IL30895A - Dehydrated edible fibrous fruit product and method of obtaining it - Google Patents

Description

DEHYDRATED^EDIBLE FIBROUS FRUIT PRODUCT AND METHOD OF OBTAINING IT This invention relates to foodstuffs.

It deals with dehydrated foods and a dehydration method. It has to do especially with those portions of various fruits, such as citrus fruits, which are naturally somewhat spongy and after dehydration are subject to reconstitution by the addition of water so tha.t they may be used advantageously in other food products such as for baked cakes and yield a natural "bite" feeling in the mouth. The presently preferred fruits or fruit portions are citrus peels, including orange, lemon, tangelo, lime, grapefruit, and tangerine peels. These citrus fruit peels, after they have been dehydrated according to this invention, and also subjected to further' treatment if de3ired, have inherent natural flavors that render them attractive for food additions.

Importantly, the method includes as an early stage rapid dehydration of the fruit portions, such as the mentioned citrus peel, in hot vegetable oil for the purpose cf evaporating a very substantial portion of the original natural water content, which treatment is done above the boiling point of water, such as 275°F. After such treatment at atmospheric pressure for twenty . or thirty minutes, the treating equipment (reactor) Is then placed under vacuum, such as a 26" (Hg) vacuum, and the treatment continued for another five to twenty minutes to reduce the water content to a desired range, such as between about and 10$ b weight, or to an optimum percentage around 6% to 8#, where the oil temperature at start of processing might have been about 275°F. Because of evaporative cooling during vacuum treatment the temperature will fall and rise again. When the temperature rises to around 200°F o 230°P depending on nature of the peel, the perforated basket carrying the peel pieces Is then preferably raised from the hot oil, In which the peel had been treated, to a position above the surface of the oil for drainage of excess oil from the peel, while still maintaining the vacuum. After breaking the vacuum, the basket and contents are preferably centrlfuged for a short time, such as one to three minutes, to further remove residual vegetable oil.

The peel thus treated may be reduced to desired particle or piece sizes and used in that state. On the other hand, and preferably, the treated peel will be subjected to an impregnation step to. yield a product of maximum utility and stability. This Impregnation will be accomplished, for example, by Introduction of the dehydrated product into a hot flavor- improving syrup, such as 50 dextrose dissolved in glycerol which will harden and fill the cellular interstices of the particles upon cooling. Unexpectedly, we have discovered that impregnation of the peel with, polyol-sugar mixtures greatly improves the oxidative stability of the product. During this treatment additional residual vegetable oil will be displaced by operating with a vacuum make-and-break procedure to facilitate both impregnation and vegetable oil removal. The product is then drained in the carrying basket used and allowed to cool. It is then reduced to whatever size is required or desired for marketing. In the preparation of citrus peel, the. whole peel, including the outer flavedo. layer and the inner white albedo layer may be used. It is preferable to remove the rag that clings to the inner side of the peel. Again, the flavedo layer may be shaved off and used, or the flavedo layer may be shaved off and discarded, only the albedo layer being then used. The portion employed for processing will depend largely upon the flavor and color of the product required.

BACKGROUND So far as known, my earlier Patent No. 2 .976, 15 of March 21 , 1961 , constitutes the principal prior art here concerned. The outstanding difference Is that the citrus peel, or other fruit portion being treated, Is, according to the present Invention, first dehydrated by treatment In heated vegetable oil, such as soybean oil or coconut oil or other oils hereinafter mentioned. The use of stannous chloride to treat citrus Juices is disclosed In Hlgby et al Patent No. 3 , 219, 453 of November 23, 1965.

The principal advantages of peel prepared according to the present Invention over that as described In Patent No. 2, 976, 159 are as follows: ( 1 ) the peel can be easily ground to any desired size without clogging up the mill; ( 2 ) there are no hard lumps that are Irreversibly dehydrated, making the product hard to reconstitute and difficult to eat; ( 3 ) for the first time a flavorful and useful dehydrated lemon peel can be made; and ( 4 ) the peel retains a considerable amount of natural vitamin C.

