A method for preparing high-quality frozen dough

Abstract

The present invention provides a method for preparing high-quality frozen dough, which includes separately dissolving ι-carrageenan and antifreeze protein in phosphate buffer solution and then respectively performing cavitation jet treatment; mixing the ι-carrageenan solution after cavitation jet treatment and the antifreeze protein solution after cavitation jet treatment to obtain a first mixed solution; mixing the activated yeast solution and the first mixed solution to obtain a second mixed solution; pouring high-gluten wheat flour, water and the first mixed solution into a dough mixer, performing the first stirring, then adding the second mixed solution, and then performing the second stirring to obtain a preliminary dough; taking out the preliminary dough, standing, dividing, shaping it into small doughs, fermenting, quickly freezing and then storing frozen. The preparation method of the present invention can effectively improve the water holding capacity of the dough, can improve the survival rate of yeast at low temperature, improve the low-temperature stability of the frozen dough system, thereby effectively improving the structural quality of the frozen dough, achieving the purpose of delaying the aging of the dough, and further extending the shelf life of the dough.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and particularly relates to a method for preparing high-quality frozen dough. Background Art

[0002] With the rapid development of the flour product industry, freezing technology has been increasingly applied to dough production. Frozen dumplings, steamed buns, wontons, buns, and frozen dough used for producing bread, etc. all belong to frozen dough products, that is, frozen dough in a broad sense. They are mainly semi-finished or finished dough blanks formed by machine stirring, kneading with flour and water as the main raw materials, and then quick-freezing. In the later stage, they are thawed and cooked to produce finished products. However, with the extension of the frozen storage time, problems such as the surface of the dough cracking, the final product volume decreasing, the structure becoming rough, the taste becoming worse, and the quality of the finished product declining seriously restrict the development of frozen dough technology. Long-term research shows that the quality deterioration of frozen dough is mainly manifested as the aging of the dough, which is attributed to the formation of ice crystals and starch recrystallization, resulting in the quality deterioration of the key components of the dough. The specific manifestations are as follows: the yeast activity and gas production ability decline; the gluten network structure is damaged, weakening the gas-holding ability of the dough; the starch granule structure is damaged, and the starch crystallinity increases; the water is redistributed in the dough. Eventually, it leads to an extended dough fermentation time, a reduced bread volume, a dry and hard bread core, a rough structure, and an affected taste. Therefore, the quality deterioration of frozen dough during frozen storage is an urgent problem to be solved in the production of frozen foods.

[0003] Research at home and abroad shows that the formation and recrystallization of ice crystals in frozen dough cause the quality deterioration of the key components of the dough. Among them, the decline of yeast activity and the damage of the gluten network structure are the main influencing factors leading to the quality deterioration of the dough. At present, the improvement methods of frozen dough mainly include: the improvement of the raw materials and formulas of frozen flour products, the improvement of the freezing process, and the addition of anti-aging agents. For foods with a high starch content, additives are usually selected to delay aging, such as enzyme preparations (α-amylase), emulsifiers (lecithin, sodium stearoyl lactate (SSL), glycerol monostearate (GMS), diacetyl tartaric acid monoglyceride (DATEM)), and water retention agents (alginate salts), etc. Research shows that these different types of anti-aging agents can play a good role in delaying the aging of bread. However, most of the existing anti-aging agents are applied to the production or storage process of products such as bread and cakes, and there are few directly for the anti-freezing and anti-aging treatment of frozen dough during low-temperature frozen storage, which greatly restricts the scope of use of frozen dough.

[0004] Therefore, it is necessary to invent a method for preparing high-quality frozen dough that can effectively improve the survival rate of yeast and has good water retention, so that frozen dough can be applied to various products and effectively increase the scope of use of frozen dough. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method of high-quality frozen dough that can effectively improve the survival rate of yeast and has good water retention, so that the frozen dough can be applied to various products, effectively increasing the scope of use of the frozen dough.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A preparation method of high-quality frozen dough, comprising the following steps:

[0008] Step 1: Dissolve ι-carrageenan and antifreeze protein in phosphate buffer solution with a concentration of 0.01 mol / L and a pH value of 7.0 respectively to prepare ι-carrageenan solution and antifreeze protein solution;

[0009] Step 2: Carry out cavitation jet treatment on the ι-carrageenan solution and antifreeze protein solution in Step 1 respectively;

[0010] Step 3: Mix the ι-carrageenan solution after cavitation jet treatment in Step 2 and the antifreeze protein solution after cavitation jet treatment according to a volume ratio of 0.5 - 3.0∶1 to obtain a first mixed solution;

[0011] Step 4: Mix the activated yeast solution and the first mixed solution in Step 3 according to a volume ratio of 1∶1.0 - 3.0 at 4 - 10 °C, and then let it stand in an environment of 4 - 10 °C for 6 - 12 h to obtain a second mixed solution;

[0012] Step 5: Pour 100 parts by weight of high-gluten wheat flour, 25 - 35 parts by weight of water, and 3 - 5 parts by weight of the first mixed solution in Step 3 into a dough mixer and carry out the first stirring for 5 min. After the first stirring stops, add 10 - 20 parts by weight of the second mixed solution in Step 4 and then carry out the second stirring for 7 min to obtain a preliminary dough;

[0013] Step 6: Take out the preliminary dough in Step 5, let it stand, divide it, and shape it into small doughs for fermentation;

[0014] Step 7: Cool the small doughs after fermentation in Step 6 to room temperature, then quick-freeze and store them frozen.

