A kind of fermentation method of high-quality fermented bean curd

Abstract

The present invention belongs to the field of food, and specifically relates to a fermentation method for high-quality fermented bean curd. The present invention prepares high-quality fermented bean curd with high content of esters, aldehydes and ketones, alcohols, acids, phenols, amino acids and peptides by making tofu white base, pre-fermentation, rubbing, lactic acid bacteria fermentation, pickling and post-fermentation. The present invention selects Lactobacillus reuteri, Lactobacillus germanium and Lactobacillus acidophilus from Lactobacillus bulgaricus, Lactobacillus germanium, Lactobacillus fermentation, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus plantarum, Bifidobacterium adolescentis, Bifidobacterium longum and Lactococcus lactis, and combines them with Actinobacillus elegans for fermentation, reduces the content of salt and liquor in the fermented bean curd, reduces the influence of high salt on post-fermentation in the prior art, and can significantly improve the quality of the fermented bean curd. The present invention optimizes the ratio of Lactobacillus reuteri, Lactobacillus germanium and Lactobacillus acidophilus, so that the content of amino acids and peptides in the fermented bean curd is higher.

Description

[0001] The invention belongs to the field of food, and particularly relates to a fermentation method for high-quality fermented bean curd. Background Art

[0002] Fermented bean curd, also known as moldy tofu, is made from soybeans through a process such as pulping to make tofu, which is then pressed and cut into small pieces of tofu white blanks, inoculated with fungi such as Mucor and Rhizopus, or bacteria such as Micrococcus luteus and Bacillus subtilis for pre-fermentation, rubbed, salted, marinated with soup, and filled into jars, sealed, and fermented.

[0003] The unique nutrition and flavor of fermented bean curd are formed during the fermentation and storage process. It is mainly due to the complex enzyme systems such as proteases and lipases produced by fungi such as Mucor and Rhizopus, or bacteria such as Micrococcus luteus and Bacillus subtilis during the fermentation process, as well as the nucleotides carried by the bacteria themselves. They work synergistically to form a variety of alcohols, organic acids, esters, aldehydes, ketones, etc. These trace components, together with artificially added spices and liquor, constitute the very special aroma of fermented bean curd. The fermented bean curd prepared by the prior art generally has low content of alcohols, organic acids, esters, aldehydes, and ketones, insufficient flavor, or low content of amino acids and peptides, resulting in low overall quality of the fermented bean curd. In order to improve the quality of fermented bean curd, the prior art already has the method of combining fermentation of different fungi such as Mucor and Rhizopus, or combining fermentation of Mucor and bacteria to improve the quality of fermented bean curd.

[0004] After searching, it is found that the prior art already has the combined fermentation of fungi and bacteria to prepare fermented bean curd, such as CN 112772849A discloses the preparation of fermented bean curd by combined fermentation of Mucor racemosus and Lactobacillus plantarum, CN 111972498A discloses the preparation of fermented bean curd by combined fermentation of Actinobacillus elegans, Monascus, Aspergillus oryzae and Enterococcus faecalis, CN101283772A discloses the preparation of fermented bean curd by combined fermentation of mold and lactic acid bacteria, and the document (“Research on Production Technology of Fully Fermented Fermented Bean Curd”, Shao Wei, et al., China Brewing, Issue 2, 2002) discloses the preparation of fermented bean curd by combined fermentation of Lactobacillus bulgaricus, Streptococcus thermophilus and Mucor racemosus.

[0005] It can be seen that the method of preparing fermented bean curd in the prior art is only to ferment molds and lactic acid bacteria in combination, and the mold is not the most common and mature Actinobacillus elegans for fermentation of fermented bean curd, but Mucor racemosus; the effect of the addition time of Actinobacillus elegans and lactic acid bacteria, and the combination of Actinobacillus elegans and different lactic acid bacteria on the quality of fermented bean curd is not studied. The present invention ferments the most common and mature Actinobacillus elegans for fermentation of fermented bean curd with different lactic acid bacteria, and systematically studies the effect of fermentation of different lactic acid bacteria and Actinobacillus elegans on the flavor and nutrition of fermented bean curd, thereby screening out the combination of Lactobacillus reuteri, Lactobacillus delbrueckii, Lactobacillus acidophilus and Actinobacillus elegans, optimizing the ratio of Lactobacillus reuteri, Lactobacillus delbrueckii and Lactobacillus acidophilus, and the prepared fermented bean curd has high flavor components such as esters, aldehydes and ketones, alcohols, acids, phenols, and high content of nutrients such as amino acids and peptides, and is a high-quality fermented bean curd with broad industrial application prospects. Summary of the invention

