A method for preparing bean-based pastries using scraps of dried tofu sheets as raw material

Abstract

This invention relates to the field of soy-based food products and discloses a method for preparing soy-based pastries using scraps of dried tofu sheets as raw materials, comprising the following steps: (1) soaking the scraps of dried tofu sheets to make soy paste; (2) mixing the soy paste, glutinous rice flour, and transglutaminase to obtain mixed soy paste; (3) placing the mixed soy paste into a molding mold and pressing it to remove water to obtain a pressed cake; (4) heating the pressed cake at 50-65℃ for 20-40 minutes, then steaming it at 85-100℃ for 30-50 minutes, and then cooling it. Using the preparation method of this invention, soy-based pastries with a fine texture, certain molding strength and elasticity, and good taste can be made from scraps of dried tofu sheets, realizing the reuse of scraps and increasing the added value of dried tofu products.

Description

Technical Field

[0001] The present invention relates to the field of bean products, and particularly to a method for preparing bean cakes using leftover materials from dried bean curd sheets as raw materials. Background Art

[0002] Soybeans have high nutritional value, containing about 40% protein, and are listed as complete proteins because they contain 8 essential amino acids for the human body. Soybeans do not contain cholesterol and have the effect of reducing cholesterol in the body. The fat they contain is mainly composed of unsaturated fatty acids, and the content of vitamin E is also relatively high, which has the effect of preventing arteriosclerosis, hypertension, and coronary heart disease. The calcium, phosphorus, and iron contained in soybeans are easily absorbed by the human body, and they are beneficial foods for anemic patients, so they have the reputation of "plant meat". China is the origin of soybeans, and "shu" among the five grains refers to soybeans. At the same time, China has a long history of processing soy products. Beans and their products, as traditional foods in China, have unique resource advantages, historical and cultural heritages and roots.

[0003] A large amount of leftover materials, such as strips and broken pieces, are generated during the processing of dried bean curd sheets. With the increase in the production of dried bean curd sheet products, the amount of leftover materials generated increases accordingly. It is urgent to find an effective way and method to utilize the leftover materials from dried bean curd sheets, so as to effectively increase the added value of soy product processing. In the context of the continuous upgrading of consumption concepts and consumption demands, pastry-like snack foods have become popular consumption choices among consumers. Bean cakes products meet the consumption demands of the new era. Their production processes are sophisticated, the flavoring raw materials are carefully considered, and the product varieties are novel. They are unique in both form and flavor and can be used as instant snacks for daily leisure time. Making bean cakes from the leftover materials of dried bean curd sheets can solve the losses caused by the abandonment of the leftover materials of dried bean curd sheets and increase their added value. However, bean cakes have requirements for their tissue state and taste. At present, there is no relevant research on making bean cakes with delicate tissue state and good taste from the leftover materials of dried bean curd sheets. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for preparing bean cakes using leftover materials from dried bean curd sheets as raw materials. By using this preparation method, it is possible to make bean cakes with delicate tissue state, certain forming strength and elasticity, and good taste from the leftover materials of dried bean curd sheets, realizing the reuse of the leftover materials of dried bean curd sheets and increasing the added value of dried bean curd sheet products.

[0005] The specific technical solution of the present invention is as follows:

[0006] A method for preparing bean cakes using leftover materials from dried bean curd sheets as raw materials, comprising the following steps:

[0007] (1) Soak the leftover materials of dried bean curd sheets and then make them into bean paste;

[0008] (2) Mix the bean paste, glutinous rice flour and transglutaminase to obtain mixed bean paste;

[0009] (3) Put the mixed bean paste into the molding mold, press it to remove water, and obtain the pressed cake;

[0010] (4) Heat the pressed cake at 50-65℃ for 20-40 minutes, then steam it at 85-100℃ for 30-50 minutes, and then cool it.

[0011] In this invention, by soaking the scraps of dried bean curd sheets to absorb water, they can be made into a fine bean paste, resulting in a delicate texture in the final bean-based pastry. Furthermore, to help the fine bean paste hold its shape, this invention adds transglutaminase (TG enzyme) and glutinous rice flour. TG enzyme catalyzes the reaction between the γ-amide group of glutamine residues in proteins and the ε-amine group of primary amines or lysine to form isopeptide bonds, thereby creating cross-links between proteins. Simultaneously, glutinous rice flour contains a significant amount of amylopectin, which interweaves between protein molecular chains to form a complex network, enabling the bean-based pastry to hold its shape and possess a certain strength (its structure is less prone to collapsing and crumbling) and elasticity, thus giving the bean-based pastry a better texture.

