Method for improving freeze-thaw tolerance of yeast in fermented flour product based on polyol
By treating yeast with polyol culture medium, its freeze-thaw tolerance was improved, which solved the problem of yeast activity loss in frozen raw dough products and achieved stable survival and fermentation activity of yeast during the freeze-thaw process.
Patent Information
- Application Number
- CN202511024440.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-24
- Publication Date
- 2025-11-07
AI Technical Summary
Existing technologies are insufficient to effectively improve the freeze-thaw tolerance of yeast in frozen dough products, resulting in the loss of yeast activity during temperature fluctuations and affecting the dough fermentation effect.
Yeast was modified using polyol culture medium to enhance its freeze-thaw tolerance by creating a hypertonic environment, regulating cell membrane permeability, and providing energy substrates.
Improve the survival rate and fermentation activity of yeast during the freeze-thaw process to ensure that the dough can maintain good fermentation performance after freeze-thaw cycles.
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Figure CN120905112A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of frozen dough processing, and particularly relates to a method for improving the freeze-thaw tolerance of yeast in fermented dough based on polyols. BACKGROUND
[0002] Yeast plays an important role in dough fermentation, especially in the fermentation of frozen raw dough. The CO2 produced by yeast metabolism makes the dough expand and become larger during the fermentation process, forming a porous internal structure. However, the most important factor limiting the development of the frozen raw dough industry is the tolerance of yeast. During temperature fluctuation in the cold chain transportation process, fermented raw dough inevitably undergoes freeze-thaw cycles, and how to maintain the viability of yeast in raw dough during freeze-thaw cycles is still a great challenge.
[0003] Current research on yeast viability maintenance mainly focuses on optimizing the freezing rate to reduce the damage to yeast cells caused by freezing (such as Zhang, M., et al., Frozen dough steamed products: Deterioration mechanism, processing technology, and improvement strategies. Comp Rev Food Sci Food Safe. 2024, 23, e70028.), or screening yeast strains that are more resistant to freezing (such as F., et al., Frozen-dough baking potential of psychrotolerant Saccharomyces species and derived hybrids. Food Microbiology. 2021, 94, 103640.) and biological engineering modification of yeast to improve its resistance to freezing (such as Nakagawa, Y., et al., Development of intra-strain selfcloning procedure for breeding baker’s yeast strains. Journal of Bioscience and Bioengineering. 2017, 123(3), 319-326.), but the cost is high and it has not yet been able to improve the freeze-thaw tolerance of yeast in a way that can be put into actual production. Therefore, it is necessary to develop a simple, effective and economical method to improve the tolerance of yeast during freeze-thaw cycles. SUMMARY
[0004] [TECHNICAL PROBLEM]
[0005] The application provides a method for improving the freeze-thaw tolerance of yeast, which is simple to operate, low in cost and suitable for industrial production.
[0006] [Technical scheme]
[0007] To solve the above problems, the application provides a method for improving the freeze-thaw tolerance of yeast by modifying the yeast with a culture solution containing polyols, improving the freeze-thaw tolerance of yeast cells, maintaining good activity of the yeast after freeze-thaw, and improving the fermentation activity in green dough.
[0008] Compared with the reported screening and modification of yeast, the method is more low-cost, effective, suitable for industrialization and industrialization. The method improves the freeze-thaw tolerance of yeast cells, protects the cells from damage, so that the yeast has better ability to cope with freeze-thaw, maintains the stability of the cells, maintains the survival rate of the yeast in the process of stable fluctuation freeze-thaw and the fermentation activity in green dough.
[0009] The specific scheme is as follows:
[0010] The first object of the application is to provide a method for improving the freeze-thaw tolerance of yeast, which is to modify the yeast in a culture solution containing polyols to improve the freeze-thaw tolerance of the cells.
[0011] In an embodiment of the application, the culture solution containing polyols also contains pure water and / or yeast culture medium.
[0012] In an embodiment of the application, the yeast culture medium is specifically YPD solid culture medium.
[0013] In an embodiment of the application, the method is to mix the yeast slurry with the culture solution containing polyols.
[0014] In an embodiment of the application, the concentration of the yeast slurry is 0.1wt%-20.0wt%, and specifically 10.0wt% can be selected.
[0015] In an embodiment of the application, the concentration of polyols in the culture solution is 0.5wt%-20.0wt%, and specifically 3.5wt% can be selected.
[0016] In an embodiment of the application, the volume ratio of the yeast slurry to the culture solution containing polyols is 1:(80-120), and specifically 1:100 can be selected.
