Method for making koji and fermenting bean halves

Abstract

The invention discloses a method for koji-making fermentation of bean halves, and relates to the technical field of fermented food. Comprising the following steps: scalding broad beans, soaking and cooling to obtain pretreated broad beans; uniformly mixing the pretreated broad beans with the mixed powder and the koji essence to obtain a koji material; wherein the mixed flour comprises wheat flour and broad bean flour; performing koji-making on the koji material under the conditions that the temperature is 28-32 DEG C and the humidity is 75-85%, and turning the koji during the koji-making process to obtain broad bean koji; adding salt and water into the broad bean koji, uniformly mixing, and fermenting at the constant temperature of 37-43 DEG C for 35-45 days to obtain sweet petals; and uniformly mixing the sweet petals with the chili fermented grains, performing constant-temperature fermentation at 37-43 DEG C for 35-45 days, and performing stirring during fermentation so as to obtain the thick broad-bean sauce. The broad bean powder is used for partially replacing wheat flour for starter propagation and fermentation, so that the product is endowed with deeper color and luster and stronger sauce flavor, the broad bean paste is friendly to gluten allergy people, and the product quality of the broad bean paste is improved.

Description

Technical Field

[0001] The present application relates to the technical field of fermented foods, and in particular to a method for fermenting bean curd. Background Art

[0002] As an important component of traditional fermented condiments, bean paste is the main auxiliary material for Sichuan cuisine and is known as the "soul of Sichuan cuisine". The preparation of bean paste is based on red pepper and broad bean as the main raw materials, edible salt, wheat flour, etc. as auxiliary materials, and is brewed through stages such as koji making, sweet bud fermentation, and pepper fermentation. Bean paste has the advantages of mellow fragrance, sweet aftertaste, bright red and oily, which is a significant feature different from other condiments. However, the raw material wheat flour for fermentation of bean paste contains gluten, which will cause indigestion to some consumers, and even allergic reactions in severe cases. In addition, there are still problems such as long fermentation cycle, lighter color of sweet bud, and weak flavor of bean paste in the industrial production of bean paste. Based on this, the present application proposes a method for fermentation of bean paste. Summary of the invention

[0003] The main purpose of the present application is to provide a method for fermenting fermented soybeans, aiming to solve the technical problem that the existing raw materials and processes for fermenting soybeans need to be improved.

[0004] To achieve the above object, the present application proposes a method for fermenting bean curd, comprising the following steps:

[0005] The broad beans are blanched, soaked and cooled to obtain pre-treated broad beans;

[0006] The pretreated broad beans are mixed with mixed flour and koji extract to obtain koji material; wherein the mixed flour comprises wheat flour and broad bean flour;

[0007] The koji material is made under the conditions of temperature of 28-32° C. and humidity of 75-85%, during which the koji is turned over to obtain broad bean koji;

[0008] Add salt and water to the broad bean koji, mix well, and ferment at a constant temperature of 37-43° C. for 35-45 days to obtain sweet bean peels;

[0009] The sweet bean paste is mixed evenly with the chili fermented rice, and then fermented at a constant temperature of 37-43° C. for 35-45 days, with stirring during the fermentation, to obtain the bean paste.

[0010] Optionally, the step of blanching the broad beans and then soaking and cooling them to obtain pretreated broad beans comprises:

[0011] The broad beans are blanched in 90-95°C water for 20-30 seconds, then taken out and filtered, and then soaked in 40-50°C water for 100-120 seconds, then taken out and filtered to obtain pretreated broad beans.

[0012] Optionally, in the step of uniformly mixing the pretreated broad beans with the mixed powder and the koji extract to obtain the koji material, the mass ratio of the pretreated broad beans to the mixed powder is 10:(3-4), and the mass ratio of the pretreated broad beans to the koji extract is 1:(2.5×10 -7 -3.0×10 -7 ).

[0013] Optionally, the mass ratio of wheat flour to broad bean flour in the mixed flour is (0.5-2):1.

[0014] Optionally, the mass ratio of wheat flour to broad bean flour in the mixed flour is 1:1.

[0015] Optionally, the step of making koji with the koji material at a temperature of 28-32° C. and a humidity of 75-85% comprises:

[0016] The koji material is spread out so that the layer height of the koji material does not exceed 13-17 cm, and the koji is made in an incubator at a temperature of 28-32° C. and a humidity of 75-85% for 65-75 hours.

