly good products upon reconstitution. The potato pieces are finish dried to a moisture content of about 6 to 10% by total weight in air having a dry bulb temperature within the range of about 160F to 180F.
Finish drying using a stationary bed, continuous belt dryer is completed in less than about 6 hours and typically in about 3 to 5-1/2 hours. The partially dried potato pieces having a moisture content of about 67% by total weight were finished dried to a moisture content based on total weight of about I by subjecting the pieces to air having a dry bulb temperature of about 160 F for about 3-1/2 hours. By the process of the present invention, dehydration time may be reduced compared to conventional procedures using similar belt-trough dryers. Moreover because of the porous nature of the partially dried product, moisture is more readily removed from the interior of the product. Thus, the depth to which the partially dried product can be loaded onto the drying belt of a conventional belt-trough dryer is greater than heretofore was practical.
Hence for a given period of time, a substantially larger quantity of product may be dehydrated to a similar extent. In addition to the other technical .
achievements resulting from the practice of the present invention, therefore, there is an increase in production capacity with attendant economic advantages.
The dehydrated potato pieces having a storage stable moisture content were packaged in a conventional manner for handling and storage purposes. To prepare the dehydrated foodstuff of the invention for consumption, the product is merely placed in water and permitted to stand until essentially reconstituted and heated. Particularly good results are achieved when water having a temperature within the range of about 170F to 212F is added to the dehydrated foodstuff or the product is added to water which is brought to a boil and simmered for up to 10 to 15 minutes. The potatoes and other vegetables prepared in this manner are essentially completely reconstituted and have a taste, texture, appearance, and other organoleptic - characteristics more closely resembling vegetables prepared directly from the fresh state than heretofore has been commercially available. The reconstituted vegetables make excellent soups, stews, sauces, casseroles and side dishes with potatoes also being particularly suitable for use in salad mixes.
In addition to the high quality of the food products made in accordance with the present invention, they are also quick dehydrating For purposes of the ; present invention, quick dehydrating means reconstitution of the dehydrated product in less than about 15 minutes to a moisture content closely approaching the moisture content of the raw material from which it was made. Replacement of at least 85%
and preferably greater than 90 to 95% of the water is required in order for the product to resemble its fresh food counterpart. Moisture replacement can be expressed in terms of the dehydration ratio of the product Dehydration Ratio, i.e., OR is determined -. .
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P34~9S01 - It - `
by weighing a quantity of dehydrated product, dehydrating such product in water, draining the product of free water, and weighing the dehydrated product. As used herein, dehydration ratio is calculated by dividing the weight of the product after dehydration by the weight of the product in its dehydrated state Upon reconstitution, vegetables which have been dehydrated in accordance with the present invention exhibit dehydration ratios which are substantially higher than their conventionally dehydrated counterparts. Dehydration ratios for dehydrated vegetables of the present invention which represent a replacement of at least about 85~ of the moisture which had previously been removed during dehydration are 15 listed below:
TABLE II
Vegetable Dehydration Rusher Russet Burbank Potatoes 3.6 - 5.6 20 Red Pontiac Potatoes 5.2 - 6.5 White Rose Potatoes 5.3 - 6.6 Carrots 5.1 - 10.5 Sweet Potatoes 2.7 - 4.6 Bell Peppers 6.5 - 9.5 25 Barley - 2.9 - 3.8 Another characteristic by which dehydrated products can be evaluated is Bulk Index. Although the determination of Bulk Index is useful to some extent for certain purposes in judging products, sulk Index data can also give a distorted picture of the product.
Bulk Index represents the volume (cc) occupied by lo grams of product as measured in a Lowe ml. graduated beaker having a 65 mm. internal diameter. It is inversely proportional to bulk density. As such, bulk density and index are somewhat indicative of porosity I
P3489SOl - 18 -but not if viewed alone For example, two dehydrated products may have similar densities but not exhibit the same uniformity of porosity. This could be true if a product of the present invention were compared to a dehydrated puffed-type product. It has been found, therefore, that not all products having similar bulk induces dehydrate in an equivalent manner in terms of time or characteristics of the reconstituted product.
Thus, it has been discovered that in order for lo dehydrated products to be quicX-rehydrating in less than about 15 minutes, they should not only exhibit a Bulk Index within the ranges listed in the Table III, but must also manifest a Dehydration Ratio within the ranges listed in Table II. Bulk indices, for representative vegetables having dehydration ratios within the ranges listed in Table II, are shown below:
Taste III
Vegetable Bulk Index so 20 Russet Burbank Potatoes 390-600 Red Pontiac Potatoes 500-630 White Rose Potatoes 500~630 Carrots 400-700 Sweet Potatoes 350-550 25 Bell Peppers 260-300 Barley 285-335 The potato pieces, dehydrated in accordance with the present invention as described above to a final moisture content of about I by total weight having a Bulk Index of 495, were held in water that had been brought to a boil for 10 minutes. The reconstituted potato pieces having dimensions of about l/2" x 3/4" x 3/411 were determined to have a Dehydration Ratio of 4.75. This product was considered excellent in taste, texture and appearance and exhibited no sign of , ;22~`~
3g~9S01 - 19 -sloughing.
SAMPLES
Carrots In addition to potatoes, carrots are another prime example of vegetable material which can be processed in accordance with the present invention into large, dehydrated pieces which exhibit excellent organoleptic qualities upon subsequent reconstitution Raw Chinatown variety carrots were lye peeled, cleaned and trimmed Afterwards the peeled carrots were subdivided into 1/2" x 1/2" x 3/4" pieces using a Urschel Model s cutter. The carrot pieces were cooked for 60 minutes in water having a temperature of about 160 F and then frozen. The frozen carrot pieces at essentially their natural moisture content of about 90~ by total weight were taken from the freezer and subjected to a stream of forced air having a velocity of about 1000 PPM
and a temperature of about 325 F dry Balboa F wet bulb for 11 minutes and partially dried to remove about 74% by weight moisture from the carrots to reduce the moisture content by total weight thereof to about 71%.
The partial dried carrots were then finish dried in air having a temperature of about 160F to a moisture content of about 5% by total weight in about g hours.
To dehydrate, the dehydrated carrot pieces having a Bulk Index of 750 were added to boiling water and held for 10 minutes. The reconstituted carrot pieces processed as described above were determined to have a Dehydration Ratio of 9.8. They were judged to be excellent in taste, texture and appearance.
Sweet Potatoes ___ Sweet- potatoes are yet another example of foodstuff which is particularly suitable for processing in accordance with the present invention. Jewel Jo ..
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- ' . ' '' ' .~' . . - .
P3~89~01 - I -variety sweet potatoes were cleaned of dirt and debris and then lye peeled by submersion in a 13% caustic solution having a temperature of about 20QF for about 8 minutes. The peeled sweet potatoes were then cut using an Urschel OX machine into 3/16" slices and blanched in water having a temperature of 180F for about five minutes prior to freezing to a solid state.
Thereafter, the frozen slices at essentially their natural moisture content of about 83% by total weight were partially dried by exposure to a forced air stream having a velocity of about 1000 PPM and a temperature of about 310F dry bulb/140F wet bulb for 10 minutes to remove about 55~ by weight moisture from the slices thereby reducing the moisture content by total weight thereof to about 69%. Following partial drying the sweet potato slices were finish dried to a final storage stable moisture content of about 11% by total weight in about 4 hours using air having a temperature of about 140F. The finish dried slice had a Bulk Index of 4100 Afterwards these dehydrated sweet potato slices were rerouted for 10 minutes in water - that had been brought to a boil. The reconstituted product was determined to have a Dehydration Ratio of 3.3. The sweet potato slices exhibited a taste, texture and appearance which were considered to be very acceptable.