[0017] In an embodiment of the application, the yeast includes liquid yeast, compressed yeast, semi-dry yeast, instant active dry yeast and other leavening agents containing yeast.
[0018] In one embodiment of the present application, the polyol is selected from any one or more of erythritol, xylitol, sorbitol, maltitol, mannitol, lactitol and the like polyol compounds. Preferably, any one or more of erythritol, xylitol, sorbitol.
[0019] In one embodiment of the present application, the temperature of the modification treatment is 0°C to 45°C and the time is 0.1h to 24h. Specifically, the incubation is at room temperature for 30min.
[0020] A second object of the present application is to provide a method for preparing a high freeze-thaw tolerant yeast, which comprises suspending the yeast in purified water, mixing to form a yeast slurry, and mixing the yeast slurry with a culture medium containing a polyol to form a yeast treatment mixture.
[0021] In one embodiment of the present application, the culture medium containing a polyol further contains purified water and / or a yeast culture medium.
[0022] In one embodiment of the present application, the method comprises mixing the yeast slurry with a culture medium containing a polyol.
[0023] In one embodiment of the present application, the concentration of the yeast slurry is 0.1wt% to 20.0wt%.
[0024] In one embodiment of the present application, the concentration of the polyol in the culture medium is 0.5wt% to 20.0wt%.
[0025] In one embodiment of the present application, the temperature of the mixing is 0°C to 45°C and the time is 0.1h to 24h.
[0026] A third object of the present application is to provide a method for preparing a fermented frozen dough, which comprises the following steps:
[0027] (1) mixing yeast, a polyol and a dispersion system, and performing a modification treatment to obtain a yeast treatment solution;
[0028] (2) mixing the obtained yeast treatment solution and wheat flour to form a dough, and making the dough uniform and smooth by calendering, and then cutting and shaping, and then performing a pre-fermentation, and then performing a freeze-thaw treatment to obtain a frozen dough.
[0029] In one embodiment of the present application, the dispersion system is water and / or a yeast culture medium.
[0030] In one embodiment of the present application, the amount of yeast added relative to the dispersion system is 2wt% to 4wt%.
[0031] In one embodiment of the present application, the polyol is added to the dispersion system in an amount of 5-15 wt%.
[0032] A fourth object of the present application is to provide a frozen dough prepared by the above method.
[0033] A fifth object of the present application is to provide the use of the frozen dough prepared by the above method in the processing of frozen dough products.
[0034] Advantages of the present application:
[0035] The present application improves the freeze-thaw tolerance of yeast by culturing the yeast in a medium containing a polyol. First, the high-osmotic environment formed by the polyol promotes the accumulation of compatible solutes such as trehalose and glutathione in the yeast, which can stabilize the structure of the cell membrane and reduce cold-induced damage. Second, the polyol inhibits ice crystal formation by reducing water activity and freezing point, thereby reducing mechanical damage to the cells caused by ice crystals. In addition, the polyol can adjust the permeability of the cell membrane, promote the retention or secretion of protective substances such as glutathione, and further enhance the anti-freezing ability. At the same time, the polyol, as an energy substrate, can activate ATP synthase and promote the synthesis of antioxidant substances such as glutathione, thereby alleviating oxidative stress caused by freezing. The present application improves the freeze-thaw tolerance of yeast by treating the yeast in a medium containing a polyol, thereby maintaining the fermentation activity of the yeast in the dough during the freeze-thaw process. BRIEF DESCRIPTION OF DRAWINGS
[0036] Figure 1 Graph of the change in cell survival rate of the yeast of Example 1 during freeze-thaw cycles.
[0037] Figure 2 Graph of the change in cell survival rate of the yeast of Example 2 during freeze-thaw cycles.
[0038] Figure 3 Graph of the change in cell survival rate of the yeast of Example 3 during freeze-thaw cycles.
[0039] Figure 4 Graph of the change in cell survival rate of the yeast of Comparative Example 1 during freeze-thaw cycles.
[0040] Figure 5 Graph of the change in cell survival rate of the yeast of Comparative Example 2 during freeze-thaw cycles.
[0041] Figure 6 Graph of the change in cell survival rate of the yeast of Comparative Example 3 during freeze-thaw cycles.
[0042] Figure 7 Graph of the change in CO2 production of the fermented dough of Example 4 during freeze-thaw cycles.
[0043] Figure 8Graph of yeast CO2 production change of the fermented green dough of Example 5 during freeze-thaw cycle.
