CA1062949A

CA1062949A - Food product

Info

Publication number: CA1062949A
Application number: CA 240938
Authority: CA
Inventors: Sidney Pendlington; Michael W. Clarke
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1974-12-04
Filing date: 1975-12-02
Publication date: 1979-09-25
Also published as: ATA918975A; BE836194A; JPS5182750A; PH11445A; GB1531219A; NL7514065A; DE2553958A1; AT344494B; SE7513646L; AU8715775A; LU73929A1; FR2293155A1; ZA757526B

Abstract

ABSTRACT OF THE DISCLOSURE

A rapidly-reconstitutable dehydrated food product is prepared by chemically setting and dehydrating a foamed thermostable gel containing dispersed therethrough a characterising foodstuff such as a vegetable puree.
The food product can be in the form of shaped pieces, such as dice, which can be air-dried without the severe structural collapse exhibited when conventional vegetable dice are air-dried.

Description

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The present invention relates to dehydrated food products.
me invention provides a dehydrated food product comprising a finely-divided foodstuff dispersed in a foamed thermostable edible chemically-set gel.
The invention also provides a process for the manufacture of a dehydrated food product, in whic~ process a finely divided foodstuff, an edible foam stabilizer and a gelling agent capable of forming an edible thermostable gel are mi~ed together, the mixture is whipped and set by chemical means to a foamed gel having the flnely divided foodstuff dispersed therethrough, and the gel is dehydrated. ~
The finely divided foodstuff can be elther raw or cooked.
However, a major advantage of a dehydrated food product of the ;
invention is that it will reconstitute in hot water ~ery rapidly and hence if the finely-divided foodstuff is one that would normally be consumed cooked, then idea~ly any such finely-divided foodstuff should be pre-cooked before being incorporated into a dehydrated food product of the invention. The invention , .
is particularly appropriate to the use of finely-divided foodstuffs such as vegetables and fruit~ particularly those that are conventionally marketed in dehydrated form for reconstitution by the consumer. Examples of suitable vegetables and fruit are carrots, swedes, turnips7 potatoes, peas, beans, onions, peppers, tomatoes, beetroots, parsnips, celery, apples, peaches, apricots, pineapples and pears. However, the invention is also applicable to other finely-divided foodstuffs, for example proteinaceous foodstuffs such as finely , ~ . .
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materated meat or fish, and cereals such as wheat flour of maize flour. Moreover, confectionery ingredients in which the finely-divided foodstuff is, for example, finely crushed nuts can also be prepared by the invention. In general, the dehydrated food product of the invention will contain from 20 to 80% by weight of the finely-divided foodstuff.
Ideally the degree to whlch the foodstuff is finely-divided is one such that to the naked eye the mixture of ;
the finely-divided foodstuff9 foam stabilizer and gelling agent appears homogeneous, and hence the dehydrated food product appears to be of homogeneous material. Nevertheless, depending upon the intended use of the dehydrated food product, a lesser ~-~ degree of division of the foodstuff can be acceptable. For ., . , ;
foodstuffs such as vegetables and fruit, a satisfactory degree . .
of division can be achieved using conventional homogenising ... :
~'!blending") equipment.
: me foam stabilizer can be any of those agents, for example aIbumen and hydrolysed proteln whipping agents such as hydrolysed soy protein, conventionally used in the food industry .tG assist 20 ~ the preparation of edible foams. Whipping agents of the types utilised in the production of high overrun ice creams can be ~ , - .
employed. If the gelling agent is of the charged polysaccharide type (see below), the foam stabilizer should ideally be phosphate ; free. Generally the foam stabilizer will be used in an amount 25 in the range of 1 to 25%, preferably 2 to 20%~ expressed by ;
- weight of the dehydrated food product.

