GB1596271A - Spinning proteins - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO SPINNING PROTEINS (71) We, BIOTECHNICAL PROCESSES LIMITED, a British Company, Hillsborough House, Ashley, Nr. Tiverton, Devon EX16 SPA (formerly of 61 Catherine Place, Westminster, London, S.W.1), do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the production of protein products, especially meat analogues and cheese analogues, containing some or all of the protein in fibrous form obtained by the technique known as spinning.

The process of spinning proteins is known in the art and generally comprises the steps of: (i) dissolving a protein in a solution of a suitable solubilizing agent, such as salts or alkali; (ii) passing the resulting protein solution through apertures in a spinnerette into a bath of a medium in which the pro tein is coagulated into fibres, usually by acid but sometimes by thermal treat ment; (iii) optionally stretching the fibres in an appropriate medium such as an acid solution or a salt solution; (iv) treating the fibres, in a manner which may vary greatly amongst users, to neutralise and/or wash out from the fibres the residual acid.

At step (iv) the fibres exist in a fairly stable condition (apart from microbial attack) and the process of fibre production may be regarded as complete. However, it is usual to pass the fibres through additional processing steps in order to convert them into meat and cheese analogues, in particular, treatment with fat, flavours and binding agents. Finally, after treatment with one or more such agents, the fibres may be used as such but are commonly formed into a discrete shape, the shape being built up by placing layers of fibres on top of each other by various means, e.g. by folding them upon themselves, by cutting and stacking them, or by rolling or winding them together with or without the application of pressure.

The shaped proteins then may be set by heat.

The processes of folding, cutting, stacking, rolling or winding are referred to generically herein as "orientating" the fibres.

The present invention is concerned with processes for the improvement of orientation and the steps immediately preceding orientation.

Spun protein products made according to prior art processes have generally possessed adequate fibre strength but insufficient tendency for the individual fibres to adhere together. The development and improvement of the binding agents used has not been entirely successful in solving this problem.

In accordance with the present invention there is provided a process for the prepara tion of a textured protein composition which comprises stacking or winding a plurality of spun protein fibres in the form of grouped fibre formations as hereinafter defined, or assemblies of grouped fibre formations, in substantially planar sheet form, incorporating therebetween discrete layers of largely untexturized matrix comprising a binding agent with or without inclusion of chopped spun fibres to form a layered structure comprising alternate layers of fibres and matrix, the fibre layers being either continuous or discontinuous, and additionally either (i) incorporating in the said product natural edible vegetable fibres that are not substantially aligned with the spun protein fibres or (ii) incorporating in the said product chopped lengths of spun protein fibres which are only partially aligned with each other or are randomly orientated or (iii) orientating the fibres in the said product, so that one or more grouped fibre formations, or a plurality or layer of grouped fibre formations, is or are set at an angle to at least one other grouped fibre formation, or plurality or layer of grouped fibre formations, or (iv) any combination of two or more of steps (i), (ii) or (iii).

As defined herein a grouped fibre formation is a group of spun protein fibres of any length and any cross-sectional size and shape that satisfies the following criteria: t1} the individual fibres it contains are close together and are substantially parallel to each other throughout substantially their entire length; (2) the number of fibres in the group is similar throughout substantially the sntire length of the group; (3) roost of the individual fibres run con tinuously from one end of the group to the other; (4) most of the fibres in the group were formed at substantially the same time; EPd (5) ti.t length of the longest fibres approxi- mutes to the greatest dimension of the group.

Grouped fibre formations may comprise bundles, sheets or tubular formations of fibres and the formation may be straight, bent, coiled twisted, kinked or contorted.

Particularly preferred formations are those in the form of sheets or layers as hereinafter described.

In one embodiment of the invention the desired orientation is accomplished by building up the composition from grouped fibre formations in the form of layers of fibres and ensuring hat the fibres in each successive layer are at angles to the fibres in the immediately adjacent layers.

In a second embodiment the desired effect is accomplished by depositing between the successive layers of fibres from which the composition is built up a paste or slurry containing short lengths of spun protein fibres.

In a third embodiment the desired effect is accomplished by depositing between successive layers of fibres from which the composition is built up a paste or slurry containing lengths of plant fibre, meat fibre or other naturally occurring fibre.

Any two or all three of these embodiments may be combined within any one process for preparing a single end product.

The composition according to the invention also may include minor proportion of spun protein fibre which is effective in imparting texture to a major proportion of otherwise largely untexturised inter-fibre matrix. Preferably the.ratio of matrix solids to spun protein fibres is at least 2:1.

The texturised protein composition also may include finely divided or dissolved meat solids.

In performing the present invention it is advantageous to form the spun protein fibres into one or more grouped fibre formations, preferably in the form of substantially planar sheets of fibres. Such sheet or sheets may be readily formed into separate layers of fibres which may be readily juxtaposed on top of each other to form a composite structure wherein the fibres in each layer are at an angle to the fibres in each immediately adjacent layer, the structure being bound by impregnating the layers or each of the layers with binder either after, during or before the juxtaposition of the layers.

As used herein the term "juxtaposing the layers" means placing the layers one on top of another so that the fibres in each layer may, if desired, be placed at an angle to the fibres in each immediately adjacent layer either by cutting the original sheet of fibres in discrete portions to form each layer and placing the resulting separate layers on top of each other or by using at least two sheets at an angle, preferably a right angle, to each other and simply folding discrete lengths of the sheet to form the required layers, e.g. using two sheets at right angles to each other, a length of the first sheet will form the first layer, a length of the second sheet will form the second layer, a further length of the first sheet folded over the second layer will form the third layer, and so on until the required depth for the composite structure is obtained.