[0017] Optionally, before the koji making step, the moisture content of the koji material is controlled between 28% and 32%.

[0018] Optionally, the step of turning the song includes:

[0019] The first turn of the song is carried out at the 18th hour of koji making, and the second turn of the song is carried out at the 32nd hour of koji making.

[0020] Optionally, in the step of adding salt and water to the broad bean koji, the mass ratio of the broad bean koji to the salt and water is 1000:(330-350):1100.

[0021] Optionally, in the step of uniformly mixing the sweet peel and the chili fermented pepper, the sweet peel and the chili fermented pepper are uniformly stirred in a mass ratio of (3-4): (6-7).

[0022] This application includes at least the following beneficial effects:

[0023] The present application utilizes broad bean flour to partially replace wheat flour for koji making and fermentation. The amino acid content in broad bean flour accounts for about 20% of the total amount, of which 8 are essential amino acids for the human body, and the total amount of these 8 essential amino acids accounts for about 9-10% of the total amount of amino acids. Among them, the content of isoleucine, leucine, lysine, phenylalanine, threonine and valine is relatively rich, especially the content of lysine is more than twice that of wheat flour, and lysine is one of the substrates of Maillard reaction. Adding broad bean flour with richer lysine content can increase the concentration of Maillard reaction substrate, giving the product a darker color and richer flavor. Compared with the traditional process of using only wheat flour for koji making and fermentation, after broad bean flour partially replaces wheat flour for koji making and fermentation, the egg content in the koji making process is reduced. The activity of white enzyme is stronger, and the content of amino acid nitrogen and free amino acids in the fermentation process of sweet bean paste is higher, which makes the sweet bean paste rich in nutrients and rich flavor, and promotes higher red index and free amino acid content in the subsequent mixed fermentation stage with chili mash, thereby improving the redness of the bean paste and enriching the nutritional diversity of the bean paste, making the obtained bean paste have a prominent sauce aroma and a delicious and strong taste. At the same time, the types of volatile flavor substances in the bean paste have basically not changed. Using broad bean flour to partially replace wheat flour for koji making will not change the basic flavor of the bean paste, but will give it a richer sauce flavor. At the same time, because broad bean flour does not contain gluten, it is more friendly to people with gluten allergies, thereby improving the product quality of bean paste and making its application range wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. It is obvious that the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 The present invention is a schematic diagram of the process of fermentation of bean curd described in the embodiments of the present application.

[0026] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] In view of the technical problems existing in the prior art, the embodiments of the present application provide a method for fermenting bean curd, such as Figure 1 As shown, the following steps are included:

[0029] The broad beans are blanched, soaked and cooled to obtain pre-treated broad beans;

[0030] The pretreated broad beans are mixed with mixed flour and koji extract to obtain koji material; wherein the mixed flour comprises wheat flour and broad bean flour;

[0031] The koji material is made under the conditions of temperature of 28-32° C. and humidity of 75-85%, during which the koji is turned over to obtain broad bean koji;

[0032] Add salt and water to the broad bean koji, mix well, and ferment at a constant temperature of 37-43° C. for 35-45 days to obtain sweet bean peels;

[0033] The sweet bean paste is mixed evenly with the chili fermented rice, and then fermented at a constant temperature of 37-43° C. for 35-45 days, with stirring during the fermentation, to obtain the bean paste.

[0034] The present application utilizes broad bean flour to partially replace wheat flour for koji making and fermentation. The amino acid content in broad bean flour accounts for about 20% of the total amount, of which 8 are essential amino acids for the human body, and the total amount of these 8 essential amino acids accounts for about 9-10% of the total amount of amino acids. Among them, the content of isoleucine, leucine, lysine, phenylalanine, threonine and valine is relatively rich, especially the content of lysine is more than twice that of wheat flour, and lysine is one of the substrates of Maillard reaction. Adding broad bean flour with richer lysine content can increase the concentration of Maillard reaction substrate, giving the product a darker color and richer flavor. Compared with the traditional process of using only wheat flour for koji making and fermentation, after broad bean flour partially replaces wheat flour for koji making and fermentation, the egg content in the koji making process is reduced. The activity of white enzyme is stronger, and the content of amino acid nitrogen and free amino acids in the fermentation process of sweet bean paste is higher, which makes the sweet bean paste rich in nutrients and rich flavor, and promotes higher red index and free amino acid content in the subsequent mixed fermentation stage with chili mash, thereby improving the redness of the bean paste and enriching the nutritional diversity of the bean paste, making the obtained bean paste have a prominent sauce aroma and a delicious and strong taste. At the same time, the types of volatile flavor substances in the bean paste have basically not changed. Using broad bean flour to partially replace wheat flour for koji making will not change the basic flavor of the bean paste, but will give it a richer sauce flavor. At the same time, because broad bean flour does not contain gluten, it is more friendly to people with gluten allergies, thereby improving the product quality of bean paste and making its application range wider.