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106Z94~ cQ.7~5 Preferably the gelling agent (ie an agent that can be induced to siet to a gel, as distinct from any initiator that may have to be added in order to cause the gelling agent to set) is a charged polysaccharide such as an alginate or a low-methoxy pectate, and is used in an amount in the range of 1 to 25%~
preferably 2 to 2~/o~ expressed by weight of the dehydrated food product. Such charged polysaccharide gelling agents are usually added to the characterising ~oodstuff in the form of water-soluble salts, such as their sodium salts, and the setting of such gelling agents can be accomplished by the addition of polyvalent metallic ions, such as calcium, in the form of a salt, such as a carbonate or an acid phosphate, that is at least sparingly soluble in water. Charged polysaccharide gelling agents are now familiar ingredients in food processing.
Alginates of high molecular weight (typically at least MW 100,000) are preferred, and a further preference is given to alginates having a low content of mannuronic acid residues (mannuronic : guluronic ratio less than 1:1); use of these ; gelling agents can lead to enhanced heat stability of the food product. Alternatively, where enhaDced heat stability is not essZential, alginates having a high content of mannuronic acid ~residues can be used to give a dehydrated food product of the invention that shows enhanced softness after a brief reconsti-tution time, although such alginates will not give a gel $hat is so easily handleable during processing.
If the gelling agent is of the charged polysaccharide type it can ~e advantageous to include as an optional ingredient an ~.i edible acid, for example citric acid or maleic acid, or acid-, . . .
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cQ.7~5 ` `` ~ 1~629~9 releasing a~ent, for example a lactone. A lactone can provide ~ -a controlled release of the calcium or other metallic ion (by slowly hydrolysing to its acidic form and then displacin~ ions from the metallic salt) and thereby provide greater control over the setting of the gel~ ~urther control over the setting of the gel can be achieved by the presence of a source of citrate ions, which will chelate the free metallic ions. Suitable sources are trisodium citrate and disodium hydrogen citrate. me quantities of setting agents and controlling agents used can vary widely, depending on their relative efficiency and on the setting time required. Simple tests will reveal optimum proportions of these ingredients for use with any given combination of finely-divided foodstuff and gelling agent.
A further additive that can usefully be incorporated into the mixture before gelling is a cellulose derivative, such as carboxymethylcellulose. mis can be used as a VlSCOSity control and can therefore aid handling of the ungelled mixture. me addition of a cellulose derivative can enhance the stability of the foam, particularly when deal-ng with a high water con~ent mixture. Alternatively, starches can be used to control viscosity.
In general any such addltive present solely to control viscosity will not comprise more than 5% by weight of the dehydrated food product.
It may be necessary to add water durinæ the preparation of the initial mixture of finely-divided foodstuff, foam stabili~er and gelling agent in order to obtain a mixture sufficiently fluid to foam. The quantity of water required will vary considerably ..
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depending upon the moisture content of the finely-divided food-stuff, and in tlle oase of certain vegetables and fruits, such as tomatoes and peppers that have very high water contents, no additional water may be re~uired at all. The Examples below illustrate the wide di~ergence in this requirement, and in practice the amount of water needed for any given mixture will be readily ascertainable by inspection.
Minor ingredients such as anti-oxidants and vitamins, and sweetening, seasoning, flavouring and colourlng agents can be added to the ungelled mixture as desired.
The foaming of the mixture of the finely-divided foodstuff, gelling agent and foam stabiliser prior to gelation can be achieved by whipping in air, although for some delicate food-stuffs it may be beneficial to foam the mixture in an atmosphere of, for example, nitrogen or carbon dioxide.
Ideally the gelled product should be in a sub-divided form before it is dehydrated. This sub-division can be achieved by, for e~ample, cutting or shredding after the gelled product is fully set, or the sub-di~ision can be effected while the gel is ~ being set, for example by extrusion or moulding.
Dehydration of the gelled product can be achieved by any ;~ conventional means, for example by drying on trays in an oven or, if desired, by freeze drying. Drum~drylng and ribbon drying can also be employed. However, the gelled food product lends itself in particular to hot air drying in, for example, a fluidised bed. In a preferred drying method, the gelled food product is dried partially in a.through-draught drier, such as -, ' ~,. .

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~6Z949 . . a Snellin~ drier, tllen allowecl to equilibrate by for example being sealed in a container lor several hours, and finally fully .-dehydrated by fluidiscd bed drying. -~
The invention is l)articularly applicable in the production S o dehydrated vegetable and fruit products in sub-divided shaped form, such as dice, ribbons, rings or slices. Conventional .
vegetable and ruit products in the form of dehydrated shaped pieces, prepared by hot air or oven drying, look unattractive in the unreconstituted state because, during the drying, case-hardening occurs and subsequent dehydration of the interior of the shaped pieces causes ~h0 surface to collapse and contract7 .:
deforming the overall shape; moreover, the proper shape is not necessarily restored when the product is reconstituted Conventionally, this loss of shape can be avoided by the use of more expensive techniques such as freeze-drying, but particularly in the production of dehydrated vegetables, freeze-dryîng is -~
considered an uneconomic procedure. Shaped vegetabIe and fruit - ~ ~ pieces prepared from the foamed gel of the invention, however, can be air dried without any severe collapse of structure and ;~
: -remain as attractive shapes even in the fully dehydrated state.
. Moreover reconstitution of the dehydrated product of the invention . can be accomplished very rapidly ln hot or boiling water, whereas . conventlonal dehydrated food products such as dehydrated ~.
: vegetables require simmering in boiling water for at least ;~
several minutes before an acceptably reconsti.tuted edible product is obtained. Dellydrated vegetable pieces prepared according to the invention are particularly suited for use in dry instant * trade mark ~ : .
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"` 1~6Z9~9 soup mixes that are intended to be reconstitutable within oneor two minutes by admixture with boiling water.
The invention is applicable also in the production of crisp snack products and breakfast-cereal ingredients, or crisp ingredients for inclusion in confectionery products such as ice cream. Where necessary, crispness oE the dehydrated food product can be maintained by coating with a water-repellant or water-impervious material such as an edible silicone or chocolate.
The use of a free acid or of an acidic ingredient suoh as a lactone may be undesirable in some instances, because this will impart an acid taste to the food product when reconstituted and consumed. Ideally for many finely-divided foodstuffs which are vegetables or meat, the pH of the food product when reconstituted should be at or near neutrality. This can be achieved by employing as an alternative setting system for the charged polysaccharide gelling agent a calcium buffer. Essentially a calcium buffer is a mixture of a fully ionised calcium salt plus one or more ligands capable of complexing calcium. ~We ;
belleve the calcium buffer should be chosen such that it is ZO capable of maintaining an ionic calcium activity in the molar range of 4 x 10 4 to 1.5 x 10 3, while having a total calcium n content sufficient to yield a handleable gel. Preferably the calcium buffer aomprises calcium sulphate plus calcium ;~ citrate, or calcium sulphate plus calcium hydrogen phosphate.
Different~weight ratios of the sulphate to the citrate or hydrogen phosphate can be chosen, giving different 'B, . . .

