GB2116415A - Improved rapid cooking foodstuffs - Google Patents

Abstract

A rapid cooking food product, especially a rice or a pasta is produced by treating the food product with a starch degrading enzyme under starch degrading conditions. The enzyme is an enzyme which attacks either the 1,4-glucoside links or the 1,6- glucoside links in the starch molecules and is preferably ???-amylase or pullulanase or a mixture thereof. Rice that can be cooked merely by pouring on boiling water and leaving it to stand can be produced by the process.

Description

SPECIFICATION Improved rapid cooking foodstuffs This invention relates to rapid cooking foodstuffs, for example starchy cereal grains such as rice, wheat, oats, etc., and flour products such as pastas.

Numerous attempts have previously been made to produce a form of rice that cooks in a considerably shorter time than that which is normally required for cooking rice, whether it be husked, dehusked, milled, unmilled, parboiled or non-parboiied rice. The majority of these attempts have revolved around disrupting the structure of the rice grain to allow easy and rapid access of cooking water into the grain. These methods which have normally been either mechanical or physical have for example involved crushing or flaking the rice grains, expanding or puffing the rice grains by heating water contained therein under pressure then rapidly releasing the pressure, or producing surface cracks in the grains by drying them.It has also been proposed to produce a fast cooking rice by steeping rice grains in water or a chemical solution, for example sodium chloride, for a substantial period prior to drying.

These prior methods have produced fast cooking rices that differ in terms of speed, convenience of preparation, organoleptic characteristics of taste, texture and mouthfeel, appearance in the dry and cooked form and the presence of chemicals in the end product.

It is particularly desirable to produce a satisfactory rice product that can be cooked merely by covering the rice grains with boiling water.

This invention provides a process for producing a rapid cooling starchy foodstuff such as, for example, cereal grains and pasta, which comprises subjecting the foodstuff to the action of one or more starch degrading enzymes under starch degrading conditions.

The starch degrading enzymes are those that attack the 1 ,4-glucoside links or the 1,6glucoside links. As examples of those enzymes that attack the 1 ,4-glucoside links there may be mentioned a-amylase (an endoamylase), p- amylase (an exoamylase) and amylomaltase, which enzymes have the enzyme Numbers 3.2.1.1., 3.2.1.2., and 2.4.1.3., respectively. As enzymes that attack the 1 6-glucoside links there may be mentioned pullalanase, isoamylase and dextrine-1 ,6-glucosiddase, which enzymes have the Enzyme Numbers 3.2.1.41., 3.2.1.68., and 3.2.1.33, respectively. These enzymes all serve to degrade the starch granules in the starchy foodstuff by breaking the linkages in and between the individual starch moiecules of the starch granule.

The enzymes, for example those described hereinbefore may be used singly or in combination but preferably amylase or pullulanase or a mixture thereof are used.

The enzymes are usually operative at a temperature within the range of from about 200C to 1 200C and can be used under pH conditions ranging from approximately 3 to 9. Individual enzymes of a given type, however, depending on their source, will normally operate at optimum efficiency under fairly narrow process conditions within the ranges specified, these conditions normally being specified by the manufacturer.

The enzymes may be used in any concentration above the minimum concentration at which the enzyme activity is so slow as to be negligible but is preferably not used in a concentration of more than 30 thousand enzyme units per kilogram of foodstuff to be treated although this is merely an economic limit since concentrations greatly in excess of this could be used without producing any advantage.

Preferably the concentration of enzymes used is such that the enzyme treatment to produce a desired product can be continued for a period within the range of from 5 minutes to 24 hours, preferably from 30 minutes to 4 hours.

The period of exposure to the enzyme is related to the concentration of enzyme used and is primarily determined by the amount of degradation required, the higher the concentration of enzyme the shorter the period of exposure needed to achieve a given degree of degradation. The treatment is carried out until a desired proportion of the links in and between the individual starch molecules forming the starch granule are broken. The exact proportion desired to be broken depends on the nature of the product desired but it is necessary to strike a balance between the desired rapid cooking time and the need to retain the desired organoleptic and other characteristics of the product. After treatment the product is dried to a moisture content at which the product has adequate stability against spoilage to enable satisfactory packaging, storage and distribution.

If desired, enzyme activity can be removed at any one of several stages following the action of the enzyme on the starch grains by the use of conventional techniques, e.g. pH adjustment and raising to high temperatures.

Rice grains to be treated according to the invention may be in any form such as for example, paddy, cargo, brown, white or parboiled rice grains. Other cereals that can be treated are for example wheat and oats, and cereal flour products such as pasta, for example marconi and spaghetti.

It is possible to combine the enzyme treatment of the invention with a parboiling treatment of paddy or cargo rice whereby the enzyme is added to any steeping stage of the various parboiling processes.