[0006] The present invention provides a high-quality fermented bean curd fermentation method, comprising the following steps:

[0007] 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks;

[0008] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 4 CFU / g-1×10 7 CFU / g of the spore suspension of Actinobacillus elegans, fermented at 18-25°C for 1.5-2.5 days;

[0009] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0010] 4) Lactic acid bacteria fermentation: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 4 CFU / g-1×10 7 CFU / g of lactic acid bacteria suspension, fermented at 28-32°C for 1.5 days; the lactic acid bacteria suspension consists of: Lactobacillus reuteri, Lactobacillus delbrueckii and Lactobacillus acidophilus;

[0011] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5-100:5. Pickle for 5-7 days to obtain salted tofu.

[0012] 6) Post-fermentation: bottle the salted tofu, pour the prepared soup into the bottle and cover the salted tofu, seal it and ferment it at a constant temperature of 23-28° C. for 40-60 days until it is mature; the soup contains 8%-12% of liquor, which is adjusted to an alcohol content of 15% vol with water before use.

[0013] Furthermore, the mass ratio of Lactobacillus reuteri:Lactobacillus delbrueckii:Lactobacillus acidophilus is 2:1:1.

[0014] Furthermore, the concentration of the uniformly sprayed bacterial suspension is 1×10 4 CFU / g of Actinobacillus elegans spore suspension, fermented at 28°C for 1.5 days.

[0015] Furthermore, the concentration of the uniformly sprayed bacterial suspension is 1×10 7 CFU / g of Actinobacillus elegans spore suspension, fermented at 25°C for 3 days.

[0016] Furthermore, the concentration of the uniformly sprayed bacterial suspension is 1×10 5 CFU / g of Actinobacillus elegans spore suspension, fermented at 20°C for 2 days.

[0017] Furthermore, the concentration of the bacterial suspension uniformly sprayed in the tofu blank is 1×10 5 CFU / g lactic acid bacteria suspension was fermented at 30°C for 2 days.

[0018] Furthermore, the concentration of the bacterial suspension uniformly sprayed in the tofu blank is 1×10 7 CFU / g of lactic acid bacteria suspension was fermented at 32°C for 1.5 days.

[0019] Furthermore, the mass fraction ratio of the tofu blank to the salt is controlled to be 100:2.5, and the tofu blank is pickled for 5 days in total.

[0020] Furthermore, the mass fraction ratio of the tofu blank to the salt is controlled to be 100:5, and the tofu blank is pickled for 7 days in total.

[0021] Furthermore, the soup is mature after fermentation at a constant temperature of 25° C. for 45 days; and the soup contains 8% of liquor.

[0022] High-quality fermented bean curd prepared by any of the aforementioned methods.

[0023] Another aspect of the present invention provides a method for fermenting high-quality fermented bean curd, comprising the following steps:

[0024] 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks;

[0025] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×104 CFU / g-1×10 7 CFU / g of the spore suspension of Actinobacillus elegans, fermented at 18-25°C for 1.5-2.5 days;

[0026] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0027] 4) Lactic acid bacteria fermentation: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 4 CFU / g-1×10 7 CFU / g of lactic acid bacteria suspension, fermented at 28-32°C for 1.5 days; the lactic acid bacteria suspension consists of: Lactobacillus reuteri, Lactobacillus delbrueckii and Lactobacillus acidophilus;

[0028] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5-100:5. Pickle for 5-7 days to obtain salted tofu.

