Yeast improved frozen dough and preparation method thereof

Abstract

The invention relates to the field of food processing, and particularly discloses yeast improved frozen dough and a preparation method thereof. The yeast-improved frozen dough comprises the following raw materials in parts by weight: 800-1000 parts of a flour mixture, 3.2-4 parts of a yeast composition, 0.8-1 part of table salt, 4-5 parts of sugar, 400-500 parts of distilled water and 5-6.25 parts of a freezing improver, and the yeast composition comprises selenium-enriched yeast, silver carp zymolyte, calcium chloride and short-cluster-shaped maltodextrin in a mass ratio of 1: (0.4-0.8): (0.1-0.2): (0.3-0.5). The frozen dough has the advantages that the survival rate and activity of yeast can be improved, the gluten protein structure is increased, the specific volume and texture characteristics of flour products are improved, and the taste is improved.

Description

Technical Field

[0001] The present application relates to the technical field of food processing, and more specifically, to a yeast-modified frozen dough and a preparation method thereof. Background Art

[0002] The fermentation power of yeast in dough is a decisive factor in the quality of fermented dough. When the fermentation power of yeast in dough is insufficient, the volume and specific volume of the final product such as bread or steamed bread are small, the hardness is large, the color is darker, and the sensory quality is poor. Especially for frozen dough, the ice crystals formed during the freezing process will damage the yeast cells, causing them to lose vitality or even die, and the gas production capacity will be reduced, which will seriously affect the proofing of the frozen dough and the quality of the final product. Therefore, how to improve the problem of low yeast fermentation power in frozen dough is a technical problem that urgently needs to be solved in the production of frozen dough.

[0003] In order to reduce the impact of frozen storage on the deterioration of frozen dough processing properties and improve the baking quality of whole wheat bread, people have begun to turn their attention to the development of composite improvers including enzyme preparations and hydrophilic colloids to control the negative effects of frozen dough through food additives.

[0004] In the prior art, the Chinese invention patent with application number CN2022105626069 discloses a composite frozen dough improver for whole wheat bread and its application. The composite frozen dough improver for whole wheat bread includes xanthan gum, lipase and xylanase; the mass ratio of the three is 3.1:0.25:0.12. The composite improver can effectively improve the processing ability of frozen dough, resist the adverse effects of freeze-thaw, improve the specific volume of bread, and reduce the hardness and chewiness of whole wheat bread.

[0005] In the above-mentioned related technologies, lipase and xylanase are used, which can reduce the damage to the gluten network structure by reducing ice crystals. They only involve physical protection and do not have much improvement effect on the cell membrane stability of yeast and the antioxidant capacity in cells. Therefore, the effect is often not good. Summary of the invention

[0006] In order to improve the maintenance of yeast activity and improve the quality of frozen dough, the present application provides a yeast-modified frozen dough and a preparation method thereof.

[0007] In the first aspect, the present application provides a yeast-modified frozen dough, which adopts the following technical solution: A yeast-modified frozen dough comprises the following raw materials in parts by weight: 800-1000 parts of flour mixture, 3.2-4 parts of yeast composition, 0.8-1 part of salt, 4-5 parts of sugar, 400-500 parts of distilled water and 5-6.25 parts of freezing improver, wherein the yeast composition comprises selenium-enriched yeast, silver carp enzymolysate, calcium chloride and short-cluster maltodextrin in a mass ratio of 1:0.4-0.8:0.1-0.2:0.3-0.5.