[0015] Furthermore, in Step 1, the concentration of the ι-carrageenan solution is 2 - 5 g / 100 mL; the concentration of the antifreeze protein solution is 2 - 5 g / 100 mL.

[0016] Furthermore, the conditions for cavitation jet treatment of the ι-carrageenan solution in Step 2 are: cavitation pressure 0.01 MPa, temperature 20 °C, and treatment time 4 - 10 min.

[0017] Further, the conditions for the cavitation jet treatment of the antifreeze protein solution in step 2 are as follows: the cavitation pressure is 0.01 Mpa, the temperature is 4-10°C, and the treatment time is 2-10 min.

[0018] Further, the mixing in steps 3 and 4 is carried out by stirring with a magnetic stirrer at a rotation speed of 800 r / min for 10-20 min.

[0019] Further, the activated yeast solution in step 4 is prepared by the following method: dry yeast powder and distilled water are mixed at a mass-to-volume ratio of 1:5, and then placed under constant temperature and humidity conditions at a temperature of 25°C and a relative humidity of 80% for 30 min to obtain the activated yeast solution.

[0020] Further, in step 5, the specific operation of the first stirring is as follows: first stir at a rotation speed of 60-70 r / min for 3 min, and then stir at a rotation speed of 100-120 r / min for 2 min; the specific operation of the second stirring is as follows: first stir at a rotation speed of 60-70 r / min for 2 min, and then stir at a rotation speed of 100-120 r / min for 5 min.

[0021] Further, the specific operation of step 6 is as follows: take out the primary dough from step 5 and let it stand for 10 min, roll the standing primary dough with a dough sheeter 5 times, then divide and shape it into small dough pieces, and then place them in a proofing box at a temperature of 35°C and a relative humidity of 85% for 30 min.

[0022] Further, the specific operation of step 7 is as follows: cool the small dough pieces fermented in step 6 to room temperature, then place them in a -40°C environment for quick freezing for 30 min, and then store them in a -18°C environment.

[0023] The beneficial effects of the above technical solutions are as follows: (1) In this application, ι-carrageenan and antifreeze protein are creatively selected, and the cavitation jet treatment is used to further promote the exertion of their efficacy. Then, the first mixed solution and the activated yeast solution are mixed into the second mixed solution and added to the dough, enhancing the activity of yeast cells, increasing the stability of their cell membranes, enhancing the gas production ability of yeast, and improving the survival rate of yeast during low-temperature storage. Multiple means are used in combination to prepare a high-quality dough with better softness, higher water retention (low water loss rate), high yeast activity in the dough, and good maximum expansion height of the frozen dough compared with the prior art; (2) In this invention, ι-carrageenan with more hydrophilic sulfate groups and hydroxyl groups compared with other carrageenans, forming a gel network with a larger space, better elasticity and viscosity, is creatively selected. Its ability to wrap water molecules is used to improve the water holding capacity of the dough, inhibit the recrystallization of starch, reduce the damage of ice crystals to the gluten protein network structure and yeast cells during frozen storage, and improve the low-temperature stability of the frozen dough system, thereby achieving the purpose of slowing down the aging of the frozen dough. The antifreeze protein has good effects of inhibiting ice crystal recrystallization and protecting cell membranes, effectively improving the survival rate of yeast during freezing. The introduction of cavitation jet treatment further effectively promotes the functional effects of ι-carrageenan and antifreeze protein. Description of the Drawings

[0024] Figure 1 For the hardness of the frozen doughs of Examples 1 to 3 and Comparative Examples 1 to 6 after 3 weeks of frozen storage;

[0025] Figure 2 For the water loss rate of the frozen doughs of Examples 1 to 3 and Comparative Examples 1 to 6 after 3 weeks of frozen storage;

[0026] Figure 3 For the maximum height of the gas release curve of the frozen doughs of Examples 1 to 3 and Comparative Examples 1 to 6 after 3 weeks of frozen storage;

[0027] Figure 4 For the maximum expansion height of the frozen doughs of Examples 1 to 3 and Comparative Examples 1 to 6 after 3 weeks of frozen storage;

[0028] Figure 5 For the yeast cell survival rate of the frozen doughs of Examples 1 to 3 and Comparative Examples 1 to 6 after 3 weeks of frozen storage.

[0029] Figures 1 to 5 In the figure: A is Comparative Example 1; B is Comparative Example 2; C is Comparative Example 3; D is Comparative Example 4; E is Comparative Example 5; F is Comparative Example 6; G is Example 1; H is Example 2; I is Example 3; Different lowercase letters in the figure indicate significant differences (P < 0.05). Detailed Description of the Invention

[0030] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings as follows:

[0031] A method for preparing a high-quality frozen dough provided by the present invention includes the following steps:

[0032] Step 1: Dissolve ι-carrageenan and antifreeze protein in a phosphate buffer solution with a concentration of 0.01 mol / L and a pH value of 7.0 respectively to prepare an ι-carrageenan solution and an antifreeze protein solution;

[0033] Step 2: Carry out cavitation jet treatment on the ι-carrageenan solution and the antifreeze protein solution in Step 1 respectively;

[0034] Step 3: Mix the ι-carrageenan solution after cavitation jet treatment in Step 2 and the antifreeze protein solution after cavitation jet treatment in a volume ratio of 0.5 - 3.0∶1 to obtain a first mixed solution;

[0035] Step 4: Mix the activated yeast solution and the first mixed solution in Step 3 in a volume ratio of 1∶1.0 - 3.0 at 4 - 10°C, and then let it stand in an environment of 4 - 10°C for 6 - 12 h to obtain a second mixed solution;

[0036] Step 5: Pour 100 parts by weight of high-gluten wheat flour, 25 - 35 parts by weight of water, and 3 - 5 parts by weight of the first mixed solution in Step 3 into a dough mixer and carry out the first stirring for 5 min. After the first stirring stops, add 10 - 20 parts by weight of the second mixed solution in Step 4 and then carry out the second stirring for 7 min to obtain a preliminary dough;

[0037] Step 6: Take out the preliminary dough in Step 5, let it stand, divide it, and shape it into small doughs for fermentation;

[0038] Step 7: Cool the small doughs after fermentation in Step 6 to room temperature, then quick-freeze and store them frozen.