SUMMARY OF THE INVENTION This invention, therefore, resides in first treating the citrus peel pieces, or selected pieces of other appropriate fruits, in a suitable hot vegetable oil at temperatures somewhat above- the boiling point of water for the purpose of reducing the moisture content to whatever is considered optimum for the purpose, such as between 5% an 10 or about 8$, and in any event below 15 , treatment having preferably been first conducted at atmospheric pressure and then completed under vacuum. For minimum retention of vegetable oil, the peel is drained while under vacuum. Another aspect of the invention is the subsequent treatment of the dehydrated product with a hot viscous 3yrup containin dextrose or the like dissolved In such a polyol as glycerol which will become a semi-solid upon cooling, whereby further to displace some of the residual vegetable oil and also to harden the treated food particles to yield a product of natural texture and color having outstanding flavor stability.

THE PROCESS AD THS PKODUCT The accompanying drawing is a flow sheet representing the various steps and stages of the process hereof.

In summary, the process involves the rapid removal of the natural water content from fresh raw citrus peel (or other indicated fruit) by immersion of pieces or particles thereof in a hot edible vegetable oil (or partially hydrogenated vegetable oil) above the boiling point of water, e.g., at about 275°F, for a time to remove much of the water, such as for about a half hour, followed by finishing under vacuum in the hot vegetable oil, whereby to remove that portion of the water more tightly bound within the cellulose-proto-pectin complex without overheating and thus lower the water content into a preferred range of about to 10$ , more particularly approximately δ^, by weight.

The citrus peel, which is commonly received in the half-shell (cups) from juicing operations, is desirably subdivided into appropriate sizes, such as quarters, strips, diced particles or shaved portions. It may be whole peel including both the outer colored layer or flavedo and the inner white layer or albedo. Or it may be shaved to eliminate the flavedo, or to recover the flavedo only for a particular use. Or it may be very lightly shaved to merely clean the surface and leave m03t of the pigmented portion and essential oils.

Since the inner surface of the peel from Juicing operations commonly carries a quantity of stringy fiber known as "rag", this is usually removed, but such is net required.

Besides citrus peels, other fruits may be treated by the process. These include apples, especially the harder apples such as pippins, pineapples, cranberries coconut meats, pears, and other pomes.' Citrus faults, such as lemons and oranges, are, however, generally considered herein as the fruit treated because the flavors and colors of these peels are very attractive for addition to other foods such as prepared cake, cookies, and dessert mixes.

IN DETAIL .

Referring to the outline expressed by the flow sheet, several specific examples are now furnished as representative of the preferred form of the Invention.

Example 1 — A batch of 150 pounds of raw whole navel orange peel cut into quarters was prepared. Ey the term "whole" is meant raw peel embodying both the outer colored flavedo layer containing the carotenold pigment which it is desired to preserve and also the inner white albedo layer. The prepared peel was placed in a perforated 3tainless steel basket having a hinged lid of similar construction and immersed in an open steam Jacketed reactor containing 400 pounds of food grade soybean oil at 275°F. After 27 minutes boiling at atmospheric pressure, the reactor was closed and the boiling orange peel bath subjected to a 26.5 inch vacuum for five minutes during which time the oil temperature fell and then recovered to 2140F. The vacuum was then broken and the basket raised above the surface of the hot oil. The oil was allowed to drain from the peel for ten minutes. The peel was then found to have a moisture content of 7.¾S. The 150 pound orange peel charge yielded 60 pounds of dehydrated product.

Example 2 — Λ like charge of quartered navel orange peel was similarly treated with the difference that a 26 inch vacuum was used with a temperature drop and recovery to 212°F, and the soybean oil was removed by centrifuging the peel for two minutes at 1000 RPM with a similar yield. The basket of peel was lowered into a second Jacketed reactor containing a hot syrup at 220°F made up of 50/ glycerol and 50$ dextrose monohydrate, and the peel immersed in the hot syrup. A 26 inch make-and-break vacuum treatment was applied five times to fully impregnate the peel.