[0008] By adopting the above technical scheme, organic selenium is enriched in yeast, which can improve the stability of cell membrane and the antioxidant capacity in cells. Selenium is an important trace element and can participate in the formation of some antioxidant enzymes, thereby helping to eliminate peroxides in cells and protect cell membranes from oxidative damage, thereby improving the frost resistance of yeast. Silver carp hydrolysate can promote the expression of fatty acids, glycerol, and amino acids in yeast cells and ribosome anabolism, and can also promote the upregulation of fatty acid synthesis-related genes such as LEO2 and LEO, which is beneficial to the accumulation of unsaturated fatty acids in cells and increase cell membrane fluidity. The upregulation of genes related to the anabolism of glycerol, phenylalanine, tyrosine, tryptophan, histidine, arginine and lysine and the downregulation of genes related to the catabolism promotes the expression of glycerol mixed with these amino acids to exert its antifreeze effect, thereby improving the sensory quality of dough after freezing and thawing, and increasing 2,3-butanediol, 3-methylthiopropanol, phenylethyl alcohol, isopentanol, 3- The increase of aromatic substances such as hydroxy-2-butanone does not produce fishy smell and improves the aroma characteristics; the appropriate addition of calcium ions can effectively enhance the growth and metabolic capacity of yeast, reduce dependence on intracellular glycerol of yeast, significantly enhance the antioxidant capacity of yeast, and reduce oxidative damage. At the same time, yeast may increase mitochondrial respiratory metabolism, thereby providing yeast with more ability to face freezing. Increased mitochondrial respiration can increase the temperature inside the cell, thereby improving the antifreeze ability of yeast; short-cluster maltodextrin effectively reduces the loss of bound water in the dough, delays the deterioration of the protein network structure during frozen storage, significantly reduces the exposure of hydrophobic amino acid residues, increases the surface hydrophilicity of gluten protein after refrigeration, reduces its hydrophobicity, and further improves the stability of the frozen dough system. In addition, short-cluster maltodextrin effectively delays the breakage of disulfide bonds and reduces the decrease in the elastic modulus of the dough, so that the gluten network of the dough remains relatively compact and continuous after cyclic freezing. The short cluster structure can form more hydrogen bonds with water molecules, and based on the steric hindrance effect, it can more effectively weaken the hydrogen bonding between protein and water, inhibit the unfolding of α-helix, and alleviate the cold denaturation of protein. It enhances lipid metabolism, regulates amino acid metabolism and energy metabolism, and makes the physiological state of yeast more inclined to frozen semi-dry yeast without ice crystal stress, making the ultrastructure of yeast relatively intact, enhancing the integrity and fluidity of cell membrane, and reducing the damage caused by ice crystal recrystallization. In addition, short-cluster maltodextrin can promote the movement of phospholipid molecules at low temperatures and enhance the stability of phospholipids when experiencing temperature changes. The stability of the bilayer interacts with the ice-water molecules around the yeast to create a micro-water environment, reduce ice crystal stress, change the yeast's intracellular metabolic pattern and cell membrane physiological characteristics, maintain yeast cell membrane homeostasis during refrigeration and thawing, thereby increasing yeast survival rate and yeast activity and fermentation ability after thawing. Therefore, by improving the physiological characteristics and intracellular metabolic pattern of yeast cells, starting from yeast cells, the frost resistance of yeast cells is more prominently improved, the freeze-thaw survival rate is increased, the dough's gas production and gas retention are improved, and the quality of pasta products is increased.

[0009] Optionally, the preparation method of the selenium-enriched yeast is as follows: after activating the yeast, inoculate it into YEPD liquid culture medium at a rate of 10%, culture it for 5-6 hours, add 20-25 μg / mL sodium selenite solution, culture it at 28-30°C for 10-12 hours, seal it, culture it at 28-30°C for 46-48 hours, centrifuge it, and wash it.

[0010] By adopting the above technical scheme, yeast has a strong ability to bio-accumulate and convert inorganic selenium during the cultivation process, converting inorganic selenium into organic selenium. Moreover, after adding sodium selenite and sealing, yeast ferments glucose to produce ethanol and carbon dioxide under anaerobic conditions, thereby generating a certain pressure in the sealed container, thereby increasing the yeast's ability to enrich selenium, enabling the yeast to enrich more selenium, thereby better improving the yeast's antifreeze property.

[0011] Optionally, the preparation method of the silver carp enzymatic hydrolysate is as follows: the silver carp meat is crushed and dispersed in distilled water at a solid-liquid ratio of 1:5-6, and 2.5-3% of the weight of the silver carp meat is added with a composite protease at 50-55°C and pH 6-6.5, and enzymatic hydrolysis is performed for 30-50 minutes, and the enzyme is inactivated at 90-100°C, cooled, centrifuged, the supernatant is collected, and freeze-dried.

[0012] By adopting the above technical scheme, the silver carp meat is enzymatically hydrolyzed by a composite protease, which contains rich free amino acids, of which the content of charged amino acids and hydrophilic amino acids is 68%, which is related to the ice crystal binding ability and low-temperature protection activity of antifreeze protein, can increase the specific volume of the dough, and maintain the stability of the dough gluten structure.

[0013] Optionally, the freezing improver includes sesbania gum, fish collagen peptide and antifreeze polysaccharide in a mass ratio of 1:0.3-0.6:0.2-0.5.

[0014] By adopting the above technical scheme, sesbania gum is a polysaccharide macromolecular substance, which exists in the inner embryo of sesbania seeds, and its main components are D-galactose and D-mannose. At high temperature, sesbania gum can be dispersed in water to form a viscous sol solution with high viscosity, and has a strong affinity and water holding capacity for water, and can combine with gluten and bound water to form a hydrophilic complex, reduce the water loss of flour products during the freeze-thaw process, protect the freeze-thaw dough from free water loss during the freeze-thaw cycle, reduce the degree of damage to gluten protein by ice crystals, keep the internal structure of gluten protein in a hydrated state, and promote the gluten protein network. The structure is stable and continuous, thereby optimizing the dough fermentation characteristics and improving product quality; sesbania gum can further increase the particle size of gluten protein through cross-linking aggregation, and its own strong viscosity can produce spatial distance for binding to gluten protein, thereby increasing the hydrophobicity of the gluten protein surface, hindering the breakage of disulfide bonds during the freeze-thaw cycle to form free thiol groups, promoting gluten protein aggregation and inhibiting gluten protein depolymerization, thereby reducing the damage to gluten protein, and can also regulate the water environment, weaken the influence of ice crystals on the gluten protein structure, improve the viscoelasticity of gluten protein, and increase the mechanical strength. Fish collagen peptides have good antifreeze protection effects on yeast cells and frozen dough gluten structure during freeze-thaw cycle treatment, because fish collagen peptides can bind to the surface of ice crystals through hydrophobic interactions of hydroxyl agents, reduce the growth of ice crystals, prevent cell membrane protein denaturation, and show good microbial antifreeze protection activity. They can also modify ice crystals and inhibit recrystallization, making the ice crystals generated during dough freezing small and relatively uniform, slowing down the damage to gluten structure caused by freeze-thaw cycles, slowing down the decline in gluten content, and forming a denser gluten network in dough through hydrogen bonds, limiting water loss and protecting gluten structure. Antifreeze polysaccharides are hydrophilic and high molecular weight, and can form a protective film in dough, reduce water loss during freezing, maintain dough humidity, inhibit the formation and growth of ice crystals, reduce ice crystal damage to dough and yeast, enhance the stability of gluten protein, and reduce the depolymerization and denaturation of gluten protein during freeze-thaw cycles.