[0035] As an implementable method of the present application, the step of blanching broad beans, soaking and cooling to obtain pretreated broad beans comprises:

[0036] The broad beans are blanched in 90-95°C water for 20-30 seconds, then taken out and filtered, and then soaked in 40-50°C water for 100-120 seconds, then taken out and filtered to obtain pretreated broad beans.

[0037] By blanching the broad beans and controlling the blanching time to maintain at 20-30 seconds, most bacteria can be quickly killed to enhance the fermentation advantage of mold in the subsequent koji and reduce contamination from other bacteria.

[0038] As an implementation method of the present application, in the step of uniformly mixing the pretreated broad beans with the mixed powder and the koji essence to obtain the koji material, the mass ratio of the pretreated broad beans to the mixed powder is 10:(3-4), and the mass ratio of the pretreated broad beans to the koji essence is 1:(2.5×10 -7 -3.0×10 -7 ).

[0039] Preferably, when the mass ratio of pretreated broad beans to mixed powder is 10:3, it can ensure that the bean paste has a rich taste and moderate texture; koji can play a role in fermentation and seasoning in the production of bean paste. In this application, the mass ratio of pretreated broad beans to mixed powder is 1:3.0×10 -7 It can effectively promote the decomposition of protein in broad beans, produce rich amino acids and flavor substances, and thus enhance the aroma and taste of bean paste.

[0040] As an implementable method of the present application, the mass ratio of wheat flour to broad bean flour in the mixed flour is (0.5-2):1.

[0041] As an implementable method of the present application, the mass ratio of wheat flour to broad bean flour in the mixed flour is 1:1. If broad bean flour completely replaces wheat flour, it will cause serious adhesion of sweet flakes, which is not conducive to fermentation. When the proportion of broad bean flour added is small, the activity of broad bean koji protease is not high enough, which will affect the content of amino acid nitrogen and free amino acids in the subsequent sweet flakes fermentation stage and mixed fermentation stage. The present application preferably uses a 1:1 mixing ratio of wheat flour and broad bean flour for koji fermentation. The obtained broad bean koji has high protease activity in each stage, which is beneficial to improve the product quality of sweet flakes and bean flakes.

[0042] As an implementation method of the present application, the step of making koji at a temperature of 28-32° C. and a humidity of 75-85% comprises:

[0043] The koji material is spread out so that the layer height of the koji material does not exceed 13-17 cm, and the koji is made in an incubator at a temperature of 28-32° C. and a humidity of 75-85% for 65-75 hours.

[0044] By controlling the height of the koji material to no more than 13-17cm, it is beneficial to the growth of Aspergillus microorganisms, and the koji is made in an environment with a temperature of 28-32℃ and a humidity of 75-85%. When making koji in an environment with a certain humidity, appropriate moisture can absorb the heat generated during the fermentation process, help regulate the fermentation temperature, and prevent the temperature from being too high, thereby maintaining a stable fermentation environment and ensuring the normal fermentation of the koji material, so as to avoid the risk of burning the koji due to high temperature during the koji making process, which can not only ensure the softness of the koji material, but also prevent agglomeration.

[0045] As an implementable method of the present application, before the step of making koji, the moisture content of the koji material is controlled between 28% and 32%. In the process of making koji, since moisture is an important medium for completing biochemical reactions such as protein decomposition and starch conversion in the process of making koji, controlling the moisture content of the koji material can promote the activity of enzymes, thereby accelerating the fermentation process of the koji material and improving the efficiency of making koji. Too much moisture will cause the koji material to agglomerate, affecting ventilation and the growth of microorganisms. Too little moisture will make the koji material too dry, affecting the activity of enzymes and the fermentation effect of the koji material. Controlling the moisture content is crucial to maintaining the looseness and air permeability of the koji material. Therefore, the present application controls the moisture content of the koji material between 28% and 32% before making koji.