The separate layers or sheets, as the case may be, may be impregnated with a suitable binder before being placed on each other or, alternatively binder may be added during the operation or even after the structure is formed, the interstices between the fibres in each layer allowing the structure to be impregnated with the binder. Of these alternatives, impregnation of the layers before juxtaposition is preferred as this leads to a more homogeneous product.

It is also preferred to introduce between the layers a paste containing both a binding agent, such as a soluble protein, and chopped spun fibres so that the long spun protein fibres become set into a relatively large quantity of tough texturised matrix.

It is further preferred to add flavouring agents and other additives, as hereinafter described, to improve the flavour and texture of the final composition, and these additives are preferably incorporated with or at the same time as the matrix or binder.

It is also preferred to heat the composition to a temperature above 75"C. to heat-set the protein.

The present invention also provides a texturised protein composition comprising a plurality of grouped fibre formations, as hereinbefore defined, or assemblies of grouped fibre formations, of spun protein fibres in a stacked or wound product, each formation or assembly of formations in the product being in substantially planar sheet form and being separated from the next adjacent planar formation or assembly of formations by the incorporation therebetween of a discrete layer of largely untexturized matrix comprising a binding agent with or without inclusion of chopped spun fibres, each formation or assembly of formations further being juxtaposed so that the fibres therein are set at an angle to the fibres in the next adjacent formation or to the chopped spun fibres present in the binding matrix or to both sets of fibres.

The juxtaposed formations are preferably at an angle of approximately 90" to each other.

In the preferred embodiments of this invention the individual fibres in each of the formations of the above described composite structure are generally substantially parallel to each other, particularly since such a configuration would normally result from the preferred mode of preparation described herein. However, the invention also includes within its scope a structure wherein the fibres in each layer are randomly orientated with respect to each other, provided that a substantial proportion of the fibres in any layer are an angle to the fibres in each immediately adjacent layer or in the matrix in the final composition.Such a configuration may arise, for example, when the composite structure in built up by allowing a layer of fibres, which initially may be paralleled to each other, to fall freely under gravity into an appropriate receptacle, tray or mould and repeating the procedure with each subsequent layer and either dropping each layer from a different angle to the previous layer or turning the receptacle after it has received a layer and before the next layer is dropped. It will be appreciated that in such a procedure the individual fibres in each layer may align themselves in the receptacle at random orientations with respect to each other but it has been found that in the resulting composite structure the fibres in each layer are at an angle to the fibres in each immediately adjacent layer.

A similar effect may be obtained if any of the intermediate layers is in the form of a slurry.

The improved composition prepared by the process of this invention possesses many advantages over prior art products. For example: (i) The resulting orientation of the fibres in the finished meat or cheese analogue gives it better physical strength and cohesion.

(ii) In the preparation of meat or cheese analogues according to the process of the invention it is possible to use in addition to the spun protein fibres other fibres of natural origin, especially meat fibres or plant fibres, to give the analogues better physical strength and cohesion.

(iii) By using short lengths of spun protein fibres together with longer lengths of spun protein fibres it is possible to produce a finished meat or cheese analogue containing both short and long fibres, which combination has improved physical strength, texture and cohesion.

(iv) By using a combination of short chopped lengths of spun protein fibre together with a suspension or slurry which may be applied onto the longer spun protein fibres in great or small quantity, so that the soluble protein coagulates during the heat-setting state, it is possible to obtain a product in which the long fibres become set within an interfibre matrix which itself comprises short chopped lengths of spun protein fibre which are more or less randomly orientated within an amorphous protein coagulum. This secures savings in the use of the relatively expensive spun protein fibre and overall cost savings in making the finished meat or cheese analogue.

(v) The flavour and binding of meat analogues may be improved by adding homogenised meat comprising suspended, dissolved or emulsified meat solids, this is true regardless of the type of fibre orientation employed.

In the finished meat or cheese analogue of the present invention some fibres run at angles to other fibres, and, in general this requirement may be achieved regardless of the conformation or spatial positioning of the fibres as they leave the coagulation bath.

However, as already indicated the process of the invention is facilated if, either in or on emerging from the coagulation bath, the fibres are caused to take up the conformation of a thin planar sheet and are progressed through all subsequent bath treatments in this form.

Indeed, to progress the fibres through the process in the form of a sheet is an advantage in itself, since the neutralizing and washing operations are rendered more effective by the much reduced thickness of the fibre-bundle and impregnation with the desired binding agents, flavourings and fat is also made more effective. The reason for the improvement is that the diminished thickness of the fibre-bundle permits solutes to diffuse more rapidly out of the bundle and permits applied additives to penetrate more rapidly into it. The thin sheet form of the fibres is also advantageous at the orientating and compacting stages when the fibres are being incorporated into meat analogues and cheese analogues with discrete shapes according to the invention.

The thin sheets of fibres merge together readily when building up a compact mass of the material and offer a much greater surface area over which the binding agents may act as an effective adhesive than when rope-like tows, as in the prior art, are used; the products therefore hold together more effectively than prior art products derived from rope-like tows.

It is possible to obtain a sheet of fibres, as required in some embodiments of this invention, from one of the disc-shaped spinnerettes commonly employed in the art at present; all that is necessary is to spread out the fibres either in the coagulation bath or as they emerge from it. In practice, it has been found that this is not very easy to do because the fibres, upon emerging wet from the bath, tend to cling together by surface tension. They tend to form a ropelike tow of almost circular cross-section.

Accordingly, the production of a sheet of fibres is more readily accomplished by utilising one or more of the following devices:-- (i) A spinnerette which is oval, rectangular or any other shape wherein the dimen sion of the spinnerette in the plane across the width of the bath is greater than the height of the spinnerette when it is assembled for operation.