If it should be desired to obtain extremely rapid contact of the enzyme with the centre of the cereal product, especially when rice is treated, it is possible to subject the grains to a conventional technique such as vacuum infiltration and/or rolling to produce cracks in the surface of the grain.

Although the enzyme treatment alone produces a product that can be cooked very much more quickly than the corresponding untreated product, (in the case of rice, for example, the cooking time can be reduced to 6 minutes or less) the cooking time of the foodstuff can be considerably further reduced if, during or after the enzyme treatment, the foodstuff is contacted with an electrolyte, especially a common food approved electrolyte such as, for example, sodium or potassuum chloride or sodium or potassium iodide or sodium glutamate.

Very quickly cooking can be achieved by heating the product after the enzyme treatment, for example for a period of about 5 minutes in water with or without an electrolyte such as one of those described above.

The treatment of the invention in addition to providing a rapid cooking foodstuff, for example rice that can be cooked in under 10 minutes and especially in under 5 minutes and more ideally can be cooked merely by pouring boiling water over the grains, also provides a rice with a lower starch content per rice grain and which may therefore be described as being a "diet rice".

The following Examples illustrate the invention.

In the Examples the references to "enzyme units" are references to the amount of enzyme that under standard conditions has a standard effect.

In the case of pullulanase the standard conditions are that on 2% pullulan concentration and a temperature of 450C, pH 7.0 and over a reaction period of 30 minutes one enzyme unit hydrolyses pullulan liberating reducing carbohydrate with a power equivalent to 1 micromole of gluclose per minute. For emylase the enzyme unit is defined as the amount of enzyme that breaks down 5.26 grams of soluble starch per hour under standard conditions of temperature 37 0C pH 5.6 and calcium 0.0043 m. All the enzymes used in these Examples are obtained from NOVO Industri A/S.

The pH in all the following examples was approximately 6.5 but no attempt was made to control the pH.

Example 1 100 gram of parboiled rice was soaked for 4 hours at 300C in 500 mls. of water containing 7.5 grams (6000 enzyme units) of powdered pullulanase. Preferably throughout the soaking period the mixture was stirred. At the end of the soaking period the excess liquid was drained off, at which time the hydrated rice has a weight of 212 grams. The rice was then dried to a moisture content at which the product was stable, that is to say to a water activity (Aw) less than 0.5. Rice produced by this process could be cooked in boiling water within 10 minutes and the cooked rice showed no tendency to clumping, being fluffy and consisting of separate grains.

Example 2 200 grams of parboiled rice was soaked for 2 hours at 450C in 1 litre of water containing 4,800 units of pullulanase and 720 units of bacterial a- amylase. At the end of the period of incubation 20 grams of salt was added and the mixture boiled for 5 minutes. The excess water was drained off and the rice dried overnight at 30 C to an AW < 0.5. The product could be rehydrated and made ready for eating by pouring on boiling water and leaving to stand for 3-5 minutes.

Example 3 200 grams of parboiled rice was soaked for 2 hours at450C in 800 ml of water containing 4,800 units of pullulanase and 1,200 units of fungal a-amylase. The mixture was incubated with stirring. At the end of the period of incubation 20 grams of salt was added and the mixture boiled for 2 minutes. Excess water was drained off and the rice dried at 300C for 24 hours to an AW < 0.5. The rice could be cooked by adding boiling water and leaving to stand for 5 minutes.

Example 4 200 grams of parboiled rice was soaked for 2 hours at 450C in 800 ml of water containing 1,200 units of bacterial a-amylase. At the end of the period of incubation 30 grams of salt was added and the mixture boiled for 5 minutes.

Excess water was drained off and the rice dried at 30 C for 24 hours to an AW < 0.5. The rice could be cooked by pouring on boiling water and leaving to stand for 3-5 minutes.

Example 5 Three examples of wheat were taken:- 1. Was soaked overnight at room temperature.

2. Was parboiled for 1 T hours.

3. Was not pretreated.

Samples 1 and 2 were dried overnight at 4O0C. 200 grams of each sample were soaked in 800 ml of water containing 4,800 units of pullulanase and 1,200 units of bacterial aamylase for 2 hours at 450C. A the end of the incubation period 20 grams of salt was added to each sample followed by boiling for 5 minutes.

The samples were dried overnight at 400C. The cooking times were: 1.1+ hours.

2. 45 minutes.

3. 1 hour.

Untreated wheat had to be cooked for 1 T hours to reach a similar texture.

Example 6 200 grams of spaghetti was soaked for 20 minutes at 450C in 800 ml of water containing either 1. 4,800 units of pullulanase and 600 units of bacterial -amylase, or 2. 1,200 units of bacterial amylase.

At the end of the incubation period the spaghetti was dried in a fluid bed drier at 5O0C.