After the last vacuum break, the basket was raised above the surface of the syrup and the excess syrup allowed to drain from the peel for five minutes. The product yield was 79 pounds of impregnated dehydrated orange peel containing 4.7# moisture. These products had the attractive carotenoid color of natural peel.

Example 3 — A batch of 150 pounde of whole lemon peel in a basket such as that of Example 1 was immersed for five minutes at room temperature in a water solution of stannous chloride containing about 0.125# 3nCl2 by weight of the peel to prevent a grayish discoloration that typically develops in dehydrated lemon peel.

After draining the aqueous solution from the peel for five minutes, the basket and the peel were immersed In a reactor as in Example 1 containing hot soybean oil at 275°F under atmospheric ressur for.25 minutes.

This was followed by vacuum treatment at about 26 inches for 15 minutes during which the oil temperature dropped and recovered to 2150F . The basket was raised above the oil, the vacuum broken, and the product drained for five minutes, yielding 35 pounds of dehydrated lemon peel having 8. $ moisture and a natural yellow color.

Example k — Lemon peel treated as in Example 3 was impregnated for five minutes by the previously described make -and-break technique at 222°F in a hot syrup composed of J glycerol and 0$ dextrose monohydrate. The peel was drained for five minutes, yielding 7 pounds of dehydrated Impregnated lemon peel containing 5. ^ moisture.

Example 5 Haw whole orange peel in the form of 150 pounds of quarters was treated as in Example 1 in hot soybean oil at about 275°F for 22 minutes at atmospheric pressure, and then for eighteen minutes under 26 inches vacuum with a temperature fall and recovery to 211°F. After breaking the vacuum and centrifuging the peel for two minutes at 1000 RPM, the peel was impregnated for five minutes by the previously described make-and-break vacuum techlnque in hot ( 220°F) syrup of 50$ glycerol and 50# dextrose as In Example . After draining off the syrup for five minutes a yield of 7k pounds of impregnated dehydrated peel having 5# moisture was recovered.

The use of stannous ion (3n++") to control the off-color development is particularly important and valuable for processing lime and lemon peels but may be considered optional with the otiher varieties of oitrus peels which do not contain the xanthophyll pigments of the type found in the skins of lemons and limes. Although stannous chloride i3 suitable, other stannous salts that have some water solubility, such as di-sodlum stannous citrate, rnayise used.

The temperatures and propor io s of the above examples are not critical. However,, they represent good operating techniques, although others are usable.

Thus, the first dehydration stage The vacuum temperature range may vary between the highest temperature employable (as above indicated) down to where it ceases to be practically effective for volatilizing the water to be removed, such as 170°F.

Similarly, the vacuum treating periods and drainage or centrifuging times vary as functions of practical operations as do the vacuum values. .Fr'001 the standpoint of first, stage heat treating in an oil, if the temperature is 250°F when peel is first immersed, tii;.e required might be in a range of thirty to fifty minutes, and a temperature of 300OF. ight require only 15 to 25 minutes. These are readily determinable by close observation of the peel during processing or by determining moisture content of peel samples as by the toluene distillation .method.

The vegetable oils which are usable are preferably those that are normally liquid Including the mentioned soybean and coconut oils, as well as cor oil, peanut oil, cottonseed oil, rice oil, a specially prepared ell known by the trade name Durkex 500, and even the highl unsaturated safflcwer oil. Hydrogenated shortenings such as Crisco may also be used. Although it would seem that relatively unstable triglyceride oils such as soybean and coconut oils, that are normally considered to be oxidation-prone, would not be satisfactory, I have made the surprising discovery that citrus peels dehydrated in such oils have, unexpectedly, a very good storage life. A further discovery is that soybean oil which is subject to flavor reversion is superior to cottonseed oil and that coconut oil yields products even more stable with a storage life of a year or more.

For extra storage life, small amounts of food antioxidants, up to about 0.02,¾, may be added to the oils, such as butylated hydroxy anlsole (BHA ) and butylated hydroxy toluene (EHT).