[0039] Specifically, the working principle of the present invention is as follows:

[0040] At present, the use of hydrophilic colloids to prevent the aging of starchy foods has been widely applied in the food field. Carrageenans can be classified into different types according to the number and position of sulfate ester groups, mainly including κ-(24%), ι-(32%), and λ-(38%) carrageenans. Existing research shows that sulfate ester groups have strong hydrophilicity. Therefore, people in the industry have always believed that the higher the content of sulfate ester groups in carrageenan, the stronger its hydrophilicity and the better its water retention when used in products. However, the inventors of this application unexpectedly found in their research that although the sulfate ester group content of ι-carrageenan is lower than that of λ-carrageenan, ι-carrageenan actually exhibits better water retention during specific use. This may be because the position of the ether bond in the structure of λ-carrageenan prevents it from forming a gel network structure to bind water molecules, while ι-carrageenan forms a gel network with a larger space, better elasticity and viscosity, and strong ability to wrap water molecules, thus showing good water retention. It may be that the hydrophilic hydroxyl groups rich on the surface of ι-carrageenan interact with each other through hydrogen bonds in the presence of water molecules, reducing the chance of collision between starch molecules during the aging process, increasing the content of water molecules around starch molecules, making the system become a viscous liquid, effectively inhibiting the formation of the double helix structure during the aging of amylose, and playing a role in inhibiting starch retrogradation. However, existing research shows that the anti-aging effect of a single hydrophilic colloid is far less than that of a compound anti-aging agent. Because the action mechanisms of different types of anti-aging agents are different, after compounding, they interact with each other, can improve the anti-aging effect from different levels, and play a synergistic effect. In addition, when the addition amount of hydrophilic colloid is relatively large, it will have a negative effect on inhibiting starch aging, showing certain limitations in anti-aging.

[0041] Antifreeze proteins (AFPs) are a new type of additive that was approved for use in frozen foods in China in 2006. AFPs are a class of special proteins that can inhibit ice crystal growth, capable of changing the growth morphology of ice crystals and inhibiting ice crystal recrystallization. Antifreeze proteins can easily bind to water molecules in solution, reducing the content of free water and increasing the viscosity of the solution, and can slow down the growth process of ice nuclei, making the formed ice crystals finer, so as to achieve the purpose of protecting cells, while other protectants only play a role of protective layer. Although there have been many studies on AFPs in China, most of them focus on bread production, and the research on applying them to traditional Chinese steamed and frozen noodle products is relatively less.

[0042] Cavitation jet treatment has characteristics such as high heat, high pressure, strong shear force, and strong shock waves. Cavitation jet technology is to make solvent molecules in the cavitation chamber undergo cavitation, high-speed shear, and violent vibration, promoting the generation of cavitation bubbles. These cavitation bubbles expand rapidly and then instantaneously collapse, generating intense shock waves, resulting in strong impact between liquid particles, degrading macromolecular polymers, opening the dense structure, exposing a large number of functional groups, and effectively reducing the molecular particle size.

[0043] The ι-carrageenan selected in this application has more hydrophilic sulfate groups and hydroxyl groups compared with other carrageenans, has a strong ability to wrap water molecules, can improve the water holding capacity of dough, inhibit the recrystallization of starch, reduce the damage of ice crystals to the gluten protein network structure and yeast cells during the freezing and storage process, improve the low-temperature stability of the frozen dough system, and thus achieve the purpose of slowing down the aging of the frozen dough; the antifreeze protein has good effects such as inhibiting ice crystal recrystallization and protecting cell membranes, effectively improving the survival rate of yeast during the freezing process.

[0044] After the ι-carrageenan liquid is treated by cavitation jet, the interfacial structure changes, the adsorption ability of the colloid at the interface and the effect of interaction are enhanced, and at the same time, the particle size of the ι-carrageenan liquid also changes, which increases its stability. The nano-scale ι-carrageenan exposes more glycosidic bonds and hydroxyl hydrophilic groups, further improving the water holding capacity of ι-carrageenan in dough and promoting the effective exertion of its functional properties - enabling ι-carrageenan to more effectively fix the water in the dough, slow down the formation of ice crystals in the dough, and prevent ice crystals from damaging yeast cells; while the antifreeze protein is processed into nano-scale antifreeze protein by cavitation jet, and the protein molecules depolymerize into subunits, so that the hydrophilic groups, hydrophobic groups and polar groups inside the globulin are exposed. The exposure of these groups increases the binding ability of the protein to water, thereby improving the solubility of the protein molecules. The nano-scale antifreeze protein can also effectively soften the gluten network structure, further reduce the damage of ice crystals to the gluten protein network structure, inhibit the recrystallization of starch, protect the dough network structure, and can also effectively reduce the amount of ice crystals formed in yeast cells, significantly improving the survival rate and fermentation activity of yeast; mixing the first mixture (ι-carrageenan-antifreeze protein water retention / antifreeze agent) with the activated yeast liquid to form a second mixture (high-activity dry yeast-ι-carrageenan-antifreeze protein suspension) and then adding it to the dough can enhance cell activity, increase cell membrane stability, play an antifreeze role, enhance the gas production ability of yeast, improve the survival rate of yeast during low-temperature storage, and thus effectively improve the structural quality of the frozen dough and achieve the purpose of delaying the aging of the dough, further extending the shelf life of the dough.