[0029] 6) Post-fermentation: the salted bean curd is bottled, and the prepared soup is poured into the bottle to cover the salted bean curd, and then sealed and fermented at a constant temperature of 23-28° C. for 40-60 days to mature; the soup contains 8%-12% of liquor and rapeseed oil, and the liquor is adjusted to an alcohol content of 15% vol with water before use to make oil-fermented bean curd.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention selects Lactobacillus reuteri, Lactobacillus delbrueckii and Lactobacillus acidophilus from Lactobacillus bulgaricus, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus plantarum, Bifidobacterium adolescentis, Bifidobacterium longum and Lactococcus lactis to ferment in combination. The fermented bean curd with Lactobacillus reuteri and Actinobacillus elegans has the highest content of alcohols, aldehydes and ketones, and also has high content of esters and phenols; the fermented bean curd with Lactobacillus delbrueckii and Actinobacillus elegans has the highest content of esters; the fermented bean curd with Lactobacillus acidophilus and Actinobacillus elegans has the highest content of acids and phenols, which can significantly improve the quality of the fermented bean curd.

[0032] (2) Compared with the single fermentation of Lactobacillus reuteri, Lactobacillus delbrueckii or Lactobacillus acidophilus and R. euphausiae (two bacteria), the combined fermentation of Lactobacillus reuteri, Lactobacillus delbrueckii or Lactobacillus acidophilus and R. euphausiae (four bacteria) can significantly increase the content of esters, aldehydes, ketones, alcohols, acids and phenols in fermented bean curd under the same concentration and parameters. The possible reason is that the combination of bacteria such as Lactobacillus reuteri, Lactobacillus delbrueckii, Lactobacillus acidophilus and the fungus R. euphausiae produces more enzymes such as protease and lipase, and the bacterial and fungal enzymes complement each other.

[0033] (3) The present invention optimizes the ratio of Lactobacillus reuteri, Lactobacillus delbrueckii, and Lactobacillus acidophilus, so that the content of amino acids and peptides in fermented fermented bean curd is relatively high. The possible reason is that the fermentation of Lactobacillus reuteri, Lactobacillus delbrueckii, Lactobacillus acidophilus and Actinobacillus elegans in a specific ratio produces more enzymes such as protease, and at the same time quickly reduces the pH in the tofu blank, so that the pickling and post-fermentation are carried out in a low-salt, low-alcohol environment, which greatly reduces the inhibition of protease activity by high salt, high alcohol, etc. Therefore, the protease activity is relatively high, which greatly promotes the hydrolysis of protein in the fermented bean curd into amino acids and peptides, strengthens the nutrition of the fermented bean curd, and improves the quality of the fermented bean curd.

[0034] (4) After the tofu blank is prepared by fermentation with Actinomucor elegantis, a combination of multiple lactic acid bacteria is used for fermentation to produce a large amount of organic acid, thereby significantly reducing the pH of the tofu blank. The low pH environment can significantly inhibit the growth of miscellaneous bacteria, thereby reducing the content of salt and liquor during pickling and post-fermentation. Generally, 10%-20% salt and 13%-15% liquor are required for fermentation to prepare fermented bean curd. The salt content of the fermented bean curd of the present invention is as low as 2.5g / 100g. The low-salt environment can reduce the inhibitory effect of salt on microorganisms and complex enzymes during post-fermentation, thereby increasing the content of enzyme systems such as protease produced by post-fermentation fungi and bacteria, enhancing protease activity, increasing protein degradation in fermented bean curd and the generation of amino acids and peptides, and significantly improving the quality of fermented bean curd. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Example 1 Contents of esters, aldehydes, ketones, alcohols, acids, phenols, etc. in fermented bean curd prepared by combined fermentation of different lactic acid bacteria and Actinobacillus elegans.

[0036] Figure 2 It is the content of peptides and amino acids in the fermented bean curd prepared by Schemes 1-4 of Example 2.

[0037] Figure 3 This is a real picture of the fermented bean curd prepared in Example 3. DETAILED DESCRIPTION

[0038] The specific implementation of the present invention is described below with reference to the accompanying drawings. The experimental methods used in the implementation examples are all conventional methods unless otherwise specified; the materials and reagents used are all commercially available unless otherwise specified.

[0039] The contents of esters, aldehydes, ketones, alcohols, acids, phenols, etc. in fermented bean curd were determined according to the method in the literature (“Study on key volatile flavor substances in Qingfang fermented bean curd”, Ma Yanli, Modern Food Science and Technology, Vol. 31, No. 5, pp. 316-321, 2015)

[0040] Peptide determination: refer to the method in the literature (“Study on the determination method of peptides in soybean peptide fermentation broth”, Shao Wei, et al., China Brewing, pp. 71-72, 2007).

