GB1597550A

GB1597550A - Process for preparing precooked potatoes

Info

Publication number: GB1597550A
Application number: GB23999/78A
Authority: GB
Original assignee: US Department of Commerce
Current assignee: US Department of Commerce
Priority date: 1977-06-03
Filing date: 1978-05-30
Publication date: 1981-09-09
Also published as: FR2392609B3; IT7868283A0; IT1109696B; FR2392609A1; NL7806045A; DE2822964A1; BE867655A

Description

(54) PROCESS FOR PREPARING PRE-COOKED POTATOES (71) We, UNITED STATES DEPARTMENT OF COMMERCE, a Department of the United States Government, of 5285 Port Royal Road, Springfield, Virginia, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to and has among its objects the provision of novel prepared potato products and methods for making them. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified.

Many homes and restaurants take pride in serving baked potatoes with certain meat dishes such as steaks, chops, fish, chicken, and the like. Basically, these baked potatoes are prepared by placing raw whole potatoes in a hot oven and maintaining them therein until they are properly baked. Although this time-honored method yields a completely satisfactory product, it possesses certain disadvantages. A primary consideration is that the baking process is slow, requiring about 1 hour for an 8 oz. potato and correspondingly longer for larger tubers. The demands of present day American life require a shorter-cooking baked potato product with a flavor and texture equivalent to that obtained through the lengthy baking process. In restaurants baked potatoes must be prepared in advance and cannot be prepared for individual orders as they arise because of the lengthy baking procedure. Accordingly, it is conventional practice to bake a sizeable lot of potatoes and then hold them in a warming oven or the like as individual orders are filled. With this system, those guests whose orders are filled shortly after the baked potatoes are prepared receive a tasty and flavourable dish; those who come in later are disappointed with a product that is stale, dried out and shriveled.

At present there are a limited number of frozen, prepared baked potato products. One such product consists of a peeled, whole potato that is frozen and is designed to be used as a boiled or baked potato. This product contains many additives to maintain its color and appearance and, as a result, has a flavor not typical of a freshly baked product.

Another prepared baked potato product consists of a potato mash, with seasonings, placed in a shell of metallic foil such as aluminium foil. The potato mash is usually prepared from reconstituted dehydrated potatoes, which contain a number of preservatives. The resulting product does not possess the natural flavor and texture of a freshly prepared baked potato.

The problem facing the industry can be summarized as follows: A potato which is pre-cooked, frozen, thawed, and then baked does not hold its texture. Generally, a potato treated in this way has a wet, soggy interior, rather than a dry, mealy one, which is desirable. Low- solids potatoes are more susceptible to this condition than high-solids potatoes, but even the latter cannot be prepared as described above for baking.

According to the invention there is provided a process for preparing pre-cooked potatoes, comprising washing raw whole potatoes, subjecting the whole potatoes to two partial cooking stages using steam or hot water as cooking medium, in which, when the same cooking medium is used for both partial cooking stages either of the partial cooking stages is at a temperature above that at which sloughing of the potato surface would occur if the potatoes were cooked to their centers at that temperature and the other partial cooking stage is at a lower temperature, or when a different cooking medium is used for each of the partial cooking stages, both stages are at a temperature above that at which sloughing of the potato surface would occur if the potatoes were cooked to their centers at that temperature, and then heating the cooked potatoes in air.

The prepared potato product can be finish-cooked to yield a baked potato with excellent flavor, texture, and appearance. In the process of the invention raw potatoes are cooked to their centers without damage to their surface tissue.

The pre-cooked potatoes may be frozen or chilled to preserve them.

The method of the invention can be applied with equal success to both high and low-solids potatoes. The finish-baked product of the invention has the characteristics of a freshly-baked potato, but can be prepared in a much shorter time.

Another advantage of the process of the invention is that it can be applied to numerous varieties of potatoes. Thus, these varieties are available to the baked potato industry whereas otherwise they would not be.

Another advantage of the invention is that it can be applied to both peeled and unpeeled potatoes. The ability to leave the skin on the potato gives rise to certain advantages such as higher retention of flavor and nutritional components, reduction in biological oxygen demand (B.O.D.) of waste effluents, and the like.

Another advantage is that the potatoes of the invention do not shatter during freezing, especially during blast freezing. Consequently, the loss of valuable potato material due to such shattering is avoided.

Another advantage of the invention is that additives are not necessary to improve the texture; thus, the finished product is free from such chemical agents which can affect the flavor of the product and the well-being of its consumers.