[0012] Furthermore, while soaking the scraps of dried bean curd sheets helps to make the bean paste smoother, it also introduces a large amount of water. If the final bean-based pastry has an excessively high moisture content, it will not only make the pastry soft and easily deformed, affecting its texture, but also accelerate the growth of bacteria and mold, affecting its shelf life. Therefore, the process of preparing bean-based pastries in this invention requires strict dehydration. The invention team noticed that after the TG enzyme acts to form a cross-linked network of proteins, it locks in the moisture in the pastry, hindering moisture removal. Therefore, this invention first presses the mixed bean paste to remove water, and then heats it at the optimal temperature for TG enzyme action (50-65℃) to form a three-dimensional network structure of proteins, which can reduce the impact of TG enzyme action on the dehydration effect.

[0013] Preferably, in step (3), the molding mold includes a plate frame and a base plate. The plate frame includes a frame body and at least one handle located outside the frame body. The frame body has several through holes on its wall. The process of loading the mixed bean paste into the molding mold includes the following steps: placing the plate frame on the base plate, placing a cloth inside the frame body, pouring the mixed bean paste into the cloth, smoothing the surface so that the mixed bean paste fills the frame body, and the smoothed upper surface is flush with the top of the plate frame. Then, the cloth is used to cover the smoothed upper surface. In the above manner, one base plate and one plate frame are stacked as one layer, and one or more layers are stacked together.

[0014] This invention improves the dewatering effect by providing through holes in the frame wall of the molding die, facilitating the filtration of liquid during pressing. Furthermore, the invention employs a base plate and frame structure, with handles on the outside of the frame for easy handling and stacking into multiple layers, reducing space requirements.

[0015] Preferably, in step (3), the specific process of pressing and dewatering includes the following steps: first pressing for 10-15 minutes under a pressure of 0.15-0.2MPa, then pressing for 5-10 minutes under a pressure of 0.35-0.4MPa, and then pressing for 3-8 minutes under a pressure of 0.6-0.65MPa.

[0016] During the pressing and dehydration process, first use low pressure and slow pressing, which helps to squeeze out some of the free water locked in the bean paste by the protein network. Then increase the pressure to further squeeze out the water from the bean paste.

[0017] Preferably, in step (2), before mixing the bean paste, glutinous rice flour, transglutaminase and seasonings, the transglutaminase is first embedded in the butter.

[0018] Butter can enhance the nutritional value of soy-based pastries and give them a richer, more mellow flavor. This invention embeds TG enzyme in butter, allowing the butter to perform the following functions: Although the optimal operating temperature for TG enzyme is around 50-65℃, it remains active at room temperature. When mixed with soy paste, it catalyzes cross-linking of the soy protein before pressing and dehydration, negatively impacting the dehydration effect. By embedding the TG enzyme in butter, contact between the TG enzyme and the soy protein is prevented before pressing and dehydration, thus reducing cross-linking under the action of the TG enzyme and ensuring better dehydration. During heating at 50-65℃ after pressing and dehydration, the butter melts and permeates into the pastry, releasing the TG enzyme, which then comes into contact with the soy protein and exerts its effect. Therefore, the embedding of butter does not significantly affect the effect of TG enzyme in improving the shaping strength and elasticity of soy-based pastries.

[0019] Preferably, the encapsulation process includes the following steps: heating and melting butter, adding a lipophilic emulsifier, mixing well to obtain an oil phase solution; adding an aqueous solution of transglutaminase at a temperature of 45-65℃ to the oil phase solution, emulsifying to obtain a W / O pre-emulsion; mixing the W / O pre-emulsion with a hydrophilic emulsifier, adding it to water at a temperature of 45-65℃, emulsifying, then cooling to below 28℃, and separating the product at a temperature below 28℃.

[0020] In the above process, a W / O / W multiple emulsion method was used to embed the TG enzyme in the butter. This method can effectively embed the enzyme to reduce its activity while giving the product a smaller particle size, thus allowing the TG enzyme to be better dispersed in the cake and effectively exert its role in cross-linking the bean paste protein.

[0021] Preferably, the concentration of the aqueous glutamine transaminase solution is 10-35 wt%.

[0022] Preferably, the mass ratio of the aqueous glutamine transaminase solution to the oil phase solution is 1:1.5-2.5.

[0023] Preferably, the mass ratio of the W / O colostrum to water is 1:4-6.

[0024] Preferably, the lipophilic emulsifier is sorbitan monooleate (Span-80), and the mass ratio of butter to lipophilic emulsifier is 1:0.05-0.2.

[0025] Preferably, the hydrophilic emulsifier is polysorbate 80 (Tween-80), and the mass ratio of W / O colostrum to hydrophilic emulsifier is 1:0.1-0.3.

[0026] Preferably, in step (2), the mass ratio of the soybean paste to transglutaminase is 70-90:0.1-3.

