IE48545B1 - Dehydrated edible products and processes for preparing them - Google Patents

Abstract

Readily rehydratable dehydrated edible products are obtained by drying compositions comprising finely divided foodstuff dispersed in edible gel substantially free of aeration and having a gel strength corresponding to yield stress of 200 grams of a cylinder of gel having 12 mm diameter and 12 mm height compressed at 5 cm/minute between pressure plates; the gels are produced for example by mixing solid calcium sulphate particles rapidly throughout gellable aqueous alginale or low-methoxy pectate sols and then allowing the solid calcium sulphate to dissolve and the mixtures to gel under shear-free conditions.

Description

The present invention relates to dehydrated edible products and to processes for preparing them, and in particular to products including pieces or particles of comminuted food, for example derived from pureed meat and vegetables.

Cried foods capable of reconstitution on the addition of water are well known. Examples include soups, desserts and snack products. Some of these products, often referred to as 'instant', are suitable for consumption within a short time after reconstitution, e.g. 1-2 minutes, while others require a longer period of soaking to allow the constituents of the food to rehydrate. Clearly, specification of the rehydration conditions depends on the nature of the ingredients comprising the food. Vhen the food contains pieces of dried vegetables or meats, Simmering in boiling water for up to 20 minutes may be required and consequently such foods are not acceptable as instant products.

Instant products comprising dried food pieces such as dried vegetables and dried meats are commercially available. These may be obtained by freeze-drying pieces of the appropriate food. However, pieces obtained by such a process do not always possess all of the desired characteristics: e.g. the rehydrated product may be spongy and may be deficient in flavour, colour or texture, so that it may entirely fail to resemble the original foodstuff. As an example, it has been found that rehydrated freeze-dried tomato pieces can be undesirably light and spongy and lacking in flavour. In addition, such pieces are also expensive.

An alternative source of dried edible products is described in the prior art (Belgian Specification No 836 194). These are made by preparing a dispersion of comminuted foodstuff in an aerated calcium alginate or calcium pectate gel, cutting the gel into pieces and drying the said pieces. Use of an aerating agent is expensive and may also in some cases result in an undesirable spongy texture in the rehydrated pieces. This approach, therefore, also has disadvantages .

Ve have surprisingly discovered that unaerated alginate gels containing comminuted foodstuffs, e.g. purees, after 8 5 4 5 cutting and air drying, can be so made as to provide dried foodstuff pieces which are acceptable for use in instant products .

The ability of alginate solutions to form films on 5 drying is well known. Consequently, it would not be entirely surprising, and in fact we find, that pieces of alginate gel also tend to form films after air drying. In some cases, depending on the geometry of the gel pieces prior to drying, a dried outer skin with a hollow interior is obtained. Such an effect can he obtained when drying gelled dice. It has to be noted, moreover, that the dried materials so obtained have very poor rehydration characteristics .

In contrast, hy including a comminuted foodstuff in the gel matrix in accordance with the present invention as described below, an excellent texture simulating vegetable or meat pieces can be obtained after rehydration of the air-dried gel pieces. Without being bound by theory, the presence of the comminuted food particles appears to hinder collapse of the alginate network with the accompanying film formation and provides in the dried products particles of comminuted food dispersed throughout a dried alginate matrix. The food particles are thus free to hydrate on the addition of water hut in so doing, are prevented from separating hy the alginate matrix. Discrete rehydrated particulates result. - 5 According to the invention there is provided a dehydrated edible product obtained by drying a ccmposition ecnprising a finely divided, e.g. canminuted or pureed, foodstuff dispersed in an edible ( and preferably thermostable ) gel which has not been stbjected to aeration, and which has been made ty producing gelation throughout the bulk of a gelling mixture under substantially shear-free conditions, and vhich has a gel strength corresponding to a value of at least 200 grams when determined by the method defined belcw.

Since the gel has not been subjected to aeration, it has before drying either no overrun or else a minor amount due to unintentional incorporation of bubbles not sufficient to render the material a foam, e.g. not more than 10%, preferably 5% or less, e.g. less than 1%, fcr exanple 0.5%.

Desirably the product is capable of satisfactory rehydratlon in 60-120 seconds of inmsrsian in water, e.g. hot water. Of course, the gels are prepared without adding aerating or foaming agents as such: any constituents vhich are added for other reasons and are capable of promoting aeration are preferably restricted to levels at vhich any foam-promoting effects are negligible.

In order to produce a dried product capable of satisfactory rehydration, the drying is preferably carried out by air-drying or ovendrying.