A further advantage of the process of the invention is that the pre-cooked potatoes may be fried, rather than baked, prior to being consmed. This is an important advantage of the present process. First of all, pre-cooked frying potato products, such as hash browns and pan-fries can be prepared from both high and low-solids potatoes using the method of the invention whereas only high-solids potatoes can be used for making such products according to current technology. Secondly, even though high-solids potatoes can be employed under the present state of the art to make pre-cooked frying potatoes, such potatoes require an extended drying time of about 3 to 5 days at refrigeration temperatures in order to allow then to be thin-sliced or shredded. Potatoes prepared in accordance with the process of the invention can be cut into thin pieces, i.e., shredded or thin-sliced, after chilling at a temperature of about 0.5 to 4.50C. for only 1.5 to 4 hours, and are then fried in edible oil to make them ready for consumption. Fried potatoes that can be prepared in this manner include hash-brown potatoes and pan-fried potatoes. It is important to note, however, that the potatoes of the invention cannot be used to prepare French-fried potatoes or shoestring potatoes.

As mentioned above, in the process of the invention whole potatoes are subjected to a cooking procedure followed by a heating in air. In order to prepare a pre-cooked baking potato product, a potato must be cooked to the center. In addition, the potato must at some time be cooked at a temperature above that at which sloughing of the potato surface occurs, which is usually in the region of 81"C to 830C. The problem is that, if the entire cooking process is conducted above such a temperature in the same medium and the potato is cooked to the center at this temperature, the surface of the so-prepared potato becomes cracked and easily sloughs off valuable potato tissue. The above problem cannot be rectified by treating unpeeled potatoes, for they also exhibit similar detrimental surface characteristics under such cooking conditions. Furthermore, if the potatoes are cooked to the center at a temperature below about 81 to 830C., suitable pre-cooked baking potatoes are not obtained. This is so even if the cooking time is extended well beyond that needed to cook the potatoes to their centers.

We have found that excellent pre-cooked potatoes can be prepared by employing the process mentioned above wherein two cooking steps form the cooking procedure.

Preferably the first and second treatment stages are at a temperature in the range 60"C to 100"C for a period in the range 5 to 45 minutes, the temperature of either the first or the second treatment stage is greater than 81"C, and if the temperature of the first stage is greater than 81"C, then the second stage is at a temperature less than 81"C or uses a cooking medium different from the first stage.

After application of the cooking steps the potatoes are heated in air at a temperature preferably in the range 66" to 93"C. for a period in the range 5 to 20 minutes.

It should be noted that the use of a double cooking technique followed by a heating in air is totally unexpected and unobvious. Particularly, it is not obvious that the potatoes at some point must necessarily be cooked above a temperature of about 81-83"C. and that cooking the potatoes to their centers would not be sufficient. However, we have found that the potatoes must be cooked for a part of the time at a temperature in excess of 81-83"C. in order to yield a pre-cooked baking product which upon finish-baking exhibits a dry, mealy interior characteristic of a baked potato. If this cooking step is eliminated, the finish-baked product is wet and mushy.

The pre-cooked baked potato products are preferably prepared by application of the following steps: 1. Raw potatoes, either peeled or unpeeled as desired, are washed and then subjected to a first cooking. The temperature and length of this cooking step are dependent upon the size of the potatoes to be treated. Potatoes that are suitable for baking have a diameter of about 2.5-5.0 centimeters. In the first cooking step the potatoes are treated with either water or steam at a temperature of about 60-100 C. Generally, the duration of the first cook is about 5 to 45 minutes. The usual mode of cooking the potatoes in water involves immersing the potatoes therein at the proper temperature. Alternatively, steam can be applied to the potatoes at the desired temperature and at atmospheric or superatmospheric pressure. It must be emphasized that the duration of this cooking step is dependent upon the size, maturity, and type of potato used. Exact condition for a particular lot of potatoes can be determined using pilot trials.

2. Following the first cooking step the potatoes are subjected to another cooking step.

It is an important feature of either the first or the second cooking steps that the surface tissue of the potatoes not be damaged by overcooking, a state which leads to cracking of both the potato peel itself or, if the potato is peeled, of the surface tissue. To avoid overcooking, we have found that it is desirable that the second cooking step be carried out according to the following rules: If the first cooking step is conducted at about 60"C to 80-82"C., then the second cooking is carried out at temperatures above 81-83"C., i.e., 82-100"C. The cooking medium can be either water or steam and the duration of the cooking is about 5-45 minutes.