[0015] Optionally, the antifreeze polysaccharide is okra polysaccharide.

[0016] By adopting the above technical scheme, okra polysaccharide can enhance the storage stability of frozen dough, improve the quality of frozen dough, increase the water absorption rate and viscoelasticity of dough, prolong the stability time of dough, enhance the gluten strength of dough, and improve the air holding capacity of dough. During frozen storage, it can slow down the rate of decrease of dough viscoelasticity, improve the quality of frozen dough by affecting the water distribution in dough and the non-covalent bond between molecules, reduce the freezable water content in dough, shorten the relaxation time of dough, and reduce the free water content at the same time, and enhance the water holding capacity of gluten protein system. It promotes the increase of α-helix and -fold structure content in gluten protein, and further speculates that okra polysaccharide can interact with gluten protein through non-covalent bonds, thereby strengthening the strength of gluten protein network structure; in addition, okra polysaccharide significantly slows down the migration of strongly bound water and water loss during frozen storage, and alleviates the formation and recrystallization of large ice crystals during freezing, thereby protecting yeast and gluten protein and improving the quality of frozen dough.

[0017] Optionally, papain is further added to the freezing improver, and the mass ratio of papain to sesbania gum is 0.1-0.3:1.

[0018] By adopting the above technical scheme, papain has the characteristics of high enzyme activity, good thermal stability, natural safety, etc., and can be used in pasta products to make the dough have good plasticity and extensibility. In addition, papain lightly enzymatically hydrolyzes gluten protein, which is conducive to reducing the amount of sesbania gum and antifreeze polysaccharides added as gluten enhancers and reducing the impact on taste.

[0019] Optionally, the flour mixture comprises wheat flour and okra straw insoluble dietary fiber in a mass ratio of 1:0.08-0.1.

[0020] By adopting the above technical scheme, because the gluten network in the dough will also be destroyed during refrigeration, the ductility of the dough will decrease, thereby reducing the air holding capacity of the dough. The insoluble dietary fiber from okra straw is extracted from the okra straw and added to the dough. It can increase the bound water content in the dough, reduce the free water content, and make the water more tightly combined with the dough. The water holding capacity of the dough is improved, the elasticity and cohesion are increased, the texture is better, the yeast activity and the overall microstructure are improved, and the insoluble dietary fiber from okra straw can protect the secondary structure of gluten protein and increase the structural stability of gluten protein.

[0021] In a second aspect, the present application provides a method for preparing yeast-improved frozen dough, which adopts the following technical scheme: A method for preparing yeast-improved frozen dough, comprising the following steps: The wheat flour and the insoluble dietary fiber of okra straw are mixed to prepare a flour mixture. Dissolve the yeast composition in distilled water and activate for 15-20 minutes; Dissolve salt, sugar and freezing improver in the remaining distilled water, add the flour mixture and the activated yeast composition, knead the dough, and divide it into a plurality of small doughs of (30-50) g ​​each to prepare dough; The dough was proofed at 35-38° C. and 70-75% relative humidity for 20-30 minutes, then frozen at -(18-20)° C. for 18-20 hours, and then thawed at 4-6° C. for 6 hours, which was one cycle. The freeze-thaw cycle was repeated 6 times to obtain frozen dough.

[0022] By adopting the above technical scheme, the flour mixture is mixed with the activated yeast composition, sugar, salt and freezing improver are added, the dough is kneaded and cut into pieces, and the dough is frozen after proofing.

[0023] Optionally, the wheat flour is dry-heat treated at a temperature of 100-120° C. for 1-2 h.

[0024] By adopting the above technical scheme, after dry heat treatment at 100-120°C, the wet gluten content and gluten index in the flour can be increased, the gluten protein molecules in the dough can be easily combined into a gluten protein network structure, the shear resistance of the dough can be improved, the tensile strength can be increased, the hydrophobic bonds and hydrogen bonds in the wheat flour dough can be increased, the non-covalent bonds between the proteins in the wheat flour dough can be enhanced, the gluten proteins in the dough can be more tightly bound, the dough can be more elastic, the disulfide bond content in the heat-treated wheat flour dough can be significantly increased, the connection between the glutenin subunits in the dough can be increased, the content of glutenin macromers can be increased, the content of glutenin macromers is closely related to the processing quality of wheat, and determines the gluten strength and dough characteristics. Therefore, appropriate heat treatment can improve the quality of the dough.