Usable citrus peels include the following, namely, lemon, navel orange, Valencia orange, grapefruit, tangerine, and even lime and tangelo peels, in a · fresh raw condition. The peels are subdivided into suitable sizes for processing, such as quarters, eighths,, strips, and diced and shredded portions as desired. Other fruits as previously mentioned may be used. The finished product, whether dehydrated only or also impregnated with the hardening, stabilizing and preserving glycol-sugar syrup, may be further subdivided as in a hammermlll (Fitzmill ) to reduce to small "bite" sizes for cakes and other baked goods, or' it may be still further reduoed as by grinding to condimen or. spice size such as in the range of ten to twenty raesh and then if desired additionally tumbled with a suitable antl-caklng agent such as starch, magnesium carbonate, diatomaceous earth, etc., to yield a free-flowing . product.. During grinding, contact of the peel with such metals as iron or copper should be avoided as the peel may become off-colored.

With respect to using the impregnating preserving syrup on the dehydrated fibrous fruit, whether citrus peels or other fruits previously mentioned, such as apples, pomes, cranberries, pineapple, coconut meats, and the like, these syrups impart maximum utility and stability, and later facilitate rehydration to yield a product having good "mouth feel,! or "bite" when added to cakes and the like. The presently preferred impregnating syrup is 50S dextrose dissolved in 50» hot glycerol. Alternatively, dextrose (about 58j¾) ■dissolved in hot propylene glycol (about 42>¾) may be used but is le≤s desirable, particularly with respect to flavor. Again, a molten solution of dextrose monohydrate heated to dissolve in its own water of crystallization or in a genera lly corresponding small amount, say to 20 ,of edible polyol such as glycerol, propylene glycol, or 1, 3-butanediol may be used.

Other sugars that may be used at least in part include sucrose, maltose, lactose, fructose and corn syrup solids.

Several other important functions of the impregnating sugar-pol ol syrup are: 1. The residual vegetable oil level in the ' dehydrated peel is lowered by displacement during impregnation; 2. The semi-solid syrup acts along with the vegetable oil to prevent loss of essential volatile oils remaining in . he peel as well as the possible development of terpiness or rancidity. Chemical te3 3 for peroxide number indicates that the. esidual vegetable oil in dehydrated peel Is well protected against rancidity by the impregna ion process. 3. Protects the colored peel carotenolds and xanthcphylls from oxidative breakdown that yield products of poor odor and flavor having straw-like character 4. Improves the color of the dehydrated peel pieces by rendering them semi-translucent; . Imparts humectant properties making the dried peel softer and more quickly and easily reconstituted than horny air-dried pieces.

For use in many convenience foods, quick _,· . reconstitutlon is a "must" for 3ucces . 6. The presence of the pblyol protects against mold growth should moisture exceed about 10 .

Upon reconstltution or rehydration with water, the dehydrated peel pieces swell. to their original volume or larger as compared with raw peel. This is unexpected since dehydrated pieces of peel generally never swell to equal their original volume. In general, one pound of dehydrated peel (with or without impregnation with polyol-sugar syrup) is equivalent to ove three pounds of rebydrated peel. Reconstltution in sugar syrups, such as sucrose, may bring the product to over four pounds.

By the present process, it is possible to up-grade citrus peel, as well as other fruits mentioned, to a tasty nutritious product for human consumption, where the original material normally would have been used for making dried cowfeed. The color of the peel product is that of the natural carotenoids. The peel product, although dehydrated in a hot oil bath to a relatively low moisture content, surprisingly retains appreciable amounts of the heat-labile vitamin C ,. in a range of about 130 to 160 mg per 100 gms of the dehydrated peel. Wo dehydrated peel materials commercially available are known that contain more than trace amounts of vitamin C.

.An important feature is that the dehydrated peel pieces upon rehydration become uniformly soft for use in baked goods and the like, without offering the usual problem of hardened lumps resulting from drum or air drying. Although the mechanism is not apparent, we have observed that peel dehydrated In the presence of hot oil has quite different characteristics from peel dried by any other means. Conceivably, this unexpected favorable result may be due to the rupture of fibrous bonds within the peel because of the almost explosive release of steam from the interior of the peel during dehydration. Peel products as herein described reconstitute in water quickly and uniformly without hard lumps or case-hardened pieces. Since the product may be provided in any desired size and shape it is usable for cake and cookie mixes, fruit cakes, and pies, as well as for icings, and being reducible to condiment size it may be applied from shaker top dispensers, and may also be ( sprayed with or dipped in melted glyceryl monostearace' or other liquid or semi- • liquid material to produce non-tacky superior coatings.