[0041] Determination of total amino acid content: double indicator formaldehyde titration method was used.

[0042] Lactobacillus bulgaricus, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus plantarum, Bifidobacterium adolescentis, Bifidobacterium longum, and Lactococcus lactis were purchased from Hubei Mingtuo Biotechnology Co., Ltd.

[0043] Example 1 Effect of combined fermentation of different lactic acid bacteria and Actinobacillus elegans on the quality of fermented bean curd

[0044] 1) Making tofu blank: using soybean as raw material to make small pieces of tofu blank;

[0045] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 5 CFU / g of Actinobacillus elegans spore suspension, fermented at 20°C for 2 days;

[0046] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0047] 4) Lactic acid bacteria fermentation: The tofu blank was divided into 10 portions, 1 portion was used as a blank control, and the remaining 9 portions were evenly sprayed with a bacterial suspension at a concentration of 1×10 5 CFU / g of Lactobacillus bulgaricus, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus plantarum, Bifidobacterium adolescentis, Bifidobacterium longum, and Lactococcus lactis. 10 portions of tofu blanks were fermented at 30°C for 2 days;

[0048] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5. Pickle for 5 days to obtain salted tofu.

[0049] 6) Post-fermentation: bottle the salted tofu, then pour the prepared soup into the bottle and cover the salted tofu, seal it and ferment it at a constant temperature of 25° C. for 45 days until it is mature; the soup contains 8% liquor, and the alcohol content of the liquor is adjusted to 15% vol with water before use.

[0050] The contents of esters, aldehydes, ketones, alcohols, acids, phenols, etc. in fermented bean curd obtained by combining different lactic acid bacteria with Actinomucor elegantis were determined by referring to the literature (“Study on Key Volatile Flavor Compounds in Qingfang Fermented Bean Curd”, Ma Yanli, Modern Food Science and Technology, Vol. 31, No. 5, pp. 316-321, 2015). The specific results are as follows: Figure 1 shown.

[0051] According to the attached Figure 1 It can be seen that the fermented bean curd fermented by Lactobacillus reuteri and Actinobacillus elegans has the highest content of alcohols, aldehydes and ketones, and the content of esters and phenols is also relatively high; the fermented bean curd fermented by Lactobacillus delbrueckii and Actinobacillus elegans has the highest content of esters; the fermented bean curd fermented by Lactobacillus acidophilus and Actinobacillus elegans has the highest content of acids and phenols. Therefore, in order to prepare high-quality fermented bean curd and make the esters, aldehydes and ketones, alcohols, acids and phenols in the fermented bean curd higher, Lactobacillus reuteri, Lactobacillus delbrueckii, Lactobacillus acidophilus and Actinobacillus elegans are selected to ferment and prepare fermented bean curd.

[0052] Example 2 Effect of different lactic acid bacteria ratios on the quality of fermented bean curd

[0053] 1) Making tofu blank: using soybean as raw material to make small pieces of tofu blank;

[0054] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 5 CFU / g of Actinobacillus elegans spore suspension, fermented at 20°C for 2 days;

[0055] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0056] 4) Lactic acid bacteria fermentation: Divide the tofu blank into 4 portions and evenly spray the tofu blank with the bacterial suspension of schemes 1-4 at a concentration of 1×10 5 CFU / g bacterial suspension was fermented at 30°C for 2 days;

[0057] Scheme 1: Lactobacillus reuteri: Lactobacillus germanium: Lactobacillus acidophilus = 1:1:1

[0058] Scheme 2: Lactobacillus reuteri: Lactobacillus germanium: Lactobacillus acidophilus = 2:1:1

[0059] Scheme 3: Lactobacillus reuteri: Lactobacillus germanium: Lactobacillus acidophilus = 1:2:1

[0060] Scheme 4: Lactobacillus reuteri: Lactobacillus germanium: Lactobacillus acidophilus = 1:1:2

[0061] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5. Pickle for 5 days to obtain salted tofu.