[0025] Optionally, the mass ratio of the yeast to the distilled water for activation is 1:22.5-30, and the temperature of the distilled water for activation is 30-35°C.

[0026] In summary, this application has the following beneficial effects: 1. Since the present application adopts selenium-enriched yeast, silver carp hydrolysate, calcium chloride and short-cluster maltodextrin as the yeast composition, and adds a certain amount of freezing improver, and prepares frozen dough with flour mixture, salt and sugar, the silver carp hydrolysate can improve the antifreeze ability of yeast from the aspects of intracellular fatty acid anabolism of yeast cells, fatty acid synthesis, cell membrane fluidity, etc., and increase the dough aroma, calcium ions enhance the growth and metabolic capacity of yeast, and increase the antifreeze ability by increasing the respiratory metabolism of mitochondria, and short-cluster maltodextrin can enhance lipid metabolism, regulate amino acid metabolism and energy metabolism, so that the physiological state of yeast is more inclined to refrigerated semi-dry yeast without ice crystal stress, with good antifreeze ability, reduce ice crystal recrystallization damage, improve yeast survival rate and yeast activity and fermentation ability after thawing, and adopt a variety of raw materials as the yeast composition, starting from the yeast itself, combining physical protection and chemical protection to improve the antifreeze ability of yeast.

[0027] 2. In this application, sesbania gum, fish collagen peptides and antifreeze polysaccharides are used as freezing improvers, which can not only improve the stability and continuity of the gluten structure in the dough and optimize the fermentation characteristics of the dough, but also regulate the water environment, weaken the effect of ice crystals on gluten protein and yeast, increase the viscoelasticity of gluten protein, and reduce the destruction of gluten during freeze-thaw cycles.

[0028] 3. In the present application, a certain amount of papain is added to the freezing improver to make the dough have better plasticity and extensibility, and the wheat flour is dry-heat treated to increase the wet gluten content and gluten index of the dough, making the gluten protein network structure more uniform and tighter, and the dough has better elasticity. DETAILED DESCRIPTION

[0029] The following examples further illustrate the present application in detail. Example

[0030] Embodiment 1: A yeast-modified frozen dough, the raw materials comprising: 1000g flour mixture, 4g yeast composition, 1g salt, 5g white sugar, 500g distilled water and 6.25g freezing improver; the freezing improver is trehalose, the flour mixture comprises high-gluten wheat flour (protein 11.1g / 100g, fat 1.5g / 100g, carbohydrate 75.3g / 100g) and okra straw insoluble dietary fiber in a mass ratio of 1:0.1, and the preparation method of okra straw insoluble dietary fiber is as follows: peel okra to obtain okra peel, dry, crush and sieve, acid hydrolyze, centrifuge, take filter residue, add deionized water according to a solid-liquid ratio of 1:30, adjust the pH to 7, heat to 100°C, keep warm 100min, then cooled to 60℃, adjusted pH to 5, added α-amylase to a concentration of 0.7%, enzymolysis for 60min, heated to 100℃, inactivated enzyme for 1min, centrifuged at a speed of 5000r / min for 15min, dried, and obtained okra straw insoluble dietary fiber, α-amylase was selected from Henan Yiduoyuan Biotechnology, and the enzyme activity was 20,000U / g, the yeast composition was prepared by mixing selenium-enriched yeast, silver carp enzymolyte, calcium chloride and short cluster maltodextrin in a mass ratio of 1:0.8:0.2:0.5, and the preparation method of selenium-enriched yeast was as follows: 3g Angel active dry yeast was cultured in a sterilized 2% glucose yeast activation liquid medium at 30℃ for 4h, so that the number of active yeast reached 9×10 9 / mL, and then the activated yeast is inoculated into YEPD liquid culture medium at a rate of 10%, and after culturing for 6 hours, a 20μg / mL sodium selenite solution is added, and the culture is shaken at 28°C at a speed of 200r / min for 12 hours, and then sealed and placed at 28°C for 48 hours, centrifuged, and washed. The YEPD liquid culture medium includes 2% glucose, 2% peptone, 1% Angel yeast powder, and the remainder is distilled water. The preparation method of silver carp enzymatic hydrolysate is as follows: the silver carp meat is crushed and dispersed in distilled water at a material-liquid ratio of 1:5, and a composite protease of 3% of the weight of the silver carp meat is added at 50°C and pH6.5. The enzymatic hydrolysis is carried out for 30 minutes, the enzyme is inactivated at 90°C for 15 minutes, cooled to room temperature, centrifuged at 4000r / min for 15 minutes, the supernatant is collected, and freeze-dried. The composite protease is selected from Novozymes, and the enzyme activity is 1.6AU-N / g, and the model is Protamex 1.6; Preparation method of short-cluster maltodextrin: dissolve corn starch with deionized water to prepare corn starch milk with a concentration of 10wt%, stir at 50℃ for 15min, add 25U / g pullulanase, maintain constant temperature at 50℃ for 10h, and then put it in a water bath at 95℃ for 30min to terminate the reaction and make the starch fully gelatinized, put the starch paste in a water bath at 50℃ for 30min, add 25U / g pullulanase, maintain constant temperature at 50℃ for 10h, and then put it in a water bath at 95℃ for 30min to terminate the reaction, freeze-dry, grind, and pass through a 100-mesh sieve to obtain the pullulanase, which is selected from Shandong Yiwei Bioengineering and has an enzyme activity of 20,000U / g.

