NO127790B - - Google Patents

Description

Process for the production of proteinaceous

foods based on plant proteins.

The invention relates to the utilization of plant proteins, in that

such are transferred from liquid form to foodstuffs in solid form.

It is already known to transform plant protein, e.g. soy protein, into the form of a liquid protein product and to convert the latter into solid or hardened material which is usable as a component in foodstuffs, e.g. in simulated meat. Thus, soy protein can be brought into solution using alkali, and the alkaline solution can be spun into an acid/salt bath to form protein fibers. A bundle of the soy protein fibers can then be impregnated with an edible binder and fat and compressed into coherent form (US 2,682,466). Or, when the binder is heat-setting, such as e.g. an albumen/gluten mixture (DAS 1,259,690), the impregnated fiber-1

bundle is given coherent shape by heating. The spinning solution, which according to US 2,730,447 may contain an agent that will modify the aroma of the fibers produced, may have a protein concentration of

from 10 to 30^, usually approx. 15%, by weight, this concentration being achieved by using a pH value which is sometimes stated to lie in the range 9 to 13.5 (US 3,403,027), but which in practice lies at

at least 10.5 (US 3,416,929).

A serious disadvantage of these known processes is their use of a high pH value, which tends to cause degradation of the sample and which requires complex methods to ensure uniformity in the alkaline solution subjected to spinning.

The method according to the present invention avoids the use of a high pH value when producing the plant protein in the form of a mesophase.

Animal protein in the form of a mesophase is already known. Thus describes the academic paper published in 1944 entitled "The Dielectric Properties of Beta-lactoglobulin in Aque-

ous Glycine Solutions and in the Liquid Crystalline State" by Shaw," Jansen and Linewéaver (Journal of Chemical Physics, vol. 12, no. 11, pages 439-448, see especially page 440) a two-phase milk protein product whose lower, dense phase is a protein mesophase, i.e. a liquid, aqueous protein product which has a relatively high content of protein in a dissolved state and which at room temperature is significantly more viscous than water and is able to coexist with and be prepared from ordinary saline aqueous solutions of the protein. Shaw,

Jansen and Linewéaver prepared their B-lactoglobulin mesophase by dialysis at 10-15°C of a concentrated solution of B-lactoglobulin containing sodium chloride until sufficient salt had been removed to cause some of the protein to separate as a lower "oil- like" layer of mesophase. This preparation method, and their properties, indicate that protein mesophases have a significant degree of internal molecular order. They are probably made up of aggregated units of the protein molecules present.

The mesophases in plant protein used according to the invention are new products and combine fluidity with a relatively high dissolved plant protein concentration at a pH value that is well below the value at which the protein is destroyed. Moreover, these protein products, in contrast to protein solutions with a high pH, can

which had a tendency to break down when heated, is hardened by means of heat as opposed to the effect of acids. These characteristics

makes the products particularly suitable for the production of foodstuffs, especially in fiber form. The products are also useful as heat-setting binders for edible materials, e.g. powdered meat.

The mesophases used according to the invention include

from 20 to 50% by weight of a substantially undenatured plant protein which is kept in a dissolved state at pH from 3 to 9 by means of a

edible, water-soluble salt, as the products are hardened by heating above 80C-C, possibly in a mixture with meat. The preferred protein content for fiber formation is 20-45% by weight. The pH value is preferably from 4.5 to 7.5, and a pH value which is not far from the isoelectric pH value of the plant protein, i.e. in the range 4-6, is particularly preferred.

The amount of water-soluble salt that is required is usually measured in terms of ionic strength. The actual minimum ionic strength required, which can be found by a simple test for each particular salt, depends on the individual salt and the protein concerned, but an ionic strength of at least 0.2 (calculated on the water content of the product) is usually required. The ionic strength is calculated in accordance with the well-known equation:

where = Mol concentration for each ion z. = valency of each ion.

The protein used for the production of the mesophases is undenatured, i.e. it is as close to its natural state as possible and is especially not exposed to extreme pH values such as in alkali treatment, or to high temperatures or other destructive treatments.

The mesophases can be produced in two ways. The first method involves preparing an aqueous saline solution of the protein and then changing the physical conditions in the solution in such a way that the mesophase is caused to separate. The change to be made depends on the nature of the solution. For example, the mesophase can be caused to separate by cooling (see example 8 later in the description) or by otherwise changing the aqueous environment. If e.g. the protein is kept in solution at a high salt concentration,

then the salt concentration (according to Shaw, Jansen and Linewéaver) can be reduced by dialysis at a reduced temperature (see example 7) and a mesophase is separated. The other method for producing mesophases consists in mixing protein, water and water-soluble salt in the required quantities

conditions, as indicated in Example 1 below, or in some cases by simply mixing a protein isolate and salt (see Example 12).

During the isolation for the production of the mesophase, the protein is precipitated, e.g. in soy or peanut protein, preferably at pH

4 to 6, the yield being highest at 4.8 to 4.9. Acid, preferably

show hydrochloric acid, or alkali, preferably caustic soda, can

set for changing the pH value, provided that one is careful

equal to avoiding a high local concentration during the addition.

The following description covers mostly raw soy protein,

but other plant proteins, e.g. purified soybean protein, raw peanut protein and arachin (a purified peanut protein), rapeseed protein, pea protein, cottonseed protein and sunflower seed protein, will form mesophases and can be used in the method according to the invention. Furthermore, mesophases can be prepared from mixtures of proteins. Many proteins can be mixed in mesophases and incorporated into them, by forming e.g. mesophases containing soy protein and -zein or peanut protein and ^zein, or soy protein and gelatin or casein,

or meat proteins, or soy and peanut protein together.

With some proteins, especially soy protein, the presence of an anti-disulfide reagent (a reagent capable of preventing the formation of, or capable of breaking up, disulfide bonds in the protein) is desirable, or gelatinization can take place at room temperature at the high concentrations used. Sulfites, bisulfites and dithionites are the preferred reagents.

Mesophases obtained under some conditions can additionally

to the 20% or more of plant protein in the dissolved state containing a smaller proportion (smaller in relation to the dissolved protein) of dispersed amorphous protein, which gives the mesophase an opaque appearance.

Upon centrifugation, the dispersed amorphous protein sediments and concentrates in a lower layer, which in the table below is referred to as the "dense mesophase". At pH 4.9, soy pro-

tein a mesophase whose total protein content partly consists of variables

in

small amounts of such dispersed amorphous protein. At pH 6, a single transparent mesophase can be obtained from soy protein, with a composition varying between 20 and 50% protein. Such a variation is expected, as the effect of the pH value is different on the different proteins present and on their interactions.

The distinction between mesophases and ordinary salt-containing protein-

in

solutions are illustrated by the results of certain experiments, see below-- ~~~ standing table. In these experiments, isolated soy protein was mixed with water to give a final solids non-ash content of 28.6% by weight

(of which a small proportion, no more than 1/10 of the protein's weight,

was formed from carbohydrate material), and a solid salt was added and thoroughly mixed. The mixture was centrifuged at 50,000 G i

60 min. The two layers that formed (upper and lower) were separated and analyzed with respect to total dry matter, ash and water. The table shows the protein contents for the mesophases obtained at a salt concentration of 0.5m (molar), and for the sake of comparison the protein contents for the solution and the precipitated (solid) protein obtained at a salt concentration of 0.1m. The "dense mesophase"

referred to was a dispersion of amorphous protein in the "lighter mesophase".