[0044] Figure 9 Graph of yeast CO2 production change of the fermented green dough of Example 6 during freeze-thaw cycle.
[0045] Figure 10 Graph of yeast CO2 production change of the fermented green dough of Example 7 during freeze-thaw cycle.
[0046] Figure 11 Graph of yeast CO2 production change of the fermented green dough of Example 8 during freeze-thaw cycle.
[0047] Figure 12 Graph of yeast CO2 production change of the fermented green dough of Example 9 during freeze-thaw cycle.
[0048] Figure 13 Graph of yeast CO2 production change of the fermented green dough of Comparative Example 4 during freeze-thaw cycle. DETAILED DESCRIPTION
[0049] The specific embodiments of the application will now be described in connection with the drawings and specific embodiments. It is noted that the application is not limited to the specific embodiments described below, which are presented as examples only, because the application can be practiced in other ways than those described herein, and by persons skilled in the art without departing from the scope of the application. It is further noted that the specific embodiments described below do not limit the scope of the application, which is defined by the claims.
[0050] Example 1:
[0051] A method for improving freeze-thaw tolerance of yeast:
[0052] (1) Polyol solution preparation (A solution): 350 mg of erythritol was added to 10 mL of deionized water in a centrifuge tube, and mixed well to obtain a polyol solution with an addition amount of 3.5 wt%.
[0053] (2) Yeast suspension preparation (B solution): 1 g of semi-dry yeast (available from Angel Yeast Co., Ltd., Yichang, Hubei Province) was added to 10 mL of deionized water, and mixed well to obtain a yeast suspension with a concentration of 0.1 g / mL (equivalent to 10 wt%).
[0054] (3) Mixing of A solution and B solution: 0.1 mL of B solution was added to 10 mL of A solution, and mixed well. The yeast suspension after incubation at room temperature for 30 min was subjected to freeze-thaw cycle treatment, and the freeze-thaw tolerance of the yeast was tested.
[0055] Freeze-thaw tolerance test:
[0056] Freeze-thaw cycle treatment: the incubated yeast suspension was frozen at temperature -40℃ for 1 h, then thawed in water bath at 30℃ for 30 min, which was 1 freeze-thaw cycle, and 1, 2, 3 freeze-thaw cycles were carried out respectively.
[0057] Fresh sample: the incubated yeast suspension was used directly after mixing evenly, without freezing treatment.
[0058] Observation and counting: 0.05% methylene blue dye was mixed with the yeast suspension at volume ratio of 1:10, observed and counted under 400x optical microscope.
[0059] Calculation formula: yeast cell survival rate (%) = (number of viable cells stained with dye / total cell number) x 100%.
[0060] Example 2:
[0061] A method for improving freeze-thaw tolerance of yeast:
[0062] (1) Polyol solution preparation (A solution): 350 mg of xylitol was added into 10 mL of deionized water in a centrifuge tube, and mixed evenly to obtain a polyol solution with an addition amount of 3.5 wt%.
[0063] (2) Yeast suspension preparation (B solution): 1 g of semi-dry yeast was added into 10 mL of deionized water, and stirred and mixed evenly to obtain a yeast suspension with a concentration of 0.1 g / mL.
[0064] (3) Mixing of A solution and B solution: 0.1 mL of B solution was added into 10 mL of A solution, and mixed evenly, and the incubated yeast suspension was subjected to freeze-thaw cycle treatment to test the freeze-thaw tolerance of the yeast.
[0065] Freeze-thaw tolerance test:
[0066] Freeze-thaw cycle treatment: the incubated yeast suspension was frozen at temperature -40℃ for 1 h, then thawed in water bath at 30℃ for 30 min, which was 1 freeze-thaw cycle, and 1, 2, 3 freeze-thaw cycles were carried out respectively.
[0067] Fresh sample: the incubated yeast suspension was used directly after mixing evenly, without freezing treatment.
[0068] Observation and counting: 0.05% methylene blue dye was mixed with the yeast suspension at volume ratio of 1:10, observed and counted under 400x optical microscope.
[0069] Calculation formula: yeast cell survival rate (%) = (number of viable cells stained with dye / total cell number) x 100%.
[0070] Example 3:
[0071] A method for improving freeze-thaw tolerance of yeast:
[0072] (1) Polyol solution preparation (A solution): 350 mg of sorbitol was added into 10 mL of deionized water, and mixed well to obtain a polyol solution with an addition amount of 3.5 wt%.
