JPS6210624B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to structured proteins, and more particularly to a new method for producing fibrous proteins that can be used as or in the production of meat analogs. In recent years, considerable research has been focused on developing new techniques for producing meat-like protein-containing foods from a variety of plant and animal protein sources. Economics is the main motivation for research. It would be clearly beneficial to replace at least some of the inefficient ways in which animals convert plant protein into meat by more efficient methods of growing plant protein. This is particularly true when continued population growth far exceeds the availability of pasture for meat-producing animals. In addition, efforts have recently been directed toward eliminating certain natural products that may be unwanted for religious, racial, or health reasons. All natural meats, such as fish and poultry meat, have a fibrous structure. The texture of meat products is specific to the fiber characteristics of the meat. Similarly, the presence of a fibrous structure is also an important factor in manufactured meat-like products. Therefore, in the production of such meat-like products, such as meat analogues, much effort has been put into creating a fibrous structure similar to natural meat. Many researchers have developed many techniques to obtain fiber properties, and much literature has been published on the production of meat analogues with fibrous structures. Boyer, an early researcher, published U.S. Patent 2,682,466.
In the issue, it describes the production of artificial meat products containing a large amount of vegetable protein fleeting. These protein filaments are produced by extruding a colloidal protein dispersion through a porous fat such as a die into a coagulation bath to precipitate the protein into filaments. A meat-like product is created by combining these many filaments with a binding material selected from shellfish, proteins, and the like. The use of spun vegetable protein fibers allows the formation of highly oriented fiber structures. Unfortunately, however, the production of spun fibers is complicated and fairly expensive. Additionally, spun vegetable proteins generally have low nutritional value because the starting material is soybean extract. In view of the inherent difficulties in spinning fiber technology, many other researchers have enthusiastically investigated alternative techniques. One alternative technique, described in US Pat. No. 3,488,770, shows the production of protein meat-like products having open cells where the cell length is greater than the cell width, and where the cells are substantially oriented. This product is made by extruding a dough containing substantially non-protein fillers into a vacuum zone to cause expansion. Another alternative technique for contrasting dough is US Pat. No. 3,693,533.
It is described in. According to this method, the protein-containing dough is coagulated while passing through a set of conveyors. Elongation during coagulation produces a product that is described as a unidirectional fiber. Although these methods are potentially less expensive than spun fiber techniques, they suffer from the lower quality of the fibers produced. Some researchers have published JP-A-48-21502, JP-A-Sho.
No. 48-34228, U.S. Pat. No. 3,870,808 and U.S. Pat.
No. 3,920,853 describes the production of fibrous protein masses by a process comprising freezing a protein solution or dispersion and heating the frozen mass to solidify the protein. These fibrous products are described as meat-like and can be further improved by freeze drying before heat setting. Broadly defined, the present invention involves freezing an aqueous mixture of thermosetting proteins by cooling in a manner and at a rate effective to produce long ice crystals oriented generally perpendicular to the cooling surface, and then lowering the freezing point of the water. The process consists of immersing the resulting frozen mass in an aqueous solution consisting of an edible, water-soluble substance that can be submerged to stabilize the protein for a period of time effective to stabilize the protein in the frozen mass. According to the present invention, a wide range of meat-like tissues can be imitated by using various protein materials. A common feature of these products is the presence of well-independent and aligned fibers. The fibers are produced by the method of the invention using proteins of animal or vegetable origin, each individually or in combination. According to this method, it is possible to easily balance the texture, flavor, and nutritional properties of the fibers and provide a structured protein material having desired properties. A feature important to the invention is the need for cooling in a direction and rate effective to produce well-separated and aligned ice crystals and the need to immerse the frozen mass in a stabilizing solution to separate the ice crystals from each other. It is necessary to stabilize proteins that reliably maintain the fiber structure. When used alone or in combination,
Any edible protein or combination of proteins can be used in the method of the invention, provided that at least one protein is soluble or partially soluble and can be stabilized by the treatment of the invention. In general, proteins with good solubility give good, discrete fibrous structures. This is probably because ice crystals are not restricted by insoluble solids and can grow freely. However, protein solutions containing significant amounts of insoluble substances such as soybean flour, ground meat and ground fish meat can also be used and the fibrous structures according to the invention can be produced successfully. Typical protein materials that can be used to obtain the excellent results of the present invention are soy milk, soy extract, whole milk, meat slurry, fish slurry gluten, soy flour, wheat protein concentrate, milk whey, egg protein, blood. There are proteins, single cell proteins, etc. The final texture of the product depends in part on the protein source used, as well as additives such as flavorings, fillers, fats, carbohydrates, and salts. For example, products prepared from soy milk have a juicy, smooth and soft texture and the fibers exhibit good tensile strength. Soy milk can provide a product with smoothness and tenderness similar to raw chicken. This is probably due to the oil emulsified in the protein. On the other hand, soy flour gives a product with lower tensile strength than that with soy milk, but this type of flexibility is desirable as an ingredient alone or in combination with other protein materials. Protein of any origin is mixed with water to form an aqueous protein mixture. Here, at least a portion of the protein is dissolved in water. Aqueous protein mixtures can be described as solutions, dispersions, or suspensions of water and protein. Depending on the protein, the PH of the mixture can be adjusted to increase protein solubility.