In each case, the remainder of the mixture was water with 1 or 2% ash content, depending on the added salt. The salts were distributed approximately equally between the phases.

In addition, lithium chloride, sodium chloride, sodium sulphate, sodium sulphite, potassium chloride, ammonium chloride, magnesium chloride, calcium chloride and sodium phosphate or mixtures of these are effective at ionic strengths of approx. 0.5. Sodium bicarbonate, a concentration of 0.5 m, will also produce the mesophases, with the advantage that it can be used to raise the system's pH value, either alone or in conjunction with other salts such as e.g. sodium chloride to give the required ionic strength.

The effect of the salts depends mainly on the ionic strength of the

than on the nature of the anions or cations, with certain exceptions

looks like e.g. aluminum chloride where specific interactions with the protein are predominant. Part of the ionic strength can be supplied by salts present in the protein as it is normally isolated from flour, as it derives from salts present in the oilseed

self. The salts and other non-protein components in the flour are, however,

time necessary for the formation of mesophases, which can be made from iso-

clay, purified peanut and soy protein.

Soy mesophases form at approx. 0.15 m (0.45 ion-

strength) with calcium chloride, at approx. 0.2 - 0.3 m with ammonium chloride and at approx. 0.5 m with sodium chloride. They remain stable up to at least 0.5 m for calcium chloride and ammonium chloride, and 1.5 m for sodium chloride.

rid, all at pH 4.9.

Peanut proteins behave similarly to soy pro-

teen. Mesophases can be prepared in the presence of sodium phosphate or sodium chloride or a mixture of the two. Samples of mesophases made by cooling saturated solutions in 10% w/v NaCl and separating the mesophase had the composition: 40.6% < protein, 52% water, 7.4% salt (2.5 m on the water content ). Similar samples made from 5% w/v NaCl solutions contained: 43.3%] protein, 54.4% water, 2.3% salt (0.8 m on the water content). All samples had a pH value of approx. 5.8.

Peanut mesophase can also be made by directly mixing protein, salt and water in suitable proportions. For example, when protein at pH 5 is mixed with water containing 5 - 20% sodium chloride so that it becomes a 45% protein mixture, and more water, or salt solution, is added, two phases appear, namely a mesophase which contains approx. 43% protein, and a protein solution containing a few percent protein, in equilibrium.

in ■ ■

Peanut protein does not require the presence of a disulfide bond preventing agent, although it can be prepared in the presence of one.

Arakin, a purified peanut protein can be obtained as a mesophase with protein concentration 43%, prepared with 10% w/v sodium chloride solution.

The mesophases are remarkably stable on storage. The

can e.g. stored in a frozen state, and while the system changes -

which manifests itself in a more opaque appearance - the mesophase reappears on thawing. This freeze-thaw ability is a valuable feature

cabinet.

The mesophases are resistant to precipitation with organic solvents, e.g. alcohols. When adding ethanol to a soy-protein mesophase at pH values ranging from 4.6 - 6.5,

up to 40% by weight ethanol, based on the water present, can be added before precipitation of the protein is initiated. This is a remarkable result as glycinin, the main soy protein, precipitates

read from ordinary solutions with a low protein content at approx. 10% ethanol, and most globular proteins precipitate under similar conditions. This exceptional stability is believed to be attributable to

ves the molecular structure of the mesophases and serves to further differentiate it from solutions.

The stability of the mesophase towards alcohol allows the formation

se of mesophases containing both soy protein and zein by adding a solution of zein in ethanol to the soy mesophase. Solutions of zein in aqueous ethanol with a concentration of from 20 - 40% can be used, and if desired, the soy ptortin mesophase can be diluted with a little ethanol before adding the zein solution. The addition of zein usually increases the viscosity of the mesophase. Many other proteins can be silenced, without affecting to any particular extent the mesopha-

sense characteristics. The most common effect is an increase in viscosity.

Valuable products, suitable for incorporation into foodstuffs, are obtained by simply curing the mesophase. A desirable chewing structure can be given to foodstuffs by incorporating the here-

ded material in them as described later.

Cured products can be incorporated into foodstuffs in different forms. A liquid mesophase mass can be hardened in rela-

very large pieces, e.g. long stripes or ]ag. These can then be cut up into small cubes so that they become meat-like lumps, or they can be minced so that they resemble finely chopped meat.

The mesophase can also be extruded, e.g. in the form of fibres, such as

can be bound in a suitable matrix and look like flesh. Alternatively, the mesophase before curing can itself be used as a binder for foodstuffs,

e.g. pieces of meat or simulated pieces of meat, and then here-

dec,

Since the method for producing the mesophases avoids

in

go the strongly alkaline conditions used in previously known methods; the production of edible fiber products from soya flour and other protein sources has been simplified. Mesophases can easily be used for processing as they are easy-flowing and have a high protein content. They can e.g. easily pumped. Also the relatively low cost associated with plant proteins such as soy protein, in comparison with other protein sources such as e.g.

meat, allows a significant reduction in costs without deterioration of nutritional or organoleptic quality. Often an improved quality can be achieved by incorporating mesophase. The protein does not need to be destroyed at any stage during production from the flour and the degree of bean aftertaste in the product can be kept very low.

When fibers are made, much of the off-bean taste and color can be found

after extrusion in the curing bath rather than being bound to the protein. in

Other1 material that forms part of a finished food product can| is incorporated before the mesophase hardens. For example, ground meat particles can be added to the mesophase, and this constitutes a means of making use of meat that would otherwise be thrown away,

e.g. cut parts or cut material of poor quality

tight. When ground meat particles are added to the mesophase, they are found to dissolve while the viscosity of the mixture hardly changes. A real solution does not take place in reality,

as a mass of fragmented muscle fibers which are striated and doubly refracting can be observed in the system when examined under the microscope. The apparent "solutions" can be shaped, e.g. by extrusion into fibres, so that you get products that are very useful as simulated meat or for incorporation into meat products

is. The presence of the meat in the mesophase increases its nutritional value, since the meat serves as a source of animal protein.

Furthermore, the mesophases are able to carry at least a part of

the soluble and especially the insoluble carbohydrate component of the oilseed meal, and consequently extensive purification of the protein is unnecessary. Mesophases have been made that contain up to 40% carbohydrate by weight, calculated on the total weight of protein and carbohydrate

rat, and these can be hardened. They can also be extruded into fibers if any large pieces of insoluble carbohydrate are removed.

The carbohydrate-containing mesophases can easily be

mes from a mixture of protein isolate and whey. E.g. a mesophase can be made from a mixture of (a) soy protein isolate which is com-

met state by precipitation at the isoelectric pH value and (b)

up to twice its weight of a solvent-extracted soybean meal. This has the advantage that only part of the flour needs

is cleansing. The addition of carbohydrate also provides a method of softening the structure of the hardened mesophases. In particular, the fibers produced from a carbohydrate-containing mesophase have less mechanical strength than fibers containing protein,

salt and water alone, and have a softer texture for eating when incorporated into food products. The structure of pieces of here-

the mesophase can also be softened in this way.