On the other hand, if the temperature employed in the first cook is above 81-83"C., then the second cook must be conducted in either of two ways. In one embodiment of the invention the partially cooked potatoes are treated with water or steam at a temperature of about 60"C to 80-820C. for a period of about 5-45 minutes. Alternatively, the second cooking stage is at a temperature above 81"C with the proviso that the cooking medium not be the same as in used in the first stage. Thus, if steam is used in the first cooking stage water must be used in the second stage. However, if water is employed in the first stage, the potatoes must be treated with steam in the second cooking stage.

3. The potatoes are next heated (dried) in air preferably at a temperature of about 66 to 93"C. for about 5 to 20 minutes. During this period the moisture content of the potatoes is generally reduced by 1% to 15%, depending on the temperature, the time, and the size, type and nature of the potato, i.e., whether the potato is peeled or unpeeled. The heating step is critical to the method of the invention. By application of heat the retrogadation of starch is promoted. Further, the texture of the final product is enhanced. The removal of water from the surface tissue avoids cracking of the surface when the product of the invention is fast-frozen. However, although it appears that the reduction of moisture content is responsible for the improved texture, it may be that the important feature is solely the application of heat regardless of the extent of moisture removal. In any event the heating step must be employed to obtain a good quality potato product.

4. Following the heating step the potatoes are treated to preserve them. Usually, the pre-cooked potatoes are frozen and then packaged for retain sale or institutional use. The potatoes can be frozen in any conventional manner including refrigeration rooms, blast freezing, and the like. Alternatively, the prepared product can be chilled at about 0.5 to 4.5"C. to preserve them for future use.

To prepare them for consumption the products of the invention are simply heated or baked to the desired internal mealiness. In general, a frozen product is baked for a period of about 30 to 45 minutes at a temperature of about 177 to 232"C whereas a chilled product is baked for about 20 to 30 minutes at the same temperature. It should be remembered, however, that the baking time will vary with the size of the potato. The finish-baked product has the appearance, flavor, and texture of a freshly-baked potato.

Alternatively, the products of the invention, after chilling for about 1.5-4 hours, may be thin-sliced or shredded and then frozen or chilled to preserve them. The product is fried in oil, either on pans or grills or in a deep-fat fryer, at about 150 to 1900C for about 5 to 20 minutes or until they are ready for consumption.

The product prepared in accordance with the procedures of the invention must be baked or fried in order to consume it. If the pre-cooked potatoes are boiled, they disintegrate into pieces and are totally unacceptable as a consumable item. Thus, the present process is specific for preparing a baking or frying potato product.

The invention is further demonstrated by the following illustrative examples. Some of the experiments are not in accordance with the invention but are provided for purposes of companson.

Example I Raw potatoes (White Rose, 3.5 cm. in diameter) were washed but not peeled. The whole potatoes were then subjected to two cooking steps followed by a heating period at varying times and temperatures. The so-treated potatoes were examined and then frozen by blast-freezing. The frozen product was baked for 30 minutes at 2180C. The experiments and results are summarized in the following table.

First Cook Second Cook Heat Weight Quality of surface Temp Time Temp Time Temp Time loss after blast Run Medium ( C) (min) Medium ( C) (min) ( C) (min) (%) freezing Quality after bake 1 Water 100 10 Steam 100 10 66 15 2.0 No cracking Dry, mealy, skin intact 2 Water 100 15 Steam 100 10 66 15 2.1 Beginning to crack Dry, mealy and slough 3 Water 100 10 Steam 100 15 66 15 1.9 Excellent, no Dry, mealy, excellent cracking flavor and appearance 4 Water 100 10 Steam 100 10 93 10 3.0 Excellent, no Dry, mealy, excellent cracking flavour and appearance 5 Water 100 10 Steam 100 10 93 15 4.0 do. do.

6a Water 71 30 Steam 100 15 66 15 2.1 No cracking or Dry, mealy, excellent sloughing appearance, best flavor of all 7b Water 100 10 Steam 100 10 - - - Cracking Wet, mushy, poor appearance a Russet Burbank, 3.5 cm, in diameter. b Not in accordance with the invention.

Example 2 Raw, whole potatoes (White Rose, 3.5 cm. in diameter) were washed, peeled, and treated as described in Example 1. The results are summarized below.