To obtain optimal tensile strength and fiber integrity, it is usually desirable to adjust the PH of the aqueous protein mixture to maximize protein solubility. The PH of the mixture appears to directly affect the tensile strength of the final structured product. Certain protein materials, such as soy flour, give better texture and tensile strength at high PH, eg PH10, than at low PH. The reason for this is probably that these proteins are more soluble at high PH and are partially dissociated and denatured by alkaline conditions before assembly. At high PH, protein molecules spread out and dissociate more completely,
During the freezing stage, movement is freer and more complete fibers are formed. Certain proteins, such as egg proteins, exhibit good solubility at their natural PH and there is no need to adjust the PH to alkaline. Although high PH is often useful in making structured products, a PH that is too high is not necessarily desirable for meat analog products. However, lowering the PH of a structured product to a PH where certain proteins are immobilized often affects the texture of the product. Depending on the specific end use intended, this impact on texture may or may not be desirable. Natural pH of 6 to 8
Neutralization is not necessary for proteins that are soluble in Aqueous protein mixtures can be easily prepared by mixing protein with water. If necessary, the protein material may be finely ground before or after stirring with water;
And the PH can be adjusted to obtain maximum solubility. The presence of soluble and insoluble non-coagulating materials is also acceptable and in some cases desirable as long as it does not adversely affect the desired qualities of the fiber structure for the particular application. In some cases, the presence of excessive amounts of fat is undesirable as it will reduce the tensile strength of the fibers. However, in other cases a reduction in tensile strength is desirable as it will give the product a softer texture. in this way,
Additives commonly used in fibrous meat analog products can be used in the present invention, thereby allowing the process of the present invention to vary the composition of the fiber-forming material over a wide range from a basic single process to a variety of A method of effecting histological and nutritional changes in a patient is provided. It is another advantage of the present invention that relatively high fat contents can be used and good fiber structure can be obtained. The solids concentration of the mixture will affect both the texture and processing efficiency of the product. Generally, it is desirable to have a low solids content. One reason for this is that the clarity of the fiber structure tends to disappear as the solid content concentration increases. Typically, the solids concentration should not exceed about 40% by weight of the mixture, and preferably should not exceed about 35% by weight. If the solids concentration increases, increase the immersion time in the stabilizing solution. however,
Processing at excessively low concentrations becomes uneconomical due to increased costs for removing water. Decreasing concentrations dramatically increase costs for energy, containers, transportation, and storage equipment. However, the quality of fibers produced at low concentrations is high. Therefore, it is necessary to determine the optimal concentration for each specific system with the understanding that there are many influences to consider. In very broad terms, the optimum concentration for freezing is 3 to about 35, based on the total weight of the aqueous mixture.
%, preferably 10 to 30% protein. However, the optimum values for individual proteins and additives can vary within the above ranges;
It will be clear that the above ranges may often be exceeded. Those skilled in the art will be able to determine the optimum for the particular equipment used, especially with knowledge of the economics of particular processing equipment and processing methods. By referring to the examples described below, those skilled in the art will understand examples for many different systems. Any concentration effective to create substantially independently oriented fibers is acceptable in the present invention. The specific concentration must be determined in each individual case with regard to the balance of product properties and desired and adequate processing efficiency. Gelling proteins of the type used in making tofu, whose gel structure prevents water from forming long ice crystals, cannot be used in the present invention. The prepared aqueous mixture is frozen by cooling in a defined direction, giving a well defined and ordered fibrous structure made up of ice crystals. When the water is frozen into ice crystals, the remaining protein mixture becomes more concentrated. The formation of ice crystals delimits the protein material and separates it into generally parallel aligned sections. Any means by which this result can be achieved is suitable for the present invention. Ice crystals form proteins entrapped in arranged fibrous areas between elongated ice crystals. The areas of protein material are almost completely separated from each other and when solidified,
Substantially independent protein fibers are formed. However, the regions of the protein are not completely independent of each other and are linked at sufficient positions to link the individual regions into a branched, cross-linked structure. The degree of bonding achieved is just sufficient to provide a cohesive force that gives a final product similar to cooked meat, but without substantially destroying the independent fiber structure.