Additional materials can be incorporated into the protein mesophases, e.g. fat. A fat emulsion in an aqueous protein mesophase can be hardened or can be extruded as fibers that hold the fat.

The use of fats emulsified in the mesophase provides a method for incorporating oil-soluble additives, such as flavoring and coloring substances, into a food product containing material derived from a protein mesophase.

A suitable method for incorporating flavor and color

substances in mesophase products make use of fats that are emulsified into the mesophase. Fat-soluble flavoring and coloring substances can be incorporated into the fat, which is then emulsified into the mesophase. It has been found that these flavoring and coloring substances are preserved in the mesophase during pre-processing, even when the mesophase is extruded into a bath to form fibers. If it is desired to use water-soluble flavoring and coloring substances, these substances are dissolved in water which is then emulsified in fat. The fat is then emulsified in the mesophase so that it becomes a double emulsion. In this case, the flavoring and coloring substances are preserved in the mesophase during fiber formation and other processing steps more stubbornly than if they are incorporated directly. If no fat is included, in the mesophase, then water-insoluble color and flavor

substances directly into the mesophase.

The mesophase is hardened by heating. The necessary temperature to harden the mesophase is usually above 80°C

and preferably above 90°c. Curing can take place in large pieces, e.g. castings, or mesophase can be extruded into water-

or salt solution in the form of sheets, ribbons or fibres. Extrude-

ring into cold, warm or fairly warm water through a spinning nozzle produces separated fibres. The fibers harden on the surface initially, by loss of salt from the outer zone, which causes the precipitation of protein and the formation of a skin. Fibers which are formed by extrusion into water at 80°C or more do not require any further heat treatment. If the temperature in the extrusion bath. is below 80°c, the fibers require a heat treatment or texturing to fully harden them and give them elasticity or "chewability".

The main factors that relate to the rate of heat curing are the protein content in the mesophase and type of protein, the salt content in the mesophase and type of salt, the temperature at which the curing takes place, and the mesdphase's pH. The higher the protein content and the temperature, the faster the hardening. The protein mesophase is usually close to its isoelectric pH (4.8-4.9 for soy), and the yield of precipitation of protein during the processing of flour is best at this pH. Changing the pH away from this and towards pH 4.0 increases the rate of heat curing. In addition, soy protein hardens faster than peanut protein. An example is fibers formed by extruding soy mesophase into water with a solids content of 33% by weight, a salt content of 4% by weight sodium chloride and with a pH close to the isoelectric pH, which is usually cured by heating at 90 to 100°C for at least 1 second. Peanut requires several seconds,

Variation of the salt content in the mesophase, when the salt used is the salt of a monovalent cation and a monovalent anion, has a very marked effect by increasing the time for heat curing.

An example is a mesophase containing 2% by weight sodium chloride which is heat cured in 35 seconds at 91°C, while a similar mesophase containing 16% by weight sodium chloride required 59 minutes for full cure at this temperature. Potassium chloride and ammonium chloride also have a very marked effect in increasing the time for heat curing, although they are not as effective in this as sodium chloride. The salts of divalent cations with monovalent anions, however, do not have a very strong effect on the time for heat curing. A mesophase which•contains 16% by weight of magnesium chloride needs approx. double! as long to harden as a mesophase containing 2% by weight of magnesium chloride. When mesophases containing calcium chloride are formed, the heat curing time is almost independent of the salt

the concentration.

The presence of small amounts of certain specific salts also has a marked effect on heat setting time, although large amounts of other salts may be present. As an example, when mesophases are formed which contain varying amounts of sodium chloride together with a small amount of calcium chloride or magnesium chloride, e.g. 0.5% by weight, then the time for heat curing of mesophases containing concentrations of sodium chloride in the range 4-12% by weight is much less than the time for heat curing of mesophases containing these amounts of sodium chloride without any other salt.

As indicated above, the mesophases can be spun or formed into fibrous materials. The bath into which the fibers are extruded may be tap water, softened water or distilled water, or it may be an aqueous salt solution. It is possible to extrude fibers into air with subsequent water treatment, e.g. can the spinning nozzle be above and thus not in the bathroom.

If the produced fibers are treated with hot water at over 80°C, preferably 90 - 100°C, or with steam e.g. on a conveyor belt, they become elastic and tougher, with properties that give good texture when chewed and can be processed into food products. Alternatively, these fibers can be obtained by extruding the protein mesophase directly into hot water.

The mesophase can be extruded with a protein content of up to

to approx. 50% by weight, the upper limit being determined as much by the high viscosity as by any other factor. The viscosity of the mesophases is highly non-Newtonian, and viscosities can therefore only be referred to as apparent viscosities. The apparent viscosities at room temperature (20°c) may vary, e.g. between 0.2 poise for soy protein mesophases containing 23%, to 2000 poise at 40% solids for the same protein at comparable shear rates. When using soy protein, mesophases are preferred for fiber formation which have apparent viscosities (measured with a Rheogoniometer) of 50 poise at shear rates of 30-70 sec.

When the extrusion takes place in water below 25°c, the fibers are soft and pasty, and although they are exposed to water at this temperature for many hours and thereby become tougher, they do not develop the elastic qualities that appear at temperatures above 80 °C. In the "hot water process", mesophases are extruded directly into water of 80 or 90 to 100°c. In the second process, the "cold water process", the mesophases are extruded into water at temperatures between 15 and 80°c.' The fibers are thereby given elasticity and the desired texture by subsequent heating above 80°c.

In the "cold water process", the formation of fibers is believed to be due to the formation of a skin over the surface of the fiber, this being formed by precipitated protein, which is caused by the loss of salt into the bath from the mesophase. At this stage, the fiber comprises a hardened, outer skin which still contains liquid mesophase material. When heated, the liquid gives a textured material which forms the main mass of the fibre, in The skin is well-defined, which is shown by electron micrograms. Below 40°c, the hardening process is reversible, and a mass of such fibers can, if the surrounding salt concentration becomes high enough, revert to a mesophase. This tendency is eliminated or reduced by slightly raising the temperature in the water bath to 40 - 70°c. This temperature range is below that required to produce the elastic textural property of fibers produced by the hot water process, but it improves the stability of the fibers to salt solution. If the mesophase is prepared at a pH above the isoelectric pH-, a curing bath containing a buffer solution of 0.1 M sodium acetate gives good results.

In the hot water process," i.e. at temperatures in the water bath above about 80°C and| preferably above 90°C, the elastic fibers are formed directly. A skin is still formed, but the core of liquid mesophase is rapidly converted into a cross-linked mesh by the heat, which as shown by electron micrographs of the heated fibers. The effectiveness of the method is affected by the speed at which it is carried out. If the speed is not sufficiently great, the fibers, while still strong and elastic, are broken into short lengths. These are themselves desirable and useful products, for example in the formation of simulated meat.