First Cook Second Cook Heat Weight Quality of surface Temp Time Temp Time Temp Time Loss after blast Run Medium ( C) (min) Medium ( C) (min) ( C) (min) (%) freezing Quality after bake 1 Water 100 10 Steam 100 10 66 15 8.6 No cracking Dry, mealy, excelent color and flavor 2 Water 100 15 Steam 100 10 66 15 7.8 Beginning to crack Dry, mealy and slough 3 Water 100 10 Steam 100 15 66 15 - No cracking or Dry, mealy, excellent sloughing flavor and appearance 4 Water 100 15 Steam 100 15 66 5 - Beginning to crack Dry mealy, excellent and slough flavor, cracked appearance 5 Walter 77 30 Steam 100 10 82 15 - No cracking or Dry, mealy, good sloughing flavor and appearance 6 Water 77 30 Steam 100 15 82 15 - No cracking or Dry, mealy, fair sloughing flavor, good appearance 7 Water 100 10 Steam 100 15 66 15 8.5 Excellent Dry, mealy, excellent appearance flavor and appearance 8 Water 100 10 Steam 100 10 93 10 10.1 do. do.

9a Water 71 30 Steam 100 15 66 15 8,0 No cracking or Dry, mealy, ecxcellent sloughing flavor and appearance, best flavor of all 10 Water 83 15 Steam 100 7 66 15 7.9 Firm texture do.

First Cook Second Cook Heat Weight Quality of surface Temp Time Temp Time Temp Time loss after blast Run Medium ( C) (min) Medium ( C) (min) ( C) (min) (%) freezing Quality after bake 11 Steam 83 15 Water 100 7 66 15 7.9 do. do.

12a Water 71 30 Water 100 15 66 15 8.1 No cracking Dry, mealy, bland flavor, fair appearance 13a Water 71 30 Water 82 20 66 15 - do. do.

14a,b Water 71 30 Steam 100 15 - - - Cracking Wet, mushy, poor appearance 15b Water 100 15 Steam 100 10 - - - Cracking and sloughing Wet, mushy 16b Water 100 5 Steam 100 10 66 15 8,0 Uncooked Uncooked 17b Water 100 10 Steam 100 5 66 15 - do. do.

18b Water 71 30 Steam 71 30 66 15 - No cracking Wet, mushy, poor appearance 19b Water 90 15 Water 100 15 66 15 - Cracking Dry, mealy, poor appearance 20b Water 100 20 - - - - - - Cracking and sloughing Wet, mushy 21h Steam 100 20 - - - - - - Cracking ans sloughing Wet, mushy a Russet Burbank, 3.5 cm in diameter. b Not in accordance with the invention.

Claims

WHAT WE CLAIM IS:

1. A process for preparing pre-cooked potatoes, comprising washing raw whole potatoes, subjecting the whole potatoes to two partial cooking stages using steam or hot water as cooking medium, in which, when the same cooking medium is used for both partial cooking stages either of the partial cooking stages is at a temperature above that at which sloughing of the potato surface would occur if the potatoes were cooked to their centers at that temperature and the other partial cooking stage is at a lower temperature, or when a different cooking medium is used for each of the partial cooking stages, both stages are at a temperature above that at which sloughing of the potato surface would occur if the potatoes were cooked to their centers at that temperature, and then heating the cooked potatoes in air.

2. A process according to Claim 1, wherein each partial cooking stage is at a temperature in the range 60"C to 1000C for a period in the range 5 to 45 minutes, the temperature of either partial cooking stage is greater than 81 C, and the other stage is at a temperature less than 81"C or uses a different cooking medium.

3. A process according to Claim 2, wherein the partial cooking stages comprise firstly treating the raw whole potatoes with water at a temperature greater than 81 C, and then treating the potatoes with steam at a temperature greater than 81"C.

4. A process according to any one of Claims 1 to 3, wherein the potatoes are peeled prior to cooking them.

5. A process according to any one of Claims 1 to 4, wherein heating of the cooked potatoes is in air at a temperature in the range 66"C to 930C for a period in the range 5 to 20 minutes.

6. A process according to any one of Claims 1 to 5, wherein the potatoes, after the heating in air, are treated by freezing or chilling to preserve them.

7. A process according to Claim 6, wherein the potatoes are chilled at a temperature in the range 0.5"C to 4.50C for a period of from 1.5 to 4 hours.

8. A process according to Claim 7, wherein the chilled potatoes are cut into thin pieces or shredded.

9. A process for preparing pre-cooked potatoes, substantially as herein described in any one of runs 1 to 6 of Example 1.

10. A process according to claim 1 for preparing pre-cooked potatoes, substantially as hereinbefore described in any one of runs 1 to 13 of Example 2.

11. Pre-cooked potatoes prepared by a process according to any one of Claims 1 to 10.