(ii) A spinnerette which is not necessarily shaped as in (i) above, but in which the holes in the spinnerette are distributed in a pattern which is elongated across the width of the coagulation bath (iii) A spinnerette which, when it is assembled in the operational position, has some or all of the individual holes elongated in one plane, so that each fibre has a substantially flattened cross section.

(iv) A jet or a plurality of jets of coagu lation bath fluid is or are aimed at or close to the fibres in the coagulation bath to encourage them to spread out horizontally or, if they are of a flattened cross-sectional shape, to make them take up a position in which their greater cross-sectional dimension lies in the horizontal plane.

(v) A comblike device or clamp by which to take hold of the fibres when they first emerge from the spinnerette in order to keep them in the form of a sheet while they are passed around the guides and rollers that are to advance them through the treatment baths.

Provided that a thin sheet conformation has been produced at the coagulation stage and maintained throughout subsequent treatments there are several different ways, according to the present invention, whereby each layer of fibres may be introduced at an angle to the adjacent layer: (i) separating off from the main fibre sheet at any point a portion which is lifted above the main fibre sheet. The sepa rated portion then may be allowed to drop on to the travelling main sheet of fibres whilst being oscillated laterally by a mechanical device. In this way the separated portion describes a zig zag on top of the travelling sheet and remains in that form as the sheet is folded, wound or otherwise layered and compacted.This superimposing of a separated portion on to the travelling sheet may be done at any point in the process but is preferably done after all bath treatments have been completed.

This requires that the separated portion should be subjected to a greater draw ratio (i.e. more stretching) than the main sheet of fibres; (ii) dropping fibres on to a travelling sheet of fibres wherein the dropped fibres may be fibres produced from the same machinery as the fibres on the travelling sheet or fibre produced on other spininng machines; (iii) dropping on to the travelling main sheet of fibres other fibres that have been cut into length: these may be orientated across the travelling sheet of fibres e.g. by slipping down a chute the lower end of which oscillates laterally across the width or part of the width of the travelling sheet or they may be dropped on to the travelling sheet in a random orientation e.g. by slipping down a wide stationary chute or by dropping onto the travelling sheet in the form of a slurry; (iv) by suspending or floating chopped spun protein fibres in one of the treatment baths in such a way that the travelling sheet of fibres which is undergoing treatment, in emerging from the treat- ment bath, picks up lengths of chopped fibre adhering to its upper surface which being randomly orientated, will mostly cross the line of the parallel fibres comprising the travelling sheet; ; (v) delivering on to a sheet of spun protein fibres a paste, suspension or slurry comprising a mixture of a heat settable binding agent, such as a heat coagulable soluble protein, with more or less randomly orientated chopped spun protein fibres. This paste, sus pension or slurry may or may not have other ingredients. This may be metered onto the long fibres during or immediately prior to the folding, wind ing, layering and compacting opera tions that comprise the final fibre orientation step.

The requirement of some embodiments that fibres of the main sheet should lie across fibres of other layers at angles may be accomplished by:- (vi) folding the sheet of fibres so that they cross one another at angles; (vii) cutting a layer or two of fibres from the sheet and placing the layers across one another so that they cross one another at an angle; (viii) In the case of winding the fibres on to a spool or bobbin, varying the angle of the spool or bobbin in relation to the direction of travel of the fibre sheet so that successive layers wound are orientated at an angle to the underlying layer. Alternatively this may be accomplished by varying the angle at which the fibres approach the spool or bobbin.

In performing the invention any combination of the foregoing procedures (i) to (viii) may be used.

As already stated it is within the scope of the present invention to additionally use fibres other than spun protein fibres. These additional include meat fibres and plant fibres, such as those derived from cereals, fruits or vegetables.

These meat or plant fibres may be added to the sheet of spun protein fibres by any of the techniques proposed in steps (iii), (iv) or (v) above. The meat fibres employed for this purpose may be from low grade meat residues, especially from tough meats, and has the advantage that some genuine meat flavour is introduced in this way. The use of plant fibre for this purpose has the advantage that the resulting meat or cheese analogues then act as a medium for introducing these desirable fibres into the human diet for health-giving purposes, such as their mild laxative effect and alleged preventive effect against diverticulosis of the colon.

They may also exert a desirable waterbinding action.

In all cases, whether the fibres added to the sheet of spun protein fibres have been another continuous tow or sheet of spun protein fibres, chopped spun protein fibres, meat fibres or plant fibres, they have been found very advantageous to the cohesive properties of the resulting meat or cheese analogues, provided that they are either fairly randomly orientated or are orientated at an angle to the main sheet of long spun protein fibres. Similar advantages are obtained when sections of a sheet of spun protein fibres are overlaid in another direction by other sections of the same sheet of fibres either as a result of folding the sheet of fibres upon itself or by winding it, as already described, on to a spool or bobbin which is set at a varying angle to the direction of travel of the fibres.

Preferred embodiments of the present invention are illustrated in the drawings accompanying provisional specification 13709/76, each figure of which is a perspective view of a segment of a protein composition after forming which is partly in cross-section to reveal the internal structure, and in which: Figure 1 illustrates composition comprising planar layers of fibres 1, 2, produced either by cutting or folding, placed at right angles to each other. Between the layers 1 and 2 is a substantial thickness of interfibre matrix containing chopped spun fibres 3. If desired, the interfibre matrix may include meat fibres and bran. In a modified form of this embodiment (not shown) the interfibre matrix may be omitted entirely or alternatively may contain material other than chopped spun fibres.