The protein content of the fibers is usually not the same as the protein content of the mesophase from which they are formed. The protein content is usually higher when extruded into water. When a mesophase with a protein content of approx. 25% is extruded into water, the fibers formed generally have a protein content of approx. 30 - 32%. If it is desired to produce fibers with a lower protein content, extrusion of a mesophase into a curing bath containing from 1-4% of a salt may be suitable. For example, if a soy-protein mesophase containing sodium chloride is extruded into a bath of 1% sodium chloride solution, the fibers formed generally have a somewhat lower protein content than the mesophase from which they are formed. If extrusion takes place into baths containing a stronger sodium chloride solution, e.g. 4% by weight, the fibers formed have a much lower protein content than the mesophase from which they are made

e/

The availability of a method for varying the protein content in the fibers is an important feature of the invention. The texture of the fibers produced depends largely on the protein content. Fibers with a high protein content are tougher and have a more chewable texture than those with a lower protein content, e.g. such as are produced by extrusion into a bath with a high salt concentration. If it is desired to produce a food product, e.g. simulated meat, with a marked fibrous structure and which requires more chewing, fibers with a high protein content are used, e.g. such as are produced by extrusion into a water bath. It has been found that a small variation in the protein content, e.g. 2 or 3% variation has a marked effect on the texture of the fibers produced.

The use of a curing bath containing a brine also provides a means of varying other properties of the fibers. The presence of salt has a marked effect on skin formation on the fibres. The fibers which have been extruded into a bath with a relatively high salt content, e.g. 4-8% by weight, are translucent, swollen and spongy. In general, the diameter of the fibers produced is increased by extrusion into sal-floss compared to extrusion into water. The presence of salt in the curing bath appears to prevent shrinkage of the fibers during curing. The fibers produced by extrusion into a brine have a smoother surface than fibers produced by extrusion into water. The fibers are also more translucent, which probably indicates that the formation of a skin of precipitated protein is a less important feature of curing when the extrusion bath contains a salt, and the fibers are slower in curing and have a lower protein content.

If it is desired to regulate the bath's pH value, a strong puffer, e.g. sodium acetate, is used.

... Elbre; which are produced by extruding mesophase through a spinneret, generally have a diameter that is larger than the holes in the spinneret through which they were extruded, and which

given above, this effect is more marked when they are extruded into a salt solution. For example, when extrusion takes place in water through a spinneret with a 0.1 mm diameter hole, the fibers produced, which have a somewhat rough surface and an irregular cross-section, have an average diameter of approx. 0.2 mm. Likewise, fibers produced by extrusion through a spinning die with 0.2 mm diameter holes have a diameter of approx. 0.3 - 0.4 mm, but fibers produced by extrusion through a spinning die with a 0.5 mm diameter hole have a diameter that is very little larger

in

than the holes in the spinning nozzle. The fibers produced by extruding

ring through larger holes, also has a smooth surface and a more regular cross-section.

In the hot water process, it is desirable, in order to prevent the mesophase from hardening in the pipes leading to the spinning nozzle,

or in the spinning nozzle itself, that these are kept at 20°C or lower.

For this reason, the pipes leading to the spinning nozzle are preferably

surrounded by a water jacket, and the spinning nozzle itself is equipped with cooling channels through which cold water is circulated. The mesophase should harden just as it exits the spinneret, but not before.

The mesophases that are extruded need not be homogeneous.

As previously mentioned, they can contain a smaller proportion of dispersed, amorphous protein and the soy mesophases are often of this type, containing dispersed material of the order of 10 microns.

When these are extruded, the holes in the spinneret should have at least a certain minimum volume. It is important to maintain a uniform and stable extrusion rate when extruding mixtures of shapes that the total volume of the spinneret hole should be noticeably higher than the volume of the dispersed material. This can easily be achieved by using spinning nozzles consisting of tubes, e.g. tubes 1 cm long and 0.1 mm in; internal diameter. This restriction does not come into question when extruding a possible homogeneous phase, and although the use of such tubes causes significant shear forces on the mesophases before fiber formation, it is assumed that this is not important for fiber formation.

When using spinning nozzles with holes of 0.1 mm diameter el-

less, it is desirable that large pieces of carbohydrate remove

es from the original protein extract, e.g. by recentrifugation.

An extrusion apparatus which is suitable for carrying out the method according to the invention is shown in operation in the accompanying drawing.

A reservoir 1 contains mesophase to be spun 2. The mesophase is fed to a gear pump 5 under the influence of compression

mixed air from a supply 3 and presses against a die 4 which forms a piston to prevent channel formation, and then to the relevant extruder which is generally indicated at 6. In the extruder, the mesophase passes through a supply channel 7 to a spinning nozzle 8. The spinning nozzle is only shown schematically, but consists of 20 steel tubes with an internal diameter of 0.2 mm, which are set in a steel plate that serves as a support.

Cooling water passing through a jacket 10 from a store

9, surrounds the mesophase until it enters the spinneret. The water passes from the cooling jacket through the spinning nozzle and then to the

ack through a channel 11. The fibers, which are shown coming out at 12, pass into a water bath formed by a tank 13 of stainless steel, and are carried away on a conveyor belt 14. The bath is provided with a. electric heating element 15 which is strong enough to

keep the bath at the boiling point if desired, and is located below the extruder, but separated from it by a shielding wall 16 to prevent direct heating of the spinning die.

The extrusion process is not limited to extruding

ing through a spinning nozzle to form fibres. Ribbons and other wishes

ede shapes can be formed. E.g. a mesophase can be extruded in the form of a corrugated ribbon and. this material breaks up, when it rolls

read carefully, so that you get a material similar to fiber bundles. Such a material has a texture suitable for incorporation into foodstuffs, e.g. simulated meat products.

A completely different area of application for the mesophase is

that curry is used in its uncured> liquid form as a binding agent in foodstuffs. The products formed in this way can be hardened by heating to a temperature in the center of 80°C, preferably 90°C.

The food products made in this way may be based on

a large selection of foodstuffs, especially meat and simulated meat products. Mesophase curry" is used to bind chopped or diced meat, or can be used to bind converted meats made from ground, raw meat and cooked, fine-

minced meat which can then be dried or canned. It

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can also be used as a binder for the hardened mesophase products, e.g. heat-cured, large pieces or fibres, or for other protein products of vegetable origin, e.g. fibers produced by extruding an alkaline protein solution into an acid coagulating bath.

It has been found that the mesophase, when used as a binder, after curing in a variety of products has a particular advantage in terms of texture over known binders, since it has an inherent chewable texture, in addition to the textures provided by it other material contained.

A further advantage of mesophase used as a binding agent in meat products is its ability to bind water and thus to reduce the weight loss1 of the meat when it is cooked. This binding of the liquids in the meat in the meat product improves the texture of the cooked meat, making it juicier and more enjoyable. The water-retaining ability of mesophases and of meat/mesophase mixture varies with the pH value, which makes it possible to form a meat product with the desired water-retaining ability, by varying the ratio between meat and mesophase binder in the product.

When soy protein mesophase at its isoelectric pH value (approx. 4.6 - 4.9) is added to finely chopped meat and the mixture is heated to 100°C for 1 hour, there is little variation in water retention capacity up to approx.:40 % mesophase content. Above this mesophase concentration, the juice that can be squeezed out decreases rapidly. The juice that can be squeezed out means the weight percent liquid that can be decanted from a sample after centrifugation at 157,000 g for 30 minutes in a 10 ml test tube. This is a very serious test regarding the material's water-retaining ability. When the mixture's pH value is increased, the amount of juice that can be squeezed is reduced significantly (and the water-retaining ability therefore increases), and at pH approx. 6.5 - 6.8, the replacement of only 10 7. of the meat with mesophase causes a drop of up to 25% in the squeezeable juice: When the mesophase is adjusted to the pH value of the meat, which is 5.7, for mixing in follows the variation in squeezeable juice with the mesophase concentration an intermediate course between the above two examples. An addition of 10% mesophase to the meat causes a drop in extractable juice, and thereafter there is little change until the mesophase concentration is greater than 40%. This is a very useful property of the mesophase when it is used as a binder, since the mesophase can be added in quantities varying between 10 and 40 7o, and it will increase the water-retaining ability of the meat to a desirable level for processed meat products.. A further property of the mesophase is that it noticeably reduces the viscosity of minced meat without changing the protein concentration. This makes it easier to mix and pump the meat during product manufacture.