The examples heretofore furnished disclose procedures which are somewhat different in some respects and which yield somewhat different products. Also, a given weight of lemon peel yields an appreciably smaller weight of product than does orange peel. Similarly, there are weight variations in the other fruits mentioned. Again, the residual water content of the impregnated fruit sclidsis usually smaller than that - which Is only hot-oil treated. Thus, the latter, as appears from the examples, may have a moisture content of around 8·¾ to whereas the impregnated product may have a moisture content of only 5 to 6%. - Again* these products may vary greatly in the relative proportions of oil to moisture-free fruit solids. Thus, while often it is deemed preferable to have a lower vegetable oil content than dry fruit-solids content, such as one part oil to two and one-half or three parts fruit solids, it is feasible sometimes that these proportions be reversed so that there is more oil than solids. Further, there might be as little as one part dry-base solids to four or five parts oil, depending upon the use to which the product Is to be put.

Also, the polyol-sugar content of impregnating hardenable material is commonly considered optimum when it amounts to about cne-half the impregnated product, but this may be varied rather widely as to a given composition or from compos itior; to composition, which composi ions may include others than those mentioned, although in general of similar type, as obvious to the chemist and the confectioner.

In order the better to indicate ranges which are signified above, tables are given below which provide specific examples as well as ranges usable for the various materials. While these have been selected primarily from the standpoint of citrus peel solids, they are also to be considered as generally representative of the other fruits mentioned.

Typical Compositions of Citrus Peel Products Dehydrated in Hot Vegetable Oils Impregnated Specimens II III IV Range Parts Parts Vegetable Oil 26/ 45/ 37/ = 1¾¾ to 80/ Peel Solids 66/ 45/ 6 "j¾ - 3 80/ 18/ Water Content 8/ 10/ 3/ 1¾έ Peel Impregna ed in Hot Polyol-Sugar Syrup Specimens A B C D K Ra ge Vegetable Oil 13;i 13/ 9/ 0-S 18/ 9/ to 40/ Peel Solids 33/ 33/ 40/ 9/ 27/ 40 9/ Wa er 5/ 5/ 7/ 5/ 5/ 3/ 10/ Glycerol 24/ 22/ 5/ 20/ to 30 Dextrose 25/ 22/. 5/ 2a/ 30/ Dex rose 28/ 24/ 25/ to 35/ Propylene Glycol 21/ 2 / 18/ 25/ As indicated by the above tables, in products not impregnated by polyol-sugar mixtures, the oil to solids ratio- may often be one part oil to about 2.5 parts fruit solids, or two parts oil to three parts solids, the latter being a hO%> to oOjo ratio. Again, these ratios maybe reversed when much higher oil relationships are desired. These oil to fruit solids ratios exist also in the polyol-sugar impregnated products. In the latter it is generally preferred that the sugar lmpregnant be approximately half the product, but the impregnant might be much less, such as one-fourth the product, according to the amount of stabilizing and bodying material needed or desired. It might also be somewhat greater than one-half if desired to improve body or flavor characteristics or the like.

Thus, the various percentages and proportions given are not critical even though optimum. Further, where relatively minor percentages might be indicated, these may be enlarged with respect to other constituents.

This applies especially to flavor-fixative agents such as the mentioned polyol-sugar mixtures, in connection with which almost any proportion may be used which will control oxidation and volatility of the essential oils of the fruit solids, for example, sucrose and glycerol with lemon peel where the sucrose might range from 20 to 80 of the Impregnating agent. Also, the various Impregnating agents may be used for the Indicated . purposes even though dehydration to the Indicated low molBture range may have been attained by other means (such as hot air drying under vacuum). This will apply, for example, to the Indicated use of glyceryl monostearate alone for the preparation of a dry free-flowing condlment-llke material wherein the dehydrated lemon peel or the like Is sprayed with or dipped in melted glyceryl monostearate as heretofore mentioned.