Potatoes Red Pontiac variety potatoes were cut into 1/2"
dice after being prepared for processing in a conventional manner including cleaning and peeling The dices were then precooked in water at 170F for 30 minutes, cooled for about 10 minutes in 60F water and cooked in water having a temperature of about 190F for 30 minutes prior to freezing. Following freezing the frozen dice at essentially their natural moisture content of about 85% by total weight were subjected to -.
I
P3~89S01 -- 21 -a forced air stream having a velocity of 1200 PPM
and a temperature of about 300F dry bulb/140F wet bulb for about 8 minutes to partially dry the dice by removing about 58% by weight moisture from the dice thereby reducing the moisture content by total weight thereof to about 71%. Thereafter the partially dried dice were finished dried to a storage stable moisture content of about 6% by total weight in 3-1/2 hours using air having a temperature of about 160F. The Bulk Index of the finished dried dice was 590~ After reconstitution for 8 minutes in water that had been brought to a boil, the dice were determined to have a Dehydration Ratio of 6.5. The reconstituted dice exhibited excellent texture and appearance and had a very good flavor.
COMPARISON
In order to compare various products made in accordance with the present invention with what is commercially available in the marketplace, the following test was conducted:
Conventional Dehydrated Products - A dehydrated noodle, vegetable, and flavoring mix sold as Soup Starter for use in the preparation of soups was obtained in the grocery store. The dehydrated vegetable products listed in the Table below were selected from this mix and compared for completeness of reconstitution with the potatoes, carrots, barley, green and red bell peppers made in accordance with the present invention as described below Products M_ OX the Invention Potatoes Idaho Russet Burbank potatoes were peeled and cut into 3/8-inch dice. The dice were precooked in water at 170F for 30 minutes, cooled in 70F water for 10 minutes, cooked in water at 180F for 30 minutes and .
frozen. The frozen dice at essentially their natural moisture content of about 81% by total weight were subjected to air having a temperature of about 300F
dry bulb/l4ooF wet bulb and a velocity of about 1200 PPM for about 8 minutes to remove about 45% by weight moisture from the dice thereby reducing the moisture convent by total weight thereof to about 70~.
The partially dried dice were then finish dried in air at a temperature of about 160F dry bulb to a storage stable moisture content of about I by total weight in about 3-1/2 hours.
Carrots Raw carrots were cleaned, peeled and sliced before being cooked in water having a temperature of about 160F for 60 minutes and frozen. The frozen slices at essentially their natural moisture content of about 90%
were removed from the freezer and subjected to air having a velocity of 1000 PPM and a temperature of about 325F dry bulb/140F wet bulb for 11 minutes to remove about 74~ by weight moisture from the slices thereby reducing the moisture content by total weight thereof to about 70%. The partially dried slices were then dehydrated to a storage stable moisture content of about 5% by total weight in about 4 hours in air having a temperature of about 160F.
Barley Dry, unprocessed barley was placed in boiling water for 60 minutes prior to being subjected to steam under a pressure of 20 prig. for 10 minutes and then frozen. Prior to freezing the barley had a moisture content of about 85% by total weight. The frozen barley was subjected to an air stream having a velocity of 1000 PPM and a temperature of about 300F dry bulb/140F wet bulb for 16 minutes to remove about 99~
by weight moisture from the barley thereby reducing the moisture content by total weight thereof to a storage .
I
stable extent of about I
Peppers Bell peppers of the green and red varieties having natural moisture content of about 81% by total weight were prepared in essentially the same manner. The peppers were first peeled prior to removing their cores and seeds and cut into l/4-inch square pieces the thickness of which corresponds to the thickness of the flesh of the pepper. The pieces of pepper were then frozen and subjected to air having a velocity of about 750 PPM and a temperature of about 300F dry bulb/140F wet bulb for about 4 l/2 minutes to partially cry the pieces to remove about 12~ by weight moisture from the pepper pieces thereby reducing the moisture content by total weight thereof to about 80~.
Afterwards the pepper was dried to a storage stable moisture content of about 13~ by total weight in two hours using 130F air.
the dehydrated vegetable products made in accordance with the invention as described above as well as the conventional dehydrated vegetables from the soup mix were reconstituted for purposes of this comparison in an identical manner. The same weight of each dehydrated product was added to a separate container of boiling water and simmered for the time listed in the Table below. The shorter of the two times are considered acceptable for a quick reconstituting product. In the alternative, ninety minutes was used because such time was specified in the recipe of the commercial soup mix. After simmering for the prescribed times, the vegetables were removed from the water drained and weighed again. As discussed above, the ratio of the weight of the reconstituted product and the weight of the dehydrated product is referred to herein as Dehydration Ratio, i.e., OR
.
.
~3~9S01 aye The results are tabulated below:
TABLE IV_ OR OR
of of ProductSi.zeInvention Min. Conventional .__________ _________ __ ____._______ Potatoes3/8"x3/8"x3/8" 4.7 10 2.7 5.4 90 47 Carrots Slice 5.1 15 3.1 10.9 90 4.6 15 Barley Whole 3.8 15 2.2 5.2 90 4.8 Green Bell 1/4"xl/4" 6.5 5 5.3 Peppers 8.3 90 TV
Red Bell 1/4"xl/4" 6.6 . 5 4.8.
Peppers 8.3 90 5.2 :
The tabulated data indicates that each sample of vegetable processed in accordance with the present invention exhibits a Dehydration Ratio consistently higher than their conventionally dehydrated counterpart. The differences are particularly : significant for the shorter reconstitution times which are indicative of what is typically the case for a quick-reconstituting product. It is generally recognized that dehydrated products which have higher Dehydration Ratios more closely resemble the fresh material from which it is made. This was fount to be 35 :true..for:th:e comparison made herein particularly for the samples reconstituted for the shorter times.
.
. , : - . . - , . . .. . - . ' - .
- ' ' : ... .. .
P 3 4 8 go 0 of' Whereas the products made in accordance with the present invention were considered to be excellent in taste, texture and appearance, the conventionally dehydrated products from the soup mix were found to have hard, chewy interior textures and incompletely developed taste upon reconstitution.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
- ,
Field _ Invention The invention relates to a method for producing dehydrated vegetables capable of rapid reconstitution.
More particularly, the invention is directed to a sequence of cooking, freezing and dehydration steps carried out under controlled conditions so as to produce a product having a porous interior and exterior surface.
Description of the Prior Art Dehydration is one of the oldest methods for preserving food. Commercial production of dehydrated foods, however is a development o-f the twentieth century. During the last forty years many procedures have been developed in an attempt to produce dehydrated products which upon reconstitution resemble fresh food in taste, texture, and appearance. More recently there has keen a general concern for quick dehydrating products. Most of these efforts have resulted in unsatisfactory processes and products. A problem common to prior dehydration methods is a phenomenon referred to as case-hardening or the formation of a - horny, vitreous material primarily on the surface of the food. It has teen postulated that this may result from the collapse of the cellular structure of the vegetable which dehydrates into a dense mass of material of low dehydration characteristics.
Prior art methods for producing quick rewriting products include soaking the material in solutions of salt or leavening agents prior to dehydration ; subjecting food material to dehydration techniques which effect an expansion or puffing of the product and freeze-drying. U.S. Patent No. 2,705,697 dehydrates ; potato dice using a fluidized bed dryer to form tan-colored pieces hollow in the center with the sides puffed out much as are the sizes of a pillow. U.S.
' ,.
a Jo I En 6 ?3489S01 - 2 -Patent No 3,338,724 discloses the importance of soaking potato pieces in a salt solution prior to such dehydration to produce puffed potato products having a density of 0.15 to 0.20 gm/cc. U.S. Patent No.
3,438,792 freeze dries potatoes prior to finish drying in hot air to avoid case-hardening. U.S. Patent No.