[0031] The method for preparing the yeast-improved frozen dough comprises the following steps: S1, mixing wheat flour and okra straw insoluble dietary fiber to prepare a flour mixture, wherein the wheat flour is pre-dry-heat treated at a temperature of 120° C. for 2 h; S2, dissolving the yeast composition in distilled water at a temperature of 30° C. and activating for 20 minutes, wherein the mass ratio of the yeast composition to distilled water is 1:30; S3, dissolving salt, sugar and freezing improver in the remaining distilled water, adding the flour mixture and the activated yeast composition, kneading, and dividing into a plurality of small doughs of 50 g each to prepare dough; S4. The dough was proofed at 35° C. and 75% relative humidity for 20 min, then frozen at -18° C. for 18 h, and then thawed at 4° C. for 6 h, which was one cycle. The freeze-thaw cycle was repeated 6 times to obtain frozen dough.

[0032] Embodiment 2: A yeast-modified frozen dough, the raw materials comprising: 800g flour mixture, 3.2g yeast composition, 0.8g salt, 4g white sugar, 400g distilled water and 5g freezing improver; the freezing improver is trehalose, the flour mixture comprises high-gluten wheat flour (protein 11.1g / 100g, fat 1.5g / 100g, carbohydrate 75.3g / 100g) and okra straw insoluble dietary fiber in a mass ratio of 1:0.08, and the preparation method of okra straw insoluble dietary fiber is as follows: peel okra to obtain okra peel, dry, crush and sieve, acid hydrolyze, centrifuge, take filter residue, add deionized water according to a solid-liquid ratio of 1:30, adjust the pH to 7, heat to 100°C, keep warm 100min, then cooled to 60℃, adjusted pH to 5, added α-amylase to a concentration of 0.7%, enzymolysis for 60min, heated to 100℃, inactivated enzyme for 1min, centrifuged at a speed of 5000r / min for 15min, dried, and obtained okra straw insoluble dietary fiber, α-amylase was selected from Henan Yiduoyuan Biotechnology, and the enzyme activity was 20,000U / g, the yeast composition was prepared by mixing selenium-enriched yeast, silver carp enzymolysate, calcium chloride and short cluster maltodextrin in a mass ratio of 1:0.4:0.1:0.3, and the preparation method of selenium-enriched yeast was as follows: 3g Angel active dry yeast was cultured in a sterilized 2% glucose yeast activation liquid medium at 30℃ for 4h, so that the number of active yeast reached 9×10 9 / mL, and then the activated yeast is inoculated into YEPD liquid culture medium at a rate of 10%, and after culturing for 5 hours, a 25μg / mL sodium selenite solution is added, and the culture is shaken at 30°C and a speed of 200r / min for 10 hours. After sealing, it is placed at 30°C for 46 hours, centrifuged, and washed. The YEPD liquid culture medium includes 2% glucose, 2% peptone, 1% Angel yeast powder, and the rest is distilled water. The preparation method of silver carp enzymatic hydrolysate is as follows: the silver carp meat is crushed and dispersed in distilled water at a material-liquid ratio of 1:6, and a composite protease of 2.5% of the mass of the silver carp meat is added at 55°C and pH 6. The enzymatic hydrolysis is carried out for 50 minutes, the enzyme is inactivated at 100°C for 15 minutes, cooled to room temperature, centrifuged at 4000r / min for 15 minutes, the supernatant is collected, and freeze-dried. The composite protease is selected from Novozymes, and the enzyme activity is 1.6AU-N / g, and the model is Protamex 1.6; Preparation method of short cluster maltodextrin: corn starch is dissolved in deionized water to prepare corn starch milk with a concentration of 10wt%, and after stirring at 50°C for 15min, 25U / g of pullulanase is added, and the reaction is maintained at 50°C for 10h, and then the reaction is terminated by water bath at 95°C for 30min to fully gelatinize the starch, and the starch paste is kept in a 50°C water bath for 30min, and 25U / g of pullulanase is added, and the reaction is maintained at 50°C for 10h, and then the reaction is terminated by water bath at 95°C for 30min, and then the reaction is freeze-dried, ground, and passed through a 100-mesh sieve to obtain the pullulanase, which is selected from Shandong Yiwei Bioengineering and has an enzyme activity of 20,000U / g The method for preparing the yeast-improved frozen dough comprises the following steps: S1. Mixing wheat flour and okra straw insoluble dietary fiber to prepare a flour mixture, wherein the wheat flour is pre-dry-heat treated at a temperature of 100° C. for 1 h; S2, dissolving the yeast composition in distilled water at a temperature of 30° C. and activating for 15 minutes, wherein the mass ratio of the yeast composition to distilled water is 1:22.5; S3, dissolving salt, sugar and freezing improver in the remaining distilled water, adding the flour mixture and the activated yeast composition, kneading, and dividing into a plurality of small doughs of 30 g each to prepare dough; S4. The dough was proofed at 38° C. and 70% relative humidity for 30 min, then frozen at -20° C. for 20 h, and then thawed at 6° C. for 6 h, which was one cycle. The freeze-thaw cycle was repeated 6 times to obtain frozen dough.