[0027] Preferably, in step (2), the mass ratio of the bean paste to the glutinous rice flour is 70-90:10-30.

[0028] Preferably, in step (2), sugar and salt are added during the mixing of soybean paste, glutinous rice flour and transglutaminase, and the mass ratio of soybean paste, sugar and salt is 70-90:10-30:0.1-1.

[0029] As a preferred option, the specific process of step (1) includes the following steps: soaking the scraps of dried bean curd sheets in water at 90-100℃ for 10-20 minutes, taking them out and draining them, and then chopping and mixing them into bean paste.

[0030] Preferably, the frame is formed by four side panels of the same height, two of which extend out of the frame and the portion extending out of the frame has an arc surface with an opening facing downwards to form the handle.

[0031] Preferably, both the side plate and the bottom plate are made of plastic.

[0032] Traditional bean paste molding molds use a square wooden frame, made of four wooden planks pieced together. This is relatively heavy, and small wood shavings may be generated during use. If these shavings fall into the product, they can pose a potential quality risk. Furthermore, wood is highly permeable, allowing yellow pulp to easily seep into the material, making it difficult to clean and prone to causing excessive microbial levels. Alternatively, stainless steel square frames are also used, but the containers themselves are bulky and inconvenient to use. This invention, however, uses a plastic material, making the molding mold lighter and more flexible to use, and solving the problems of wood shavings falling and difficulty in cleaning.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) This invention soaks the scraps of dried tofu before making bean paste, adds glutinous rice flour and TG enzyme to the bean paste, and combines the process of pressing to remove water before heating and steaming. This makes the bean pastry have a delicate texture, a certain molding strength and elasticity, and a suitable moisture content, thus giving it a better taste.

[0035] (2) The present invention embeds TG enzyme in butter, which can reduce the cross-linking of soybean protein under the action of TG enzyme before pressing and dehydration, thereby improving the dehydration effect, and will not have too much impact on the effect of TG enzyme in improving the molding strength and elasticity of soybean pastries. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a plate frame structure in a molding die.

[0037] The attached diagram is labeled as follows: side plate 1, handle 1-1, through hole 1-2. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments.

[0039] General Implementation Examples

[0040] A method for preparing bean-based pastries using scraps of dried tofu sheets as raw material includes the following steps:

[0041] (1) Soak the scraps of dried tofu sheets and then make them into bean paste;

[0042] (2) Mix the bean paste, glutinous rice flour and transglutaminase to obtain mixed bean paste;

[0043] (3) Put the mixed bean paste into the molding mold, press it to remove water, and obtain the pressed cake;

[0044] (4) Heat the pressed cake at 50-65℃ for 20-40 minutes, then steam it at 85-100℃ for 30-50 minutes, and then cool it.

[0045] As a specific implementation method, the specific process of step (1) includes the following steps: soaking the scraps of dried bean curd sheets in water at 90-100℃ for 10-20 minutes, taking them out and draining them, and then chopping and mixing them into bean paste.

[0046] In one specific implementation, in step (2), before mixing the bean paste, glutinous rice flour, transglutaminase, and seasonings, the transglutaminase is first embedded in the butter. Optionally, the embedding process includes the following steps: heating and melting the butter, adding 5-20% by weight of a lipophilic emulsifier to it, mixing well to obtain an oil phase solution; adding a 10-35wt% aqueous solution of transglutaminase at a temperature of 45-65℃ to the oil phase solution at a mass ratio of 1:1.5-2.5, emulsifying to obtain a W / O promulgated milk; mixing the W / O promulgated milk at a mass ratio of 1:0.1-0.3 with a hydrophilic emulsifier, adding it to water at a temperature of 45-65℃, wherein the mass ratio of the W / O promulgated milk to water is 1:4-6, emulsifying, and then cooling to below 28℃, separating the product at a temperature below 28℃.

[0047] In one specific implementation, in step (2), the mass ratio of the bean paste, glutinous rice flour and transglutaminase is 70-90:10-30:0.1-3.

[0048] In one specific implementation, in step (2), during the process of mixing bean paste, glutinous rice flour and transglutaminase, white sugar and edible salt are added, and the mass ratio of bean paste, white sugar and edible salt is 70-90:10-30:0.1-1.

[0049] In one specific implementation, in step (3), the molding mold includes a frame and a base plate. The frame includes a frame body and at least one handle located outside the frame body. The frame body has several through holes on its wall. The process of loading the mixed bean paste into the molding mold includes the following steps: placing the frame on the base plate, placing a cloth inside the frame, pouring the mixed bean paste into the cloth, smoothing the surface so that the mixed bean paste fills the frame body, and the smoothed upper surface is flush with the top edge of the frame. Then, the cloth is used to cover the smoothed upper surface. Following the above method, one or more layers are stacked, with one base plate and one frame as a layer. Optionally, the frame body is formed by four side plates of the same height, wherein two opposing side plates extend out of the frame body, and the portion extending out of the frame body has an arc surface with an opening facing downwards to form the handle. Optionally, the side plates and the base plate are both made of plastic.