The gel strength can be measured with a commercial Instron (Trade Mark) test machine which empresses a gel of defined size between two plates at a defined speed: the stress increases to a peak at the yield point and the yield stress measures the gel strength. The gels used in this invention have at least 200 grams gel strength for a cylindrical gel sample 12mti diameter and 12mm high, ccnpressed at 5am/minute. Desirably the strengths are even higher, corresponding to 350 or more and can conveniently reach 600 or 700 or more.

One highly desirable method of producing gels vhich give satisfactoay dehydrated products according to this invention is a fast-setting method 8 5 4 5 -(,( e.y. with gelling time below 30 minutes, e.g. 6 minutes), e.g. as described in copending Patent Application No. 1669/79 , corresponding to EP 0 009 897, the disclosure of which is hereby incorporated by reference: the nethod disclosed conprises mixing solid calcium sulphate particles, for example as an aqueous slurry with a comminuted foodstuff, rapidly throughout a gellahle aqueous alginate or low-meihoxy pectatesol, and then under shear-free conditions allowing solid calcium sulphate to dissolve and the mixture to gel.

However, other methods of producing the gels to he dehydrated are also usable in the performance of this invention, e.g. that described in our Patent Specifications Nos 35807-8, the disclosure of which is also incorporated herein by reference : it relates to rapidly making a mixture comprising an alginate or a lowmethoxy pectate sol, a source of calcium ions (e.g. dicalcium phosphate) that in the absence of an agent capable of releasing calcium ions (e.g. acid) provides insufficient calcium ions to gel the sol, fruit pulp or puree and an agent capable of releasing calcium ions, and allowing the mixture so made to gel under substantially shear-free conditions.

Using this invention, dried pieces of vegetables and meats which possess excellent colour, flavour and texture after reconstitution for 1-2 minutes in water have been produced.

After formation, the gel may be cut to the desired shape, e.g. dice, strips, and dried on commercial air-drying equipment, e.g. an oven or through draught drier. The preferred temperature range for drying is 60-80°C. Use of lower drying temperatures results in extended drying times while use of higher temperatures can result in unacceptable flavour loss and charring. Alternatively, drying may be carried out or facilitated with the aid of a vacuum and/or a desiccant such as Ρ2°5 or calcium chloride. For most applications it is desirable to dry the particulates to a final moisture content of 4-125(, preferably 4-9((, e.g. 7((. Choice of the appropriate drying conditions depends on the type of gelled comminuted food to be dried and its intended usage. Such conditions are readily determined by simple experiment. It may be desirable to carry out two-stage drying with intermediate storage for a period to allow equilibration of the water content of the partially-dried material.

When the products are used as ingredients in instant foods, best results are obtained by rehydration for 1-2 minutes in boiling water.

When necessary, rehydration may be improved and the texture of the rehydrated particulates suitably modified by the addition of a texture modifying agent during the gel preparation step. Such texture modifying agents are normally proteinaceous or carbohydrate in nature, for example, caseinates, albumen, gelatin, starch derivatives, cellulose derivatives, carrageenans, xanthan gum etc.

For economic reasons, an inexpensive texture modifying 8 5 4 5 - 8 agent is preferred. Pre-cooked or modified starches at a level of around 0,5-3$ hy weight of the gelled comminuted food have been found to give acceptable results.

The dehydrated products of the invention can he in 5 the form of particles, slices or small blocks or other conveniently-shaped regular or irregular pieces.

Although the products of the present invention can be used acceptably in instant products, they maintain their structural integrity and organoleptic quality under more prolonged and extreme conditions of rehydration, e.g. boiling in water for 20 minutes, and can, therefore, he used generally as ingredients in dry food products, e.g. dry soup mixes.

The invention is illustrated by the following examples, the table given below showing the composition of the mixtures used therein. 48S45 8 5-15 ιο Ο (Ex Laing National) |Η - 11 Example 1 A gel containing 40% by weight of comminuted tomato (28-30% solids) was prepared hy mixing together an alginate phase and a comminuted food phase, formulated as shown in the accompanying table, and allowing the mix to set under shear free conditions. The gel was cut into parallelepipeds with edges varying between 0.4-2,0 cm which were dried on a commercial through draught drier at 75°C for 4 hours. The dried product had an average moisture content of 8.7% and rehydrated in boiling water after ca one minute to provide tomato slivers of excellent taste and pleasant texture.

Example 2 A gel containing 40% by weight of comminuted cooked chicken was prepared as in Example 1 using the formulations for the alginate phase and the comminuted food phase shown in the accompanying table. The gel was cut into cubes of 0.8 cm edge which were dried on a through draught drier at 70°C for three hours. The dried product had an average moisture content of 8.1% and on rehydration in boiling water attained a fibrous texture somewhat akin to cooked chicken after two minutes.