[0033] Example 3: A yeast-improved frozen dough, which is different from Example 1 in that no sodium selenite solution is added when the selenium-enriched yeast is prepared. Specifically, 3g of Angel active dry yeast is cultured in a sterilized 2% glucose yeast activation liquid culture medium at 30°C for 4h until the number of active yeast cells reaches 9×10 9 / mL, and then the activated yeast was inoculated into YEPD liquid culture medium at a rate of 10%. After culturing for 6 hours, the culture was shaken at 200 r / min at 28°C for 12 hours. The YEPD liquid culture medium included 2% glucose, 2% peptone, 1% Angel yeast powder, and the remainder was distilled water.

[0034] Example 4: A yeast-improved frozen dough, which is different from Example 1 in that the selenium-enriched yeast is not cultured under pressure after culture. Specifically, 3 g of Angel active dry yeast is cultured in a sterilized 2% glucose yeast activation liquid culture medium at 30°C for 4 h until the number of active yeast cells reaches 9×10 9 / mL, and then the activated yeast was inoculated into YEPD liquid culture medium at a rate of 10%. After culturing for 6 hours, 20μg / mL sodium selenite solution was added, and the culture was shaken in a shaker at 200r / min at 28°C for 12 hours. The YEPD liquid culture medium included 2% glucose, 2% peptone, 1% Angel yeast powder, and the balance was distilled water.

[0035] Example 5: A yeast-improved frozen dough, which differs from Example 1 in that the freezing improver includes sesbania gum, fish collagen peptide and antifreeze polysaccharide in a mass ratio of 1:0.3:0.2, sesbania gum is selected from Shandong Shengyuan Food, item number 001, fish collagen peptide is selected from Xi'an Tianguangyuan Biotechnology, model number TGYYJY-586123, and the antifreeze polysaccharide is okra polysaccharide, which is selected from Weinan Dongjiang Tiancheng Industrial Co., Ltd., item number DJQK.

[0036] Example 6: A yeast-improved frozen dough, which differs from Example 1 in that the freezing improver includes sesbania gum, fish collagen peptide and antifreeze polysaccharide in a mass ratio of 1:0.6:0.5, sesbania gum is selected from Shandong Shengyuan Food, item number 001, fish collagen peptide is selected from Xi'an Tianguangyuan Biotechnology, model number TGYYJY-586123, and the antifreeze polysaccharide is okra polysaccharide, which is selected from Weinan Dongjiang Tiancheng Industrial Co., Ltd., item number DJQK.

[0037] Example 7: A yeast-modified frozen dough, which differs from Example 5 in that the frozen dough improver comprises sesbania gum and fish collagen peptide in a mass ratio of 1:0.5.

[0038] Example 8: A yeast-improved frozen dough, which differs from Example 5 in that the freezing improver comprises sesbania gum and antifreeze polysaccharide in a mass ratio of 1:0.5.

[0039] Example 9: A yeast-modified frozen dough, which differs from Example 5 in that the freezing improver comprises fish collagen peptide and antifreeze polysaccharide in a mass ratio of 1.3:0.2.

[0040] Example 10: A yeast-improved frozen dough, which is different from Example 5 in that papain is also added to the frozen improver, the mass ratio of papain to sesbania gum is 0.3:1, and the papain is selected from Xi'an Xihai Biotechnology Co., Ltd., with a product number of XH054.

[0041] Example 11: A yeast-improved frozen dough, which is different from Example 5 in that papain is also added to the frozen improver, the mass ratio of papain to sesbania gum is 0.1:1, and the papain is selected from Xi'an Xihai Biotechnology Co., Ltd., with a product number of XH054.

[0042] Example 12: A yeast-improved frozen dough, which is different from Example 10 in that an equal amount of Artemisia sphaerocephala gum is used instead of Sesbania sesbania gum.

[0043] Comparative Example Comparative Example 1: A yeast-modified frozen dough, which is different from Example 1 in that an equal amount of trehalose is used in the yeast composition to replace calcium chloride.

[0044] Comparative Example 2: A yeast-improved frozen dough, which is different from Example 1 in that an equal amount of trehalose is used in the yeast composition to replace the silver carp enzymatic hydrolysate.

[0045] Comparative Example 3: A yeast-improved frozen dough, which is different from Example 1 in that an equal amount of trehalose is used in the yeast composition to replace selenium-enriched yeast.

[0046] Comparative Example 4: A yeast-modified frozen dough, which is different from Example 1 in that an equal amount of wheat flour is used in the flour mixture to replace the insoluble dietary fiber of okra straw.

[0047] Comparative Example 5: A yeast-modified frozen dough, which is different from Example 1 in that the wheat flour is not subjected to dry heat treatment.