[0045] All in all, in this application, by creatively selecting ι-carrageenan and antifreeze protein and using cavitation jet treatment to further promote the exertion of their effects, then mixing the first mixture with the activated yeast liquid to form a second mixture and adding it to the dough, enhancing the cell activity of yeast, increasing its cell membrane stability, enhancing the gas production ability of yeast, improving the survival rate of yeast during low-temperature storage, and using multiple means in combination to prepare a high-quality dough that is softer after thawing, has higher water holding capacity (low water loss rate), high yeast activity in the dough, and good maximum expansion height of the frozen dough compared with the prior art.

[0046] As can be seen from the above description, the present invention has the following beneficial effects: (1) In this application, ι-carrageenan and antifreeze protein are creatively selected, and the cavitation jet treatment is used to further promote the exertion of their efficacy. Then, the first mixed solution is mixed with the activated yeast solution to form a second mixed solution and then added to the dough, which enhances the activity of yeast cells, increases the stability of their cell membranes, enhances the gas production ability of yeast, improves the survival rate of yeast during low-temperature storage, and multiple means are used in combination to prepare a high-quality dough that is softer after thawing, has higher water retention (low water loss rate), has high yeast activity in the dough, and has a good maximum expansion height of the frozen dough compared with the prior art; (2) The present invention creatively selects ι-carrageenan with more hydrophilic sulfate ester groups and hydroxyl groups relative to other carrageenans, forms a gel network with a larger space, and has good elasticity and viscosity. The water-holding capacity of the dough is improved by its ability to wrap water molecules, the recrystallization of starch is inhibited, the damage of ice crystals to the gluten protein network structure and yeast cells during frozen storage is reduced, and the low-temperature stability of the frozen dough system is improved, so as to achieve the purpose of slowing down the aging of the frozen dough. Antifreeze protein has good effects such as inhibiting ice crystal recrystallization and protecting cell membranes, effectively improving the survival rate of yeast during freezing; and the introduction of cavitation jet treatment further effectively promotes the functional effects of ι-carrageenan and antifreeze protein.

[0047] Further, in step 1, the concentration of the ι-carrageenan solution is 2 - 5 g / 100 mL; the concentration of the antifreeze protein solution is 2 - 5 g / 100 mL.

[0048] As can be seen from the above description, when the ι-carrageenan solution and the antifreeze protein solution are controlled at the above concentrations, the best anti-aging effect is obtained.

[0049] Further, the conditions for the cavitation jet treatment of the ι-carrageenan solution in step 2 are: cavitation pressure 0.01 MPa, temperature 20 °C, and treatment time 4 - 10 min.

[0050] As can be seen from the above description, under the above cavitation jet treatment conditions, the interfacial structure of the ι-carrageenan solution changes, the adsorption ability of the colloid at the interface and the effect of interaction are enhanced, and at the same time, the particle size of the ι-carrageenan liquid also changes and becomes nanoscale. The component distribution of the ι-carrageenan solution is uniform, which increases its stability and thus effectively exerts the functional properties of ι-carrageenan.

[0051] Further, the conditions for the cavitation jet treatment of the antifreeze protein solution in step 2 are: cavitation pressure 0.01 Mpa, temperature 4 - 10 °C, and treatment time 2 - 10 min.

[0052] As described above, under the cavitation jet treatment conditions, the antifreeze protein solution becomes a nano-scale solution with a more uniform component distribution. The protein molecules depolymerize into subunits, exposing the hydrophilic, hydrophobic, and polar groups inside the globulin. The exposure of these groups increases the binding ability of the protein to water, thereby improving the solubility of the protein molecules and helping to further promote the exertion of their functional properties.

[0053] Further, the mixing in steps 3 and 4 is carried out with a magnetic stirrer at a rotation speed of 800 r / min for 10 - 20 min.

[0054] As described above, by mixing using the above method, the mixing between the solutions is more sufficient and efficient.

[0055] Further, the activated yeast solution in step 4 is prepared by the following method: Mix dry yeast powder and distilled water at a mass-to-volume ratio of 1:5, and then place it under constant temperature and humidity conditions at 25°C and 80% relative humidity for activation for 30 min to obtain the activated yeast solution.

[0056] As described above, only by activating the yeast first and then mixing it with the first mixed solution can the amount of ice crystals formed inside the yeast cells be effectively reduced, significantly improving the survival rate and fermentation activity of the yeast in the frozen dough, and further improving the quality of the frozen dough.

[0057] Further, in step 5, the specific operation of the first stirring is as follows: First, stir at a rotation speed of 60 - 70 r / min for 3 min, and then stir at a rotation speed of 100 - 120 r / min for 2 min; the specific operation of the second stirring is: First, stir at a rotation speed of 60 - 70 r / min for 2 min, and then stir at a rotation speed of 100 - 120 r / min for 5 min.

[0058] As described above, controlling different speeds and times according to the added raw materials during the above dough preparation process helps the gluten network of the dough to be fully formed in a shorter time, helps to further lock in the moisture of the dough, and lays a foundation for providing high-quality frozen dough later.