[0050] As a specific implementation method, in step (3), the specific process of pressing and dewatering includes the following steps: first pressing for 10-15 minutes under a pressure of 0.15-0.2MPa, then pressing for 5-10 minutes under a pressure of 0.35-0.4MPa, and then pressing for 3-8 minutes under a pressure of 0.6-0.65MPa.

[0051] Example 1

[0052] Using scraps of dried tofu sheets as raw material, bean-based pastries are prepared through the following steps:

[0053] (1) TG enzyme pretreatment:

[0054] Take 10 kg of butter, melt it at 50℃, then add 1 kg of sorbitan monooleate (Span-80) and stir until homogeneous to obtain an oil phase solution. Add 2 kg of TG enzyme to 4.5 kg of water, heat to 50℃, and then add it to the oil phase solution. Homogenize and emulsify to obtain a W / O promulgated emulsion. Maintain the temperature of the W / O promulgated emulsion at 50℃, add 1.75 kg of polysorbate 80 (Tween-80), mix, and then add to 70 kg of water at 50℃. Homogenize and emulsify. Then cool to 25℃, centrifuge at 4℃ to separate the precipitate, and freeze-dry the precipitate to obtain pretreated TG enzyme with an average particle size of 28.47 μm.

[0055] (2) Preparation of bean paste:

[0056] Add the scraps of dried tofu sheets to boiling water at 100℃, soak for 15 minutes, remove and drain, then put them into a chopper and chop into bean paste.

[0057] (3) Seasoning and flavoring:

[0058] Mix 80kg of bean paste, 20kg of glutinous rice flour, the pretreated TG enzyme obtained in step (1), 20kg of white sugar and 0.5kg of edible salt evenly to obtain mixed bean paste.

[0059] (4) Molding:

[0060] The molding die used consists of a frame and a base plate, both made of plastic. The frame structure is as follows: Figure 1 As shown, it consists of four side panels 1, two of which are 60cm×2mm×12cm in size, and the other two are 75cm×2mm×12cm in size; the four side panels form a square frame with a side length of 60cm, two of which are opposite each other and extend out of the frame, and the part extending out of the frame has an arc surface with an opening facing downward to form a handle 1-1; through holes 1-2 are distributed on the wall of the frame.

[0061] In use, place the base plate on the work surface, then place the frame on the base plate. Next, place a square cotton cloth inside the frame, pour the mixed bean paste into the cloth, and smooth the surface with a scraper until the bean paste fills the frame, aligning the smoothed top surface with the top edge of the frame. Then, tightly wrap the cloth to cover the smoothed top surface. Next, place a new base plate on the cloth, and repeat the process of placing the frame and cloth, pouring the mixed bean paste, smoothing, and wrapping. That is, one base plate and one frame constitute one layer, stacking two layers in total. Finally, cover the top layer with a lid.

[0062] (5) Pressing to remove water:

[0063] The molding mold, along with the mixed bean paste inside, is pushed into the pneumatic skid. It is first pressed at 0.15 MPa for 15 minutes, then the pressure is increased to 0.35 MPa and pressed for another 10 minutes, and then the pressure is increased to 0.6 MPa and pressed for another 5 minutes to obtain the pressed cake.

[0064] (6) Steaming:

[0065] After pressing the cake, heat it at 50°C for 30 minutes, then steam it at 90°C for 40 minutes.

[0066] (7) Cooling:

[0067] Place the steamed cake under a fan to cool it until the center temperature reaches room temperature, then unmold it.

[0068] (8) Cutting:

[0069] Cut the cooled cake into strips measuring 7cm × 4cm × 1cm to obtain long strip cakes.

[0070] (9) Packaging and sterilization:

[0071] After vacuum packaging the long strip-shaped cake in aluminum foil bags, sterilize at 121℃ for 20 minutes to obtain bean-based cakes.

[0072] Example 2

[0073] Using scraps of dried tofu sheets as raw material, bean-based pastries are prepared through the following steps:

[0074] (1) TG enzyme pretreatment:

[0075] 12.7 kg of butter was melted at 50°C, and 0.65 kg of Span-80 was added and stirred until homogeneous to obtain an oil phase solution. 3 kg of TG enzyme was added to 5.5 kg of water, heated to 50°C, and then added to the oil phase solution. The mixture was homogenized and emulsified to obtain a W / O promulgated emulsion. The W / O promulgated emulsion was maintained at 50°C, and 2.2 kg of Tween-80 was added and mixed. This mixture was then added to 87.5 kg of water at 50°C and homogenized and emulsified. The mixture was then cooled to 25°C, centrifuged at 4°C to separate the precipitate, and the precipitate was freeze-dried to obtain pretreated TG enzyme with an average particle size of 30.75 μm.