This bonding that occurs during fiber formation eliminates the need for a separate bonding material. Freezing can be carried out by cooling at least one surface, preferably only one surface or two opposing surfaces, of the mixture below the freezing temperature of the mixture. Preferably, this cooling causes freezing through the entire thickness of the mass, producing fibers that are generally parallel and generally perpendicular to the cooling surface. The one or more cooling surfaces described above are preferably planar, but may have other regular or irregular shapes. For example, a single hemispherical, spherical or cylindrical cooling surface can be used in contact with the aqueous protein mixture. In these instances, the ice crystals (and thus the protein fibers) will generally be perpendicular to the tangent of the contact surface and will form radially from the surface toward the center. During freezing, a boundary between the frozen mixture and the liquid mixture appears, which moves in the direction of cooling. At typical freezing temperatures used in the present invention, and when the cooling surface is not very irregular, this boundary approximately corresponds to the shape of the cooling surface of the aqueous protein mixture. However, under conditions different from those in the present invention, the boundary will likely have a slightly different shape. It will be appreciated that after the mixture has been frozen to its final thickness, the moving boundary of the freeze becomes a cooling surface through which heat transfer occurs. It is this moving boundary that then controls the morphology of ice crystal (ie fiber) formation. An important consideration in all cases is the production of individually well-delimited fibers with an ordered arrangement similar to natural meat. If desired, other surfaces not in contact with the cooling surface can be thermally insulated to reduce heat transfer to these surfaces. In most cases, the surfaces that are not in contact with one or more opposing cooling surfaces exhibit somewhat irregularly oriented fibers of constant thickness. Directional cooling at the distal end is difficult to achieve due to heat transfer from an external heat source.
This end portion may be retained in the final product or may be removed, for example by cutting with a knife heating wire or the like. When cooling from two opposing surfaces, a discontinuous horizontal plane appears to bisect the thickness of the frozen mass. This is thought to be because crystal growth occurs independently from each opposing surface toward the contact surface in the middle of the mass. A large number of cooling surfaces can be used according to the invention.
For example, simply place the aqueous protein mixture in a pan and place the pan on dry ice or slightly (e.g., 1/8 inch) submerged in a cooling liquid such as liquid nitrogen, ethylene glycol, canned water, etc. It can also be frozen. Alternatively, the container of aqueous protein material can be placed on a plate freezer or between two opposing plate freezers. Also desirable would be the moving belt type refrigerators described in US Pat. Nos. 3,253,420 and 3,606,763. The temperature used may be any temperature effective to obtain substantially independent and ordered ice crystals. Although the cooling rate is not a factor for the production of well-separated and aligned long fibers when cooling is carried out in a single direction, it clearly influences the size and shape of the crystals. Rapid cooling produces microscopic ice crystals.
Slow cooling or freezing produces long needle-shaped ice crystals. The preferred cooling rate, defined as the rate of progression of the frozen boundary, is about 0.02 to about
1.0 ft/hr (0.61 to 30.5 cm/hr), preferably about 0.03 to about 0.5 ft/hr (0.96 to 15.3 cm/hr)
time). Although there is currently no criticality regarding the temperature of the protein solution or slurry before freezing, it is considered preferable to bring the temperature of the solution or slurry as close to the freezing temperature as possible before freezing. This is currently only good from an economic point of view.
Cooling a liquid by conventional means by large surface contact with a heat transfer medium and turbulent flow is less expensive than cooling by one or two opposing heat transfer components used for freezing. However, the liquid mixture must not be supercooled before the freezing operation.