[0059] Further, the specific operation of step 6 is as follows: Take out the preliminary dough from step 5 and let it stand for 10 min, roll the standing preliminary dough with a dough sheeter 5 times, then divide and shape it into small doughs, and then place them in a proofing box at 35°C and 85% relative humidity for fermentation for 30 min.

[0060] Further, the specific operation of step 7 is as follows: Cool the small doughs after fermentation in step 6 to room temperature, then place them in a -40°C environment for quick freezing for 30 min and then store them in a -18°C environment.

[0061] As described above, the above-mentioned dough is first rapidly frozen at -40°C, which is beneficial to quickly reducing the central temperature of the dough to -18°C and avoiding severe local freeze-thaw.

[0062] The following are several more preferred embodiments or application examples to help those skilled in the art better understand the technical content of the present invention and the technical contributions made by the present invention compared with the prior art. Example 1

[0063] Step 1: Dissolve ι-carrageenan and antifreeze protein in a phosphate buffer solution with a concentration of 0.01 mol / L and a pH value of 7.0 respectively, and stir thoroughly until completely dissolved to prepare an ι-carrageenan solution with a concentration of 5 g / 100 mL and an antifreeze protein solution with a concentration of 5 g / 100 mL;

[0064] Step 2: Subject the ι-carrageenan solution in Step 1 to cavitation jet treatment for 10 min under the conditions of a cavitation pressure of 0.01 MPa and a temperature of 20°C using a cavitation jet machine; subject the antifreeze protein solution in Step 1 to cavitation jet treatment for 10 min under the conditions of a cavitation pressure of 0.01 MPa and a temperature of 10°C using a cavitation jet machine;

[0065] Step 3: Mix the ι-carrageenan solution after cavitation jet treatment in Step 2 and the antifreeze protein solution after cavitation jet treatment at a volume ratio of 3.0:1, and stir with a magnetic stirrer at a rotation speed of 800 r / min for 20 min to obtain a first mixed solution;

[0066] Step 4: Mix dry yeast powder and distilled water at a mass-to-volume ratio of 1:5, and then activate it for 30 min under the conditions of a constant temperature of 25°C and a relative humidity of 80% to obtain an activated yeast solution; mix the activated yeast solution and the first mixed solution in Step 3 at a volume ratio of 1:3.0, stir with a magnetic stirrer at a rotation speed of 800 r / min for 20 min at 10°C, and then let it stand in a 10°C environment for 12 h to obtain a second mixed solution;

[0067] Step 5: Use the direct method to make dough. Pour 100 g of high-gluten wheat flour, 25 g of water, and 3.33 g of the first mixed solution in Step 3 into a dough mixer, and perform the first stirring for 5 min (first stir at a low speed of 70 r / min for 3 min, and then stir at a high speed of 120 r / min for 2 min). After the first stirring stops, add 20 g of the second mixed solution in Step 4, and then perform the second stirring for 7 min (first stir at a low speed of 70 r / min for 2 min, and then stir at a high speed of 120 r / min for 5 min) to obtain a preliminary dough;

[0068] Step 6: Take out the preliminary dough from Step 5 and let it stand for 10 min. Press the well - stood preliminary dough 5 times with a dough sheeter (each time pressing it into a sheet with a thickness of 5 mm), then divide it into 30 - g portions and shape them into small dough balls, and then place them in a proofing box at a temperature of 35 °C and a relative humidity of 85% for fermentation for 30 min;

[0069] Step 7: Cool the small dough balls fermented in Step 6 to room temperature, then quick - freeze them in an environment of - 40 °C for 30 min and then store them frozen in an environment of - 18 °C. Example 2

[0070] Step 1: Dissolve ι - carrageenan and antifreeze protein separately in a phosphate - buffered solution with a concentration of 0.01 mol / L and a pH value of 7.0, and stir well until completely dissolved to prepare an ι - carrageenan solution with a concentration of 2 g / 100 mL and an antifreeze protein solution with a concentration of 2 g / 100 mL;

[0071] Step 2: Subject the ι - carrageenan solution from Step 1 to cavitation jet treatment for 4 min with a cavitation jet machine under the conditions of a cavitation pressure of 0.01 MPa and a temperature of 20 °C; subject the antifreeze protein solution from Step 1 to cavitation jet treatment for 2 min with a cavitation jet machine under the conditions of a cavitation pressure of 0.01 MPa and a temperature of 4 °C;

[0072] Step 3: Mix the ι - carrageenan solution and the antifreeze protein solution after cavitation jet treatment in Step 2 in a volume ratio of 0.5∶1 and stir with a magnetic stirrer at a rotation speed of 800 r / min for 10 min to obtain a first mixed solution;

[0073] Step 4: Mix dry yeast powder and distilled water in a mass - to - volume ratio of 1∶5, then activate it under the conditions of a constant temperature of 25 °C and a relative humidity of 80% for 30 min to obtain an activated yeast solution; mix the activated yeast solution and the first mixed solution from Step 3 in a volume ratio of 1∶1.0 and stir with a magnetic stirrer at a rotation speed of 800 r / min for 10 min at 4 °C, and then let it stand in a 4 °C environment for 6 h to obtain a second mixed solution;

[0074] Step 5: Pour 100 g of high - gluten wheat flour, 35 g of water and 5 g of the first mixed solution from Step 3 into a dough mixer and conduct the first stirring for 5 min (first stir at a low speed of 60 r / min for 3 min, and then stir at a high speed of 100 r / min for 2 min). After the first stirring stops, add 10 g of the second mixed solution from Step 4 and then conduct the second stirring for 7 min (first stir at a low speed of 60 r / min for 2 min, and then stir at a high speed of 100 r / min for 5 min) to obtain a preliminary dough;