[0076] (2) Preparation of bean paste:

[0077] Add the scraps of dried tofu sheets to boiling water at 100℃, soak for 15 minutes, remove and drain, then put them into a chopper and chop into bean paste.

[0078] (3) Seasoning and flavoring:

[0079] Mix 90kg of bean paste, 10kg of glutinous rice flour, the pretreated TG enzyme obtained in step (1), 30kg of white sugar and 0.1kg of edible salt evenly to obtain mixed bean paste.

[0080] (4) Molding:

[0081] The molding die used is the same as in Example 1.

[0082] In use, place the base plate on the work surface, then place the frame on the base plate. Next, place a square cotton cloth inside the frame, pour the mixed bean paste into the cloth, and smooth the surface with a scraper until the bean paste fills the frame, aligning the smoothed top surface with the top edge of the frame. Then, tightly wrap the cloth to cover the smoothed top surface. Next, place a new base plate on the cloth, and repeat the process of placing the frame and cloth, pouring the mixed bean paste, smoothing, and wrapping. That is, one base plate and one frame constitute one layer, stacking two layers in total. Finally, cover the top layer with a lid.

[0083] (5) Pressing to remove water:

[0084] The molding mold, along with the mixed bean paste inside, is pushed into the pneumatic skid. It is first pressed at 0.15 MPa for 10 minutes, then the pressure is increased to 0.35 MPa and pressed for another 10 minutes. Finally, the pressure is increased to 0.65 MPa and pressed for another 3 minutes to obtain the pressed cake.

[0085] (6) Steaming:

[0086] After pressing the cake, heat it at 50°C for 30 minutes, then steam it at 90°C for 40 minutes.

[0087] (7) Cooling:

[0088] Place the steamed cake under a fan to cool it until the center temperature reaches room temperature, then unmold it.

[0089] (8) Cutting:

[0090] Cut the cooled cake into strips measuring 7cm × 4cm × 1cm to obtain long strip cakes.

[0091] (9) Packaging and sterilization:

[0092] After vacuum packaging the long strip-shaped cake in aluminum foil bags, sterilize at 121℃ for 20 minutes to obtain bean-based cakes.

[0093] Example 3

[0094] Using scraps of dried tofu sheets as raw material, bean-based pastries are prepared through the following steps:

[0095] (1) TG enzyme pretreatment:

[0096] Take 2.5 kg of butter, melt it at 50℃, add 0.5 kg of Span-80, and stir well to obtain an oil phase solution. Add 0.1 kg of TG enzyme to 0.9 kg of water, heat to 50℃, and then add it to the oil phase solution. Homogenize and emulsify to obtain a W / O promulgated emulsion. Maintain the temperature of the W / O promulgated emulsion at 50℃, add 1.2 kg of Tween-80, mix, and then add it to 24 kg of water at 50℃. Homogenize and emulsify. Then cool to 25℃, centrifuge at 4℃ to separate the precipitate, and freeze-dry the precipitate to obtain pretreated TG enzyme with an average particle size of 21.19 μm.

[0097] (2) Preparation of bean paste:

[0098] Add the scraps of dried tofu sheets to boiling water at 100℃, soak for 15 minutes, remove and drain, then put them into a chopper and chop into bean paste.

[0099] (3) Seasoning and flavoring:

[0100] Mix 70kg of bean paste, 30kg of glutinous rice flour, the pretreated TG enzyme obtained in step (1), 10kg of white sugar and 1kg of edible salt evenly to obtain mixed bean paste.

[0101] (4) Molding:

[0102] The molding die used is the same as in Example 1.

[0103] In use, place the base plate on the work surface, then place the frame on the base plate. Next, place a square cotton cloth inside the frame, pour the mixed bean paste into the cloth, and smooth the surface with a scraper until the bean paste fills the frame, aligning the smoothed top surface with the top edge of the frame. Then, tightly wrap the cloth to cover the smoothed top surface. Next, place a new base plate on the cloth, and repeat the process of placing the frame and cloth, pouring the mixed bean paste, smoothing, and wrapping. That is, one base plate and one frame constitute one layer, stacking two layers in total. Finally, cover the top layer with a lid.