[0048] Comparative Example 6: A yeast-improved frozen dough, which is different from Example 1 in that active dry yeast is used instead of the yeast composition, and no freezing improver is added.

[0049] Comparative Example 7: A method for improving the fermentation power of frozen dough, comprising the following steps: Frozen dough preparation: At a room temperature of 25°C, 300.0g of all-purpose flour, 0g of amylopectin, and 0g of gluten are mixed to prepare a flour mixture. The raw materials are weighed according to the following formula: the above flour mixture, 180.0g of water, 5.0g of active dry yeast, 3.0g of edible salt, 15.0g of salad oil, and 6.0g of white sugar. Among them, the starch content of the flour mixture is 68.0g / 100.0g of flour, the ratio of amylopectin to amylose is 3:1, the protein content is 10.0g / 100.0g of flour, and the ratio of glutenin to alcohol-soluble protein is 1:1. The raw materials for preparing frozen dough are evenly mixed and kneaded vigorously for 15 minutes, and then divided into small doughs of 100.0g each, rolled into round shapes, and used as fresh dough. The fresh dough was frozen at -20°C for 5 h, then put into a polyethylene sealable bag and stored at -20°C for 1 week as frozen dough.

[0050] Performance testing Frozen dough was prepared according to the methods in the examples and comparative examples, and performance tests were performed according to the following methods. The test results are recorded in Table 1.

[0051] 1. Detection of frozen dough: (1) Yeast survival rate: 5 g of the frozen dough prepared in the examples and comparative examples was cut into pieces and placed in 30 mL of 1% physiological saline. The dough was shaken at 30° C. for 3 h to extract yeast cells. The dough was spread on malt agar plates by a 10-fold dilution method and incubated at 28° C. for 48 h. The colony survival rate was calculated according to the following formula: Y=N / N0×100%, where Y is the survival rate of yeast colonies after freeze-thaw, %; N0 is the total number of yeast colonies after the 0th freeze-thaw; and N is the total number of yeast colonies after the 6th freeze-thaw.

[0052] (2) Relative fermentation capacity: With reference to GB / T 20886-2007 “Yeast for food processing”, the carbon dioxide produced by frozen dough for 180 min and 30 s was measured by displacement method. The fermentation capacity of yeast in the dough was expressed as the volume of carbon dioxide. The ratio of the carbon dioxide volume to the fermentation capacity of the dough after zero freeze-thaw cycles was the relative fermentation capacity.

[0053] 2. Detection of steamed buns made from frozen dough: (1) Specific volume: The raw dough was thawed and fermented at 38°C and 75% relative humidity for 90 min, then steamed in a multipurpose steamer for 15 min to obtain steamed buns. The steamed buns were cooled at room temperature for 30 min, and the volume of the steamed buns was measured with a volume meter (rapeseed displacement method) to an accuracy of 5 mL. The mass of the steamed buns was measured with an analytical balance to an accuracy of 0.01 g. The specific volume of the steamed buns is the ratio of the volume of the steamed buns to the mass of the steamed buns (mL / g). The measurement was repeated 3 times for each sample.

[0054] (2) Texture characteristics: The cooled steamed buns were cut into blocks of 2×3×1.5 cm in length, width and height. The center of each steamed bun was selected and the texture of the buns was tested using a texture analyzer. The parameters of the texture analyzer were as follows: the probe was P50, the speed was 3 mm / s before, during and after the test, and the deformation was 50%.

[0055] Table 1 It can be seen from the data in Table 1 that the survival rate of yeast colonies in the dough frozen and thawed 6 times in Example 1 and Example 2 reached more than 45%, and the relative fermentation power was high. The steamed buns made had a large specific volume, small hardness and chewiness, were relatively soft, and had good palatability.

[0056] Compared with Example 1, in Example 3, no sodium selenite solution was added when preparing selenium-enriched yeast, while in Example 4, no pressurized culture was performed after the sodium selenite solution was added when preparing selenium-enriched yeast. Table 1 shows that in the frozen doughs prepared in Examples 3 and 4, the survival rate of yeast colonies decreased, and after the frozen doughs were made into steamed buns, the specific volume decreased, the hardness and chewiness increased, and the palatability decreased.

[0057] Compared with Example 1, Examples 5 and 6 use sesbania gum, fish collagen peptide and antifreeze polysaccharide as freezing improvers. It can be seen that the survival rate of yeast is increased, the relative fermentation power is enhanced, and the specific volume of the steamed bread produced is increased, and the palatability is enhanced.

[0058] In Example 7, only sesbania gum and fish collagen peptide were used as freezing improvers, while in Example 8, sesbania gum and antifreeze polysaccharides were used as freezing improvers. Compared with Example 5, the survival rate of yeast in the frozen dough prepared in Examples 7 and 8 decreased, the relative fermentation power decreased, and the palatability of the steamed bread prepared decreased.

[0059] In Example 9, fish collagen peptide and antifreeze polysaccharide were used as freezing improvers. Compared with Example 5, the survival rate of yeast in the prepared frozen dough decreased, the relative fermentation power decreased, the specific volume of the steamed bread decreased, and the palatability deteriorated.