[0062] 6) Post-fermentation: bottle the salted tofu, then pour the prepared soup into the bottle and cover the salted tofu, seal it and ferment it at a constant temperature of 25° C. for 45 days until it is mature; the soup contains 8% liquor, and the alcohol content of the liquor is adjusted to 15% vol with water before use.

[0063] The contents of esters, aldehydes, ketones, alcohols, acids and phenols in fermented bean curd prepared with different lactic acid bacteria ratios were determined by referring to the method of Example 1. The specific results are shown in Table 1:

[0064] Table 1 Contents of esters, aldehydes, ketones, alcohols, acids and phenols in fermented bean curd prepared with different lactic acid bacteria ratios

[0065] Esters (μg / g) Aldehydes and ketones (μg / g) Alcohols (μg / g) Acids (μg / g) Phenols (μg / g) Solution 1 44.05±0.57 30.94±0.46 49.15±0.74 38.25±0.66 18.58±0.51 Solution 2 48.94±0.69 34.01±0.53 54.36±0.85 41.04±0.72 23.97±0.41 Solution 3 42.79±0.82 29.61±0.67 52.04±0.77 35.94±0.34 17.85±0.37 Solution 4 37.35±0.45 26.13±0.74 44.26±0.39 39.37±0.48 20.05±0.56

[0066] As can be seen from Table 1, schemes 1-4 of Example 2, i.e., the combination of Lactobacillus reuteri, Lactobacillus delbrueckii, Lactobacillus acidophilus and Actinobacillus elegans (four bacteria), can significantly increase the content of esters, aldehydes, ketones, alcohols, acids and phenols in fermented bean curd under the same concentration and parameters, and scheme 2, i.e., the combination of Lactobacillus reuteri: Lactobacillus delbrueckii: Lactobacillus acidophilus in a mass ratio of 2:1:1 and Actinobacillus elegans, has the highest content of esters, aldehydes, ketones, alcohols, acids and phenols in fermented bean curd.

[0067] The content of peptides and amino acids in the fermented bean curd prepared by Schemes 1-4 was further determined, which is also an indicator of the quality of the fermented bean curd. Figure 2 shown.

[0068] From the attached Figure 2 It can be seen that the content of amino acids and peptides in fermented bean curd in scheme 2, i.e., the mass ratio of Lactobacillus reuteri: Lactobacillus delbrueckii: Lactobacillus acidophilus = 2:1:1, is higher than that of Actinomyces elegans.

[0069] The possible reason for the above results is that the combined fermentation of Lactobacillus reuteri, Lactobacillus delbrueckii, Lactobacillus acidophilus and Actinomucor elegans in a specific ratio produces more enzymes such as protease and lipase, and quickly reduces the pH in the tofu blank, so that the pickling and post-fermentation are carried out in a low-salt, low-alcohol environment, which greatly reduces the inhibition of protease activity by high salt and high alcohol. Therefore, the protease activity is relatively high, which greatly promotes the hydrolysis of protein in fermented bean curd into amino acids and peptides, thereby enhancing the nutrition of fermented bean curd and improving the quality of fermented bean curd.

[0070] Example 3

[0071] 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks;

[0072] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 5 CFU / g of Actinobacillus elegans spore suspension, fermented at 20°C for 2 days;

[0073] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0074] 4) Lactic acid bacteria fermentation: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 5 CFU / g of lactic acid bacteria suspension, fermented at 30°C for 2 days; the lactic acid bacteria suspension composition is: Lactobacillus reuteri: Lactobacillus delbrueckii: Lactobacillus acidophilus mass ratio = 2:1:1;

[0075] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5. Pickle for 5 days to obtain salted tofu.

[0076] 6) Post-fermentation: bottle the salted tofu, then pour the prepared soup into the bottle and cover the salted tofu, seal it and ferment it at a constant temperature of 25° C. for 45 days until it is mature; the soup contains 8% liquor, and the alcohol content of the liquor is adjusted to 15% vol with water before use.

[0077] Comparative Example 1: The only difference from Example 3 is that step 4) is omitted, and the rest is the same as Example 3.