Figure 2 illustrates a composition similar to that of Figure 1 but in which the fibres in the layers 1 and 2 are parallel to each other. The interfibre matrix 3 (not shown in detail) essentially includes chopped spun fibres and/or meat fibres in this embodiment and the matrix is of sufficient thickness to ensure that at least some of the fibres are set at angles to the fibres in the layers 1 and 2 in accordance with the invention. The matrix optionally may also include bran.

Figure 3 illustrates a composition containing a continuous sheet of substatially parallel fibres 1 folded back upon itself and containing within the folds a matrix comprising, inter alla, chopped spun fibres 3.

Figure 4 illustrates a composition comprising juxtaposed layers of fibres, each layer comprising a randomly orientated rope-like tow of fibres 4. Between the layers the composition contains a matrix comprising chopped spun fibres, meat fibres and/or bran. If desired, the tow-containing layers may also include such a matrix.

Figure 5 illustrates a composition containing rope-like tows, illustrated as fibre bundles 5, 6, placed at right angles to each other, in place of the planar sheets illustrated in the above embodiments. This embodiment also includes an inter-fibre matrix comprising chopped spun fibres 3, with or without other materials, as described above.

Figure 6 illustrates a similar embodiment to that illustrated in Figure 5 but without chopped fibres in the matrix.

It is to be understood that the embodiments illustrated in Figures 5 and 6 may be further modified to include tows of fibres in a third dimension, i.e. at right angles, or any other angle, to the two layers of tows illustrated.

Figure 7 illustrates a composition comprising a planar sheet of fibres wound in a roll with an inter-fibre matrix containing chopped spun fibres 3, as described above.

Figure 8 illustrates a composition comprising a roll formed from a sheet of fibres 8 wound (with inter-fibre matrix) in a manner wherein the angle at which the sheet is introduced to the roll is varied during the winding.

In the drawings accompanying the provi sional specification the planar sheets of fibres are shown as one fibre thick for simplicity of illustration, but it is to be understood that, in practice, the layers may comprise several thicknesses of parallel fibres.

In the embodiments illustrated in the drawings, and particularly the embodiment illustrated in Figure 2, the composition may contain a substantial amount of interfibre matrix containing protein, whether or not the matrix contains fibres and whether or not the layers of fibres are orientated at angles.

The layered protein composition of the invention may comprise a minor amount, e.g. one third or less of the dry weight of the composition, of spun protein fibre arranged in discrete layers, and a major amount, e.g. two-thirds or more of the dry weight of the composition, of a proteincontaining inter-fibre matrix. In such a composition the said matrix acts as a binding agent;.

By adding, between successive layers of spun protein fibres, a paste comprising chopped spun protein fibres, water, a soluble, heat coagulable protein binding agent, with or without other ingredients such as meat fibres or plant fibres, a substantial quantity of a texturised inter-fibre matrix is established. In some embodiments of this invention, therefore, long spun protein fibres need be only a minor part of the end-product, the major part being an inter-fibre matrix containing only randomly orientated short fibres.

Such products have been found very advantageous and economical. They exhibit good texture, strength and cooking and retorting qualities. The economy arises because a relatively small proportion of expensive fibres is used to texturise a large amount of analogue material.

It has also been discovered that most types of meat analogue prepared in accordance with this invention may be improved in flavour by incorporating into the finished product a small proportion of cooked or uncooked true meat. The use of meat fibres has already been mentioned. Whereas it is known to use meat extract (e.g. beef extract) in the flavouring which may be added to protein fibres, it has been discovered that the use of homogenised meat itself is very beneficial. At first sight this might appear to negate the cost advantages of spun protein meat analogues over natural meat, but this is not the case because the proportion of meat may be low e.g. from 0.1% to 10.0% of the dry weight of finished meat analogues and the grades of meat used may be very low cost (e.g. tough meat, fragments from bone-cleaning or edible offals).Such homogenised meat may be prepared so as to contribute at the same time both flavour and texture.

The addition of homogenised meat may be accomplished at any point in the process between the washing of the fibres and the processes, i.e. folding, chopping and layering and winding, used to produce finished meat analogues in discrete shapes from the fibres.

In practice it is most conveniently added either in a bath of flavourings and binding agent through which the fibres are passed or else in a thin paste containing these materials which is extruded on to the fibres just before the different layers of fibres are contacted together and acts like an edible adhesive.

In a further embodiment of the invention the protein compositions, such as those produced by the processes described above, may be improved with respect to characteristics such as flavor retention, texture and chewiness by certain additional process steps and the resulting process of the invention is more efficient and economical than prior art processes.

In accordance with this further embodiment of the present invention there is provided a process for preparing a texturized protein composition which comprises forming spun protein fibres, neutralising and washing the spun fibres, and shaping the resulting treated fibres into a discrete texturized composition by a process as described above wherein the fibres are impregnated with agents either during or after the neutralising andlor washing steps and/or a non-fibrous substantially waterinsoluble elastic protein, such as wheat gluten, is incorporated in the composition either during or after any one or more of the neutralisation, washing or shaping steps.

It is known in the art to make use of the resilience, toughness and elasticity of wheat gluten to give some texture, "bite" or chewiness to protein products that do not contain spun protein fibres. A preferred embodiment of the present invention is predicated upon the discovery that an improved composition may be obtained by the incorporation of wheat gluten which has not been spun into fibres in a composition containing spun protein fibres (which themselves may or may not include wheat gluten as an ingredient). The role of the unspun wheat gluten in the resulting product is to act as the binding agent or as an ingredient of the binding agent, or to act as a matrix between the fibres or layers of fibres, or to act as an ingredient of such a matrix.

The texturised protein composition of the present invention may contain spun protein fibres, preferably in the form of grouped fibre formations, having incorporated therein a substantially water-insoluble elastic protein, such as non-fibrous wheat gluten.