[0073] (2) Yeast suspension preparation (B solution): 1 g of semi-dry yeast was added into 10 mL of deionized water, and mixed well to obtain a yeast suspension with a concentration of 0.1 g / mL.
[0074] (3) Mixing of A solution and B solution: 0.1 mL of B solution was added into 10 mL of A solution, and mixed well. The incubation was performed at room temperature for 30 min. The freeze-thaw tolerance of yeast was tested after freeze-thaw cycle treatment of the incubated yeast suspension.
[0075] Freeze-thaw tolerance test:
[0076] Freeze-thaw cycle treatment: the incubated yeast suspension was frozen at -40℃ for 1 h, and then thawed in a water bath at 30℃ for 30 min, which was 1 freeze-thaw cycle. The freeze-thaw cycle was performed for 1, 2, and 3 times, respectively.
[0077] Fresh sample: the incubated yeast suspension was used directly after mixing well, without freeze-thaw treatment.
[0078] Observation and counting: 0.05% methylene blue dye solution was mixed with the yeast suspension at a volume ratio of 1:10. The mixture was observed and counted under a 400x optical microscope.
[0079] Calculation formula: yeast cell survival rate (%) = (number of viable cells with no staining / total cell number) x 100%.
[0080] Comparative Example 1:
[0081] A method for improving freeze-thaw tolerance of yeast:
[0082] Referring to Example 1, the amount of erythritol in step (1) was replaced by 0 mg, and other conditions were unchanged:
[0083] (1) 10 mL of deionized water was placed in a centrifuge tube (A solution).
[0084] (2) Yeast suspension preparation (B solution): 1 g of semi-dry yeast was added into 10 mL of deionized water, and mixed well to obtain a yeast suspension with a concentration of 0.1 g / mL.
[0085] (3) A liquid and B liquid mixed: 0.1 mL B liquid was added to 10 mL A liquid, mixed well, and incubated at room temperature for 30 min. The yeast suspension after incubation was subjected to freeze-thaw cycle treatment, and the freeze-thaw tolerance of the yeast was tested.
[0086] Freeze-thaw tolerance test:
[0087] Freeze-thaw cycle treatment: the yeast suspension after incubation was frozen at -40℃ for 1 h, and then thawed in a water bath at 30℃ for 30 min, which was 1 freeze-thaw cycle, and 1, 2, 3 freeze-thaw cycles were carried out respectively.
[0088] Fresh sample: the yeast suspension after incubation was used directly after mixing well, without freezing treatment.
[0089] Observation and counting: 0.05% methylene blue dye was mixed with the yeast suspension at a volume ratio of 1:10, observed and counted under a 400x optical microscope.
[0090] Calculation formula: yeast cell survival rate (%) = (number of viable cells with dye rejection / total cell number) x 100%.
[0091] Comparative Example 2:
[0092] Referring to Example 2, the amount of xylitol in step (1) was replaced with 0 mg, and other conditions were unchanged.
[0093] The cell survival rate of the obtained yeast was tested.
[0094] Comparative Example 3:
[0095] Referring to Example 3, the amount of sorbitol in step (1) was replaced with 0 mg, and other conditions were unchanged.
[0096] The cell survival rate of the obtained yeast was tested.
[0097] The yeast cell survival rate results of different freeze-thaw treatments in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1. Figures 1-6 The specific results are shown in Table 1.
[0098] Table 1 Yeast cell survival rate (%) results of different freeze-thaw treatments
[0099] Sample Fresh sample Sample frozen and thawed once Sample frozen and thawed twice Sample frozen and thawed three times Example 1 76 81 84 85 Example 2 80 81 87 88 Example 3 83 84 84 85 Comparative Example 1 86 80 68 60 Comparative Example 2 86 80 68 60 Comparative Example 3 86 80 68 60
[0100] Example 4:
[0101] A method for preparing a fermented green dough:
[0102] (1) Yeast treatment liquid: 240 mL of deionized water was added with 17.5 g of erythritol and 5 g of semi-dry yeast, mixed well to obtain a yeast treatment liquid;
[0103] (2) Preparation of fermented green dough:
[0104] Mixing: Take 500 g of wheat flour and the yeast treatment solution (262.5 g) obtained in step (1), and mix them in a mixer at a medium speed of 240 r / min for 3 min and then at a low speed of 120 r / min for 2 min;
[0105] Dividing and forming: divide the dough into 300 g each and manually knead into a ball to obtain green dough.