[0078] Results: The fermented bean curd prepared in comparative example 1 has become corrupt. The possible reason is that in step 4), multiple lactic acid bacteria fermentation can produce a large amount of organic acid, thereby significantly reducing the pH of the tofu blank. The low pH environment can significantly inhibit the growth of miscellaneous bacteria, thereby reducing the content of salt and liquor in pickling and post-fermentation. Generally, 10%-20% of salt and 13%-15% of liquor are required for fermentation to prepare fermented bean curd. Without step 4), the pH of the tofu blank cannot be reduced by fermentation. Under the conditions of low salt and low liquor in step 5) pickling and step 6) post-fermentation, miscellaneous bacteria grow slowly and the fermented bean curd slowly becomes corrupt and deteriorates.

[0079] Comparative Example 2: The difference from Example 3 is that the lactic acid bacteria combination in step 4) is used in the process of preparing tofu base in step 1), and the pH of the soy milk is lowered by fermentation with the lactic acid bacteria combination to make the soy milk coagulate and prepare tofu base, and step 4) is omitted, which is a process involved in a similar document ("Research on the Production Technology of Fully Fermented Fermented Bean Curd", Shao Wei, et al., China Brewing, Issue 2, 2002).

[0080] The amino acid and peptide contents of the tofu prepared in Comparative Example 2 were 2258.46 mg / 100 g and 1812.07 mg / 100 g, respectively. The possible reason is that the pH of the tofu blank prepared by the combined fermentation of lactic acid bacteria is low, which partially inhibits the growth and metabolism of Actinomucor elegans. Therefore, the protease produced by the metabolism of the fungus Actinomucor elegans is partially inhibited, and the protease content is reduced. In addition, the protease produced during the fermentation to prepare the tofu blank is partially inactivated after a series of operations such as subsequent pressing and cutting, and the total enzyme activity is reduced.

[0081] Comparative Example 3: The difference from Example 3 is that step 4) is incorporated into step 2), that is, lactic acid bacteria and Actinobacillus elegans are inoculated simultaneously for pre-fermentation.

[0082] The contents of amino acids and peptides in the tofu prepared in Comparative Example 3 were 2035.21 mg / 100 g and 1756.58 mg / 100 g, respectively. The possible reason is that the optimal growth temperature of the fungus Actinomucor elegantis is about 16°C-25°C, and the fermentation temperature in step 2) is 20°C, which is suitable for the growth of Actinomucor elegantis, but not for the growth of lactic acid bacteria. The optimal temperature for lactic acid bacteria fermentation is generally 28°C-35°C. Therefore, at a fermentation temperature of 20°C, lactic acid bacteria cannot grow and metabolize rapidly to produce a large amount of complex enzyme systems such as proteases.

[0083] Example 4

[0084] 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks;

[0085] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 5 CFU / g of Actinobacillus elegans spore suspension, fermented at 20°C for 2 days;

[0086] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0087] 4) Lactic acid bacteria fermentation: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 5 CFU / g of lactic acid bacteria suspension, fermented at 30°C for 2 days; the lactic acid bacteria suspension composition is: Lactobacillus reuteri: Lactobacillus delbrueckii: Lactobacillus acidophilus mass ratio = 2:1:1;

[0088] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5. Pickle for 5 days to obtain salted tofu.

[0089] 6) Post-fermentation: the salted bean curd is bottled, and the prepared soup is poured into the bottle to cover the salted bean curd, and then sealed and fermented at a constant temperature of 25° C. for 45 days to mature; the soup contains 8% of liquor and rapeseed oil, and the liquor is used after adjusting the alcohol content to 15% vol with water to make oil-fermented bean curd.

[0090] Example 5

[0091] 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks;

[0092] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 7 CFU / g of Actinobacillus elegans spore suspension, fermented at 25°C for 1.5 days;

[0093] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0094] 4) Lactic acid bacteria fermentation: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 7 CFU / g of lactic acid bacteria suspension, fermented at 32°C for 1.5 days; the lactic acid bacteria suspension composition is: Lactobacillus reuteri: Lactobacillus delbrueckii: Lactobacillus acidophilus mass ratio = 2:1:1;

[0095] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass ratio of tofu to salt to be 100:5. Pickle for 7 days to obtain salted tofu.