In performing the process of the invention the bundle or sheet of fibres emerging from the spinnerette may be neutralised and/or washed free from the acid carried over from the coagulation bath in a more efficient and thorough manner than in prior art processes.

In particular, the normally recognised prior art steps of a) coagulation b) stretching c) neutralising d) washing and e) impregnating with flavour and/or binding agent may be combined into a smaller number of separate processing operations.

Furthermore, in a preferred embodiment of the process, as hereinafter described, the penetration of flavouring agents into the bundle or sheet of fibres coming from the spinnerette is imporved and flavouring agents that have penetrated into the fibres are more firmly held there.

In another embodiment of the invention a protein powder or a powder containing substantially dry protein is mixed with the spun protein fibres, with or without the use of pressure, in such a manner that the protein powder or powder containing substantially dry protein acts as, forms, or becomes included within, a binding agent or interfibre matrix, the dry powder being moistened either by the addition of water or by taking up water from the moist spun protein fibres.

In carrying out a preferred embodiment of the process, the bundle or sheet of fibres from the spinnerette is neutralised and/or washed free from acid in a particularly efficient and thorough manner by allowing the fibres emerging from the last treatment stage immediately prior to neutralising and/or washing to drop into a neutralisa tion I washing bath containing neutralising and! our washing fluid in such a manner that for much of the time the fibres are in the bath they are not under tension. It is conventional in the prior art for the fibres to be under significant tension whilst passing through the apparatus, at least up to the point where washing is completed and also commonly during subsequent stages of impregnation with binding agent and flavour.To accomplish a situation in which the fibres in the neutralisation and/or washing bath are not under significant tension it is preferred to use a bath which is large relatlve to the required dimensions of other treatment baths used in the process and to deliver into the bath a substantial quantity of fibres before leading the fibre bundle or sheet out of the bath and onward to the next stage of the process. Most conveniently, this is accomplished by the use of two sets of driven Godet rolls, one set at each end of the bath, one set delivering fibres into the bath and other removing fibres from the bath.By operating both sets of Godet rolls at exactly the same speed, fibres are delivered into the bath and removed from it at exactly the same rate; the quantity of fibres in the bath remains constant and since this quantity is considerable the fibres have a considerable residence time in the bath and for most of this time they are exposed to the neutralisation I washing fluid whilst in a loose, tension-free condition. It has been found that when tows or sheets of spun fibres are treated in this manner the fibres tend to part slightly so that neutralisation / washing fluid readily penetrates between the individual fibres, very effectively neutralising and/or washing out the acid.It is preferred to keep the neutralisation / washing fluid moving within the bath, for example, by circulating the fluid through a recirculating pump or by introducing compressed air into the base of the bath so that the fluid is subjected to a stream of rising air bubbles.

Neutralisation and washing of the fibres may be carried out in accordance with the present invention either in a single bath or a plurality of baths containing only a slightly alkaline neutralising fluid which need not be rinsed off the fibres before the next stage of processing or in two or more baths in which treatment with a slightly alkaline neutralising fluid is followed by treatment with a different washing fluid such as water or saline solution.

If desired, it is possible to simplify the operation by combining the neutralisation and washing steps into a single step. A slight excess of the slightly alkaline neutralisation fluid which may be left on the fibres after this treatment may be rendered harmless to the subsequent fibre-orientating, forming, layering and compacting operations necessary to produce a finished meat or cheese analogue by including a weak acid in low concentration, or merely a buffering capacity, in the other ingredients used in these operations such as in the binder or inter-fibre matrix, so as to give a finished product of desired pH.

In the prior art sodium bicarbonate has been used in neutralising fluids and the presence of this salt in the finished product may not be desired. Accordingly, neutralising fluids having a composition as heréin- after disclosed and containing one or more amino acids as buffering agents may be incorporated in small quantities into the Finished product without detriment.

The penetration of flavouring materials into the bundle or sheet of fibres coming from the spinnerette may be much improved by incorporating flavouring materials in one or more of the following: washing bath, neutralisation bath, stretching bath. This aspect of the preseat invention is most advantageous in the production of meat analogues that need to be flavoured by the addition of such materials as protein hydrolysate, amino acids, yeast extract, yeast autolysate and/or compound meat flavours that may be produced by blending any of the above materials together with or without flavour enhancers such as monosodium glutamate or a nucleotide, e.g. ribotide, or by known processes that involve heating protein hydrolysates with sugars and/or other substances.These flavouring materials are stable under conditions normally used in the washing bath, neutralisation bath or stretch bath and they may be readily included therein. In the case of the stretch bath the solution normally employed in prior art processes is aqueous saline solution. The flavour materials mentioned above frequently contain substantial proportions of common salt and, accordingly, when they are added to the stretch bath their salt content should be taken into account by reducing the amount of common salt used in making up the bath solution. In the case of the neutralisation bath, instead of using sodium bicarbonate or other weak alkali as is common in the prior art, a solution of flavouring materials adjusted to a slightly alkaline- pH with sodium hydroxide may be used.In this case advantage is taken of the buffering effect of amino acids and other ionizable substances present in the flavouring materials to stabilise the pH of the solution. A similar solution of flavouring materials adjusted to a lower pH may be used as a washing solution if one is needed.

In a preferred embodiment of the invention flavouring materials are present in the neutralisation bath and wash bath. This exposure to flavouring materials during processing rather than by means of a separate flavour impregnation step simplifies the processes required for production of flavoured fibres and the presence of flavouring materials during neutralisation and washing of the fibres in a tensionless condition permits particularly ready penetration of flavouring materials into the fibres.