3f644,129 is based on the discovery that minimizing the temperature at which potato pieces are blanched prior to such combined freeze drying-hot air drying is effective in improving the dehydration characteristics of the dehydrated product. U.S. Patent No. 3,573,070 discloses a process comprising freezing prior to combined freeze drying-hot air drying in an attempt to produce improved dehydrated products. U.S. Patent No 3,188,750 attempts to produce a dehydrated product possessing a high degree of biological integrity by first hot air drying raw material prior to freeze drying which is preferably followed by another hot air - drying. U.S. Patent No. 2,729,566 teaches that rapid ; 20 freezing followed by a slow thawing at a temperature within the range of 28F to 32F for at least 15 minutes prior to hot air dehydration is critical and that potato pieces being processed should not reach a temperature higher than about 130F during dehydration.
U.S. Patent No. 2,707,684, however, discloses that if potato pieces are rapidly frozen prior to dehydration, the final products will have a slow dehydration rate.
U.S. Patent No. 2,713,003 preconditions food products by freezing, throughout or superficially, prior to dehydrating. U.S. Patent No. 2,278,472 also freezes food prior to dehydration. U.S. Patent No. 3,359l123 is directed to rendering potatoes more amenable to freeze-thaw procedures by a controlled cooking procedure which avoids moisture pickup by the potato followed by dehydrating the product under such conditions so as to avoid any further gelatinization of . :: . . '. , , ' ', - ' .' . ' , , . , , - . -,. I, .. . , P3~89S01 - 3 -the potato pieces, for example by drying in air having a 20 to 40% relative humidity GOB. Patent No 1,084,714 dehydrates vegetables in a gas containing from about I to about 50~ by weight of water vapor at a temperature from 194F to 428F. U.S. Patent No.
3,973,047 is directed to reducing the level of micro-organisms in dehydrated vegetables by subjecting vegetables, partially dried to between 8 and 50%
moisture, to air having dry bulb/wet bulb temperatures, ranging from 200F dry bulb/130F wet bulb to about 140F dry bulb/120F wet bulb, which are sufficiently high to kill bacteria without causing significant dehydration, prior to finish drying to a final moisture content of less than about 8%.
The foregoing disclosures are representative of the attempts made to overcome the shortcomings of dehydrated food products as compared to freshly prepared foodstuff. The food industry has had to rely on similar procedures to prepare dehydrated vegetables over the years. Recently, cooking and eating habits have been influenced by a number of factors which reduce the time allocated for food preparation in households as well as in eating establishments. This has caused a need for good nutritious foods which can be prepared quickly and easily. A number of frozen entree, side dish, and complete dinners, in addition to canned products, have been available in the marketplace which attempt to satisfy the consumer's need for convenient foods. Notwithstanding numerous efforts to develop industrially produced and commercially acceptable dehydrated food products, there is a limited number of dehydrated vegetable products on the market.
Such vegetables are primarily used as flavoring in soups, stocks, casseroles, and the live. Moreover, dehydrated vegetables used in instant soups, i.e., having a reconstitution time of less than about 5-20 ;
.
~3489S01 ( ~23~ 6 minutes, have been small in size in order to permit preparation within the prescribed time period.
Normally the vegetable piece size is no larger than about 1/8 inch in cross section Typically, the dehydrated products have been reduced to a powder.
Complaints about such products include that the dehydrated pieces reconstitute incompletely and are tough and chewy despite their small size. Larger vegetable pieces have only recently been used as ingredients in commercial mixes containing dehydrated vegetables, stock seasoning, and noodles. These mixes are used as starting materials for preparation of soup to which only water and meat need be added in the kitchen. Their recipe normally requires as long as 1-1/2 hours in preparation for consumption.
SUMMARY OF THE INVENTION
The present invention relates generally to the production of dehydrated food materials and preferably vegetables. More particularly the invention is directed to a process for dehydrating vegetable materials which are capable of quick dehydration in water to more closely resemble the taste, texture, and appearance of fresh vegetables than heretofore has been commercially achieved The` product of the instant invention exhibits reconstitution properties and characteristics which are not exhibited by dehydrated vegetables currently available in the market. The dehydrated product of the present invention is porous throughout its interior as well as on its exterior surface. It exhibits neither a shrunken appearance typical of conventionally dried vegetables nor an expanded or puffed shape often associated with food materials which have been subjected to the specialized techniques of previous attempts to manufacture quick dehydrating food products. Moreover, the quick dehydrating vegetable :
.. . .
~2:3~
P3489S01 i -- 5 -products of the present invention can be produced enlarger sizes than heretofore was thought possible for products for which there is a concern for dehydration time upon dehydration the product reconstitutes rapidly to a uniform degree. The resultant product does not exhibit objectionable firm, chewy, interiors and mushy exterior surfaces which tend to slough during reconstitution as is typically the case with conventionally dried products.
The products of the present invention have been found to be particularly useful as a mix for sauces, salads stews and soups which, in contrast to commercially available products requiring upwards of 90 minutes to reconstitute, can be essentially completely dehydrated in preparation for consumption in less than about 10 to I minutes.
It is believed that the advantages of the present invention are achieved by subjecting frozen foodstuff, from which essentially no moisture has been artificially removed, to dehydration in a gaseous medium having a dry bulb temperature higher than about 200F and a wet bulb temperature higher than about 120F, and dehydrating the foodstuff to a storage stable moisture content of less than about 12% by total Waco. ' It has been found to be preferable to at least partially dehydrate foodstuff by subjecting the same to a dry bulb temperature in the range of about 225 to 400F and a wet bulb temperature in the range of about 120 to 170F, fur a time sufficient to effect the removal of between about 10 to 99% by weight moisture from the foodstuff. Forced air streams having a velocity higher than about 300 PPM and preferably between about 350 to 2000 PPM to effect a fluidization of the product curing dehydration is a particularly suitable drying expedient for purposes of .
.
, - . , .
I
P34~9S01 ` - 6 -the present invention.
Finish drying partially dehydrated foodstuff to storage stable moisture content of less than about 12%
by total weight is accomplished in an atmosphere having a dry bulb temperature preferably of less than about 220 F, and more preferably between 120-185 F.
Particularly good results are achieved when temperatures between about 130 to 160 F cry bulb are used. Dehydrating foodstuff in accordance with the present invention to a storage stable moisture content less than about 12% by total weight is typically effected in less than about 6 hours total drying time, and preferably between about 3 to 5-1/2 hours.
Preliminary to partial dehydration the foodstuff is subjected to treatments with aqueous media at temperatures above about 120 F to preferably as high as about 212 F for up to 75 minutes to precook, and for between 3 to 75 minutes to cook, the foodstuff When pressurized steam is used, the product is subjected to temperature higher than 212 F. It is preferred to cool the foodstuff in water intermediate these steps.
Freezing the food material prior to partial dehydration contributes significantly to producing dehydrated products with the desired characteristics and can be accomplished preferably by exposing foodstuff to an atmosphere having a temperature between about -20 to +20 F for up to about 60 minutes or until the product is frozen throughout.
Foodstuff which is particularly suitable for purposes of the present invention include vegetable and fruit materials such as potatoes, sweet potatoes, carrots, parsnips, beets, beans, peas, peppers, onion, corn barley, rice, wheat, apples and bananas.
Particularly good results are achieved when potatoes, processed in accordance with the present ' ., - , :, , ' .. . . . . .
~3489S01 - 7 -invention, are partially dried in the gaseous medium having a dry bulb temperature in the range of about 250 to 350 F and preferably 300 F, and a wet bulb temperature in the range of 120 to 16~ F and preferably 140 F.