Claims (9)

1. CLAIMS 1. A dehydrated edible fibrous fruit product including: dehydrated firm fibrous fruit portions from the class Including citrus peel, pomes, pineapple, coconut, and the like and having a water content less than about 15$ by weight, and an edible water-displacing vegetable oil carried in the fibrous fruit solids.

2. A product as n claim 1 Including a hardened dextrose-containing composition impregnating the dehydrated oil-containing fruit solids.

3. A product as In claim 1 Including a solid dextrose-containing impregnating composition approximating the weight of the oil, fruit solids, and water content remaining in the fruit solids.

4. A dehydrated citrus peel product having a water content less than about 12$ by weight, and an edible water-displacing vegetable oil Impregnating the peel solids.

5. A product as in claim 4 containing a hardened impregnating composition including a sugar. 30895/2

6. A product as in claim 4 containing a solidified impregnating preserving composition Including dextrose.

7. A product as in claim 6 wherein the impregnating composition contains polyols, and the water content does not exceed about 10%.

8. A methof of dehydrating raw fibrous fruit portions including immersing the raw fruit portions in hot vegetable oil above the boiling point of water at atmospheric, pressure for a time t boil of a major portion of the atural water content, then subjecting the hot batch to vacuum to reduce the natural water in the fruit portions to less than about 15% water content, removing the hot residual oil, breaking th3 vacuum, and recovering the oil- ... containing fruit. A method of dehydrating fruit portions as in claim γ, and the. additional step of immersing the dehydrated portions under vacuum in a hot sugar- containing syrup to effect impregnation, and removing excess syrup, the syrup being hardenable at atmospheric temperature. (0 l-i. ' A method for preparing a stable dehydrated citrus peel food product, including immersing raw citrus peel in a hot vege able . oi 1 above the boiling point of water for a . ime to boil out the major portion of the natural water content and replace it with the hot oil, subjecting the hot batch to vacuum to further reduce the water to lose than about 15 , breaking the vacuum, separating the hot oil, and recovering the dehydrated peel. Π tS. A method of preparing a citrus peel product JO a3 in claim H, and the additional procedure of immersing the .dehydrated product in a hot bath of . a sugar-containing composition under vacuum to impregnate the peel, the sugar composition being hardenable at atmospheric temperature to impart a stabilizing body to the product, and recovering the impregnated dehydrated product. A methodas in claim ¥t wherein the citrus peel is lemon peel and the peel is treated before dehydration in an aqueous solution containing a minor proportion of stannous chloride to control discoloration. A dehydrated citrus peel product having a . water content less than about l ;l by weight, and a water-displacing vegetable oil, the oil being soybean oil. /Ιγ ¾τ5~- A product as in claim 7 wherein the polyol is glycerol. I^HT A dehydrated edible fibrous fruit product having a water content less than about 1 , and an edible water-displacing dehydrating oil, the oil and the fruit solids each being present in. a ratio between abou '20;ί and 6θί based on the oil-solids content.. if ^¾ Irf. A dehydrated fruit product as in claim 3r6 wherein the oil and water-free fruit solids are present in the proportion cf about cne to two parts of oil to one to .three parts cf dry fruit solids. A dehydrated fruit - product as in claim t6 containing an impregnating hardened polyol-sugar composition generally a proxima ing half the total composition. 30895/2 18. A dehydrated citrus peel product having a water content less than about 15% by weight, and a water-displacing hydrogenated vegetable fat. 1

9. A dehydrated citrus- peel product having a water content less than about 15%, and a hardened flavor-fixing and stabilsing agent in the form of glyceryl monostearate impregnating the fruit solids. 20. , , , A dehydrated citrus peel product having a water content less than about 12% and a hardened flavor- fixative and stabilizin agent selected from the group consisting of polyol-sugar compositions and vegetable fats and mixtures thereof, impregnating the fruit solids. AGENTS FOR APPLICANTS