[0046] As an implementable embodiment of the present application, the step of turning the song includes:

[0047] The first turn of the song is carried out at the 18th hour of koji making, and the second turn of the song is carried out at the 32nd hour of koji making.

[0048] The present application conducts turning over the koji at the 18th and 32nd hour of koji making, which is beneficial to loosen the koji material and reduce the temperature. Too high temperature will affect the enzyme production ability and cause the reproduction of miscellaneous bacteria. By turning over the koji, the temperature and moisture of each part can be adjusted to make the quality of the koji tend to be consistent, and oxygen can be supplemented, carbon dioxide can be discharged, and the normal life activities of Aspergillus microorganisms can be promoted, thereby promoting the production of enzymes such as protease, amylase, and lipase. These enzymes degrade macromolecules into polypeptides and free amino acids, thereby improving the quality of bean paste.

[0049] As an implementable embodiment of the present application, in the step of adding salt and water to the broad bean koji, the mass ratio of the broad bean koji to the salt and water is 1000:(330-350):1100.

[0050] Preferably, the mass ratio of broad bean koji to salt and water is 1000:342.3:1100. The choice of salt water ratio has an important influence on the growth of microorganisms and the quality of the product. High salinity can inhibit the growth of miscellaneous bacteria, but it will also affect the fermentation rate of sweet petals and the product flavor. Low salt conditions are conducive to increasing the fermentation rate and producing more organic acids and amino acid nitrogen and other substances, but may cause the total acid content to be too high, affecting the quality of sweet petals. After testing, the present application uses a mass ratio of broad bean koji to salt and water of 1000:342.3:1100, which can balance the flavor of the product while ensuring that the growth of miscellaneous bacteria is inhibited.

[0051] As an implementation method of the present application, in the step of uniformly mixing the sweet peels and the chili fermented pepper, the sweet peels and the chili fermented pepper are uniformly stirred in a mass ratio of (3-4): (6-7).

[0052] Preferably, when the sweet bean paste and the chili fermented pepper are mixed in a mass ratio of 3:7, the obtained bean paste has a strong sauce aroma and unique flavor, and has a darker color.

[0053] The above technical solution of the present application is described in detail below in conjunction with specific embodiments.

[0054] Example 1

[0055] A method for fermenting fermented soybeans, comprising the following steps:

[0056] The broad beans were blanched in 90°C water for 26 seconds, then taken out and filtered, and then soaked in 45°C water for 110 seconds, then taken out and filtered to obtain pretreated broad beans;

[0057] 1000 g of the pretreated broad beans are mixed evenly with 300 g of mixed flour and 0.0003 g of koji essence to obtain koji material; wherein the mixed flour includes 150 g of wheat flour and 150 g of broad bean flour;

[0058] The moisture content of the koji material is controlled between 30%, the koji material is spread out so that the koji material layer height does not exceed 15 cm, and the koji is made in an incubator at a temperature of 30° C. and a humidity of 80% for 65 hours, the koji is turned over for the first time at the 18th hour of the koji making, and the koji is turned over for the second time at the 32nd hour of the koji making, to obtain broad bean koji;

[0059] After bean koji, salt and water are mixed evenly in a mass ratio of 1000:342.3:1100, the mixture is fermented at a constant temperature of 40°C for 40 days to obtain sweet bean sprouts;

[0060] The sweet bean paste and the chili fermented pepper are evenly mixed in a mass ratio of 3:7, and then fermented at a constant temperature of 40° C. for 40 days, during which the fermentation is stirred every day, to obtain the bean paste.

[0061] Example 2

[0062] A method for fermenting fermented soybeans, comprising the following steps:

[0063] The broad beans were blanched in 95°C water for 20 seconds, then taken out and filtered, and then soaked in 40°C water for 120 seconds, then taken out and filtered to obtain pretreated broad beans;

[0064] 1000 g of the pretreated broad beans are mixed evenly with 300 g of mixed flour and 0.0003 g of koji essence to obtain koji material; wherein the mixed flour includes 200 g of wheat flour and 100 g of broad bean flour;