[0106] Freeze-thaw treatment of green dough: freeze at a temperature of -40 °C for 2 h, then store at -18 °C for 1 d, and finally thaw at 5 °C for 10 h, which is 1 freeze-thaw cycle. Perform 1, 3 freeze-thaw cycles, respectively, to obtain frozen green dough.
[0107] Fresh dough: directly use after dividing without freezing treatment.
[0108] Measurement of gas production: refer to GB / T 20886.1-2021 and perform the experiment by the drainage method. Immediately put 300 g of dough after freeze-thaw cycle into a wide-mouth bottle, and place the wide-mouth bottle into a constant-temperature water bath at 30 °C, and connect a reagent bottle containing 2000 mL of drainage liquid. Record the drainage volume at 2 h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0109] Example 5:
[0110] A method for preparing fermented green dough:
[0111] (1) Yeast treatment solution: add 25.0 g of erythritol and 5 g of semi-dry yeast to 240 mL of deionized water, and mix uniformly to obtain a yeast treatment solution;
[0112] (2) Preparation of fermented green dough:
[0113] Mixing: Take 500 g of wheat flour and the yeast treatment solution (270 g) obtained in step (1), and mix them in a mixer at a medium speed of 240 r / min for 3 min and then at a low speed of 120 r / min for 2 min;
[0114] Dividing and forming: divide the dough into 300 g each and manually knead into a ball to obtain green dough.
[0115] Freeze-thaw treatment of green dough: freeze at a temperature of -40 °C for 2 h, then store at -18 °C for 1 d, and finally thaw at 5 °C for 10 h, which is 1 freeze-thaw cycle. Perform 1, 3 freeze-thaw cycles, respectively, to obtain frozen green dough.
[0116] Fresh dough: directly use after dividing without freezing treatment.
[0117] Determination of gas production: Refer to GB / T 20886.1-2021 to conduct the experiment by using the drainage method. 300g of dough after freeze-thaw cycle is immediately put into a wide-mouth bottle, and the wide-mouth bottle is put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000mL of drainage liquid is connected. Record the drainage amount at 2h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0118] Example 6:
[0119] A method for preparing a fermented green dough:
[0120] (1) Yeast treatment liquid: 240mL of deionized water is added with 17.5g of xylitol and 5g of semi-dry yeast, and the mixture is uniformly mixed to obtain the yeast treatment liquid;
[0121] (2) Preparation of fermented green dough:
[0122] Mixing: 500g of wheat flour and the yeast treatment liquid (262.5g) obtained in step (1) are mixed in a dough mixer at a medium speed of 240r / min for 3min and then at a low speed of 120r / min for 2min;
[0123] Divide and shape: the dough is divided into 300g each and hand-kneaded into a round shape to obtain the green dough.
[0124] Freeze-thaw treatment of green dough: freeze at a temperature of-40℃ for 2h, then store at-18℃ for 1d, and finally thaw at 5℃ for 10h, which is one freeze-thaw cycle. Respectively, 1, 3 freeze-thaw cycles are carried out to obtain the frozen green dough.
[0125] Fresh dough: directly used after division without freeze-thaw treatment.
[0126] Determination of gas production: Refer to GB / T 20886.1-2021 to conduct the experiment by using the drainage method. 300g of dough after freeze-thaw cycle is immediately put into a wide-mouth bottle, and the wide-mouth bottle is put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000mL of drainage liquid is connected. Record the drainage amount at 2h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0127] Example 7:
[0128] A method for preparing a fermented green dough:
[0129] (1) Yeast treatment liquid: 240mL of deionized water is added with 17.5g of xylitol and 5g of semi-dry yeast, and the mixture is uniformly mixed to obtain the yeast treatment liquid;
[0130] (2) Preparation of fermented green dough:
[0131] Mixing: Take 500g of wheat flour and the yeast treatment liquid (270g) obtained in step (1), and mix them in a dough mixer at a medium speed of 240r / min for 3min and then at a low speed of 120r / min for 2min.
[0132] Divide and shape: Divide the dough into 300g each and manually knead and round them to obtain the green dough.
[0133] Freeze-thaw treatment of the green dough: freeze at a temperature of -40℃ for 2h, then store at -18℃ for 1d, and finally thaw at 5℃ for 10h, which is one freeze-thaw cycle, and perform 1, 3 freeze-thaw cycles respectively to obtain the frozen green dough.
[0134] Fresh dough: directly used after division without freeze-thaw treatment.