[0060] In Example 10 and Example 11, papain is added to the freezing improver to cooperate with sesbania gum, thereby further improving the texture and specific volume of the steamed bread, and enhancing the palatability and quality of the steamed bread.

[0061] In Example 11, artemisia gum was used instead of sesbania gum. Table 1 shows that the specific volume of steamed bread made from the obtained frozen dough was lower than that of Example 10, and the palatability was reduced.

[0062] In Comparative Example 1, trehalose was used to replace calcium chloride, in Comparative Example 2, trehalose was used to replace silver carp enzymatic hydrolysate, and in Comparative Example 3, trehalose was used to replace selenium-enriched yeast. Table 1 shows that the yeast survival rate of the frozen dough prepared in Comparative Examples 1-3 decreased, indicating that the replacement effect of trehalose cannot achieve the use effect of the raw materials in the yeast composition of the present application.

[0063] In Comparative Example 4, wheat flour was used to replace the insoluble dietary fiber of okra straw, and in Comparative Example 5, the wheat flour was not dry-heat treated. Compared with Example 1, the relative fermentation power of the dough prepared in Comparative Examples 4 and 5 decreased, the survival rate of yeast decreased, and the specific volume decreased, and the palatability of the steamed bread was weakened.

[0064] In Comparative Example 6, no freezing improver was added, and only active dry yeast was added as a blank control group. It can be seen that the yeast survival rate was low, the fermentation ability was poor, and the steamed bread had a small specific volume and poor softness.

[0065] Comparative Example 7 is a frozen dough provided by the prior art, which has a high specific volume, but has a high chewiness and a high degree of stickiness, and has poor palatability.

[0066] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A yeast-modified frozen dough, characterized in that: The invention comprises the following raw materials in parts by weight: 800-1000 parts of flour mixture, 3.2-4 parts of yeast composition, 0.8-1 parts of salt, 4-5 parts of sugar, 400-500 parts of distilled water and 5-6.25 parts of freezing improver, wherein the yeast composition comprises selenium-enriched yeast, silver carp enzymolysate, calcium chloride and short-cluster maltodextrin in a mass ratio of 1:0.4-0.8:0.1-0.2:0.3-0.

5.

2. The yeast-modified frozen dough according to claim 1, characterized in that: The preparation method of the selenium-enriched yeast is as follows: after activating the yeast, inoculate it into a YEPD liquid culture medium at a 10% inoculation amount, culture it for 5-6 hours, add a 20-25 μg / mL sodium selenite solution, culture it at 28-30° C. for 10-12 hours, seal it, culture it at 28-30° C. for 46-48 hours, centrifuge it, and wash it.

3. The yeast-modified frozen dough according to claim 1, characterized in that: The preparation method of the silver carp enzymatic hydrolysate comprises the following steps: crushing the silver carp meat, dispersing it in distilled water at a solid-liquid ratio of 1:5-6, adding 2.5-3% of the weight of the silver carp meat with a composite protease at 50-55° C. and pH 6-6.5, performing enzymatic hydrolysis for 30-50 minutes, inactivating the enzyme at 90-100° C., cooling, centrifuging, collecting the supernatant, and freeze-drying.

4. The yeast-modified frozen dough according to claim 1, characterized in that: The freezing improver comprises sesbania gum, fish collagen peptide and antifreeze polysaccharide in a mass ratio of 1:0.3-0.6:0.2-0.

5.

5. The yeast-modified frozen dough according to claim 4, characterized in that: The antifreeze polysaccharide is okra polysaccharide.

6. The yeast-modified frozen dough according to claim 4, characterized in that: Papain is also added to the freezing improver, and the mass ratio of papain to sesbania gum is 0.1-0.3:

1.

7. The yeast-modified frozen dough according to claim 1, characterized in that: The flour mixture comprises wheat flour and okra straw insoluble dietary fiber in a mass ratio of 1:0.08-0.

1.

8. The method for preparing the yeast-modified frozen dough according to any one of claims 1 to 7, characterized in that: The following steps are involved: The wheat flour and the insoluble dietary fiber of okra straw are mixed to prepare a flour mixture. Dissolve the yeast composition in distilled water and activate for 15-20 minutes; Dissolve salt, sugar and a freezing improver in the remaining distilled water, add the flour mixture and the activated yeast composition, knead the dough, and divide it into a plurality of small doughs of (30-50) g ​​each to prepare dough; The dough was proofed at 35-38°C and 70-75% relative humidity for 20-30 minutes, then frozen at -(18-20)°C for 18-20 hours, and then thawed at 4-6°C for 6 hours, which was one cycle. The freeze-thaw cycle was repeated 6 times to obtain frozen dough.

9. The method for preparing yeast-modified frozen dough according to claim 8, characterized in that: The wheat flour is dry-heat treated at a temperature of 100-120° C. for 1-2 hours.

10. The method for preparing yeast-improved frozen dough according to claim 8, characterized in that: The mass ratio of the yeast to the distilled water for activation is 1:22.5-30, and the temperature of the distilled water for activation is 30-35°C.

Images