[0104] (5) Pressing to remove water:

[0105] The molding mold, along with the mixed bean paste inside, is pushed into the pneumatic skid. It is first pressed at 0.2 MPa for 10 minutes, then the pressure is increased to 0.4 MPa and pressed for another 5 minutes, and then the pressure is increased to 0.6 MPa and pressed for another 8 minutes to obtain the pressed cake.

[0106] (6) Steaming:

[0107] After pressing the cake, heat it at 50°C for 30 minutes, then steam it at 90°C for 40 minutes.

[0108] (7) Cooling:

[0109] Place the steamed cake under a fan to cool it until the center temperature reaches room temperature, then unmold it.

[0110] (8) Cutting:

[0111] Cut the cooled cake into strips measuring 7cm × 4cm × 1cm to obtain long strip cakes.

[0112] (9) Packaging and sterilization:

[0113] After vacuum packaging the long strip-shaped cake in aluminum foil bags, sterilize at 121℃ for 20 minutes to obtain bean-based cakes.

[0114] Example 4

[0115] The only difference between this embodiment and Example 1 is that the TG enzyme and butter are added separately; all other ingredients and steps are the same as in Example 1. That is, the steps for preparing soy-based pastries in this embodiment are as follows:

[0116] (1) Preparation of bean paste:

[0117] Add the scraps of dried tofu sheets to boiling water at 100℃, soak for 15 minutes, remove and drain, then put them into a chopper and chop into bean paste.

[0118] (2) Seasoning and flavoring:

[0119] Mix 80kg of soybean paste, 20kg of glutinous rice flour, 2kg of TG enzyme, 10kg of butter, 20kg of white sugar and 0.5kg of salt until well combined to obtain mixed soybean paste.

[0120] (3) Molding:

[0121] The molding die used consists of a frame and a base plate, both made of plastic. The frame structure is as follows: Figure 1 As shown, it consists of four side panels 1, two of which are 60cm×2mm×12cm in size, and the other two are 75cm×2mm×12cm in size; the four side panels form a square frame with a side length of 60cm, two of which are opposite each other and extend out of the frame, and the part extending out of the frame has an arc surface with an opening facing downward to form a handle 1-1; through holes 1-2 are distributed on the wall of the frame.

[0122] In use, place the base plate on the work surface, then place the frame on the base plate. Next, place a square cotton cloth inside the frame, pour the mixed bean paste into the cloth, and smooth the surface with a scraper until the bean paste fills the frame, aligning the smoothed top surface with the top edge of the frame. Then, tightly wrap the cloth to cover the smoothed top surface. Next, place a new base plate on the cloth, and repeat the process of placing the frame and cloth, pouring the mixed bean paste, smoothing, and wrapping. That is, one base plate and one frame constitute one layer, stacking two layers in total. Finally, cover the top layer with a lid.

[0123] (4) Pressing to remove water:

[0124] The molding mold, along with the mixed bean paste inside, is pushed into the pneumatic skid. It is first pressed at 0.15 MPa for 15 minutes, then the pressure is increased to 0.35 MPa and pressed for another 10 minutes, and then the pressure is increased to 0.6 MPa and pressed for another 5 minutes to obtain the pressed cake.

[0125] (5) Steaming:

[0126] The pressed cake is heated at 55℃ for 40 minutes, and then steamed at 90℃ for 40 minutes.

[0127] (6) Cooling:

[0128] Place the steamed cake under a fan to cool it until the center temperature reaches room temperature, then unmold it.

[0129] (7) Cutting:

[0130] Cut the cooled cake into strips measuring 7cm × 4cm × 1cm to obtain long strip cakes.

[0131] (8) Packaging and sterilization:

[0132] After vacuum packaging the long strip-shaped cake in aluminum foil bags, sterilize at 121℃ for 20 minutes to obtain bean-based cakes.

[0133] Comparative Example 1

[0134] The only difference between this comparative example and Example 1 is that the scraps of tofu skin are not soaked before being chopped into bean paste; all other ingredients and steps are the same as in Example 1. That is, the steps for preparing bean-based pastries in this comparative example are as follows:

[0135] (1) TG enzyme pretreatment:

[0136] Take 10 kg of butter, melt it at 50℃, then add 1 kg of sorbitan monooleate (Span-80) and stir until homogeneous to obtain an oil phase solution. Add 2 kg of TG enzyme to 4.5 kg of water, heat to 50℃, and then add it to the oil phase solution. Homogenize and emulsify to obtain a W / O promulgated emulsion. Maintain the temperature of the W / O promulgated emulsion at 50℃, add 1.75 kg of polysorbate 80 (Tween-80), mix, and then add to 70 kg of water at 50℃. Homogenize and emulsify. Then cool to 25℃, centrifuge at 4℃ to separate the precipitate, and freeze-dry the precipitate to obtain pretreated TG enzyme with an average particle size of 28.47 μm.