The shaped, heat-cured mesophase products, e.g. diced or finely divided bulk cured material or extruded fibers or rods, can be used by incorporation into a large variety of foodstuffs or alternatively substantially flavored in a suitable manner, and if desired supplemented with amino acids or a small amount of an animal protein, e.g. casein. They can be cured in a matrix of coagulable protein which can itself be a mesophase if desired. Two or more forms of heat-set mesophase, e.g. fibers and diced bulk-cured material, can be incorporated into a food product if desired. These heat-cured materials can be used to replace all or part of the cooked meat component in known food products.

The amounts of the fibers, the hardened pieces or the liquid mesophase binder to be incorporated into the meat products will vary according to the desired product. E.g. in the product of the "beefburger" type, which is made from finely chopped meat as the main ingredient, together with onions and other flavourings, up to 60% by weight of the meat can be replaced with protein mesophase fibres, with a substitution of 20 - 40% by weight of meat by fibers gives a particularly good product. The texture of the product is improved in this way, as it becomes more fibrous. The yield of the product during boiling is also improved. Alternatively, up to 40% of the meat can be replaced with bulk-cured mesophase binder, which can be finely chopped with the meat.

A dried meat product can be made from a mixture of finely ground, raw meat and finely chopped, cooked meat. In the formation of such a meat product, it is possible to use mesophase in any of its three forms. The raw meat can be replaced in whole or in part by uncured mesophase binder and the mixed, heat-cured material to a temperature in the center of at least 80°C. E.g. can approx. 50% of the raw meat is replaced with uncured mesophase binder, which gives a product with an improved and juicier texture. Moreover, this meat product can be rehydrated as separate, coherent pieces, without the crumbling of the rehydrated product which is often a disadvantage of such meat products. Alternatively or in addition, some or all of the cooked meat content in the dried meat can be replaced with heat-cured pieces or fibres. For example, if fibers are incorporated into the cooked meat portion of dried meat, the product has improved texture due to increased fiber form.

It is possible to produce a dried meat substitute

which is made entirely from vegetable protein, using uncured mesof ase binder as a matrix for heat-cured mesof as e protein fibers with subsequent heating of the product to harden the binder. Flavorings, e.g. beef and chicken flavours, and permitted heritage ingredients can be incorporated into the product before or after curing.

The artificial meat, which is made entirely or partly from protein mesophases, can also be used for pies, e.g. in pork pies. , The texture of the bulk-cured mesophase is more suitable for pork pies than the texture of fibers, and if a proportion of the meat in the pie is replaced with bulk-cured protein mesophase, a juicier product can be obtained. In this application, it is preferred and used a mesophase with a dry matter content in the lower part of the area, where the mesophase will form e.g. about. 20% dry matter by weight, as this gives a product with a somewhat smoother texture.

It is also possible for meat for pork pies to use uncured binder as a substitute for part of the meat, preferably in addition to the use of finely chopped, cured pieces.

Mesophase protein can also be used for canned and frozen meat products made from ground, raw meat and cooked, finely chopped meat, and as is the case with the dried product, the raw meat can be completely or partially replaced with uncured mesophase binder, as e.g. up to 40% of the raw meat can thus be replaced, or the cooked meat can be replaced with bulk-cured mesophase protein or with mesophase fibres, whereby e.g. up to 50 7, of which koktje meat can be replaced. When it comes to the canned product, a product with a particularly desirable, chewable taste can be obtained which is an improvement in relation to the corresponding product which does not contain any vegetable protein,

using bulkj heat-cured mesophase protein to replace part of the cooked meat. It is also noted that when soy protein is used to make a mesophase, and this is subsequently used as a binder for heat-cured pieces of a meat product, the soy off-flavor, which is often present in soy materials, is absent even if the products are canned.

Converted meat can be prepared in the same way and can be used

as an ingredient in frozen products such as meat pies, e.g. chicken pie or "Steak and kidney pie" or as an ingredient in sauces to be cooked in the bag.

Mesophase^rotein products, especially bulk-cured mesophase, can be used in the manufacture of pulses. The hardened mesophase can be chopped in a bowl chopper by the method usually used for the production of pulses. As is the case with pie meat, it is preferred to use a relatively low solids mesophase, and when bulk heat-set mesophase is used, low solids mesophases provide a smoother textured product.

A further application for the protein mesophase is in the preparation of large, regularly shaped pieces of meat made by sticking small pieces of meat together. Such products are commercially valuable, e.g. when it is desired to produce slices of meat of uniform size. The mesophase can be used in two ways for the production of products of this type. It can be mixed in with the pieces of meat, and the whole mass can then be heat cured. This is similar to the use of mesophase as a binder in meat products. Alternatively, mesophase can be sprayed into the meat, e.g. because it is chopped into pieces, and when the pieces of meat are then mixed together and heat-cured, the protein will be secreted from the pieces of meat and will bind them together when heated. The use of mesophase in this way gives the additional advantage that the loss of liquids from the meat during cooking is reduced, and the texture of the meat is improved. The water-binding capacity of the mesophase keeps the liquids in the meat in place in the meat, and these liquids give the meat a tastier and juicier texture.

If desired, a meaty product can be made from protein mesophase, where all the protein present is derived from vegetable protein and where no meat is present. A suitable method for carrying out this is to produce a protein mesophase'

with a dry matter content of approx. 25% by weight, as well as emulsifying with this 10 - 30% by weight of fat, based on the total weight of the mesophase. This mesophase, which is emulsified with fat, serves as a binder in the protein product and is used in an amount of 20 - 50 wt-7, calculated on the entire product, together with 50 - 80 wt-7" fibers formed by the protein mesophase. These fibers preferably have a relatively bare texture, and this bare texture can be achieved by using fibers with a low protein content, e.g. 20 - 25% by weight protein, or by using fibers containing carbohydrate. The fibers may conveniently be those produced by extruding mesophase into a curing bath containing a salt solution. The binder component and the fibers are mixed, and the mixture can be stopped or extruded to align the fibers. The product, which comprises protein mesophase fibers bound in a matrix of heat-cured mesophase, can subsequently be cut into cubes or divided into 2.5 cm pieces. The product has a chewable fiber texture. Coloring and flavoring substances can

is incorporated both in the protein mesophase which is emulsified with fat, and in the protein mesophase from which the fibers are made. In the latter case is incorporated! the coloring and flavoring substances in the mesophase before extrusion. If desired, fat can be incorporated into the mesophase before the formation of fibers.

In the following, the invention will be illustrated by means of examples, where percentage indicates weight unless otherwise stated.