Supercooling causes excessively rapid and irregular cooling;
and gives the product an undesirable irregular fiber structure. After cooling, the crystal structure of the material can be easily observed, if desired, by sampling the frozen mass and observing it with the naked eye. In order to preserve the integrity of the individual protein fibers thus formed, the protein can be stabilized by immersing the frozen mass in an aqueous solution. This aqueous solution consists of edible water-soluble substances capable of lowering the freezing point of water and stabilizing proteins. If a substantially soluble protein is not stabilized prior to heating, such as thermal solidification, heating causes excessive bonding of individual fibers due to melting of the ice crystal lattice separating the fibers. For many meat analogs and especially fish analogs, this excessive binding of protein materials is undesirable. Also, in this regard, the frozen mass must not be stored for long periods at temperatures slightly below the freezing point. Storage under such conditions will cause ice recrystallization and randomization of the fiber structure. Although this may be desirable within certain limits as a means of influencing the texture of the final meat analog, it must be done with the knowledge that reorientation will occur and may not be desirable for the specific application. Permissible only within the range. The frozen mass is immersed in the stabilizing solution by any conventional method using conventional equipment. The product can be ground either before or after soaking. Proteins were precipitated using a water-miscible solvent beforehand. And any of these known substances reduce the amount of water available to the protein, reduce the hydrophilic capacity of the protein by causing morphological changes in the protein, lower the freezing point of water, and further reduce the amount of water available to the protein. They can be used as stabilizing substances in aqueous solutions as long as they reduce the surface tension of The amount of water available to the protein is simply reduced by reducing the mole fraction of water in the presence of the stabilizing substances.
Therefore, this water is less available for protein solubilization. Effective stabilizing substances have the following equilibrium,

[Table] Hydrated protein random coil
←
Shifts structure + water to the right, negatively affecting protein solubility. The most effective stabilizing substances available reduce the surface tension of water, thereby reducing the contribution of water to hydrophobic group aggregation of proteins. The most significant aggregation, which is effective in reducing protein solubility, occurs in organic solvents where the molecules have short linear hydrophobic groups. It is also essential to lower the freezing temperature of water. This is because the stabilizing substance must be able to penetrate the ice in the frozen mass. Suitable stabilizers are organic solvents such as alcohols. Ethanol is preferred due to the fact that it is non-toxic even when remaining in significant amounts in the final product. However, any solvent may be used, provided it exhibits sufficient intended function and is not toxic in reasonable amounts that may remain in the product after removal of the solvent by known techniques such as extraction and drying. . Known acids and salts which exhibit the necessary functions in aqueous solution are also suitable as stabilizing or coagulating substances. If necessary, these known salts and/or acids can be used in combination with alcohols such as ethanol or other organic solvents. Such combinations are desirable from the standpoint of balancing the advantages and disadvantages of various stabilizers for a particular process or product application. Suitable acids include hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid and other edible acids. Suitable salts include the edible ammonium, alkali metal and alkaline earth metal salts of the acids mentioned above, as well as other salts with the desired effect. Ethanol, which is an example of a suitable stabilizer that can be used in the present invention, is used as a stabilizer for convenience in the following description. When the frozen mass of protein and ice prepared as described above is brought into contact with ethyl alcohol in the coagulation solution, diffusion exchange occurs between the two phases of water and ice crystals in the protein and ethyl alcohol. As soon as the protein comes into contact with alcohol, the protein is insolubilized and the fibers are stabilized. In order to completely insolubilize the protein, the alcohol must diffuse throughout the protein phase.
After sufficient time, exchange no longer occurs and an equilibrium state is now achieved between the two phases. The final equilibrium alcohol concentration in the coagulation solution depends on the ratio of alcohol to water in the frozen protein mass. The alcohol concentration in the coagulation bath affects the freezing temperature of the solution as well as the rate of diffusion and protein coagulation, and these factors are important in controlling the method of the invention. If the unidirectionally frozen protein mass is immersed in an alcohol bath to stabilize the frozen oriented fiber structure, the temperature of the bath must be below the freezing temperature of the protein mixture. This immobilizes free water and minimizes protein rehydration and water dissolution of frozen, oriented structures. At freezing temperatures, water exists as ice crystals within the protein mass. When ice crystals come into contact with alcohol, the ice melts and the water begins to diffuse. At the same time, the protein is brought into contact with a sufficient concentration of alcohol to be insolubilized. When the temperature of the alcohol bath is close to the freezing temperature of water (above -5°C), recrystallization occurs in the frozen protein mass, the unidirectional fibrous structure disappears and irregular structures are formed. The reduction in freezing temperature depends on the concentration of solute added to the solution. Therefore, the freezing temperature of the coagulation bath can be controlled by varying the alcohol concentration. To prevent freezing of the alcohol bath, the freezing temperature of the coagulation liquid must be lower than the processing temperature. Stabilizing substances can be used at any concentration that is effective, but for ethanol, for example, the concentration is approximately