Among the many advantages realized by the practice of the present invention include the production of foodstuff, such as dehydrated vegetables, which rapidly dehydrate to replace at least 85% and preferably 90-95% of the previously removed moisture in less than about 15 minutes Another advantage of the present invention is that a process for dehydrating foodstuff is provided wherein the time required to reduce the moisture content of the foodstuff to a storage stable extent of less than about 12% by total weight is substantially reduced relative to the time required if conventional dehydration procedures were used.
A further advantage is that dehydrated vegetables having a minimum dimension as large as about 3/4 inch can be produced which are capable of such rapid dehydration.
It is, thus, an object of the present invention to produce a dehydrated food product which, when reconstituted, closely resembles the taste, texture and appearance of its fresh food counterpart.
Another object of the present invention is to produce dehydrated food products essentially devoid of a case-hardened interior.
And yet another object of the invention is to produce quick dehydrating vegetables having shapes and sizes varying from 1/16" slices to 3/4" dice, including 1/2" slices, 1/2" dice, 1/2" x 1/2" x 3/4"
strips and 1j2" x 3/4" x 3/4" strips.
I A further object of the present invention is to provide a method for dehydrating foodstuff to a storage ' -,. . .
- . . - - .
~3g89S01 - 8 -stable moisture content of less than about 12% by total weight in less than about 6 hours total drying lime.
till another object of the present invention is to provide a dehydrated food product which is substantially completely reconstituted by a process comprising dehydrating the dehydrated foodstuff in an aqueous medium to replace at least about 85% and preferably at least 90-95% of the moisture previously removed by the dehydration process.
lo An yet another object of the present invention is to produce dehydrated foodstuff having a storage stable moisture content of less than about 12~ by total weight, a Bull Index within the range of about 260-700 in addition to a Dehydration Ratio within the range of about 2.9-10.5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
_ _ Preliminary to carrying out the process of the present invention the foodstuff, which is preferably vegetable material, is normally cleaned of dirt and debris, peeled, and trimmed if necessary, prior to dividing into pieces if so desired.
While selected vegetable material such as grains and legumes can be processed whole, it is preferable to divide large vegetables such as potatoes and carrots into pus such as slices, dices, or strips. Although the invention is applicable to a variety of foodstuff and vegetables in particular, the best mode presently contemplated for carrying out the process shall be describe herein in full, clear, concise, and exact terms in connection with Russet Burbank potatoes. It should be recognized, however, that certain treatment parameters may vary depending on the size and the particular material being processed.
Potatoes were cut into large pieces having a size of about 1/2" x 3/4" x 3/4". The potatoes may also be cut into pieces having other shapes and sizes such ;
.,, .. .. , ' . , . .
I
as 3/8" dice, in addition to slices and strips. The potato pieces are then subjected to treatments comprising heating with steam or water having a temperature within the range of about 120F to 212F
and preferably between about 165F to 200F for between 3 to 75 minutes cooling in tap water to a temperature below about 80F, and cooking in steam or water having a temperature within the range of about 120F to 212F
and preferably between 165F to 200 for between 3 to 75 minutes. Particularly good results were achieved when 1/2" x 3/4" x 3/4" potato pieces were heated for 30 minutes in water having a temperature of about 170F, cooled in water having a temperature of about 60F for 10 minutes, and heated in water having a temperature of 180F for 30 minutes. Generally the nature of the raw material being processed will determine which of these treatments alone or in combination will be used. For potatoes superior results are achieved with this sequence of steps For selected frozen vegetables, however, such as green beans and corn, a blanch in water having a temperature in the range of about 1~0F to 200F or in atmospheric steam for less than about 3 to 15 minutes prior to partial drying produces good results. Among the advantages resulting from such procedures are the inactivation of enzymes, gelatinization of starch and strengthening of the cellular tissue to withstand subsequent processing.
Potatoes and other-vegetable material may also be treated with solutions containing agents to reduce discoloration and minimize stickiness of the product prior to the partial dehydration step without adversely affecting the quality of the finished product.
Although minimizing stickiness may be accomplished by surface drying the foodstuff, care must be taken to avoid removing significant amounts of natural moisture .
I.
P3g~95~1 - 10 -from the product prior to partial drying in accordance with the present invention Otherwise case-hardening is likely to occur and the quality of the product reconstituted from the finished dried state is adversely affected.
The moisture content of potato pieces are typically within the range of about 73 to 87~ by total weight prior to the removal of any moisture therefrom.
For example, the 1/2" x 3/4" x 3/4" Russet Burbank dice had a moisture content of about 81% by total weight prior to dehydration in accordance with the present invention. Typical moisture contents based on total weight of other vegetables before any dehydration occurs includes: carrots, about 90%; sweet potatoes, about 83~; bell peppers, about 81%; Red Pontiac potatoes, about 85%; White Rose potatoes, about 85~.
As is generally known, however, the natural moisture contents of all vegetables vary within ranges. The _ position of Foods; Raw, Processed and Prepared,_ _ _ _ _ Agricultural Handbook No. 8, Agricultural Research Service, USED., U.S. Government Printing Office, Washington, DO 20402 sets forth the moisture content ranges for a variety of food materials including those which can be processed in accordance with the present invention.
It has further been discovered that particularly good results were achieved when potato pieces as well as other vegetables are subjected to a freezing operation prior to any significant dehydration taking place. The potato pieces at essentially their natural moisture levels, except for moisture lost during storage and handling, were frozen. Although freezing may be carried out in a number of ways, immersion freezing in a refrigerated liquid or brine is least US preferred. While tunnel or blast freezing at temperatures between about -20 F to +20 F may be - -- . . -.' . . ' -' . : .
P3489so~ I
used, it is preferred to subject potatoes to cold air having a temperature of -20 F to 0 F in a freezing chamber such as a spiral freezer, for at least about 45, and preferably 60 to 120 minutes. Although freezing preliminary to partial drying is important to the process of the present invention, the particular manner by which the foodstuff it frozen is not critical It has been found that any expedient for freezing can be used with minimal affect on the characteristics of the final product if the frozen foodstuff is subsequently subjected to dehydration in an atmosphere having dry bulb-wet bulb temperatures as herein described.
The frozen foodstuff at essentially its natural moisture content is then subjected to a critical sequence of dehydration procedures directly from the frozen state. The foodstuff is first partially dried by exposure to hot air having a dry bulb temperature (OF
dry bulb) in excess of about 220F dry bulb, and a wet bulb temperature (OF wet bulb) of at least 120F wet bulb for a time period between about 3 to 20 minutes.
Forced air streams having a velocity as high as about 2000 PPM are used during partial dehydration with particularly good results. The fluidization effected by the forced air stream is beneficial in reducing the incidence of products sticking together as well as in promoting uniform exposure of product to the dehydrating medium. In general, this can be effected using air velocities of between about 350 to 2000 PPM depending on the size and weight of the food material being treated. The extent to which the ; moisture con-tent of the product is reduced by partial drying under such conditions depends on the natural moisture content of the foodstuff being processed. It has been found that at least about 10% by weight moisture, i.e., based essentially on the natural P3~9S01 - 12 -moisture content of the foodstuff, should be removed at this stage, although moisture removal to a greater extent can also be affected. Depending on the foodstuff being processed, for example barley as much as about 99% by weight moisture can be removed by dehydrating under such conditions. The following table lists vegetables processed in accordance with the present invention for purposes of Tables II and III
along with a range for the percent by weight moisture removed during this stage of processing.
table I
Vegetable By Weight Moisture Removed Russet Burbank Potatoes 42 - 77%
15 Red Pontiac Potatoes 56 - 62%
White Rose Potatoes 54 - 77%
Carrots 51 - 93%
Sweet Potatoes 37 - 83%
Bell Peppers lo - 52%
20 Barley 97 - 99%
Potato pieces having moisture contents within the range of about 73 - 87% by total weight may be partially dried to a moisture content in the range of about 5d-75~ by total weight by removing about 42 to 77% by weight moisture.