EXAMPLE 1

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"Soy Fluff W", a low temperature solvent extracted soybean meal, was mixed with excess water containing 0/1% sodium sulfite and a few drops of silicone antifoam emulsion and centrifuged at 5,000 G to remove insoluble carbohydrate material. The supernatant liquid was then adjusted to pH 4.6-4.9 by adding hydrochloric acid. A white precipitate appeared which was immediately collected by centrifugation as a leather-coloured, putty-like material. The analytical composition of the material produced in this way was dry matter (excluding ash): 43 - 51%, depending on the force used in the centrifugation, water (in which sodium sulphite is dissolved) 48 - 56%, salts 1 %.i Next to the sodium sulphite associated with the protein isolate, there was also approx. 10% by weight, calculated on the protein, of remaining dissolved carbohydrate in the protein isolate. The figures for dry matter without ash are given including this carbohydrate.

250 g of the protein isolate, containing 43% dry matter without ash, was mixed with 150 ml of water and 6 g of solid sodium chloride in a laboratory mixer, resulting in a final dry matter without ash content of 27% and a final sodium chloride molarity, calculated on water, of 0.39 (not including the salt derived from the soybean meal), at pH 4.82. When mixing, the viscosity dropped sharply and the transparency improved. Air was removed by centrifugation at 600 G for 15 minutes. A vacuum mixer can be used to avoid1 entrainment of air. The reservoir for the spinner was filled with the mesophase and it was pumped with a gear pump through a spinneret containing 20 openings of 0.2 mm diameter into water at 20°C. Extrusion speeds of 1.6 and 5 m/minute were used. White, continuous fibers formed in both cases and were collected. After treatment for 1 minute in water at 90°c, the fibers were tough and elastic and suitable for incorporation into food products.

By performing this example with mesophase pH values of 4.05 and 4.41, similar results were obtained.

In another experiment, at pH 4.65, in a spinning nozzle with a 0.1 mm hole

and at an extrusion speed of 7 m/minute similar results were

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EXAMPLE 2

500 g of protein isolate prepared as described in example 1, containing 43 7% dry matter without ash, was mixed with 200 ml of water and 14 g of solid sodium chloride in a laboratory mixer, so that a final dry matter without ash was obtained content of 25% weight/volume and a final salt molarity of 0.53, calculated on water (not including the salt originating from the soybean meal). The pH value was 4.8 - 4.9.

The mixture was then centrifuged at 9,000g for 60 minutes. Two protein layers and a small carbohydrate lump were separated. The upper protein layer, a transparent mesophase, was carefully removed without mixing in air, and the carbohydrate lump was discarded.

The reservoir of a spinning machine was filled with the mesophase, which contained 23% protein, and it was pumped with a gear pump through a spinning nozzle into water of 20°C. The pumping speed was approx. 6 ml/minute, and the spinneret had 2,000 holes, each of diameter QD9 mm, so that the extrusion speed was approx. 0.5 m/minute.

Continuous white fibers formed and were collected. The water in the bath turned slightly yellow, but no significant amount of protein was dissolved in it. The fibers which were extruded were treated at 95°C in water for 1% minutes and produced a good fiber suitable for incorporation into foodstuffs.

In an experiment with extrusion at pH 4.65, similar results were obtained.

EXAMPLE 3

This example illustrates the use of different salts. A similar procedure was followed as in the example

2, and the reservoir of a spinning machine was filled with mesophase, containing 25 7. protein, prepared with 0.5 m riatrim nitrate instead of the sodium chloride solution.

This mesophase was pumped through a single nozzle with

2 mm diameter, into water at 20°C. White, continuous fibers formed which, when texturized in hot water, produced good fibers.

Similar experiments with calcium chloride, potassium chloride, sodium phosphate and ammonium chloride also gave good results.

EXAMPLE 4

This example shows the extrusion of mesophases which are alkaline relative to the isoelectric pH value.

200 g of protein isolate (prepared as described in example 1) with a dry matter-without-ash content of 45% was mixed with 44 ml

water, 5.6 tg sodium chloride and 6.2 g sodium bicarbonate in a laboratory blender, so that a well-transparent mesophase with pH 7.10 was obtained, containing approx. 40% dry matter without ash and with a total ionic strength of approx. 1.1 on water. The mixture was then centrifuged at 500 G for 15 minutes, for degassing.

The reservoir of a spinner was filled with the mesophase, and it was pumped by a gear pump through eh spinneret with 2,000 holes of 0.09 mm diameter into a bath containing tap water at 25°C. The extrusion speed was approx. 1 m/see customer. The; formed weak fibers which were strengthened by heating the water <!>to 95°C.

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In an experiment according to this example using an i

mesophase of pH 5.61 prepared using 3.1 g sodium bicarbonate and 5.6 g sodium chloride, similar results were obtained.

EXAMPLE 5;

This example shows the use of disulfide bond-preventing agents after the isolation.

800 g of flour ("Soy Fluff W", a solvent-extracted flour) was mixed with 4 L of water to a mixture of pH 6.41. This was centrifuged to remove solid carbohydrate, and the supernatant liquid was brought to pH 4.8 by adding hydrochloric acid.

A precipitate formed which was removed by centrifugation to give a sticky, putty-like mass with a water content of approx. 47% and dry matter content (including remaining dissolved carbohydrate) 53%. The mass was mixed immediately after preparation with

2% (w/w) sodium chloride. It formed a clear, viscous

liquid of mesophase which, on standing, rapidly increased in viscosity,

as it hardened into a gel. 1% w/w mercaptoethanol was added to prevent this, although the gelatinization is partially reversible and if the mercaptoethanol is added to the gel, the viscosity drops and may result in a liquid mesophase.

Likewise, sodium sulphite (1% w/v) will prevent or reverse the gel formation. The mesophases could be extruded and hardened as in example 1.

EXAMPLE 6 J

This example shows the effect of different concentrations of sulphite during extract none'. •

20 g of flour ("Soy Fluff W") in each case was mixed with 200 ml of water containing the amount of sulphite shown in the table below, then centrifuged to remove carbohydrates and left to stand for approx. 30 minutes. From the supernatant liquid (pH=- . the value is shown in column 3 of the table below) the extra-hardened protein was precipitated from the supernatant liquid by adjusting the pH value to 4.8 with HCl. The yield of wet protein was as shown. The wet protein, containing about 45% protein, was then mixed with 6 ml of 2% sodium chloride solution and further, solid sodium chloride added so that there was a final content of 2% (w/w), calculated on the whole mass, as well as a total protein content of 35%. Mesophases formed and were separated by centrifugation. The less heavy form was removed and analyzed for protein content with the result shown. The mesophases remained stable, showing only a slight increase in viscosity during 48 hours.

In a similar experiment, 40 g of flour was mixed with 200 ml of water, and the total protein content in the mesophase was adjusted to 49% protein. Samples 1 - 4 in the table gave viscous, transparent mesophases which remained stable for at least 24 hours. <p>butts 5 and 6 were opaque and even more viscous.

In both cases, the mesophases could be extruded and hardened as in the previous example.

EXAMPLE 7

This example shows the preparation of the mesophase by cooling and dialysis.