[0137] (2) Preparation of bean paste:

[0138] Place the scraps of dried bean curd sheets into a food processor and chop them into bean paste.

[0139] (3) Seasoning and flavoring:

[0140] Mix 80kg of bean paste, 20kg of glutinous rice flour, the pretreated TG enzyme obtained in step (1), 20kg of white sugar and 0.5kg of edible salt evenly to obtain mixed bean paste.

[0141] (4) Molding:

[0142] The molding die used consists of a frame and a base plate, both made of plastic. The frame structure is as follows: Figure 1 As shown, it consists of four side panels 1, two of which are 60cm×2mm×12cm in size, and the other two are 75cm×2mm×12cm in size; the four side panels form a square frame with a side length of 60cm, two of which are opposite each other and extend out of the frame, and the part extending out of the frame has an arc surface with an opening facing downward to form a handle 1-1; through holes 1-2 are distributed on the wall of the frame.

[0143] In use, place the base plate on the work surface, then place the frame on the base plate. Next, place a square cotton cloth inside the frame, pour the mixed bean paste into the cloth, and smooth the surface with a scraper until the bean paste fills the frame, aligning the smoothed top surface with the top edge of the frame. Then, tightly wrap the cloth to cover the smoothed top surface. Next, place a new base plate on the cloth, and repeat the process of placing the frame and cloth, pouring the mixed bean paste, smoothing, and wrapping. That is, one base plate and one frame constitute one layer, stacking two layers in total. Finally, cover the top layer with a lid.

[0144] (5) Pressing to remove water:

[0145] The molding mold, along with the mixed bean paste inside, is pushed into the pneumatic skid. It is first pressed at 0.15 MPa for 15 minutes, then the pressure is increased to 0.35 MPa and pressed for another 10 minutes, and then the pressure is increased to 0.6 MPa and pressed for another 5 minutes to obtain the pressed cake.

[0146] (6) Steaming:

[0147] The pressed cake is heated at 55℃ for 40 minutes, and then steamed at 90℃ for 40 minutes.

[0148] (7) Cooling:

[0149] Place the steamed cake under a fan to cool it until the center temperature reaches room temperature, then unmold it.

[0150] (8) Cutting:

[0151] Cut the cooled cake into strips measuring 7cm × 4cm × 1cm to obtain long strip cakes.

[0152] (9) Packaging and sterilization:

[0153] After vacuum packaging the long strip-shaped cake in aluminum foil bags, sterilize at 121℃ for 20 minutes to obtain bean-based cakes.

[0154] Test Example 1: Enzyme Activity Test of TG Enzyme

[0155] The TG enzyme without butter encapsulation was tested for its activity at 25°C and 50°C. The pretreated TG enzymes prepared in Examples 1-3 were tested for their activity at 25°C, and then at 50°C for 5 minutes before testing their activity at 50°C. Enzyme activity was determined using the oxime acid colorimetric method, i.e., using Nα-CBZ-Gln-Gly as the substrate and an L-glutamic acid-γ-monohydroxyoxime standard solution to plot a standard curve. Enzyme activity was obtained based on the absorbance values ​​of the post-hydrolysis solution and the standard curve. Results are expressed as relative enzyme activity, with the activity of the unencapsulated TG enzyme at 50°C considered as 100%. The enzyme activity test results are shown in Table 1.

[0156] Table 1 Enzyme activity before and after TG enzyme encapsulation at different temperatures

[0157]

[0158] Table 1 shows that encapsulating TG enzyme in butter effectively reduces its enzyme activity at 25℃. Furthermore, when using the smaller molecular weight Nα-CBZ-Gln-Gly as a substrate in the enzyme activity test, the activity of the butter-encapsulated TG enzyme at 25℃ will be further reduced when applied to the preparation of bean pastries from dried tofu scraps, as the substrate is a large protein molecule. In addition, according to the enzyme activity test results at 50℃ in Table 1, after placing the butter-encapsulated TG enzyme at 50℃ for 5 minutes, the butter melts and releases the TG enzyme, and the TG enzyme activity is largely restored. Therefore, using butter to encapsulate TG enzyme allows it to function well at its optimal temperature, thus not significantly affecting its effect on improving the shaping strength and elasticity of bean pastries.

[0159] Test Example 2: Physicochemical Properties and Sensory Tests of Bean-Based Pastries

[0160] The bean-based pastries prepared in Examples 1-4 and Comparative Example 1 were tested for water content, hardness, and elasticity, and sensory evaluation was conducted. The results are shown in Tables 2 and 3, respectively.