Forced air at velocities of between 850 to 1400 PPM having temperatures in the range ox about 250F
dry bulb/l35oF wet bulb to 350F dry bulb/150F wet bulb are particularly suitable for potatoes. A
superior end product was produced when the potato pieces were subjected to a forced air stream at 1200 PPM having a temperature of about 300 F dry Balboa F wet bulb for 8 minutes to remove about 52% by weight moisture thereby reducing the moisture content by total weight thereof to about 67%.
, .
~23~ 6 As used herein for purposes of the present invention the wet bulb and dry bulb temperatures are readings taken from thermometers at an elevation of about ~,500 feet above sea level As one can appreciate, wet bulb temperatures are elevation-dependent and, therefore, may vary from the disclosed ranges relative to changes in elevation without falling outside the scope of the present invention. Standard psychometric charts can be used to convert treatment parameters measured at an elevation of 4,500 feet above sea-level to those for other elevations at which the invention is practiced.
It has been found that dehydration under the foregoing conditions substantially eliminates case-hardening of the product which can result from conventional drying. Conventional hot-air drying progressively removes water first from the surface and, only when the exterior is substantially dry, from the interior of the potato. Case-hardening of the product ; 20 is to be avoided because such condition reduces and ultimately substantially inhibits the migration of water from the interior to the exterior ox the product.
Thus, dehydration to a storage-stable moisture level is extremely slow and scorching is a concern. The case-hardened surface also adversely affects dehydration characteristics. Because the surface is not porous but rather exhibits an impervious skin, prolonged soaking is required in order for water to reconstitute the interior of the product. Often this condition prevents complete dehydration within the prescribed time.
Incompletely dehydrated products exhibit firm, chewy centers, and surfaces which are prone to sloughing.
All of such characteristics are to be avoided.
The dehydration procedure of the present invention prevents case-hardening by promoting uniform moisture removal frown throughout the product. By uniformly ~34~9S01 - 14 -dehydrating the foodstuff, the natural passages provided by the interstitial spaces between the cells and the porous condition of the product affected by freezing does not become shrunken or clogged at the S surface. The moisture, therefore, can freely pass from the interior of the piece through the exterior surface to rapidly dehydrate the product Moreover, it has been found that case-hardening appears to be a concern primarily in the initial stages of drying, i.e., during removal of the first 10 to 25% by weight moisture from the product. If case-hardening is avoided during the initial stage of the dehydration operation using the partial drying technique of the present invention, dehydration can be completed using a preferred expedient therefore such as conventional hot air techniques as discussed below, without destroying the porous characteristics of the product provided by the treatments of the present invention. although porosity is an essential characteristic in the resultant product, excessive puffing or expansion of the product during dehydration is to be avoided because attendant cell rupture releases soluble solids such as starches and sugars contained within the cell. Upon subsequent reconstitution these solids are readily solubilized into and are leached from the food material being dehydrated. The nutritional value of the product is thus substantially reduced. Such products also tend to be brittle and break or slough during reconstitution.
It has been found that such objectionable features are avoided by subjecting foodstuff to the sequence of freezing followed by partial dehydration, in accordance with the present invention, which is believed to be responsible for the desired attributes of the products of the present invention.
The partially dehydrated potato pieces and other vegetables are finished dried. Due to the effects of .
~3~89S01 - 15 -prior treatments of partial drying at the aforementioned dry bulb-wet bulb temperatures and freezing, the potato pieces have beer sufficiently conditioned so that the particular expedient used for dehydration to a storage-stable moisture content is not a major concern. It has been discovered that exposing the potatoes and other vegetables to a hot atmosphere until a storage-stable moisture content is achieved produces an end product with suitable characteristics.
For example, hot air dehydration of the product in a stationary or fluidized bed, preferably at temperatures below about 180F, to storage stable moisture contents of less than about 12% by total weight, result with particularly good products upon reconstitution. The potato pieces are finish dried to a moisture content of about 6 to 10% by total weight in air having a dry bulb temperature within the range of about 160F to 180F.
Finish drying using a stationary bed, continuous belt dryer is completed in less than about 6 hours and typically in about 3 to 5-1/2 hours. The partially dried potato pieces having a moisture content of about 67% by total weight were finished dried to a moisture content based on total weight of about I by subjecting the pieces to air having a dry bulb temperature of about 160 F for about 3-1/2 hours. By the process of the present invention, dehydration time may be reduced compared to conventional procedures using similar belt-trough dryers. Moreover because of the porous nature of the partially dried product, moisture is more readily removed from the interior of the product. Thus, the depth to which the partially dried product can be loaded onto the drying belt of a conventional belt-trough dryer is greater than heretofore was practical.
Hence for a given period of time, a substantially larger quantity of product may be dehydrated to a similar extent. In addition to the other technical .
achievements resulting from the practice of the present invention, therefore, there is an increase in production capacity with attendant economic advantages.
The dehydrated potato pieces having a storage stable moisture content were packaged in a conventional manner for handling and storage purposes. To prepare the dehydrated foodstuff of the invention for consumption, the product is merely placed in water and permitted to stand until essentially reconstituted and heated. Particularly good results are achieved when water having a temperature within the range of about 170F to 212F is added to the dehydrated foodstuff or the product is added to water which is brought to a boil and simmered for up to 10 to 15 minutes. The potatoes and other vegetables prepared in this manner are essentially completely reconstituted and have a taste, texture, appearance, and other organoleptic - characteristics more closely resembling vegetables prepared directly from the fresh state than heretofore has been commercially available. The reconstituted vegetables make excellent soups, stews, sauces, casseroles and side dishes with potatoes also being particularly suitable for use in salad mixes.
In addition to the high quality of the food products made in accordance with the present invention, they are also quick dehydrating For purposes of the ; present invention, quick dehydrating means reconstitution of the dehydrated product in less than about 15 minutes to a moisture content closely approaching the moisture content of the raw material from which it was made. Replacement of at least 85%
and preferably greater than 90 to 95% of the water is required in order for the product to resemble its fresh food counterpart. Moisture replacement can be expressed in terms of the dehydration ratio of the product Dehydration Ratio, i.e., OR is determined -. .
.
P34~9S01 - It - `
by weighing a quantity of dehydrated product, dehydrating such product in water, draining the product of free water, and weighing the dehydrated product. As used herein, dehydration ratio is calculated by dividing the weight of the product after dehydration by the weight of the product in its dehydrated state Upon reconstitution, vegetables which have been dehydrated in accordance with the present invention exhibit dehydration ratios which are substantially higher than their conventionally dehydrated counterparts. Dehydration ratios for dehydrated vegetables of the present invention which represent a replacement of at least about 85~ of the moisture which had previously been removed during dehydration are 15 listed below:
TABLE II
Vegetable Dehydration Rusher Russet Burbank Potatoes 3.6 - 5.6 20 Red Pontiac Potatoes 5.2 - 6.5 White Rose Potatoes 5.3 - 6.6 Carrots 5.1 - 10.5 Sweet Potatoes 2.7 - 4.6 Bell Peppers 6.5 - 9.5 25 Barley - 2.9 - 3.8 Another characteristic by which dehydrated products can be evaluated is Bulk Index. Although the determination of Bulk Index is useful to some extent for certain purposes in judging products, sulk Index data can also give a distorted picture of the product.
Bulk Index represents the volume (cc) occupied by lo grams of product as measured in a Lowe ml. graduated beaker having a 65 mm. internal diameter. It is inversely proportional to bulk density. As such, bulk density and index are somewhat indicative of porosity I
P3489SOl - 18 -but not if viewed alone For example, two dehydrated products may have similar densities but not exhibit the same uniformity of porosity. This could be true if a product of the present invention were compared to a dehydrated puffed-type product. It has been found, therefore, that not all products having similar bulk induces dehydrate in an equivalent manner in terms of time or characteristics of the reconstituted product.