A mixture of i) 60 g flour ("Soy Fluff W") and ii)

140 ml of a solution of potassium phosphate (0.035 m) and sodium chloride (0.4 m) at pH 7.6 and containing 1% mercaptoethanol was centrifuged to remove insoluble carbohydrate, the supernatant was cooled and dialyzed against water at 4°C for 18 hours. A hazy, loose "precipitate" with "oily" droplets appeared,

and these were separated from the supernatant protein solution by centrifugation at 1,000 g for 30 minutes in a cold

centrifuge. The sediment, which was warmed to room temperature, was a mesophase and could be extruded and textured to form fibers as in Example 1. It remained stable for several days and did not gelatinize.

EXAMPLE 8

This example shows the use of peanut protein, prepared from low-temperature solvent-extracted flour. 40 g of protein was mixed with 200 ml of 12.5 7. (w/v) sodium chloride solution at pH 5 and kept at 50°C for 1 hour, after which it was filtered in a drying cabinet of the same temperature, 50 ml of the salt solution was also used for washing. The filtrate was cleared by cooling in ice, and on standing overnight 50 ml of an apparent precipitate separated. The supernatant protein solution was decanted and the "precipitate" heated to 25°C, at which temperature it formed a clear, slightly brown mesophase.

In a further experiment, the protein solution was dialysed against water at 4 C. A precipitate formed, and after separation and heating, a mesophase containing approx.

43 7. protein.

The mesophases could be extruded and textured as in example 1.

EXAMPLE 9

300 g of the peanut protein used in example k 8 was mixed with 700 ml of water and 28 g of solid sodium chloride in a laboratory mixer. The mixture was then centrifuged at 10,000 g for 30 minutes. Two layers formed, the upper one was a solution with a volume of 386 ml containing 6.07. protein and 2.75 '7o ash, and the lower was a viscous, slightly opaque mesophase of pH 5.25. The volume was 614 ml, and it contained 45.67. protein and 1.527, ash.

The other mixtures, samples 2 and 3, were made in the same way, but contained varying amounts of salt. The numbers were:

The mesophases could be extruded and textured as before.

EXAMPLE 10

Mixtures were made in a similar manner to Example 9, but they contained approximately 45% protein.

It did not separate on centrifugation and gave viscous mesophases directly on mixing. The salt content was different:

The mesophase could be extruded and textured as before.

EXAMPLE 11

450 g of peanut protein was mixed with 550 ml of 5%

(weight/volume) sodium chloride solution, so that one mesophase was obtained as in example 10. This was further mixed with 5% (weight/volume) sodium chloride, so that a range of total protein contents (23, 26, 30, 33, 36, 41, 43, 44%). After centrifugation, a sediment containing 42.2 - 43.9 total dry matter and approx. 40% protein, together with a varying amount of supernatant, which was a solution containing 8-10% protein. The pH value was 5.25.

The mesophase could be extruded and textured as before.

EXAMPLE 12

This example shows the formation and extrusion of a mesophase from canola protein. 1 kg of ground rapeseed was extracted by stirring for 4 hours at 2.5 liters of a 2:1 mixture of chloroform and methanol. A 500g sample of the defatted seeds was then extracted with 5 liters of water where the pH value was adjusted to 7.1 with sodium hydroxide. Carbohydrate was removed by centrifugation and the pH adjusted to 5, which produced a brown protein precipitate. 4 weight-7. sodium chloride was added to the wet precipitate, and a viscous liquid mesophase appeared.

This mesophase was extruded into cold water and brown, paste-like fibers were obtained. These could be textured as described in example 1.

EXAMPLE 13

This example shows the formation and extrusion of a mesophase from pea protein. 1 kg of dried peas were pulverized and mixed with 10 liters of 0.1 7" sodium sulph Ltt. The residues were removed by settling and centrifugation, and the pH value of the supernatant liquid was then changed from 6.5 to 4.8 with hydrochloric acid. A coarse protein precipitate appeared on centrifugation. 4 weight-7. sodium chloride was added to this precipitate and a viscous liquid mesophase appeared.

This mesophase was extruded into cold water. Soft fibers were produced, which were given a good chewable texture by heating in boiling water. Much of the color of the peas was lost to the watery extrusion bath, which turned green.

EXAMPLE 14

This example describes the preparation and extrusion of a soy bean protein mesophase containing carbohydrate, from soy flour.

580 g of soy protein isolate prepared as described in Example 1 was mixed with 83 g of "Soy Fluff W" and a solution of 24.4 g of sodium chloride in 336 g of water was added. No phase separation took place and a mesophase was produced. This mesophase had the following composition, with the percentages indicating weight"

This mesophase was extruded into water through a spinneret with 20 holes, each of 0.2 mm diameter. Good, continuous fibers formed at 95°C. These fibers were found to have a carbohydrate content of 6.7%. The lower carbohydrate content of the fibers, compared to the mesophase, was thought to be due to the loss of soluble carbohydrate to the extrusion bath.

The mesophase containing 8.6% carbohydrate was also extruded into! water through a spinning nozzle with 20 holes, each of 0.5 mm diameter. Again, good, continuous fibers were formed, and these had a carbohydrate content of 7.4%.

EXAMPLE 15

460 g of soy protein isolate prepared as described in

sample 1, was mixed with 208g "Soy Fluff W" and a solution of 22.5g sodium chloride and 332g water added. A mesophase with the following properties was produced:

In two separate experiments, this mesophase was extruded into water at 95° C through spinning nozzles with holes of 0.2 mm and 0.5 mm respectively. In both cases, good, continuous fibers formed. The fibers produced by extrusion through holes of 0.2 mm diameter had a carbohydrate content of 4.07", while the fibers produced by extrusion through holes of 0.5 mm diameter had a carbohydrate content of 6.07o, which shows that more soluble carbohydrate was lost from the smaller diameter fibers.

EXAMPLE 16

361 g of "Soy Fluff W" was mixed with 160 g of the protein isolate prepared as described in Example 1, and a solution of 21.0 g of sodium chloride in 545 g of water was added. A mesophase with the following composition was produced:

This mesophase was extruded into water through holes of 0.2 mm and 0.5 mm as described in Example 14. Bare fibers were produced which were mechanically weak, and those produced by extrusion through holes of 0.5 mm diameter , had broken. The bare, weak fibers produced were useful for incorporation into meat products of the type where a highly fibrous, chewable texture was not desired. The carbohydrate content of the fibers was 4.27% for the fibers produced by extrusion through holes of 0.2 mm diameter, and 5.7% for the fibers produced by extrusion through holes of 0.5 mm diameter.

EXAMPLE 17

Part (a)

A soybean protein mesophase was prepared by mixing a precipitated protein isolate (as in the previous and subsequent examples obtained as described in ex. 1) with salt and water. The mesophase contained approx. 4% sodium chloride, based on the water present, and had a protein content of approx. 45% by weight. The pH value of the mesophase preparation was 4.9. To this (10 g) was added 15 vol% ethanol. The mesophase remained stable. 1 ml of a 20% by weight solution of zein in aqueous ethanol was then added to the system. This was incorporated into the mesophase, so that a mesophase was obtained

which contained both soybean protein and zein.

This mesophase was extruded into water and. fibers formed. The fibers had a smoother, shinier appearance than the fibers obtained from soybean protein alone. The fibers could be textured by heating.

Part (b)

To the soybean protein mesophase described in part (a), 16% ethanol was added, followed by 1 ml of a 40% solution of zein in aqueous ethanol, and the mesophase was extruded to form fibers as described above.