Must be maintained at 10% or more, preferably 20% or more. In the specific example using 5% concentration of ethanol, the protein is completely dissolved and the fiber structure is unclear. At 10% concentration, the protein was partially dissolved and the fibers were very flexible. However, the fibers do not fall apart. At 20% alcohol concentration, the protein was not dissolved. The texture was soft due to partial hydration. At alcohol concentrations above 30%, the protein was completely insoluble and the texture of the fibrous material was hard. When the final equilibrium alcohol concentration in this coagulation method was above 70%, the fibers became very brittle due to excessive dehydration. The highest concentration at equilibrium appears to be about 60% ethyl alcohol. Ethanol soluble colorants, carbohydrates and fats and oils in the protein material were diffusely released during this process. This is desirable from the standpoint of removing colorants and leavening agents from the product. The fat can be recovered and the food can be used. After stabilization in this way, the fibrous mass is dried and
It can also be stored for an indefinite period of time or heat-set immediately after drying and stored for later use. However, it is currently preferred to heat set the fibers prior to rehydration. Protein fibers are strengthened by thermal solidification. If not heat-set prior to rehydration, the desired structural properties obtained will be lost. By appropriate selection of the specific heat treatment regime, it is possible to impart texture, color, stiffness, tensile strength, rehydration and water retention properties to the final product. Textured materials that have undergone severe heat treatment tend to retain less water upon rehydration. However, it is preferred that all structured materials of the present invention undergo heat treatment to a sufficient degree to increase the structural integrity of the fibers. The mild heat treatment applied to the material is very efficient and gives the final product very good meat-like fibers. The degree of heat treatment under pressure or non-pressure to stabilize the product will vary depending on the type of protein material used. By way of example, dried soymilk fibers are preferably heat treated in an autoclave under a pressure of 15 psig for about 5 to 10 minutes to stabilize the structure. on the other hand,
Fibers obtained from soybean flour are preferably heat treated for about 20 to 25 minutes under the same conditions as described above.
Any combination of time, temperature and pressure effective to heat set the protein into substantially independent fibers can be used in the present invention. Depending on the desired texture of the final product, heat treatment for about 5 to about 30 minutes at a temperature of about 100 to 120°C is believed to be sufficient. Accurate times for various products,
Temperature and pressure can be easily determined by one skilled in the art. Reference is made to the Examples below, which demonstrate a number of specific heat treatment operations that will provide guidance to those skilled in the art. Typical heating methods available are approximately 20 psig.
There are conventional autoclaves or steam chambers capable of providing pressure conditions below and temperatures below about 130°C. Also preferred are electric or gas-fired infrared ovens that can operate under conditions of high relative humidity. Use of these devices or moist heating in an autoclave or steam chamber as described above promotes more complete coagulation or solidification of the protein material. The specific heating means used is not critical to the invention. All that is required is that the heating be sufficient in intensity and time to coagulate or solidify the protein to a degree sufficient to prevent substantial loss of individual protein fibers upon rehydration. After heat setting, the fibrous protein material can be marketed as is or immediately rehydrated to give a more meat-like texture. Dry products are easily rehydrated by soaking in water for a period of time effective to provide the desired moisture content. The rehydration solution contains acids to neutralize residual alkali, flavors, emulsified fats, flavor enhancers, spices, sugars, thermosetting or soluble proteins,
It can also contain amino acids and the like. These additives can improve the product to give it a meat-like structure and flavor. Of course, as mentioned above, these components can also be used in the aqueous protein mixture prior to freezing. Experience with these formulations will tell in which steps these additives are used. The present invention will be further explained below with reference to Examples.
This is not intended to limit the invention in any way. All parts and percentages are by weight unless otherwise indicated. Example 1 Soy milk was used as a protein source to create a structured soy protein product with highly oriented and well-defined fibers. Soy milk was produced as follows. First, 600 g of soybeans were soaked in water, and the water was changed several times and left overnight. The soaked soybeans were hot-ground in boiling water. At this time, boiling water should be used against soybeans.