Thus, it has been discovered that in order for lo dehydrated products to be quicX-rehydrating in less than about 15 minutes, they should not only exhibit a Bulk Index within the ranges listed in the Table III, but must also manifest a Dehydration Ratio within the ranges listed in Table II. Bulk indices, for representative vegetables having dehydration ratios within the ranges listed in Table II, are shown below:
Taste III
Vegetable Bulk Index so 20 Russet Burbank Potatoes 390-600 Red Pontiac Potatoes 500-630 White Rose Potatoes 500~630 Carrots 400-700 Sweet Potatoes 350-550 25 Bell Peppers 260-300 Barley 285-335 The potato pieces, dehydrated in accordance with the present invention as described above to a final moisture content of about I by total weight having a Bulk Index of 495, were held in water that had been brought to a boil for 10 minutes. The reconstituted potato pieces having dimensions of about l/2" x 3/4" x 3/411 were determined to have a Dehydration Ratio of 4.75. This product was considered excellent in taste, texture and appearance and exhibited no sign of , ;22~`~
3g~9S01 - 19 -sloughing.
SAMPLES
Carrots In addition to potatoes, carrots are another prime example of vegetable material which can be processed in accordance with the present invention into large, dehydrated pieces which exhibit excellent organoleptic qualities upon subsequent reconstitution Raw Chinatown variety carrots were lye peeled, cleaned and trimmed Afterwards the peeled carrots were subdivided into 1/2" x 1/2" x 3/4" pieces using a Urschel Model s cutter. The carrot pieces were cooked for 60 minutes in water having a temperature of about 160 F and then frozen. The frozen carrot pieces at essentially their natural moisture content of about 90~ by total weight were taken from the freezer and subjected to a stream of forced air having a velocity of about 1000 PPM
and a temperature of about 325 F dry Balboa F wet bulb for 11 minutes and partially dried to remove about 74% by weight moisture from the carrots to reduce the moisture content by total weight thereof to about 71%.
The partial dried carrots were then finish dried in air having a temperature of about 160F to a moisture content of about 5% by total weight in about g hours.
To dehydrate, the dehydrated carrot pieces having a Bulk Index of 750 were added to boiling water and held for 10 minutes. The reconstituted carrot pieces processed as described above were determined to have a Dehydration Ratio of 9.8. They were judged to be excellent in taste, texture and appearance.
Sweet Potatoes ___ Sweet- potatoes are yet another example of foodstuff which is particularly suitable for processing in accordance with the present invention. Jewel Jo ..
' - .
- ' . ' '' ' .~' . . - .
P3~89~01 - I -variety sweet potatoes were cleaned of dirt and debris and then lye peeled by submersion in a 13% caustic solution having a temperature of about 20QF for about 8 minutes. The peeled sweet potatoes were then cut using an Urschel OX machine into 3/16" slices and blanched in water having a temperature of 180F for about five minutes prior to freezing to a solid state.
Thereafter, the frozen slices at essentially their natural moisture content of about 83% by total weight were partially dried by exposure to a forced air stream having a velocity of about 1000 PPM and a temperature of about 310F dry bulb/140F wet bulb for 10 minutes to remove about 55~ by weight moisture from the slices thereby reducing the moisture content by total weight thereof to about 69%. Following partial drying the sweet potato slices were finish dried to a final storage stable moisture content of about 11% by total weight in about 4 hours using air having a temperature of about 140F. The finish dried slice had a Bulk Index of 4100 Afterwards these dehydrated sweet potato slices were rerouted for 10 minutes in water - that had been brought to a boil. The reconstituted product was determined to have a Dehydration Ratio of 3.3. The sweet potato slices exhibited a taste, texture and appearance which were considered to be very acceptable.
Potatoes Red Pontiac variety potatoes were cut into 1/2"
dice after being prepared for processing in a conventional manner including cleaning and peeling The dices were then precooked in water at 170F for 30 minutes, cooled for about 10 minutes in 60F water and cooked in water having a temperature of about 190F for 30 minutes prior to freezing. Following freezing the frozen dice at essentially their natural moisture content of about 85% by total weight were subjected to -.
I
P3~89S01 -- 21 -a forced air stream having a velocity of 1200 PPM
and a temperature of about 300F dry bulb/140F wet bulb for about 8 minutes to partially dry the dice by removing about 58% by weight moisture from the dice thereby reducing the moisture content by total weight thereof to about 71%. Thereafter the partially dried dice were finished dried to a storage stable moisture content of about 6% by total weight in 3-1/2 hours using air having a temperature of about 160F. The Bulk Index of the finished dried dice was 590~ After reconstitution for 8 minutes in water that had been brought to a boil, the dice were determined to have a Dehydration Ratio of 6.5. The reconstituted dice exhibited excellent texture and appearance and had a very good flavor.
COMPARISON
In order to compare various products made in accordance with the present invention with what is commercially available in the marketplace, the following test was conducted:
Conventional Dehydrated Products - A dehydrated noodle, vegetable, and flavoring mix sold as Soup Starter for use in the preparation of soups was obtained in the grocery store. The dehydrated vegetable products listed in the Table below were selected from this mix and compared for completeness of reconstitution with the potatoes, carrots, barley, green and red bell peppers made in accordance with the present invention as described below Products M_ OX the Invention Potatoes Idaho Russet Burbank potatoes were peeled and cut into 3/8-inch dice. The dice were precooked in water at 170F for 30 minutes, cooled in 70F water for 10 minutes, cooked in water at 180F for 30 minutes and .
frozen. The frozen dice at essentially their natural moisture content of about 81% by total weight were subjected to air having a temperature of about 300F
dry bulb/l4ooF wet bulb and a velocity of about 1200 PPM for about 8 minutes to remove about 45% by weight moisture from the dice thereby reducing the moisture convent by total weight thereof to about 70~.
The partially dried dice were then finish dried in air at a temperature of about 160F dry bulb to a storage stable moisture content of about I by total weight in about 3-1/2 hours.
Carrots Raw carrots were cleaned, peeled and sliced before being cooked in water having a temperature of about 160F for 60 minutes and frozen. The frozen slices at essentially their natural moisture content of about 90%
were removed from the freezer and subjected to air having a velocity of 1000 PPM and a temperature of about 325F dry bulb/140F wet bulb for 11 minutes to remove about 74~ by weight moisture from the slices thereby reducing the moisture content by total weight thereof to about 70%. The partially dried slices were then dehydrated to a storage stable moisture content of about 5% by total weight in about 4 hours in air having a temperature of about 160F.
Barley Dry, unprocessed barley was placed in boiling water for 60 minutes prior to being subjected to steam under a pressure of 20 prig. for 10 minutes and then frozen. Prior to freezing the barley had a moisture content of about 85% by total weight. The frozen barley was subjected to an air stream having a velocity of 1000 PPM and a temperature of about 300F dry bulb/140F wet bulb for 16 minutes to remove about 99~
by weight moisture from the barley thereby reducing the moisture content by total weight thereof to a storage .
I
stable extent of about I
Peppers Bell peppers of the green and red varieties having natural moisture content of about 81% by total weight were prepared in essentially the same manner. The peppers were first peeled prior to removing their cores and seeds and cut into l/4-inch square pieces the thickness of which corresponds to the thickness of the flesh of the pepper. The pieces of pepper were then frozen and subjected to air having a velocity of about 750 PPM and a temperature of about 300F dry bulb/140F wet bulb for about 4 l/2 minutes to partially cry the pieces to remove about 12~ by weight moisture from the pepper pieces thereby reducing the moisture content by total weight thereof to about 80~.