[0075] Step 6: Take out the initial dough from Step 5 and let it stand for 10 min. Roll the well - stood initial dough 5 times with a dough sheeter (each time rolled into a sheet with a thickness of 5 mm), then divide it into 30 - g portions and shape them into small dough balls. Then place them in a proofing box at a temperature of 35°C and a relative humidity of 85% for 30 min of fermentation;

[0076] Step 7: Cool the small dough balls after fermentation in Step 6 to room temperature, then quick - freeze them in an environment of - 40°C for 30 min and then store them frozen in an environment of - 18°C. Example 3

[0077] Step 1: Dissolve ι - carrageenan and antifreeze protein separately in a phosphate - buffered solution with a concentration of 0.01 mol / L and a pH value of 7.0, and stir well until completely dissolved to prepare an ι - carrageenan solution with a concentration of 4 g / 100 mL and an antifreeze protein solution with a concentration of 4 g / 100 mL;

[0078] Step 2: Subject the ι - carrageenan solution from Step 1 to cavitation jet treatment for 7 min with a cavitation jet machine under the conditions of a cavitation pressure of 0.01 MPa and a temperature of 20°C; subject the antifreeze protein solution from Step 1 to cavitation jet treatment for 6 min with a cavitation jet machine under the conditions of a cavitation pressure of 0.01 MPa and a temperature of 8°C;

[0079] Step 3: Mix the ι - carrageenan solution after cavitation jet treatment in Step 2 and the antifreeze protein solution after cavitation jet treatment in a volume ratio of 2:1, and stir with a magnetic stirrer at a rotation speed of 800 r / min for 15 min to obtain a first mixed solution;

[0080] Step 4: Mix dry yeast powder and distilled water in a mass - to - volume ratio of 1:5, then activate it under the conditions of a constant temperature of 25°C and a relative humidity of 80% for 30 min to obtain an activated yeast solution; mix the activated yeast solution and the first mixed solution from Step 3 in a volume ratio of 1:2, stir with a magnetic stirrer at a rotation speed of 800 r / min for 15 min at 8°C, and then let it stand in an 8°C environment for 9 h to obtain a second mixed solution;

[0081] Step 5: Pour 100 g of high - gluten wheat flour, 31 g of water, and 4 g of the first mixed solution from Step 3 into a dough mixer and conduct the first stirring for 5 min (first stir at a low speed of 65 r / min for 3 min, then stir at a high speed of 110 r / min for 2 min). After the first stirring stops, add 15 g of the second mixed solution from Step 4, and then conduct the second stirring for 7 min (first stir at a low speed of 65 r / min for 2 min, then stir at a high speed of 110 r / min for 5 min) to obtain an initial dough;

[0082] Step 6: Take out the primary dough from Step 5 and let it stand for 10 min. Press the well - stood primary dough with a dough sheeter 5 times (each time pressed into a sheet with a thickness of 5 mm), then divide it into 30 - g portions and shape them into small dough balls, and then place them in a proofing box at a temperature of 35°C and a relative humidity of 85% for fermentation for 30 min;

[0083] Step 7: Cool the small dough balls after fermentation in Step 6 to room temperature, then quick - freeze them in an environment of - 40°C for 30 min and then store them frozen in an environment of - 18°C.

[0084] Comparative Example 1 - Prior Art

[0085] Other conditions are the same as in Example 1, the difference is that in Step 5, the first mixture and the second mixture are not added. Replace the first mixture used in Step 5 with an equal amount of water, and replace the 20 - g second mixture used in Step 5 with 20 g of an equivalent activated yeast solution (mix 1 g of dry yeast powder and distilled water according to a mass - volume ratio of 1:20, and then activate it for 30 min under constant temperature and humidity conditions of 25°C and a relative humidity of 80% to obtain an equivalent activated yeast solution).

[0086] Comparative Example 2

[0087] Other conditions are the same as in Example 1, the difference is that in Step 5, the second mixture is not added. Replace the 20 - g second mixture with 20 g of an equivalent activated yeast solution (mix 1 g of dry yeast powder and distilled water according to a mass - volume ratio of 1:20, and then activate it for 30 min under constant temperature and humidity conditions of 25°C and a relative humidity of 80% to obtain an equivalent activated yeast solution).

[0088] Comparative Example 3

[0089] Other conditions are the same as in Example 1, the difference is that in Step 5, the first mixture and the second mixture are not added. Replace the first mixture in Step 5 with an equal amount of the ι - carrageenan solution in Step 1 (not treated by cavitation jet), and replace the 20 - g second mixture with 20 g of an equivalent activated yeast solution (mix 1 g of dry yeast powder and distilled water according to a mass - volume ratio of 1:20, and then activate it for 30 min under constant temperature and humidity conditions of 25°C and a relative humidity of 80% to obtain an equivalent activated yeast solution).

[0090] Comparative Example 4

[0091] Other conditions are the same as in Example 1, except that in Step 5, the first mixture and the second mixture are not added. The first mixture in Step 5 is replaced with an equal amount of the antifreeze protein solution in Step 1 (not treated with cavitation jet), and 20 g of the second mixture is replaced with 20 g of an equivalent activated yeast solution (1 g of dry yeast powder and distilled water are mixed at a mass-to-volume ratio of 1:20, and then placed under constant temperature and humidity conditions of 25 °C and 80% relative humidity for activation for 30 min to obtain an equivalent activated yeast solution).