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settiny times, but a practical weight ratio is about 1:14.
Because this setting system can cause the charged polysaccha- ~
ride gel to form rapidly, there is usually no advantage to be ~ `
gained from adding a cellulose thickener. However, when wor- `
king with a neutral gel system it can be beneficial to incor- ;
porate a calcium chelator such as disodium hydrogen phosphate, ``
in the aqueous mixture containing the charged polysaccharide to prevent any premature setting of the gel.
The following Examples illustrate the invention in greater detail.
EXAMPLE 1 ~ ~`
Fresh carrots of solids content approximateIy 10%
by weight were washed thoroughly to remove 50il, and then sliced and cooked in steam for 15 minutes. 1 kg of the cooked ~-slices were blended with 400 ml distilled water, and 1 kg of ji the resulting homogenate were mixed in a conventional household kitchen mixer with the following ingredients~
Glucano-delta lactone 40 g "Alginate F374"* (40% sugar;
a high guluronic alginate) 10 g 20Sugar 8 g Carboxymethylcellulose (Celacol M10,000)* 3 g Carrot flavour (Dragoco 9/013516)*1.5 g After mixing for three minutes, ]0 g of Soy Protein D100 WA whipping agent (supplied by Gunther Products, 70 West Sixth St., Galesburg, Illinois, U.S.A.) were added. Mixing was continued for one minute, and then the contents of the mixer j-whipped by running the mixer at maximum speed for one minute.

This increased the volume of the homogenate by 50-70~. j 8 g calcium carbonate was suspended in 300 ml di- `` -stilled water and whisked into the whipped homogenate for 30 seconds. The resulting foam was spread on a 3/4 inch deep -* Trade Mark ,. :
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~0 6Z9 4~ !, . , tray and allowed to gel for 30 minutes.

The geI was diced and dried in a fluidized bed at 70C for 4 hours. -;..-. :
The dehydrated dice had a moisture 'content of about '-' ' ;
8~ by weight. They were'reconstituted one minute'after boiling water was poured onto them. ~' ' EXAMPLE 2 ~' An essentially similar procedure was followed to make a dehydrated diced product from swede of solids content approxi~
mately 90~ by weight. However, in this instance 1 kg of cooked, '~
sliced swede were blended with 800 ml distilled water; the '!`~ ' initial ingredients added to 1 kg of homogenate were:
~., - , Glucano-delta lactone 40 g "Alginate F374"* 10 g ;`l Sugar 6 g ~' Carboxymethylcellulose 3 g ' and, after the addition of the whipping agent, the homogenate i' was mixed for two minutes before being whipped~
EXAMPL~S 3 to 5 The procedure of Example 2 was followed to make de-hydrated vegetable pieces starting from beetroot, tomato and peppers. This indicated th~e different quantities of added water needed to make a suitable initial blend of the vegetable; the amount of water added, per 1 kg of cooked vegetables was:
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Example Vegetable Approx Solids Content Added Water -' ' '' ' ' ' (96: bv Weiqht) .:~
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3Beetroot 13 400 ml 4Tomato 7 Nil ^