Afterwards the pepper was dried to a storage stable moisture content of about 13~ by total weight in two hours using 130F air.
the dehydrated vegetable products made in accordance with the invention as described above as well as the conventional dehydrated vegetables from the soup mix were reconstituted for purposes of this comparison in an identical manner. The same weight of each dehydrated product was added to a separate container of boiling water and simmered for the time listed in the Table below. The shorter of the two times are considered acceptable for a quick reconstituting product. In the alternative, ninety minutes was used because such time was specified in the recipe of the commercial soup mix. After simmering for the prescribed times, the vegetables were removed from the water drained and weighed again. As discussed above, the ratio of the weight of the reconstituted product and the weight of the dehydrated product is referred to herein as Dehydration Ratio, i.e., OR
.
.
~3~9S01 aye The results are tabulated below:
TABLE IV_ OR OR
of of ProductSi.zeInvention Min. Conventional .__________ _________ __ ____._______ Potatoes3/8"x3/8"x3/8" 4.7 10 2.7 5.4 90 47 Carrots Slice 5.1 15 3.1 10.9 90 4.6 15 Barley Whole 3.8 15 2.2 5.2 90 4.8 Green Bell 1/4"xl/4" 6.5 5 5.3 Peppers 8.3 90 TV
Red Bell 1/4"xl/4" 6.6 . 5 4.8.
Peppers 8.3 90 5.2 :
The tabulated data indicates that each sample of vegetable processed in accordance with the present invention exhibits a Dehydration Ratio consistently higher than their conventionally dehydrated counterpart. The differences are particularly : significant for the shorter reconstitution times which are indicative of what is typically the case for a quick-reconstituting product. It is generally recognized that dehydrated products which have higher Dehydration Ratios more closely resemble the fresh material from which it is made. This was fount to be 35 :true..for:th:e comparison made herein particularly for the samples reconstituted for the shorter times.
.
. , : - . . - , . . .. . - . ' - .
- ' ' : ... .. .
P 3 4 8 go 0 of' Whereas the products made in accordance with the present invention were considered to be excellent in taste, texture and appearance, the conventionally dehydrated products from the soup mix were found to have hard, chewy interior textures and incompletely developed taste upon reconstitution.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
- ,
Claims (58)
1. A method for producing dehydrated food-stuff, comprising removing moisture from frozen foodstuff, from which substantially no moisture has been artificially removed, by subjecting said food-stuff to a forced stream of gaseous medium having a velocity within the range of 350 to 2000 F.P.M.
effective to fluidize said foodstuff and having a dry bulb temperature in the range of about 250 to 350°F
and a wet bulb temperature in the range of about 120 to 160°F and then further dehydrating said foodstuff in an atmosphere having a dry bulk temperature of less than about 220°F to a storage stable moisture content of less than about 12% by total weight.
effective to fluidize said foodstuff and having a dry bulb temperature in the range of about 250 to 350°F
and a wet bulb temperature in the range of about 120 to 160°F and then further dehydrating said foodstuff in an atmosphere having a dry bulk temperature of less than about 220°F to a storage stable moisture content of less than about 12% by total weight.
2. The method of claim 1, wherein said food-stuff comprises vegetable material.
3. The method of claim 2, wherein said veg-etable material comprises potatoes, sweet potatoes, carrots, parsnips, beets, beans, peas, peppers, onions, corn, barley, rice and wheat.
4. The method of claim 3, wherein said veg-etable material is potatoes.
5. The method of claim 3, wherein said dry bulb temperature is about 300°F and said wet bulb temperature is 140°F.
6. The method of claim 1, wherein said subjec-ting said foodstuff to said gaseous medium removes an amount of moisture between about 10 to 99% by weight moisture from said foodstuff.
7. The method of claim 6, wherein said amount is between about 37 to 93% by weight moisture.
8. The method of claim 7, wherein said amount is between about 42 to 77%.
9. The method of claim 1, wherein said at-mosphere has a dry bulb temperature between about 120°F to 185°F.
10. The method of claim 1, further comprising subjecting foodstuff to an aqueous medium having a temperature above about 120°F prior to removing moisture from said frozen foodstuff.
11. The method of claim 10, wherein said aqueous medium is steam.
12. The method of claim 10, wherein said temperature is in the range of about 120 to 212°F.
13. The method of claim 12, wherein said foodstuff is cooked at said temperature for up to 75 minutes.
14. The method of claim 13, further comprising precooking said foodstuff at said temperature for between about 3 to 75 minutes followed by cooling in water before said foodstuff is cooked.
15. The method of claim 1, wherein said frozen foodstuff is provided by exposing foodstuff to an atmosphcre having a temperature between about -20 to +20°F.
16. The method of claim 1, wherein said dehy-drating is accomplished in less than about 6 hours.
17. A method for producing dehydrated veg-etables comprising:
a) treating vegetables with an aqueous medium having a temperature of about 120 to 212°F;
b) exposing said vegetables to a tem-perature of about -20 to 0°F;
c) subjecting said vegetables to a gaseous medium having a dry bulb temperature of about 250 to 350°F and a wet bulb temperature of about 135°F to 150 F; and d) dehydrating said vegetables in an atmosphere having a dry bulb temperature of about 120 to 185°F to a storage stable moisture content of less than 12% by total weight.
a) treating vegetables with an aqueous medium having a temperature of about 120 to 212°F;
b) exposing said vegetables to a tem-perature of about -20 to 0°F;
c) subjecting said vegetables to a gaseous medium having a dry bulb temperature of about 250 to 350°F and a wet bulb temperature of about 135°F to 150 F; and d) dehydrating said vegetables in an atmosphere having a dry bulb temperature of about 120 to 185°F to a storage stable moisture content of less than 12% by total weight.
18. The method of claim 17, wherein said gaseous medium is a forced stream having a velocity between about 850 to 1400 F.P.M.
19. The method of claim 17, wherein said subjecting removes about 10 to 99% by weight moisture from said vegetables.
20. The method of claim 19, wherein said subjecting removes about 42 to 77% by weight mois-ture.
21. The method of claim 17, wherein said treating comprises cooking for about 3 to 75 minutes.
22. The method of claim 18, wherein said treating further comprising precooking for up to 3 to 75 minutes prior to said cooking.
23. The method of claim 22, further comprising a cooling step intermediate said precooking and cooking.
24. The method of claim 17, further comprising subdividing vegetables into pieces prior to said treating.
25. The method of claim 24, wherein said vegetables comprise potatoes, sweet potatoes, car-rots, parsnips, beets and onion.
26. The method of claim 25, wherein said pieces have a minimum dimension of between about 1/16-inch to 3/4-inch.
27. The method of claim 26, wherein said pieces range in size from a slice having a thickness of 1/16" to a 3/4" dice.
28. The method of claim 27, wherein said pieces are slices having a thickness in the range of about 1/16-inch to 1/2-inch.
29. The method of claim 27, wherein said vegetable is potato and said pieces are 1/2" x 3/4" x 3/4" strips.
30. The method of claim 27, wherein said vegetable is carrot and said pieces are 1/2" x 1/2" x 3/4" strips.
31. The method of claim 17, wherein said dehydrating is accomplished in less than 6 hours.
32. The method of claim 31, wherein said dehydrating is accomplished in 3-5 hours.
33. A dehydrated vegetable product having a moisture content of less than about 12% by total weight, a Bulk Index within the range of about 260 -700 and a Rehydration Ration within the range of about 2.7 - 10.5.
34. The dehydrated vegetable product of claim 33, having a minimum dimension of between about 1/16-inch to 3/4 inch.
35. The dehydrated vegetable product of claim 34, wherein said product is a piece ranging in size from a 1/16' slice to a 3/4" dice.
36. The dehydrated vegetable product of claim 33, wherein said vegetable is carrot, said Rehy-dration Ratio is within the range of 5.1 - 10.5 and said Bulk Index is within the range of 400 - 700.