[0161] Table 2 Physicochemical properties of bean-based pastries

[0162] Water content (g / 100g) Hardness (g) Elasticity (mm) Example 1 45.8 1160 4.05 Example 2 45.2 1176 3.89 Example 3 47.0 1153 4.11 Example 4 60.3 992 3.37 Comparative Example 1 39.7 1252 2.81

[0163] Table 3 Sensory evaluation of bean-based pastries

[0164]

[0165]

[0166] As can be seen from Tables 3 and 4:

[0167] (1) In Example 1, the scraps of dried tofu sheets were soaked before being made into bean paste, while in Comparative Example 1, they were not soaked. Compared to Comparative Example 1, the bean pastry obtained in Example 1 had a finer texture. This is because soaking the scraps of dried tofu sheets helped to chop them into a finer bean paste.

[0168] (2) In Example 1, TG enzyme was embedded in butter and mixed with ingredients such as bean paste. In Example 4, TG enzyme and butter were added separately. Compared with Example 4, the bean pastry prepared in Example 1 had a lower water content, higher elasticity and hardness, and was less prone to collapsing. This is because embedding TG enzyme in butter can prevent TG enzyme from contacting bean paste protein before pressing and dehydration, thereby reducing the cross-linking of bean paste protein under the action of TG enzyme before pressing and dehydration, thus ensuring a better dehydration effect. During the heating process after pressing and dehydration to allow TG enzyme to take effect, the butter melts and penetrates into the pastry, releasing TG enzyme, which then contacts the bean paste protein and takes effect. Therefore, the embedding of butter does not have a significant impact on the effect of TG enzyme in improving the shaping strength and elasticity of bean pastry.

[0169] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0170] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing bean-based pastries using scraps of dried tofu sheets as raw material, characterized in that, Includes the following steps: (1) Soak the scraps of dried bean curd sheets and then make them into bean paste; (2) Mix the bean paste, glutinous rice flour and transglutaminase embedded in the butter to obtain mixed bean paste; the mass ratio of bean paste, glutinous rice flour and transglutaminase is 70-90:10-30:0.1-3; (3) Put the mixed bean paste into the molding mold and press it to remove water to obtain the pressed cake body; the specific process of pressing to remove water includes: pressing at 0.15-0.2MPa for 10-15min → pressing at 0.35-0.4MPa for 5-10min → pressing at 0.6-0.65MPa for 3-8min; (4) Heat the pressed cake at 50-65℃ for 20-40 minutes, then steam it at 85-100℃ for 30-50 minutes, and then cool it.

2. The method for preparing bean-based pastries as described in claim 1, characterized in that, In step (3), the forming mold includes a plate frame and a base plate. The plate frame includes a frame body and at least one handle located outside the frame body. The wall of the frame body has several through holes.

3. The method for preparing bean-based pastries as described in claim 2, characterized in that, In step (3), the process of loading the mixed bean paste into the molding mold includes the following steps: placing the frame on the base plate, placing a cloth inside the frame, pouring the mixed bean paste into the cloth, smoothing the surface so that the mixed bean paste fills the frame, and the smoothed upper surface is flush with the top of the frame, and then covering the smoothed upper surface with the cloth; in the above manner, one or more layers are stacked with one base plate and one frame as a layer, and then a cover plate is placed on the top layer.

4. The method for preparing bean-based pastries as described in claim 1, characterized in that, The encapsulation process includes the following steps: heating and melting butter, adding a lipophilic emulsifier, mixing well to obtain an oil phase solution; adding an aqueous solution of transglutaminase at a temperature of 45-65℃ to the oil phase solution, emulsifying to obtain a W / O pre-emulsion; mixing the W / O pre-emulsion with a hydrophilic emulsifier, adding it to water at a temperature of 45-65℃, emulsifying, then cooling to below 28℃, and separating the product at a temperature below 28℃.

5. The method for preparing bean-based pastries as described in claim 1, characterized in that, In step (2), sugar and salt are added during the process of mixing soybean paste, glutinous rice flour and transglutaminase.

6. The method for preparing bean-based pastries as described in claim 5, characterized in that, The mass ratio of the soybean paste, white sugar, and edible salt is 70-90:10-30:0.1-1.

7. The method for preparing bean-based pastries as described in claim 1, characterized in that, The specific process of step (1) includes the following steps: soak the scraps of tofu skin in water at 90-100℃ for 10-20 minutes, take them out and drain them, and then chop and mix them into bean paste.

8. The method for preparing bean-based pastries as described in claim 2, characterized in that, The frame is formed by four side panels of the same height, with two opposing side panels extending out of the frame.

9. The method for preparing bean-based pastries as described in claim 8, characterized in that, The portion of the side panel extending outside the frame has a downward-opening arc surface that forms the handle.

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