[0135] Measurement of gas production: refer to GB / T 20886.1-2021 to perform the experiment by the drainage method. Put 300g of the dough after freeze-thaw cycle into a wide-mouth bottle immediately, and put the wide-mouth bottle into a constant-temperature water bath at 30℃, and connect a reagent bottle containing 2000mL of drainage liquid. Record the drainage volume at 2h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0136] Example 8:
[0137] A method for preparing a fermented green dough comprises the following steps:
[0138] (1) Yeast treatment liquid: add 17.5g of sorbitol and 5g of semi-dry yeast to 240mL of deionized water, and mix uniformly to obtain the yeast treatment liquid;
[0139] (2) Preparation of the fermented green dough:
[0140] Mixing: Take 500g of wheat flour and the yeast treatment liquid (262.5g) obtained in step (1), and mix them in a dough mixer at a medium speed of 240r / min for 3min and then at a low speed of 120r / min for 2min.
[0141] Divide and shape: Divide the dough into 300g each and manually knead and round them to obtain the green dough.
[0142] Freeze-thaw treatment of the green dough: freeze at a temperature of -40℃ for 2h, then store at -18℃ for 1d, and finally thaw at 5℃ for 10h, which is one freeze-thaw cycle, and perform 1, 3 freeze-thaw cycles respectively to obtain the frozen green dough.
[0143] Fresh dough: directly used after division without freeze-thaw treatment.
[0144] Determination of gas production: Refer to GB / T 20886.1-2021 to conduct the experiment by using the drainage method. 300g of dough after freeze-thaw cycle is immediately put into a wide-mouth bottle, and the wide-mouth bottle is put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000mL of drainage liquid is connected. Record the drainage amount at 2h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0145] Example 9:
[0146] A method for preparing a fermented green dough:
[0147] (1) Yeast treatment solution: 25.0g sorbitol and 5g semi-dry yeast are added to 240mL of deionized water, and the mixture is uniformly mixed to obtain a yeast treatment solution;
[0148] (2) Preparation of fermented green dough:
[0149] Mixing: 500g of wheat flour and the yeast treatment solution (270g) obtained in step (1) are mixed in a dough mixer at a medium speed of 240r / min for 3min and then at a low speed of 120r / min for 2min;
[0150] Divide and shape: the dough is divided into 300g each and hand-kneaded into a round shape to obtain a green dough.
[0151] Freeze-thaw treatment of green dough: freeze at a temperature of -40℃ for 2h, then store at -18℃ for 1d, and finally thaw at 5℃ for 10h, which is one freeze-thaw cycle. Perform 1, 3 freeze-thaw cycles respectively to obtain frozen green dough.
[0152] Fresh dough: directly used after division without freeze-thaw treatment.
[0153] Determination of gas production: Refer to GB / T 20886.1-2021 to conduct the experiment by using the drainage method. 300g of dough after freeze-thaw cycle is immediately put into a wide-mouth bottle, and the wide-mouth bottle is put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000mL of drainage liquid is connected. Record the drainage amount at 2h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0154] Comparative Example 4:
[0155] A method for preparing a fermented green dough:
[0156] Refer to Example 4, replace the amount of erythritol in step (1) with 0mg, and other conditions remain unchanged.
[0157] (1) Yeast treatment solution: 5g of semi-dry yeast is added to 240mL of deionized water, and the mixture is uniformly mixed to obtain a yeast treatment solution;
[0158] (2) Fermented green dough preparation: same as Example 4.
[0159] Freeze-thaw treatment of green dough: freeze at -40℃ for 2h, then store at -18℃ for 1d, and finally thaw at 5℃ for 10h, which is one freeze-thaw cycle. Respectively, 1, 3 freeze-thaw cycles were carried out to obtain frozen green dough.
[0160] Fresh dough: directly used after division without freeze treatment.
[0161] Gas production measurement: refer to GB / T 20886.1-2021 to carry out the experiment by drainage method. 300g dough after freeze-thaw cycle was immediately put into a wide-mouth bottle, and the wide-mouth bottle was put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000mL drainage liquid was connected. Record the drainage volume at 2h, which is the CO2 gas production of the dough, and is recorded as the fermentation power of the yeast.