5Peppers 7 Nil 1!'''~ '' EXA~P~E 6 The following ingredients:
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Sodium alginate ~'lManucol LN"*, a high mannuronic alginate) 10 g Sugar 8 g Carboxymethylcellulose 3 g Water 990 ml Dry potato flake 30 g were blended, the potato flake being added last. The mixture was then gelled and converted to dry "potato" dice following the procedure of Example 1. The gel before dehydration was , ~ ~-softer than that obtained in the previous Examples, but was still handleable. A very soft organoleptically-acceptable food product resulted when the dice were reconstituted by the addi-tion of boiling water.
...~ :- .-EXAMæ~E 7 The following components: -Vegetable puree (10% solids by weight)l kg Hydrolysed soy protein ;- ~
whipping agent 25 g ~ ;
.
Sodium alginate ("Manucol LN"*, a high mannuronic alginate) 37.5 g Disodium hydrogen phosphate 5 g ~
Water 1 L ~ ~-~ were mixed and whipped to a foam. Then:

! Calcium sulphate (CaSO4.2H2O) 0.5 g i ~ Calcium citrate 7 g Water 200 ml ` were blended with the foam, which was then poured into shallow i, :., ~i trays and allowed to set. Setting took only 5 minutes. The gel was then cut into small appropriately-shaped pieces, such as dice and rings, and the pieces were air-dried. The pieces ~ could be reconstituted rapidly simply on the addition of boiling ,,~
water, and possessed a neutral vegetable taste.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the manufacture of a dehydrated food product, in which process a finely-divided foodstuff, an edible foam stabiliser and a gelling agent capable of forming an edible thermostable gel are mixed together, the mixture so formed is whipped and set by chemical means to a foamed gel having the finely-divided foodstuff dispersed therethrough, and the gel is dehydrated.

2. A process as claimed in Claim 1, wherein the dehydration involves air-drying.

3. A process as claimed in Claim 1 wherein the gelling agent employed is an alginate or a low-methoxy pectate and the setting of the gel is effected by the addition of calcium ions.

4. A process as claimed in Claim 1 in which the finely-divided foodstuff is vegetable puree.

5. A process as claimed in any one of Claims 1, 2 or 3 wherein the edible foam stabiliser used is albumen or a hydrolysed protein whipping agent.

6. A process as claimed in any one of Claims 1, 2 or 3 wherein a compound selected from a cellulose derivative and a starch is used to control the viscosity of the mixture prior to setting of the gel.

7. A process as claimed in Claim 1, which involves the additional step of shaping the foamed gel, before dehydration, to give shaped pieces.

8. A process as claimed in Claim 1, which involves the additional step of shaping the foamed gel, after dehydration, to give shaped pieces.

9. A process as claimed in Claim 7 in which the shaped pieces are selected from dice, ribbons, rings and slices.

10. A process as claimed in Claim 8 in which the shaped pieces are selected from dice, ribbons, rings and slices.

11. A process as claimed in Claim 7 and which involves the additional step of incorporating the food product into a dry food mix.

12. A process as claimed in Claim 8 and which involves the additional step of incorporating the food product into a dry food mix.

13. A process as claimed in Claim 1 in which the finely-divided foodstuff is vegetable puree and which involves the additional steps of shaping the formed gel, before dehydration, to give shaped pieces followed by incorporating the food product into a dry soup mix.

14. A process as claimed in Claim 1 in which the finely-divided foodstuff is vegetable puree and which involves the additional steps of shaping the foamed gel, after dehydration, to give shaped pieces followed by incorporating the food product into a dry soup mix.

15. A dehydrated food product comprising a finely-divided foodstuff dispersed in a foamed thermostable edible chemically-set gel, whenever prepared according to the process as claimed in Claim 1 or its obvious chemical equivalent.

16. A dehydrated food product as claimed in Claim 15, wherein the gelling agent is an alginate or a low-methoxy pectate, whenever prepared according to the process as claimed in Claim 3 or its obvious chemical equivalent.

17. A dehydrated food product as claimed in claim 15, wherein the finely-divided foodstuff is vegetable puree, whenever prepared according to the process as claimed in Claim 4 or its obvious chemical equivalent.

18. A dehydrated food product as claimed in claim 15, wherein the food product is in the form of shaped pieces, whenever prepared according to the process as claimed in Claim 7 or 8 or its obvious chemical equivalent.

19. A dehydrated food product as claimed in Claim 15, wherein the food product is in the form of shaped pieces selected from dice, ribbons,rings or slices, whenever prepared according to the process claimed in Claim 9 or 10 or its obvious chemical equivalent.

20. A dry food mix incorporating shaped pieces of a dehydrated food product as claimed in Claim 15, whenever prepared according to the process claimed in Claim 11 or 12 or its obvious chemical equivalent.

21. A dry soup mix incorporating shaped pieces of a dehydrated food product as claimed in Claim 15 and in which the finely-divided foodstuff is vegetable puree, whenever prepared according to the process claimed in Claim 13 or 14 or its obvious chemical equivalent.