Each spaghetti produce was cooked after 3 minutes in boiling water.

Example 7 Example 2 was repeated except that milled non-parboiled rice was used and the boiling period was reduced to 1 minute. The product could be cooked in less than 5 minutes in boiling water, it was however more sticky than when parboiled rice was used.

Example 8 100 g of parboiled rice was soaked for 2 hours at 450C in 500 ml of water containing 4,800 units of pullulanase and 250 units of bacterial a- amylase. Excess liquid was drained off and the rice dried at 300C for 24 hours to an Aw < 0.5. The rice could be cooked by boiling for 6 minutes.

Example 9 100 g of brown rice was soaked for 4 hours at 500C in 500 ml of water containing 8,000 units of pullulanase. At the end of the period of incubation 10 g of salt was added and the product boiled for 2 minutes. The rice was dried to an AW < 0.5 and could subsequently be cooked by boiling for 1 5 minutes compares with an untreated standard which required 30 minutes to achieve a similar texture.

Example 10 500 g of paddy rice was placed under vacuum and 5 litres of water containing 5,000 units of pullulanase was then added. The treatment was continued for 2 hours at 500C. The rice was then parboiled and milled using conventional processes. The rice was found to be cooked in 1 3 minutes in boiling water with 1 8 minutes required to obtain the equivalent texture in a standard parboiled rice, which has been produced by the -same parboiling and milling method but with a pretreatment of 2 hours in water at 50 C without enzyme.

Example 11 240 units of Termamyl 1 20L, a high temperature active bacterial a-a mylase, was added to 1 kg of water at 9O0C. This was then mixed with 1 kg of milled, parboiled rice and the temperature was increased to 950C for a period of 25 minutes. After this time 750 ml of water containing 0.1% citric acid was added and the mixture boiled for 8 minutes. The rice was then drained, and dried on a fluid bed drier at approximately 1 1 OOC until a moisture content of about 12% was achieved. The rice could be cooked by pouring on boiling water and leaving for 5 minutes.

Example 12 To 1 litre of water at 900C, containing 240 units of Termamyl 120L, 1 kg of milled, nonparboiled (white) rice was added. After 20 minutes at this temperature, any excess water was drained and the rice was steamed for 8 minutes. The rice was then dried on a fluid bed drier at 1 1 OOC until approximately 12% moisture.

This rice could be cooked in a similar manner to the produce of Example 11.

Claims (20)

Claims

1. A process for producing a rapid cooking starchy foodstuff which comprises subjecting the foodstuff to the action of one or more starch degrading enzymes under starch degrading conditions.

2. A process according to claim 1, wherein the starch degrading enzyme is an enzyme which attacks the 1,4-glucoside links.

3. A process according to claim 2, wherein the enzyme is -amylase, -amylase or amylomaltase.

4. A process according to claim 1 wherein the starch degrading enzyme is an enzyme that attacks the 1,6-glucoside links.

5. A process according to claim 4 wherein the enzyme is pullulanase, isomylase or dextrine-1,6 glucosidase.

6. A process according to claim 1 wherein the enzyme is -amylase or pullulanase, or a mixture therof.

7. A process according to any one of claims 1 to 6 wherein the concentration of enzyme used is such that the desired degree of enzymatic degradation is achieved in a period within the range of 5 minutes to 24 hours.

8. A process according to claim 7 wherein the concentration of enzyme is such that the desired degree of enzymatic degradation is achieved in a period within the range of 30 minutes to 4 hours.

9. A process according to any one of claims 1 to 8 wherein after the enzyme treatment enzyme activity is removed.

10. A process according to any one of claims 1 to 9 wherein after the enzyme treatment the product is dried to a moisture content at which the product has adequate stability against spoilage to enable packaging, storage and distribution.

11. A process according to any one of claims 1 to 10 wherein the foodstuff is cereal grains.

1 2. A process according to claim 11 wherein the cereal grain is rice.

1 3. A process according to claim 12 wherein the rice is in the form of paddy, cargo, brown, white or parboiled rice.

14. A process according to claim 12 or 13 wherein the enzyme treatment is combined with a parboiling treatment of paddy or cargo rice, the enzyme being added to any of the steeping steps of the parboiling process.

1 5. A process according to claim 11 wherein the cereal grains are wheat or oats.

1 6. A process according to any one of claims 1 to 10 wherein the foodstuff is a pasta.

17. A process according to claim 1 6 wherein the pasta is macaroni or spaghetti.

18. A process according to claim 1, conducted substantially as described in any one of the Examples herein.

19. Rapid cooking rice whenever produced by a process according to any one of claims 1 to 14 or 18.

20. Rapid cooking pasta whenever produced by a process according to any one of claims 1 to 10 or 16 to 18.