[0162] The yeast gas production of fermented green dough with different freeze-thaw treatments in Examples 4-9 and Comparative Example 4 is shown in Table 2. Figures 7-13
[0163] Table 2 CO2 production (mL) of fermented green dough with different freeze-thaw treatments
[0164] Sample Fresh dough Dough frozen and thawed once Dough frozen and thawed three times Example 4 890 773 653 Example 5 723 663 623 Example 6 927 767 650 Example 7 867 667 610 Example 8 1040 750 723 Example 9 963 660 653 Comparative Example 4 1120 763 580
[0165] Comparative Example 5
[0166] A method for improving freeze-thaw tolerance of yeast:
[0167] Referring to Example 1, erythritol in step (1) is replaced with an equal amount of food-grade ethanol solution, and the others remain unchanged:
[0168] (1) Ethanol solution preparation (A solution): 350mg ethanol was added to 10mL deionized water in a centrifuge tube, and mixed well to obtain an ethanol solution with a volume fraction of 3.5wt%.
[0169] (2) Yeast suspension preparation (B solution): 1g semi-dry yeast was added to 10mL deionized water and stirred to mix well to obtain a yeast suspension with a concentration of 0.1g / mL.
[0170] (3) Mixing of A solution and B solution: 0.1mL B solution was added to A solution, and mixed well. After incubation and culture for 30min, freeze-thaw cycle treatment was carried out.
[0171] Freeze-thaw tolerance test:
[0172] Freeze-thaw cycle treatment: the mixture was frozen at -40℃ for 1 h, then thawed in a water bath at 30℃ for 30 min, which was 1 freeze-thaw cycle, and 1, 2, 3 freeze-thaw cycles were carried out respectively. Fresh sample: the mixture was mixed uniformly and used directly without freezing treatment.
[0173] Observation and counting: 0.05% methylene blue staining solution was mixed with yeast suspension at a volume ratio of 1:10, observed under a 400x optical microscope and counted.
[0174] Calculation formula: Yeast cell survival rate (%) = (number of viable cells stained) / (total number of cells) x 100%.
[0175] A method for preparing a fermented green dough:
[0176] (1) Yeast treatment solution: 17.5 mL of food grade anhydrous ethanol and 5 g of semi-dry yeast were added to 240 mL of deionized water, and the yeast treatment solution was obtained after mixing uniformly;
[0177] (2) Preparation of fermented green dough:
[0178] Mixing: 500 g of wheat flour and the yeast treatment solution obtained in step (1) were mixed in a dough mixer at a medium speed of 240 r / min for 3 min and then at a low speed of 120 r / min for 2 min;
[0179] Divide and shape: the dough was divided into 300 g each and hand-kneaded into a round shape to obtain a green dough.
[0180] Performance determination:
[0181] Freeze-thaw treatment of green dough: frozen at -40℃ for 2 h, then stored at -18℃ for 1 d, and finally thawed at 5℃ for 10 h, which was 1 freeze-thaw cycle, and 1, 3 freeze-thaw cycles were carried out respectively. Fresh dough: used directly after division without freezing treatment.
[0182] Determination of gas production: the experiment was carried out according to GB / T 20886.1-2021 by drainage method. 300 g of dough after freeze-thaw cycle was immediately put into a wide-mouth bottle, and the wide-mouth bottle was put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000 mL of drainage liquid was connected. Record the drainage volume at 2 h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0183] The results are shown in Table 3.
[0184] Table 3 Yeast cell survival rate and fermented green dough yeast CO2 production results
[0185]
[0186] Comparative Example 6
[0187] A method for improving freeze-thaw tolerance of yeast:
[0188] Referring to Example 1, erythritol in step (1) is replaced by an equivalent amount of other polyols (as shown in Table 4), and the rest remains unchanged:
[0189] (1) Preparation of polyol solution (A solution): 350 mg of polyol is added to 10 mL of deionized water in a centrifuge tube, and the mixture is mixed well to obtain a polyol solution with an addition amount of 3.5 wt%.
[0190] (2) Preparation of yeast suspension (B solution): 1 g of semi-dry yeast (available from Angel Yeast Co., Ltd., Yichang, Hubei Province) is added to 10 mL of deionized water, and the mixture is stirred and mixed well to obtain a yeast suspension with a concentration of 0.1 g / mL (equivalent to 10 wt%).
[0191] (3) Mixing of A solution and B solution: 0.1 mL of B solution is added to 10 mL of A solution, and the mixture is mixed well and incubated at room temperature for 30 min. The yeast suspension after incubation is subjected to freeze-thaw cycle treatment, and the freeze-thaw tolerance of the yeast is tested.
[0192] Freeze-thaw tolerance test:
[0193] Freeze-thaw cycle treatment: the mixture is frozen at -40°C for 1 h, and then thawed in a water bath at 30°C for 30 min, which is 1 freeze-thaw cycle. Fresh samples are used directly after mixing without freezing treatment.