37. The dehydrated vegetable product of claim 36, wherein said carrot is a 1/16" thick slice.
38. The dehydrated vegetable product of claim 36, wherein said carrot is a 1/2" x 1/2" x 3/4"
strip.
strip.
39. The dehydrated vegetable product of claim 33, wherein said vegetable is sweet potato, said Rehydration Ratio is within the range of about 2.7 -4.6 and said Bulk Index is within the range of about 350-550.
40. The dehydrated vegetable product of claim 39, wherein said sweet potato is a 3/16" thick slice.
41. The dehydrated vegetable product of claim 33, wherein said vegetable is a bell pepper, said Rehydration Ratio is within the range of 6.5 - 9.5 and said Bulk Index is within the range of about 260 - 300.
42. A dehydrated potato product having a moisture content of less than about 12% by total weight, a Bulk Index within the range of about 390 -630 and a Rehydration Ration within the range of about 3.6 - 6.6.
43. The dehydrated potato product of claim 42, wherein said Bulk Index is within the range of about 390 - 600 and said Rehydration Ratio is within the range of about 3.6 - 5.6.
44. The potato product of claim 43, having dimensions of 1/2"-inch x 3/4-inch x 3/4-inch.
45. The potato product of claim 42, wherein said Bulk Index is within the range of 500 - 630 and said Rehydration Ratio is within the range of about 5.2 - 6.6.
46. The potato product of claim 45, being a 1/2-inch cube.
47. A method for reconstituting a dehydrated foodstuff comprising rehydrating a dehydrated food-stuff having a moisture content of less than about 12% by total weight in an aqueous medium for less than about 15 minutes to replace at least 85% of the previously removed moisture.
48. The method of claim 47, wherein said foodstuff is a dehydrated vegetable material.
49. The method of claim 48, wherein said dehydrated vegetable material is selected from the group consisting of potatoes, sweet potatoes, car-rots, parsnips, beets, beans, peas, peppers, onions, corn, barley, rice and wheat.
50. The method of claim 49, wherein said dehydrated vegetable material are pieces having a minimum dimension of between about 1/16-inch to 3/4-inch.
51. The method of claim 50, wherein said pieces range in size from a 1/16" slice to a 3/4" dice.
52. The method of claim 50, wherein said dehydrated vegetable material is potato and said pieces are selected from the group consisting of 3/8"
dice, 1/2" dice and 1/2" x 3/4" x 3/4" strips.
dice, 1/2" dice and 1/2" x 3/4" x 3/4" strips.
53. The method of claim 52, wherein said potato is a 1/2" x 3/4" x 3/4" strip.
54. The method of claim 50, wherein said dehydrated vegetable material is carrot and said pieces are selected from the group consisting 1/6"
slices and 1/2" x 1/2" x 3/4" strips.
slices and 1/2" x 1/2" x 3/4" strips.
55. The method of claim 54, wherein said carrot is a 1/2" x 1/2" x 3/4" strip.
56. The method of claim 48, wherein the re-placed moisture is at least 90% of the previously removed moisture.
57. The method of claim 56, wherein said dehydrated foodstuff exhibit a Bulk Index within the range of about 260 - 700 and a Rehydration Ratio within the range of about 2.7 - 10.5.
58. A method for producing dehydrated food-stuff, comprising the steps of:
a) providing a quantity of frozen grain;
b) subjecting said grain to a forced stream of gaseous medium having a velocity within the range of about 350 to 2000 F.P.M effective to fluids said grain and having a dry bulb temperature within the range of about 250 to 350°F and a wet bulb temperature within the range of about 120 to 160°F to dehydrate said grain to a storage stable moisture content of less than about 12% by total weight.
a) providing a quantity of frozen grain;
b) subjecting said grain to a forced stream of gaseous medium having a velocity within the range of about 350 to 2000 F.P.M effective to fluids said grain and having a dry bulb temperature within the range of about 250 to 350°F and a wet bulb temperature within the range of about 120 to 160°F to dehydrate said grain to a storage stable moisture content of less than about 12% by total weight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55500983A | 1983-11-25 | 1983-11-25 | |
| US555,009 | 1983-11-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1238226A true CA1238226A (en) | 1988-06-21 |
Family
ID=24215615
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000468565A Expired CA1238226A (en) | 1983-11-25 | 1984-11-23 | Dehydrated food products and method for making the same |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS6140743A (en) |
| CA (1) | CA1238226A (en) |
| DE (1) | DE3442852A1 (en) |
| FR (1) | FR2560012B1 (en) |
| GB (1) | GB2150007B (en) |
| NL (1) | NL8403578A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2269307A (en) * | 1992-05-11 | 1994-02-09 | Unilever Plc | Food product |
| JP4999682B2 (en) * | 2004-06-16 | 2012-08-15 | フェイエコン ディベロップメント アンド インプリメンテーション ベスローテン フェンノートシャップ | Dehydration method |
| JP4505393B2 (en) * | 2005-08-22 | 2010-07-21 | アサヒビール株式会社 | Crop roasting method and storage method |
| CA2641801A1 (en) * | 2007-10-25 | 2009-04-25 | H.J. Heinz Company | Method of making mashable potatoes |
| ES2401797B1 (en) * | 2011-09-26 | 2014-07-15 | Alimentos Naturales, S.A. | PROCEDURE FOR OBTAINING LIOPHILIZED VEGETABLES |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1036469A (en) * | 1900-01-01 | |||
| NL264441A (en) * | 1900-01-01 | |||
| US2718470A (en) * | 1951-09-11 | 1955-09-20 | Vern F Kaufman | Process for food preservation |
| US2754233A (en) * | 1955-06-02 | 1956-07-10 | Harry S Owens | Inactivation of enzymes in beet cossettes prior to diffusion |
| US3063848A (en) * | 1959-06-01 | 1962-11-13 | Basic Vegets Le Products Inc | Fluid treatment for food materials |
| US3573070A (en) * | 1961-09-22 | 1971-03-30 | Uncle Ben S Inc | Processes for preparing dehydrated potatoes |
| GB1084714A (en) * | 1964-03-10 | 1967-09-27 | Unilever Ltd | Foodstuffs |
| US3973047A (en) * | 1972-12-20 | 1976-08-03 | General Foods Corporation | Process of dehydrating vegetables |
| US3950560A (en) * | 1974-06-14 | 1976-04-13 | The United States Of America As Represented By The Secretary Of The Army | Method of producing compacted, dehydrated, vegetable products of increased density |
| US4385074A (en) * | 1981-09-02 | 1983-05-24 | NS Apothekernes Laboratorium for Specialpraeparater | Quick cooking rice and process for making the same |
| GB2116818A (en) * | 1982-03-15 | 1983-10-05 | Unilever Plc | A method of preparing a dry food product |
-
1984
- 1984-11-23 CA CA000468565A patent/CA1238226A/en not_active Expired
- 1984-11-23 DE DE19843442852 patent/DE3442852A1/en not_active Withdrawn
- 1984-11-23 NL NL8403578A patent/NL8403578A/en not_active Application Discontinuation
- 1984-11-23 GB GB08429587A patent/GB2150007B/en not_active Expired
- 1984-11-26 FR FR848417991A patent/FR2560012B1/en not_active Expired
- 1984-11-26 JP JP25036284A patent/JPS6140743A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2150007A (en) | 1985-06-26 |
| GB8429587D0 (en) | 1985-01-03 |
| JPS6140743A (en) | 1986-02-27 |
| DE3442852A1 (en) | 1985-06-05 |
| GB2150007B (en) | 1988-02-17 |
| FR2560012A1 (en) | 1985-08-30 |
| FR2560012B1 (en) | 1989-12-01 |
| NL8403578A (en) | 1985-06-17 |
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