The flavouring materials used for producing meat or cheese analogues are quite expensive and hence when these are included in any of several of the process baths as described above it becomes desirable to take measures to conserve these costly materials. For example, automatic pH control may be introduced for each bath to obviate the need for rapid consumption of fresh bath fluid. Also, a washing step may be introduced before the stretching step, to avoid excessive acidification of stretch bath fluid.

The process of the present invention by which texture, "bite" or chewiness of the finished product is improved comprises adding a non-fibrous substantially nonwater-soluble elastic protein, such as wheat gluten, to the fibres in any form, wet or dry and in any order in relation to other ingredients. The wheat gluten may be used with or without the addition to the interfibre matrix of chopped spun protein fibres as described above. Wheat gluten, or similar protein, further may be admixed with chopped spun fibres along long fibres being absent from the composition.

In a preferred embodiment of the present invention the composition is built up by the juxtapositioning of successive layers of spun protein fibres, the fibres in each layer running at approximately right angles to the fibres in each of the immediately adjacent layers.

The wheat gluten is mixed dry with any other required dry ingredients such as other dry protein preparations, starch, flour, dry flavourings and salt, if desired. A substantially planar layer of spun protein fibres is prepared and the dry mix containing wheat gluten is sprinkled on to the fibre layer in whatever thickness is desired. The composition is then sprayed with a fine spray of water to thoroughly dampen the powder layer and is then sprayed with a fine spray of liquid fat. Another substantially planar layer of spun protein fibres is placed on top of the first layer and the process repeated until a desired thickness of product has been built up. The composition is then heat set in an oven or may be cooked at higher temperatures than those needed for heat-setting if desired.

The following Examples illustrate the invention and - the manner in which it may be performed.

EXAMPLE I A portion (3.2Kg) of dried mixed proteins comprising 45% by weight of soya protein isolate and 55X7O by weight of potato protein concentrate, obtained, for example, as described in Patent Application No. 33689/75 (Serial Number 1 544812), was dissolved to make up to 20 L volume using 1.2% w/v sodium hydroxide solution, employing a homogeniser to disintegrate any undissolved particles. This solution was then passed through a spinnerette of 15 cm diameter perforated by 10,000 slot-shaped holes measuring 40 microns in one dimension and 200 microns in the other. The holes were arranged closely around one diameter of the round spinnerette so as to form a band 1 cm. wide running from close to one side of the spinnerette, through the centre, to close to the opposite side. The diameter around which the holes were arranged was set in the horizontal plane whilst in operation. A pressure of 70 pounds per square inch was used to force the solution through the spinnerette. The spinnerette itself was in an upright position near one end of the coagulation bath, with its convex surface facing the other end of the same bath. The spinnerette was immersed, in the bath, in an aqueous solution, 6.5% wlv with respect to acetic acid and 5.6% wlv with respect to sodium chloride. The resulting protein fibres were continuously removed from the bath using driven rollers, stretched, and washed first with 1% sodium bicarbonate solution and then with water.

The fibres, being of flattened crosssectional shape, were passed through the coagulation bath with their greater width in the horizontal plane by means of jets of the bath solution passing at right angles to the direction of the fibres. A set of six such jets passed just above the fibre bundle and another set of six jets passed just below the fibre bundle in the opposite direction.

The fibres were passed under an undriven guide roller positioned under the surface of the coagulation bath on to 10 cm diameter driven rolls of 20 cm width, forming a fibre sheet approximately 12 cm across. The fibres were progressed in this form throughout the stretching, neutralizing and washing phases of the process. They were then impregnated, firstly with flavourings, binding agent and homogenised meat by passing through an aqueous bath solution or suspension containing homogenised meat 5% (wlv on a dry-weight basis), soya isolate (wlw 9%), hydrolysed beef protein, (wlv 3%), compound roast beef flavour, (w/v 1%), monosodium glutamate, (wlv 0.75%), glucose (w/v 0.75%).The fibres were maintained in sheet form throughout this treatment and also throughout the next treatment in which they were impregnated in a bath containing corn oil and soya oil in a 1:1 ratio. The impregnation steps were accorded a residence time of 5 minutes each.

The fibre sheet was finally built up into a thick block by a folding operation. It was run off the last driven roller on to an oscillating stainless steel surface which moved repeatedly back and forth over a distance of one metre. In this way successive layers of the fibre sheet were deposited one on top of the other.

Stationary nozzles were arranged to deposit between each successive layer, a layer of paste comprising compounded roast beef flavour (0.5% w/v), lightly homogenised fibrous meat (3.5% w/v, dry solids basis), spun protein fibres chopped to approxi mately 1 cm length, (6% wlv, dry solids basis), wheat bran (6% wjv), hydrolysed beef protein (0.8% w/v) and soya isolate (3.5% wlv). This operation was continued until a block of material 10 cm. thick had been built up, which was then heat set in an oven using a minimum final temperature at the centre of the product block of 80"C.

The resulting product was sliceable, markedly fibrous with a good meat-like texture and flavour. The most noticeable property was that the tendency for the fibres to separate from each other was markedly reduced by the combined use of meat solids, chopped spun protein fibres in randem orientation and bran.

EXAMPLE 2 The procedure of Example 1 was followed except that the building up of a block of fibres was not accomplished by folding.

A manual operation was performed in which the flavour, binder and fat impregnated fibre sheet was cut into 12 cm squares.

These were built up into 12 cmx 12 cm x 12 cm cubes by placing the 12 cm squares on top of each other with the fibres of alternate squares running at right angles to each other. A layer of paste of the same composition as in Example 1 was used between each layer of fibres. The product was similar to that from Example 1 except that the crossing over of fibres in successive layers imparted increased cohesion and hardness.