[0096] 6) Post-fermentation: bottle the salted tofu, then pour the prepared soup into the bottle and cover the salted tofu, seal it and ferment it at a constant temperature of 28° C. for 40 days until it is mature; the soup contains 10% liquor, and the alcohol content of the liquor is adjusted to 15% vol with water before use.

[0097] Example 6

[0098] 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks;

[0099] 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 4 CFU / g of Actinobacillus elegans spore suspension, fermented at 18°C ​​for 2.5 days;

[0100] 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank;

[0101] 4) Lactic acid bacteria fermentation: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 4 CFU / g of lactic acid bacteria suspension, fermented at 28°C for 3 days; the lactic acid bacteria suspension composition is: Lactobacillus reuteri: Lactobacillus delbrueckii: Lactobacillus acidophilus = 2:1:1;

[0102] 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5. Pickle for 6 days to obtain salted tofu.

[0103] 6) Post-fermentation: bottle the salted tofu, then pour the prepared soup into the bottle and cover the salted tofu, seal it and ferment it at a constant temperature of 23° C. for 60 days until it is mature; the soup contains 12% liquor, and the alcohol content of the liquor is adjusted to 15% vol with water before use.

Claims

1. A method for fermenting high-quality fermented bean curd, characterized in that The steps include: 1) Making tofu blanks: using soybeans as raw materials to make small pieces of tofu blanks; 2) Pre-fermentation: Evenly spray the bacterial suspension with a concentration of 1×10 4 CFU / g-1×10 7 CFU / g of the spore suspension of Actinobacillus elegans, fermented at 18-25°C for 1.5-2.5 days; 3) Rubbing: Rub the hyphae growing on the surface of the tofu blank with your hands, break the hyphae adhering between the blocks, separate the tofu blocks, and make the hyphae tightly wrap the tofu blank to obtain the tofu blank; 4) Lactic acid bacteria fermentation: Spray the tofu blank with a bacterial suspension at a concentration of 1×10 4 CFU / g-1×10 7 CFU / g of lactic acid bacteria suspension, fermented at 28-32°C for 1.5 days; the lactic acid bacteria suspension consists of: Lactobacillus reuteri, Lactobacillus delbrueckii and Lactobacillus acidophilus; 5) Pickling: After fermentation, pickle the tofu with one layer of salt, chili powder and spices. Add salt water on the second day, and control the mass fraction ratio of tofu to salt to be 100:2.5-100:

5. Pickle for 5-7 days to obtain salted tofu. 6) Post-fermentation: the salted tofu is bottled, and the prepared soup is poured into the bottle to cover the salted tofu, sealed and fermented at a constant temperature of 23-28° C. for 40-60 days until mature; the soup contains 8%-12% liquor, which is adjusted to an alcohol content of 15% vol with water before use; The mass ratio of the Lactobacillus reuteri:Lactobacillus delbrueckii:Lactobacillus acidophilus is 2:1:

1.

2. The method for fermenting high-quality fermented bean curd according to claim 1, characterized in that: Evenly spray the bacterial suspension at a concentration of 1×10 7 CFU / g of Actinobacillus elegans spore suspension, fermented at 25℃ for 1.5 days.

3. The method for fermenting high-quality fermented bean curd according to claim 1, characterized in that: Evenly spray the bacterial suspension at a concentration of 1×10 5 CFU / g of Actinobacillus elegans spore suspension, fermented at 20°C for 2 days.

4. The method for fermenting high-quality fermented bean curd according to claim 1, characterized in that: Spray the bacterial suspension evenly in the tofu blank at a concentration of 1×10 7 CFU / g of lactic acid bacteria suspension was fermented at 32°C for 1.5 days.

5. The method for fermenting high-quality fermented bean curd according to claim 1, characterized in that: The mass fraction ratio of tofu blank to salt was controlled to be 100:2.5, and the tofu was pickled for 5 days.

6. The method for fermenting high-quality fermented bean curd according to claim 1, characterized in that: The mass fraction ratio of tofu blank to salt was controlled to be 100:5, and the tofu was pickled for 7 days in total.

7. The method for fermenting high-quality fermented bean curd according to claim 1, characterized in that: The soup is mature after fermentation at a constant temperature of 25° C. for 45 days. The soup contains 8% of liquor.

8. High-quality fermented bean curd prepared according to the method according to any one of claims 1 to 7.

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