[0092] Comparative Example 5

[0093] Other conditions are the same as in Example 1, except that in Step 5, the first mixture and the second mixture are not added. The first mixture in Step 5 is replaced with an equal amount of ι-carrageenan solution treated with cavitation jet in Step 2, and 20 g of the second mixture is replaced with 20 g of an equivalent activated yeast solution (1 g of dry yeast powder and distilled water are mixed at a mass-to-volume ratio of 1:20, and then placed under constant temperature and humidity conditions of 25 °C and 80% relative humidity for activation for 30 min to obtain an equivalent activated yeast solution).

[0094] Comparative Example 6

[0095] Other conditions are the same as in Example 1, except that in Step 5, the first mixture and the second mixture are not added. The first mixture in Step 5 is replaced with an equal amount of the antifreeze protein solution treated with cavitation jet in Step 2, and 20 g of the second mixture is replaced with 20 g of an equivalent activated yeast solution (1 g of dry yeast powder and distilled water are mixed at a mass-to-volume ratio of 1:20, and then placed under constant temperature and humidity conditions of 25 °C and 80% relative humidity for activation for 30 min to obtain an equivalent activated yeast solution).

[0096] The frozen doughs prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were measured for various indicators

[0097] 1. The texture measurement parameters are

[0098] Thaw the frozen dough stored for 3 weeks, place it in a proofing box at 38 °C and 80% relative humidity for proofing for 1 h, shape it, and steam or bake it for 20 min. After cooling for 1 h, cut it into slices, and use a T-XT2i texture analyzer to measure the texture properties of the dough. The probe model is selected as P / 25, and the texture operation type is selected as TPA operation. The parameters are set as follows: pre-test speed: 1 mm / s; test speed: 0.80 mm / s; post-test speed: 0.80 mm / s; compression distance: 6 mm; interval time between two compressions: 3.00 s; touch force: 5 g. The results are shown in Figure 1 .

[0099] 2. Method for measuring the water loss rate of frozen dough

[0100] Take out 3 pieces from each group of frozen dough that has been frozen for 3 weeks, wrap them with plastic wrap, place them in a refrigerator at -18°C for frozen storage. After the freeze-thaw treatment, calculate the dough water loss rate according to the following formula: . In the formula: m1 is the mass of the dough before frozen storage of the sample / g; m2 is the mass of the dough after frozen storage of the sample / g. The results are shown in Figure 2 .

[0101] 3. Determination method for the fermentation rheological properties of frozen dough

[0102] Transfer the frozen dough after 3 weeks of frozen storage to room temperature, thaw for 2 h, place it in an F3 fermentation basket, and measure its fermentation rheology. The set conditions are: 150 g of dough, temperature 28°C, time 3 h, weight 1000 g. Record the parameters: H’m (the maximum height of the gas release curve), Hm (the maximum height of dough formation). The results are shown in Figure 3 and 4 .

[0103] 4. Determination method for yeast cell viability

[0104] The determination of yeast cell viability refers to the method of Xu et al., and the number of yeast colonies is counted by the plate counting method.

[0105] The specific steps for counting yeast colonies in the dough are as follows: Thaw the frozen dough that has been frozen for 3 weeks. Take 5 g from the central part of the thawed frozen dough, place it in 20 mL of distilled water, and homogenize at high speed for 10 s to fully mix the dough and water evenly. Take 1 mL of the dough suspension for appropriate gradient dilution, then transfer 200 μL of the diluted solution and spread it on a plate of Rose Bengal medium. Place it in an incubator at 38°C and incubate it upside down for 48 h. After taking it out, count the number of yeast colonies and calculate the yeast cell viability. The yeast cell viability of the fresh dough group is counted as 100%. The results are shown in Figure 5 .

[0106] From Figure 1 It can be seen that for the comparison of the hardness of the dough prepared by the above method after thawing after 3 weeks of frozen storage, the hardness of the frozen dough in Examples 1 to 3 is significantly lower (P < 0.05) than that of the frozen dough in Comparative Examples 1 to 6, indicating that adding the preparation method of the present invention can reduce the formation of ice crystals in the frozen dough, and the dough product after thawing is softer; from Figure 2 It can be seen that for the comparison of the water loss rate of the dough prepared by the above method after thawing after 3 weeks of frozen storage, the water loss rate of the frozen dough in Examples 1 to 3 is significantly lower (P < 0.05) than that of the frozen dough in Comparative Examples 1 to 6, indicating that for the water retention / anti-freezing agent after cavitation jet treatment, its hydrophobic groups and polar groups are effectively exposed, improving the binding ability to water molecules in the dough, thereby improving the water holding capacity of the frozen dough; from Figure 3and Figure 4 It can be seen that the maximum height and maximum expansion height of the gas release curves of the frozen doughs in Examples 1 to 3 are significantly higher (P<0.05) than those of the gas release curves of the frozen doughs in Comparative Examples 1 to 6; as Figure 5 shown, the survival rate of yeast cells in the frozen doughs in Examples 1 to 3 is significantly higher (P<0.05) than that of the frozen doughs in Comparative Examples 1 to 6, indicating that ι-carrageenan-antifreeze protein microparticles bind to the cell membrane of yeast, can enhance cell activity at low temperature, increase the stability of the cell membrane, play a role in protecting yeast cells and resisting freezing, enhance the gas production ability of yeast, and improve the survival rate of yeast cells.