EXAMPLE 3 A moist flattened tow of protein fibres was prepared by spinning an alkaline solution of mixed proteins comprising 1.44 Kg of soya protein isolate and 1.76 Kg of potato protein concentrate made up to 20L volume with 1.2% wlv sodium hydroxide solution.

The fibres were stretched, neutralised and washed in baths containing respectively: (i) 3% wlv NaCl solution, (ii) 0.75% wlv NaHCO3 with 0.45% w/v NaCI and (iii) tap water. No flavouring materials were used in the stretching, neutralising or washing baths in this case. Neutralisation and washing were carried out with the fibre tow in a tension-less condition.After washing, the tow was immersed in a tension-less condition in a bath of a combined flavouring and binding agent solution comprising; water 11 L, soya protein isolate (Promine D) 1.4 Kg, onion flavoured NaCl 50g, monosodium glutamate 15g, seasoning salt 50g, Yeast extract 115 g, hydrolysed maize protein 230 g, compounded roast beef flavour (Glentham Essence Co Ltd), 230 g, and glusoce 50 g, using a residence time of at least 5 minutes in the solution.

The flavoured tow was formed manually into layers, which were cut into square planar segments. These were stacked one upon the other to form a block approximately 17 cm by 17 cm having a height of approximately 10 cm. Before each new layer was placed in position the layer below was sprinkled with a layer about 4 cm thick of a dry powder comprising wheat gluten 2.25 Kg, soya isolate 1.25 Kg (Promine D), onion flavoured salt 140 g and roast beef flavour (Glentham Essence Co Ltd) 200 g.

After addition of the powder the preparation was sprayed liberally first with water then with sunflower oil before the next layer of spun fibres was applied. Gentle pressure was applied to compact the layers. The fibres in each layer of fibres were placed at right angles to those in the adjacent layers.

The completed composition was cooked in an oven at a temperature of 185"C for 50 minutes.

The product possessed particularly satisfactory flavour and texture and derived from the combination of unspun wheat gluten with spun protein fibres an eating quality not achieved by using either unspun wheat gluten or spun protein fibres separately.

EXAMPLE 4 Spun protein fibres were prepared as described in Example 3 except that the stretch bath was filled with an aqueous solution comprising 3.0% w/v maize protein hydrolysate, 1.0% wlv yeast extract (llis- tillers Company Ltd) and 1.4% w/v NaCI.

Two baths were employed for neutralising and washing, both containing maize protein hydrolysate (3.0% wlv) and yeast extract (1.0% w/v), the first being adjusted to pH 8.5 and the second being adjusted to pH 7.5.

The finished product was shaped and cooked as described in Evample 3.

The texture of the product was similar to that of the product of Example 3, but the flavour retention of the product during chewing was better.

WHAT WE CLAIM IS:- 1. A process for the preparation of a texturized protein composition from spun protein fibres which comprises stacking or winding a plurality of spun protein fibres in the form of grouped fibre formations, as hereinbefore defined, or assemblies of grouped fibre formations, in substantially planar sheet form, incorporating therebetween discrete layers of largely untexturized matrix comprising a binding agent with or without inclusion of chopped spun fibres to form a layered structure comprising alternate layers of fibres and matrix, the fibre layers being either continuous or discontinuous, and additionally either (i) incorporating in the said product natural edible vegetable fibres that are not substantially aligned with the spun protein fibres or (ii) incorporating in the said product chopped lengths of spun proteins fibres which are only partially aligned with each other or are randomly orientated or (iii) orientating the fibres in the said product, so that one or more grouped fibre formations, or a plurality or layer of grouped fibre formations, is or are set at an angle to at least one other grouped fibre formation, or plurality or layer of grouped fibre formations, or (iv) any combination of two or more of steps (i), (ii) or (iii).

2. A process according to claim 1, in which each of the grouped fibre formations comprises fibres which are rolled, folded, twisted or rendered tortouous or contorted with respect to each other to produce nonalignment of some parts of the length of the formation with other parts of the formation.

3. A process according to claim 1 or 2, in which the said largely untexturized matrix contains (a) chopped spun protein fibres which are either randomly orientated or only partially aligned with each other, or (b) natural edible vegetable fibres or meat fibres, or (c) a mixture of (a) and (b).

4. A process according to any one of claims 1 to 3, in which the matrix is heatsettable or contains heat-coagulable protein.

5. A process according to any one of the preceding claims, in which the matrix contains wheat gluten, homogenized or emulsified meat, soluble meat or blood protein.

6. A process according to any one of the preceding claims, in which the dry weight ratio of matrix solids to spun protein fibres is at least 2:1.

7. A process according to any one of the preceding claims in which dry powdered wheat gluten is incorporated in the protein fibres.

8. A process according to any one of the preceding claims, in which a paste or slurry containing short lengths of spun protein fibres is deposited between the successive layers of fibres from which the composition is built up.

9. A process according to claim 8, in which the paste contains edible fat or oil.

10. A process according to any one of the preceding claims, in which the matrix or part of the matrix is applied to the fibres in dry form.

11. A process according to any one of the preceding claims in which added flavoring tgents are incorporated in the composition.

12. A process according to claim 11, in which the flavoring agents are included in the matrix or binder.

13. A process according to any one of the preceding claims, in which the composition is heated to a temperature above 75or. to heat-set the protein.

14. A process according to any one of the preceding claims, in which the spun fibres are orientated in the form of a sheet by utilzing one or more of the devices as hereinbefore described.