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EXAMPLE 18

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To 10 g of the soybean protein mesophase described

in part (a) in ex. 17; 12% ethanol was added, followed by 5 ml of a 40% solution of zein in aqueous ethanol. The mesophase was noticeably more viscous than the original containing soybean protein alone. The mesophase was extruded into fibers, and these fibers were textured

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by treatment in hot water.

EXAMPLE 19

This example shows the use of temporary temperatures

in the extrusion bath when producing fibres. Mesophases of soy protein with pH 4.6 prepared as described in Example 1 were used at an extrusion speed of 2 m/minute through a spinning nozzle with holes of 0.2 mm diameter, the procedure being as indicated in Example 1. The results were similar to those from that

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mentioned example, as tests were carried out at 30°C, 50°C and 80°C, and the fibers were more stable in mass and better in shape the higher the temperature.

EXAMPLE 20

This example shows the extrusion of peanut protein mesophase in a bath at transient temperatures. 80 g of protein was mixed with 120 ml of water and 12 g of solid sodium chloride and centrifuged at 500 g for 15 minutes for degassing. No phase separation occurred. The mesophase was then pumped from a reservoir using a gear pump through a spinning nozzle with 20 holes of 0.2 mm into water of 20°c. Fibers formed continuously and were collected. The fibers were finally textured in hot water.

Further experiments involved extrusion in water at 40°C and 80°C. Good, continuous fibers were formed, which were somewhat more separated and stable than those formed at 20°C.

All fibers were textured by suspending in boiling water for 2 minutes. They became strong and elastic with good texture, suitable for incorporation into food products.

EXAMPLE 21

This example shows the use of hot water in the extrusion baths. 1000 g of soy protein isolate prepared as described in example 1, containing 43 7. dry matter f-without ash was mixed with 300 ml of water and 25 g of solid sodium chloride in a laboratory mixer, so that a mesophase with pH 4.8 was obtained, dry matter-without-ash content 25 7. and molarity of water 0.5. This entrained air, which was removed by centrifugation at 600 G for 15 minutes.

1333 g of the mesophase was placed in the reservoir of one spinning machine and pumped through a spinning nozzle with 20 holes of 0.5 mm diameter, into a bath of distilled water of 95°C. The pumping speed was 40 ml/minute and the extrusion speed 10 m/minute. 1317 g of wet fibers were produced, with a composition of 69.4 7. (w/w) water and 30.67. dry matter f. They contained 43.7 mg N/g wet weight and had a protein content of approx. 857. (weight/weight) on a dry matter basis.

The bath water contained 0.01 7. nitrogen and 0.43 7. dry matter f. The bath contained only 15 g of protein, if all the nitrogen was of protein origin. Analysis of the bath water after freeze-drying showed that the nitrogen was mainly of non-protein origin, and practically no protein was lost in the bath.

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The bath contained 164 mg of sodium sulphite derived from the original protein isolate, and the fibers 34 mg.

Much of the color and flavor component in the soy protein preparation remained in the water bath after extrusion. The fibers were white, strong and elastic, with a texture that made them easily chewable. The initial pH in the bath was 5.2 and the final pH 4.80.

In experiments with 0.2 and 0.1 mm spinneret holes at the same pH and pH 4.25 and 4.61 (adjusted with HC1), similar results were obtained.

The fibers were rinsed with tap water for storage.

EXAMPLE 22

This example shows the effect of different protein contents when extruding mesophase into hot water. The procedure from Example 21 was followed, with the exception that mesophase containing 25% and 27.3% protein was used. Extrude none proceeded at 6 m/minute through a spinneret with holes of 0.5 mm diameter. Fibers formed but tended to break i-pieces to give a discontinuous product, which was usable but less desirable than the continuous fibers.

In experiments with 35%, 38% and 41% protein, continuous fibers were obtained.

EXAMPLE 23 <\>

The procedure of Example 4 was followed using the mesophase of pH 5.61, but by extrusion in a solution of commercial sodium acetate 0.1 m at pH 4.7. Fibers were obtained which were more separated and continuous than those obtained in example 4, bg these were treated in hot water as before. Fibers with good texture were obtained.

In a further experiment using mesophase containing 32% dry matter-without-ash and with pH 6.25, similar results were obtained.

In a further experiment, where the mesophase with 32% dry matter content and pH 6.25 was again used, the sodium acetate solution was at 70°C. Fibers were obtained that were more separated and with greater stability in the mass.

EXAMPLE 24

The canola protein mesophase prepared in Example 12 was extruded in water maintained at 95-100°C. Tough, moderately elastic fibers with a good chewable texture and with a fairly sharp, mustard-like taste were produced.

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EXAMPLE 25

A soy protein mesophase with a protein content of 28.4% by weight was produced by mixing protein isolate with salt and water. This mesophase was then extruded into a water bath of 95°C, through spinning nozzles of three different sizes. The diameter of the fibers produced was measured and their appearance noted. The dry matter content, the protein content and the ash content of the fibers were also measured. The results are shown in the following table.

EXAMPLE 26

This example shows the extrusion of soy protein mesophase in baths with varying concentrations of sodium chloride.

A soy protein mesophase with a protein content of approx.

25 7o was prepared by mixing together a protein isolate and sodium chloride solution. The pH value of this mesophase was adjusted to 4.4 with hydrochloric acid. In separate experiments, this mesophase was extruded in five different curing baths at 95°C, containing varying amounts of sodium chloride. The following table compares the composition of the fibers formed by extrusion in the different baths. For the extrusion, the mesophase had a solids content of 31.3%, an ash content of 2.7% and a protein content of 24.9%. The fibers were washed with water for analysis.

EXAMPLE 27

This example describes the extrusion in water and sodium chloride leaching of a soy protein mesophase with a pH of 4.6 and a protein content of 24.6 7." The mesophase was prepared and extruded as described in example 26. For the extrusion, the mesophase had a dry matter content of 30.4%, an ash content of 2.6% and a protein content of 24.6%. The results obtained after washing was:

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EXAMPLE 28,

This example describes the extrusion in water and sodium chloride solution of a soy protein mesophase with pH 5.0 and

solids content of 29.9% The mesophase, which was prepared and extruded as described in Example 26, had a water content for extrusion of 70.1%, an ash content of 2.7% and a protein content of 24.3% '%.

Claims (2)

1. Method for the production of a protein-containing foodstuff by transferring a liquid, aqueous product of plant protein to solid form, e.g. soy protein or peanut protein, characterized in that a mesophase of plant protein is used as the liquid, aqueous product which contains from 20 to 50% by weight, preferably 20 to 45% by weight, of substantially undenatured plant protein, and that it preferably also contains a sulphite or bisulphite, the plant protein being kept in a dissolved state at a pH value of from 3 to 9, preferably 4.5 to 7.5, by means of a water-soluble, edible salt, which is preferably present in an ionic strength of at least 0.2, based on the water content of the mesophase, and that the mesophase is hardened by heating above 80°c, either alone or in bJaiding with other edible material, e.g. finely divided cooked or raw meat. 2. Method as stated in claim 1 in which the mesophase is hardened by heating it alone (i.e. not mixed with other material), characterized in that the mesophase is extruded into a bath above 80°c for the formation of fibres, so that the fiber formation and transformation until the hardened state takes place at the same time.