[0065] The moisture content of the koji material is controlled between 28%, the koji material is spread out so that the koji material layer height does not exceed 13 cm, and the koji is made in an incubator at a temperature of 32° C. and a humidity of 75% for 70 hours, the koji is turned over for the first time at the 18th hour of the koji making, and the koji is turned over for the second time at the 32nd hour of the koji making, to obtain broad bean koji;

[0066] After bean koji, salt and water are mixed evenly in a mass ratio of 1000:330:1100, the mixture is fermented at a constant temperature of 37°C for 40 days to obtain sweet bananas;

[0067] The sweet bean paste and the chili fermented pepper are stirred and mixed evenly in a mass ratio of 3:7, and then fermented at a constant temperature of 37° C. for 45 days, during which the fermentation is stirred every day, to obtain the bean paste.

[0068] Example 3

[0069] A method for fermenting fermented soybeans, comprising the following steps:

[0070] The broad beans were blanched in 90°C water for 30 seconds, then taken out and filtered, and then soaked in 50°C water for 100 seconds, then taken out and filtered to obtain pretreated broad beans;

[0071] 1000 g of the pretreated broad beans are mixed evenly with 300 g of mixed flour and 0.0003 g of koji essence to obtain koji material; wherein the mixed flour includes 100 g of wheat flour and 200 g of broad bean flour;

[0072] The moisture content of the koji material is controlled between 32%, the koji material is spread out so that the koji material layer height does not exceed 17 cm, and the koji is made in an incubator at a temperature of 28° C. and a humidity of 85% for 75 hours, the koji is turned over for the first time at the 18th hour of the koji making, and the koji is turned over for the second time at the 32nd hour of the koji making, to obtain broad bean koji;

[0073] After bean koji, salt and water are mixed evenly in a mass ratio of 1000:350:1100, the mixture is fermented at a constant temperature of 43°C for 40 days to obtain sweet bean cakes;

[0074] The sweet bean paste and the chili fermented pepper are stirred and mixed evenly in a mass ratio of 4:6, and then fermented at a constant temperature of 43° C. for 35 days, during which the fermentation is stirred every day, to obtain the bean paste.

[0075] Comparative Example

[0076] Compared with Example 1, 300 g of mixed flour was replaced with 300 g of wheat flour, and the other steps remained unchanged.

[0077] Experimental example

[0078] (I) Detection of protease activity during the koji making stage of broad bean

[0079] Referring to the detection method in the national standard "GB / T 23527-2009 Protease Preparation", the activity changes of the protease in the koji making stage of broad bean koji in Examples 1-3 and the comparative example were detected. The detection results are shown in Table 1 below.

[0080] Table 1 Changes in protease activity during koji making

[0081] Making time (h) Example 1 (U / g) Example 2 (U / g) Example 3 (U / g) Comparative Example (U / g) 24 40.86 34.69 27.38 10.96 48 344.52 211.22 332.56 311.87 65 385.42 266.60 366.05 257.61

[0082] As can be seen from Table 1, compared with the comparative example, the protease activity of the embodiment group in which broad bean powder was added during the koji making process was higher at each stage, among which, when the mixing ratio of wheat flour and broad bean powder was 1:1, the protease activity of broad bean koji was the highest.

[0083] (II) Detection of changes in total acid and pH at each fermentation stage

[0084] The total acid content in each fermentation stage in Example 1 and the comparative example was measured with reference to the detection method in the national standard "Determination of total acid in food GB 12456-2021", and the pH value in each fermentation stage in Example 1 and the comparative example was measured with reference to the detection method in the national standard "Determination of pH value of food GB 5009.237-2016". The test results are shown in Tables 2 and 3 below.

[0085] Table 2 Changes of total acid in each fermentation stage

[0086]

[0087] Table 3 pH changes at various fermentation stages

[0088]

[0089] It can be seen from Tables 2 and 3 that for the whole fermentation process, as the fermentation time goes by, both the comparative example and Example 1 groups show a trend of increasing total acid and decreasing pH, with slight fluctuations during the fermentation process. Compared with the comparative example group, the use of mixed powder to make koji will increase the total acid in the sweet vanilla fermentation stage and the mixed fermentation stage, and make the pH lower.

[0090] (III) Detection of changes in amino acid nitrogen content at each fermentation stage

[0091] The amino acid nitrogen content in each fermentation stage in Example 1 and the comparative example was tested with reference to the detection method in the national standard "GB 5009.235-2016 Determination of Amino Acid Nitrogen in Food", and the test results are shown in Table 4 below.