They were present in a 10:1 ratio. The resulting slurry was heated to a boil and held there for 15 minutes, then passed through a double layer of cheesecloth. The residue remaining on the cheesecloth was discarded, and the solid content in the supernatant was measured. The PH of the supernatant was adjusted to 7.5 using 2N sodium hydroxide and antioxidants were added at a level equal to 0.02% fat content. Since full-fat soybeans were used, the fat content of the supernatant liquid was approximately 1/4 of the weight of solids present. The soy milk was then poured into the aluminum pan to a depth of about 1 inch (2.5 cm). The bread was placed on a block of dry ice (-76°C) covering the entire bottom of the bread. Unidirectional ice crystals formed that were substantially perpendicular to the bottom of the pan. This mass was completely frozen in about 30 minutes. The frozen mass was taken out of the pan and immersed in about 4 times its weight of ethanol at a temperature of about -5 to -10°C for 8 hours with stirring. The stabilized fibrous material was compressed by applying a force perpendicular to the direction of the fibers to accelerate the release of ethanol trapped between the fibers. The compressed product was air dried to remove residual water and ethanol. This drying process strengthened the structure. This dry material was autoclaved at 15 psig for 10 minutes to strengthen the structure. The heat-set material was then rehydrated by soaking in water for about 20 minutes, resulting in a product with individual, long, soft or grippy fibers. Example 2 The method of Example 1, except that the aluminum pan containing soy milk is immersed in a propylene glycol cryogen bath (-32°C) to a depth of about 1/8 inch instead of being placed on dry ice. repeated. Example 3 The method of Example 2 was repeated except that the stabilized fibrous material was not compressed and placed in a vacuum chamber for 15 minutes to remove any remaining ethanol. Example 4 A fibrous soy protein product was prepared from soy protein extract. 100g of soy protein extract (91% protein)
A 10% solution was prepared by mixing with 900 g of water, and the pH was adjusted to 7.0 to 8.0. This solution was placed in a pan approximately 1 inch deep and frozen and stabilized as in Example 3. Example 5 A peanut protein product was prepared from a peanut protein extract. 150g of peanut protein extract (93% protein)
It was mixed with 850 g of water to make a 15% solution and the pH was adjusted to 7.0 to 8.0. This solution was placed in a pan approximately 1 inch deep and frozen and stabilized as described in Example 3. Example 6 A fibrous ovalbumin product was prepared from fresh egg whites. The whites were separated from the yolks from several eggs, placed in a pan, and frozen and stabilized as in Example 3.
A 10% egg albumin solution prepared from egg white powder was also used satisfactorily. Example 7 A fibrous fish protein product was prepared from a 15% aqueous mixture of fresh fish meat. To prepare this aqueous mixture, 150 g of lean fish meat was homogenized in a Waring Blendor under vacuum at high speed for about 5 minutes into 850 ml of cold 3% NaCl aqueous solution. The resulting homogenized mixture was placed in a pan, frozen and stabilized as in Example 3. Example 8 A fibrous milk protein product was prepared from fresh whole milk.
Fresh whole milk is added to the bread according to the method of Example 3;
Frozen and stabilized. Example 9 The method of Example 1 was repeated except that the soy milk was concentrated as follows. The pH of soy milk was adjusted to 4.5 by adding HCl (1N). The obtained precipitate
Separation was performed by centrifugation at 5000×G for 20 minutes, and the supernatant was removed. The precipitate was transferred to a blender and mixed with water for 20 minutes to obtain smooth and concentrated (18-20% solids) soymilk. The soy milk slurry was then adjusted to a pH of about 7.5 using 2N sodium hydroxide, and the resulting solution was placed in a pan as in Example 1, frozen, and further processed.

Claims (1)

[Claims] 1. (a) preparing a mixture consisting of a thermocoagulable protein and water; (b) cooling the mixture to freeze the water as long ice crystals; and and (c) freezing the resulting frozen mass in an aqueous solution consisting of an edible, water-soluble substance capable of lowering the freezing temperature of water and stabilizing proteins. A method for producing a structured protein material comprising the steps of soaking for an effective period of time to stabilize the protein in the mass, and (d) heating and coagulating the obtained stabilized protein. 2. The method according to claim 1, wherein the edible, water-soluble substance capable of lowering the freezing temperature of ice and stabilizing proteins is ethanol. 3. The method according to claim 2, wherein ethanol is used in the aqueous solution at a concentration of 20% or more by weight of the aqueous solution before immersion of the frozen mass. 4. The method according to claim 3, wherein the pH of a mixture of protein and water is adjusted to increase the solubility of the protein. 5. The method according to claim 4, wherein the stabilized protein is treated to remove residual ethanol. 6. The method according to claim 5, wherein residual ethanol is removed by placing the stabilized protein under reduced pressure. 7 The temperature of the aqueous solution in step (c) was kept at about -
The method according to claim 1, characterized in that the temperature is maintained at 5°C or lower.