Example 3 A gel containing 30% by weight of comminuted red pepper was prepared as in Example 1, using the formulation shown in the accompanying table. The gel was cut into parallelepipeds (1.5 cm x 0.6 cm x 0.4 cm) which were 8 5 4 5 - 12 dried on a bench-scale fluidised bed drier (Model FBD/L72 ex PRL Engineering Ltd) at 70°C for 2.5 hours. The resulting dried product of average moisture content 6.1$ still retained its strong red colour after nine months' storage and rehydrated in boiling water after ca. one minute to provide simulated pepper pieces with excellent colour, flavour and texture.

Claims (16)

1. CLAIMS 1. A dehydrated edible product which has been obtained by a method comprising drying a composition which comprises a finely divided foodstuff dispersed in an edible gel which 5 has not been subjected to aeration and which has been made by producing gelation throughout the bulk of a gelling mixture under substantially shear-free conditions, and which has a gel strength corresponding to a yield stress of at least 200 grams when a cylinder of the gel 12mm in diameter and 12mm 10 high is subjected to compression between plates moving together with a speed of 5cm/minute.

2. A dehydrated edible product according to claim 1, wherein the finely divided foodstuff comprises a c.mnnriTinted or pureed meat or vegetable product. 15 5. A dehydrated edible product according to claim 1 or 2 wherein the gel comprises an alginate or low-methoxy pectate gel.

3. 4. A dehydrated edible product according to claim J, wherein the gel has been produced by a method comprising 20 mixing solid calcium sulphate particles rapidly throughout a gellable aqueous alginate or low-methoxy pectate sol and then under shear-free conditions allowing solid calcium sulphate to dissolve and the mixture to gel.

4. 5. A dehydrated edible product according to claim 5, wherein the gel has been produced by a method comprising - 14 rapidly making a mixture comprising an alginate or lowmethoxy pectate sol, a source of calcium ions that in the absence of an agent capable of releasing calcium ions provides insufficient calcium ions to gel the sol, fruit pulp or 5 puree and an agent capable of releasing calcium ions, and allowing the mixture so made to gel under substantially shear-free conditions.

5. 6. A dehydrated edible product according to claim 5, wherein the source of calcium ions used to make the gel is 10 dicalcium phosphate and the releasing agent is an edible acid.

6. 7. A dehydrated edible product according to any preceding claim, wherein the gel strength corresponds to a yield stress of at least 350 grams under the defined conditions. 15

7. 8. A dehydrated edible product according to claim 7, wherein the gel strength corresponds to a yield stress in the range 35θ &°θ grams under the defined conditions.

8. 9. A dehydrated edible product according to any preceding claim which gives substantial rehydration in 60-120 seconds 20 of immersion in boiling water.

9. 10. A dehydrated edible product according to any preceding claim, which has been air-dried at from 60°C to 80°C. - 15

10. 11. A dehydrated edible product according to any preceding claim which has a moisture content in the range 4—12% by weight.

11. 12. A dehydrated edible product according to any preceding 5 claim which further comprises a texture modifying agent selected from caseinates, albumen, gelatin, starch derivatives, cellulose derivatives, carrageenans and xanthans.

12. 13. A dehydrated edible product according to any preceding claim, wherein any bubbles present in the gel do not exceed 10 the equivalent of an overrun of 5%·

13. 14. A rehydrated edible product formed by rehydrating a dehydrated edible product according to any of claims 1-13 in hot water for up to 20 minutes.

14. 15- A process for producing a dehydrated edible product 15 according to any of claims 1-13, which comprises drying an edible gel, which has been formed with a finely divided foodstuff dispersed therein, free of srfcjectian to aeration, hy producing gelation throughout the bulk of a gelling mixture under substantially shear-free ccnditions, and with a strength corresponding to a yield 20 stress of at least 200 grams when a cylinder of the gel 12mm in diameter and 12mm high is subjected to compression between plates moving together with a speed of 5cm/minute, to form a rehydratable dehydrated product. 4-8 54-5 -

15. 16 16. A process according to claim 15, wherein the edible gel has been produced as defined in claim 4.

16. 17· A process according to claim 15, wherein the edible gel has been produced as defined in claim 55 18. A dehydrated edible product according to claim 1 and substantially as hereinbefore described in any one of the foregoing Examples 1-519. A process according to claim 15 and substantially as hereinbefore described in any one of the foregoing 10 Examples 1-5·