[0092] Table 4 Changes of amino acid nitrogen content in each fermentation stage

[0093]

[0094] As can be seen from Table 4, with the progress of fermentation, the amino acid nitrogen content of both the comparative example and Example 1 groups showed an increasing trend; at each stage of fermentation, the amino acid nitrogen content of Example 1 group was higher than that of the comparative example group, indicating that adding broad bean powder to koji can improve the quality of sweet bean paste and bean paste semi-finished products.

[0095] (IV) Detection of changes in the total content of free amino acids at each fermentation stage

[0096] The total content of free amino acids in each fermentation stage in Example 1 and the comparative example was tested with reference to the test method in the national standard "GB 5009.124-2016 Determination of Amino Acids in Foods". The test results are shown in Table 5 below.

[0097] Table 5 Changes in total free amino acid content at each fermentation stage

[0098]

[0099] As can be seen from Table 5, the total content of free amino acids in both the comparative example and Example 1 showed a trend of increasing with the extension of fermentation time; at each stage of fermentation, the total content of free amino acids in Example 1 was higher than that in the comparative example group, and the changing trend of the total content of free amino acids was consistent with the changing trend of the amino acid nitrogen content as a whole, indicating that adding broad bean powder to koji making can improve the nutritional diversity of sweet bean paste and bean paste semi-finished products.

[0100] (V) Detection of changes in free amino acid content at different fermentation stages

[0101] The free amino acid contents at different fermentation stages in Example 1 and the comparative example were detected with reference to the detection method in the national standard "GB 5009.124-2016 Determination of Amino Acids in Foods". The free amino acids included L-lysine, L-threonine, L-methionine, L-valine, L-leucine, L-phenylalanine and L-isoleucine. The test results are shown in Tables 6 and 7 below.

[0102] Table 6 The content of free amino acids in the fermentation stage of sweet banana

[0103]

[0104]

[0105] Table 7 Content of free amino acids in mixed fermentation stage

[0106]

[0107]

[0108] L-lysine, L-threonine, L-methionine, L-valine, L-leucine, L-phenylalanine and L-isoleucine are all essential amino acids for the human body, L-glutamic acid, L-aspartic acid and L-proline have umami and sour taste, L-alanine, L-glycine and L-lysine have umami and sweet taste, L-histidine, L-serine and L-threonine have sweet taste, L-arginine, L-methionine and L-valine have bitter taste and sweet taste, L-leucine, L-phenylalanine, L-tyrosine and L-isoleucine have bitter taste. As can be seen from Tables 6 and 7, compared with the comparative example group, the content of each free amino acid in the embodiment 1 group is higher, indicating that the sauce flavor of the sweet and bean curd in the embodiment group is more prominent, and the taste is more delicious and rich. It can be seen that the addition of broad bean powder as a koji-making raw material is beneficial to increase the content of flavoring substances in the sweet and bean curd.

[0109] (VI) Detection of types of volatile flavor substances

[0110] Referring to the detection method of volatile flavor substances in the literature "Chen Jing, Ren Tian, ​​Zhao Zilong, et al. Aroma components and sensory evaluation of Pixian bean paste [J]. Food and Machinery, 2024, 40(04): 34-39. DOI: 10.13652 / j.spjx.1003.5788.2023.80662.", the types of volatile flavor substances in Example 1 and the comparative example at 30 days of mixed fermentation were detected. The volatile flavor substances with OAV ≥ 1 were classified, and the types of volatile flavor substances in the two groups at 30 days of mixed fermentation are shown in Table 8 below.

[0111] Table 8 Types of volatile flavor substances at 30 days of mixed fermentation

[0112] Types of volatile flavor substances Example 1 Comparative Example ester 27 29 Terpenes 24 25 aldehyde 18 18 ketone 17 17 Heterocyclic compounds 16 16 phenol 14 12 alcohol 14 13 Aromatics 3 3 Sulfur compounds 3 3 Nitrogen compounds 2 3 acid 2 2 ether 2 2 Halogenated hydrocarbons 2 2 amine 1 1 Total number of types 146 147

[0113] As can be seen from Table 8, at the end of fermentation, the types of volatile flavor substances in the two groups of bean curd were consistent, and only the quantities of some categories of compounds were different, indicating that adding broad bean flour to partially replace wheat flour in koji making will not have a significant impact on the basic flavor of the bean curd.