15. A process for the preparation of a texturized protein composition substantially s hereinbefore described with reference to examples 1 and 2.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (22)

**WARNING** start of CLMS field may overlap end of DESC **. 2.25 Kg, soya isolate 1.25 Kg (Promine D), onion flavoured salt 140 g and roast beef flavour (Glentham Essence Co Ltd) 200 g. After addition of the powder the preparation was sprayed liberally first with water then with sunflower oil before the next layer of spun fibres was applied. Gentle pressure was applied to compact the layers. The fibres in each layer of fibres were placed at right angles to those in the adjacent layers. The completed composition was cooked in an oven at a temperature of 185"C for 50 minutes. The product possessed particularly satisfactory flavour and texture and derived from the combination of unspun wheat gluten with spun protein fibres an eating quality not achieved by using either unspun wheat gluten or spun protein fibres separately. EXAMPLE 4 Spun protein fibres were prepared as described in Example 3 except that the stretch bath was filled with an aqueous solution comprising 3.0% w/v maize protein hydrolysate, 1.0% wlv yeast extract (llis- tillers Company Ltd) and 1.4% w/v NaCI. Two baths were employed for neutralising and washing, both containing maize protein hydrolysate (3.0% wlv) and yeast extract (1.0% w/v), the first being adjusted to pH 8.5 and the second being adjusted to pH 7.5. The finished product was shaped and cooked as described in Evample 3. The texture of the product was similar to that of the product of Example 3, but the flavour retention of the product during chewing was better. WHAT WE CLAIM IS:-

1. A process for the preparation of a texturized protein composition from spun protein fibres which comprises stacking or winding a plurality of spun protein fibres in the form of grouped fibre formations, as hereinbefore defined, or assemblies of grouped fibre formations, in substantially planar sheet form, incorporating therebetween discrete layers of largely untexturized matrix comprising a binding agent with or without inclusion of chopped spun fibres to form a layered structure comprising alternate layers of fibres and matrix, the fibre layers being either continuous or discontinuous, and additionally either (i) incorporating in the said product natural edible vegetable fibres that are not substantially aligned with the spun protein fibres or (ii) incorporating in the said product chopped lengths of spun proteins fibres which are only partially aligned with each other or are randomly orientated or (iii) orientating the fibres in the said product, so that one or more grouped fibre formations, or a plurality or layer of grouped fibre formations, is or are set at an angle to at least one other grouped fibre formation, or plurality or layer of grouped fibre formations, or (iv) any combination of two or more of steps (i), (ii) or (iii).

2. A process according to claim 1, in which each of the grouped fibre formations comprises fibres which are rolled, folded, twisted or rendered tortouous or contorted with respect to each other to produce nonalignment of some parts of the length of the formation with other parts of the formation.

3. A process according to claim 1 or 2, in which the said largely untexturized matrix contains (a) chopped spun protein fibres which are either randomly orientated or only partially aligned with each other, or (b) natural edible vegetable fibres or meat fibres, or (c) a mixture of (a) and (b).

4. A process according to any one of claims 1 to 3, in which the matrix is heatsettable or contains heat-coagulable protein.

5. A process according to any one of the preceding claims, in which the matrix contains wheat gluten, homogenized or emulsified meat, soluble meat or blood protein.

6. A process according to any one of the preceding claims, in which the dry weight ratio of matrix solids to spun protein fibres is at least 2:1.

7. A process according to any one of the preceding claims in which dry powdered wheat gluten is incorporated in the protein fibres.

8. A process according to any one of the preceding claims, in which a paste or slurry containing short lengths of spun protein fibres is deposited between the successive layers of fibres from which the composition is built up.

9. A process according to claim 8, in which the paste contains edible fat or oil.

10. A process according to any one of the preceding claims, in which the matrix or part of the matrix is applied to the fibres in dry form.

11. A process according to any one of the preceding claims in which added flavoring tgents are incorporated in the composition.

12. A process according to claim 11, in which the flavoring agents are included in the matrix or binder.

13. A process according to any one of the preceding claims, in which the composition is heated to a temperature above 75or. to heat-set the protein.

14. A process according to any one of the preceding claims, in which the spun fibres are orientated in the form of a sheet by utilzing one or more of the devices as hereinbefore described.

15. A process for the preparation of a texturized protein composition substantially s hereinbefore described with reference to examples 1 and 2.

16. A texturized protein composition

whenever prepared by a process according to any one of the preceding claims.

17. A texturized protein composition soluprising a plurality of grouped fibre Ebrmations, as hereinbefore defined or assemblies of grouped fibre formations, of spun protein fibres in a stacked or wound product, each formation or assembly of formations in the product being in substantially planar sheet form and being separated from the next adjacent planar formation or assembly of formations by the incorporation therebetween of a discrete layer of largely untexturized matrix comprising a binding agent with or without inclusion of chopped spun fibres, each formation or assembly of formations further being juxtaposed so that the fibres therein are set at an angle to the fibres in the next adjacent formation or to the chopped spun fibres present in the binding matrix or to both sets of fibres.

18. A composition according to claim 17, in which the angle between the fibres in the juxtaposed formations is approximately 90".

19. A composition according to claim 17 or 18, substantially as hereinbefore described with reference to the drawings accompanying the provisional specification of application No. 13709/76.

20. A process for preparing a texturized protein composition which comprises forming spun fibres, neutralizing and washing the spun fibres, and shaping the resulting treated fibres into a discrete texturized composition as claimed in claim 1, wherein the fibres are impregnated with agents either during or after the neutralizing and/or washing steps and/or a non-fibrous substantially water-insoluble elastic protein is incorporated in the composition either during or after any one or more of the neutralisation, washing or shaping steps.

21. A process according to claim 20, in which the non-fibrous elastic protein is wheat gluten.

22. A process according to either one of claims 20 or 21, substantially as herein before described with reference to Examples 3 and 4.