[0107] In summary, the preparation method of a high-quality frozen dough provided by the present invention creatively selects ι-carrageenan and antifreeze protein and uses cavitation jet treatment to further promote the exertion of their effects. Then, the first mixed liquid and the activated yeast liquid are mixed into a second mixed liquid and then added to the dough, enhancing the activity of yeast cells, increasing the stability of their cell membranes, enhancing the gas production ability of yeast, and improving the survival rate of yeast during low-temperature storage. Multiple means are used in combination to prepare a high-quality dough that is softer after thawing, has higher water retention (low water loss rate), has high yeast activity in the dough, and has a good maximum expansion height of the frozen dough compared with the prior art; the present invention creatively selects ι-carrageenan with more hydrophilic sulfate ester groups and hydroxyl groups compared with other carrageenans, forms a gel network space with a larger size, better elasticity and viscosity, and uses its ability to wrap water molecules to improve the water holding capacity of the dough, inhibit the recrystallization of starch, reduce the damage of ice crystals to the gluten protein network structure and yeast cells during frozen storage, and improve the low-temperature stability of the frozen dough system, so as to achieve the purpose of slowing down the aging of the frozen dough. Antifreeze protein has good effects such as inhibiting ice crystal recrystallization and protecting cell membranes, effectively improving the survival rate of yeast during freezing; and the introduction of cavitation jet treatment further effectively promotes the functional effects of ι-carrageenan and antifreeze protein.

[0108] The present invention has been described by the above related embodiments and drawings. However, the above embodiments and drawings are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and equivalent arrangements included in the spirit and scope of the claims are included in the scope of the present invention.

Claims

1. A method for preparing high-quality frozen dough, characterized in that, It includes the following steps: Step 1: Dissolve ι-carrageenan and antifreeze protein in a phosphate buffer solution with a concentration of 0.01 mol / L and a pH value of 7.0 respectively to prepare an ι-carrageenan solution and an antifreeze protein solution; Step 2: Carry out cavitation jet treatment on the ι-carrageenan solution and the antifreeze protein solution obtained in Step 1 respectively; Step 3: Mix the ι-carrageenan solution after cavitation jet treatment in Step 2 and the antifreeze protein solution after cavitation jet treatment in a volume ratio of 0.5 - 3.0∶1 to obtain a first mixed solution; Step 4: Mix the activated yeast solution and the first mixed solution in Step 3 in a volume ratio of 1∶1.0 - 3.0 at 4 - 10°C, and then let it stand in an environment of 4 - 10°C for 6 - 12 h to obtain a second mixed solution; Step 5: Pour 100 parts by weight of high-gluten wheat flour, 25 - 35 parts by weight of water, and 3 - 5 parts by weight of the first mixed solution in Step 3 into a dough mixer and carry out the first stirring for 5 min. After the first stirring stops, add 10 - 20 parts by weight of the second mixed solution in Step 4 and then carry out the second stirring for 7 min to obtain a preliminary dough; Step 6: Take out the preliminary dough in Step 5, let it stand, divide it, and shape it into small doughs for fermentation; Step 7: Cool the small doughs after fermentation in Step 6 to room temperature and then quick-freeze them and store them frozen; 2. The preparation method of the high-quality frozen dough according to claim 1, wherein In Step 1, the concentration of the ι-carrageenan solution is 2 - 5 g / 100 mL; the concentration of the antifreeze protein solution is 2 - 5 g / 100 mL.

3. The preparation method of the high-quality frozen dough according to claim 1, wherein, The conditions for the cavitation jet treatment of the ι-carrageenan solution in Step 2 are: cavitation pressure 0.01 MPa, temperature 20°C, and treatment time 4 - 10 min.

4. The preparation method of the high-quality frozen dough according to claim 1, characterized in that, The conditions for the cavitation jet treatment of the antifreeze protein solution in Step 2 are: cavitation pressure 0.01 Mpa, temperature 4 - 10°C, and treatment time 2 - 10 min.

5. The preparation method of the high-quality frozen dough according to claim 1, characterized in that, The mixing in Steps 3 and 4 is carried out with a magnetic stirrer at a rotation speed of 800 r / min for 10 - 20 min.

6. The preparation method of the high-quality frozen dough according to claim 1, characterized in that, The activated yeast solution in Step 4 is prepared by the following method: Mix dry yeast powder and distilled water in a mass-volume ratio of 1∶5, and then activate it under constant temperature and humidity conditions with a temperature of 25°C and a relative humidity of 80% for 30 min to obtain the activated yeast solution.

7. The preparation method of the high-quality frozen dough according to claim 1, characterized in that, In Step 5, the specific operation of the first stirring is: First stir at a rotation speed of 60 - 70 r / min for 3 min, and then stir at a rotation speed of 100 - 120 r / min for 2 min; the specific operation of the second stirring is: First stir at a rotation speed of 60 - 70 r / min for 2 min, and then stir at a rotation speed of 100 - 120 r / min for 5 min.

8. The preparation method of the high-quality frozen dough according to claim 1, characterized in that, The specific operation of Step 6 is: Take out the preliminary dough in Step 5 and let it stand for 10 min, press the standing preliminary dough with a dough sheeter 5 times, then divide and shape it into small doughs, and then place it in a proofing box with a temperature of 35°C and a relative humidity of 85% for fermentation for 30 min.

9. The preparation method of the high-quality frozen dough according to claim 1, wherein The specific operation of Step 7 is: Cool the small doughs after fermentation in Step 6 to room temperature, then place them in an environment of -40°C for quick-freezing for 30 min and then store them frozen in an environment of -18°C.

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