[0114] (VII) Detection of changes in the red index during the fermentation stage of sweet potato

[0115] With reference to the method for detecting the red index in the literature "Li Feng, Feng Xia, Huang Jiaquan, et al. Optimization of process conditions for improving the quality of Pixian bean curd sweet bean curd [J]. China Brewing, 2021, 40(06): 58-64.", the red index of the sweet bean curd fermentation stage of Example 1 and the comparative example was detected, and the test results are shown in Table 9 below.

[0116] Table 9 Changes of red index during the fermentation stage of sweet potato

[0117] Fermentation time (d) Example 1 Comparative Example 0 1.35 1.34 10 1.40 1.36 20 1.63 1.44 30 2.29 2.05 40 2.38 2.16

[0118] As can be seen from Table 9, the red index reflects the depth of the sample color. With the extension of fermentation time, both groups showed an increasing trend of the red index. During the fermentation process of the sweet banana, the red index of the Example 1 group was higher than that of the comparative example group, indicating that the addition of broad bean powder to make koji and fermentation is beneficial to the color change of the sweet banana as soon as possible and improves the redness of the sweet banana.

[0119] The above description is only an optional embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structural transformations made by using the contents of the present application specification and drawings under the inventive concept of the present application, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A method for fermenting bean curd, characterized in that: The following steps are involved: The broad beans are blanched, soaked and cooled to obtain pre-treated broad beans; The pretreated broad beans are mixed with mixed flour and koji extract to obtain koji material; wherein the mixed flour comprises wheat flour and broad bean flour; The koji material is made under the conditions of temperature of 28-32° C. and humidity of 75-85%, during which the koji is turned over to obtain broad bean koji; Add salt and water to the broad bean koji, mix well, and ferment at a constant temperature of 37-43° C. for 35-45 days to obtain sweet bean peels; The sweet bean paste is mixed evenly with the chili fermented rice, and then fermented at a constant temperature of 37-43° C. for 35-45 days, with stirring during the fermentation, to obtain the bean paste.

2. The method for fermenting fermented soybeans according to claim 1, characterized in that: The step of blanching the broad beans and then soaking and cooling them to obtain pre-treated broad beans comprises: The broad beans are blanched in 90-95°C water for 20-30 seconds, then taken out and filtered, and then soaked in 40-50°C water for 100-120 seconds, then taken out and filtered to obtain pretreated broad beans.

3. The method for fermenting fermented soybeans according to claim 1, characterized in that: In the step of uniformly mixing the pretreated broad beans with the mixed powder and the koji extract to obtain the koji material, the mass ratio of the pretreated broad beans to the mixed powder is 10:(3-4), and the mass ratio of the pretreated broad beans to the koji extract is 1:(2.5×10 -7 -3.0×10 -7 ).

4. The method for fermenting fermented soybeans according to claim 1, characterized in that: The mass ratio of wheat flour to broad bean flour in the mixed flour is (0.5-2):

1.

5. The method for fermenting fermented soybeans according to claim 4, characterized in that: The mass ratio of wheat flour to broad bean flour in the mixed flour is 1:

1.

6. The method for fermenting fermented soybeans according to claim 1, characterized in that: The step of making koji with the koji material at a temperature of 28-32° C. and a humidity of 75-85% comprises: The koji material is spread out so that the layer height of the koji material does not exceed 13-17 cm, and the koji is made in an incubator at a temperature of 28-32° C. and a humidity of 75-85% for 65-75 hours.

7. The method for fermenting fermented soybeans according to claim 1, characterized in that: Before the koji making step, the moisture content of the koji material is controlled between 28% and 32%.

8. The method for fermenting fermented soybeans according to claim 1, characterized in that: The step of turning the song comprises: The first turn of the song is carried out at the 18th hour of koji making, and the second turn of the song is carried out at the 32nd hour of koji making.

9. The method for fermenting fermented soybeans according to claim 1, characterized in that: In the step of adding salt and water to the broad bean koji, the mass ratio of the broad bean koji to the salt and water is 1000:(330-350):1100.

10. The method for fermenting fermented soybeans according to claim 1, characterized in that: In the step of uniformly mixing the sweet peel and the chili fermented pepper, the sweet peel and the chili fermented pepper are uniformly mixed in a mass ratio of (3-4): (6-7).

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