[0194] Observation and counting: 0.05% methylene blue dye solution is mixed with the yeast suspension at a ratio of 1:10, and observed and counted under a 400x optical microscope.
[0195] Calculation formula: Yeast cell survival rate (%) = (number of viable cells with dye rejection / total cell number) x 100%.
[0196] A method for preparing a fermented raw dough:
[0197] (1) Yeast treatment solution: 17.5 g of other polyols and 5 g of semi-dry yeast are added to 240 mL of deionized water, and the mixture is mixed well to obtain a yeast treatment solution;
[0198] (2) Preparation of fermented raw dough:
[0199] Mixing: 500 g of wheat flour and the yeast treatment solution obtained in step (1) are mixed in a dough mixer at a medium speed of 240 r / min for 3 min and then at a low speed of 120 r / min for 2 min;
[0200] Divide the dough into 300 g each piece and hand-knead into a ball to obtain the green dough.
[0201] Performance determination:
[0202] Freeze-thaw treatment of the green dough: freeze at a temperature of -40℃ for 2h, then freeze at -18℃ for 1d, and finally thaw at 5℃ for 10h, which is one freeze-thaw cycle, and the freeze-thaw cycle is 1, 3 times respectively. Fresh dough: directly used after division without freezing treatment.
[0203] Determination of gas production: refer to GB / T 20886.1-2021 to carry out the experiment by the drainage method. 300 g of dough after freeze-thaw cycle is immediately put into a wide-mouth bottle, and the wide-mouth bottle is put into a constant temperature water bath at 30℃, and a reagent bottle containing 2000 mL of drainage liquid is connected. Record the drainage volume at 2h, which is the amount of CO2 gas produced by the dough, and is recorded as the fermentation power of the yeast.
[0204] The results are shown in Table 4.
[0205] Table 4 Yeast cell survival rate and fermentation of green dough
[0206]
[0207] From the above examples and the control example, it can be seen that the yeast treated by the culture solution containing polyol can improve the freeze-thaw tolerance of the yeast, so that the yeast can still maintain good activity after freeze-thaw. Figures 1-13 As can be seen from Tables 1-4, when not subjected to freezing treatment, the addition of polyol affects the metabolic pathway of yeast cells, resulting in changes in the metabolic pathway of yeast, which can cause the yeast cell survival rate and CO2 production to decrease slightly compared with the control group (not treated with polyol). However, after freeze-thaw treatment, compared with the ethanol treatment group and the untreated control group, the yeast cell survival rate and CO2 production of the polyol treatment group of the present application are significantly improved. Therefore, the polyol treatment method of the present application improves the freeze-thaw tolerance of the yeast, so that the dough can still maintain better gas production after freeze-thaw, and the frozen green dough with good fermentation power is prepared.
[0208] The above examples provided are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the present application in combination with existing common knowledge, which also falls within the protection scope defined by the claims of the present application.
Claims
1. A method of improving freeze-thaw tolerance of yeast, characterized in that, The method is to modify the yeast in a culture solution containing polyol to improve the freeze-thaw tolerance of the yeast.
2. The method of claim 1, wherein, The culture solution containing polyol also contains pure water and / or yeast culture medium.
3. The method of claim 1, wherein, The concentration of polyol in the culture solution is 0.5wt%-20.0wt%.
4. The method of claim 1, wherein, The method is to mix the yeast solution with the culture solution containing polyol; the concentration of the yeast solution is 0.1wt%-20.0wt%.
5. The method of claim 1, wherein, The polyol is selected from any one or more of erythritol, xylitol, sorbitol, maltitol, mannitol, lactitol and other polyol compounds.
6. The method of claim 1, wherein, The modification treatment is carried out at a temperature of 0℃-45℃ for 0.1h-24h.
7. A method for preparing a high freeze-tolerance yeast, characterized by, The method for preparing the yeast with high freeze-thaw tolerance is to suspend the yeast in pure water to form a yeast solution, and then mix the yeast solution with a culture solution containing polyol to form a yeast treatment mixture.
8. A method of making a fermented frozen dough characterized in that, The method comprises the following steps: (1) mixing yeast, polyol and dispersion system to perform modification treatment to obtain a yeast treatment solution; (2) mixing the obtained yeast treatment solution with wheat flour to form a dough, rolling the dough to make it uniform and smooth, and then cutting and shaping, and then performing pre-fermentation, freeze-thawing to obtain a frozen raw dough.
9. The frozen raw dough obtained by the method of claim 8.
10. The application of the frozen raw dough of claim 8 in the processing of frozen dough products.