CN110881529A - Fermented bean curd with fermented soya beans and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of food, and particularly relates to fermented bean curd with fermented soya beans and a preparation method thereof. The invention relates to fermented bean curd making by fermented bean prepared from soy sauce koji, which comprises the steps of preparing koji powder, making fermented bean, making salted bean curd blank, sealing a bottle, solarizing for fermentation, maturing and the like. According to the invention, a novel compound seasoning novel process for brewing fermented bean curd is researched, so that novel fermented bean curd is developed, fermented beans and fermented bean curd are fused and supplemented with each other, the flavor of the traditional fermented bean curd is enriched, and the prepared fermented bean curd is unique in flavor, sufficient in fragrance, fine, smooth and soft in taste by utilizing the synergistic fermentation of aspergillus, yeast, lactobacillus and other microorganisms in soy sauce koji.

Description

Fermented bean curd with fermented soya beans and preparation method thereof

Technical Field

The invention belongs to the field of food, and particularly relates to fermented bean curd with fermented soya beans and a preparation method thereof.

Background

The fermented bean curd is also called fermented bean curd, is one of the traditional fermented soybean foods in China, has the nutritional value of soybeans, is rich in protein, linoleic acid and oleic acid, and has the characteristics of delicious taste, unique flavor, rich nutrition and the like. In China, the production places of the fermented bean curd are all over the whole country, and due to different consumption habits in various places, various characteristic traditional products and local famous special products are gradually formed, and the fermented bean curd is a red fermented bean curd, a green fermented bean curd, a white fermented bean curd, a sauce fermented bean curd, a flower-color fermented bean curd and the like, and can be used independently or used for cooking dishes with unique flavor. The brewing process of various fermented bean curds is similar and different, and the fermented bean curds are generally prepared by pre-fermentation, pickling and post-fermentation of a single strain of mucor or rhizopus. The differences between various fermented bean curds mainly comprise raw materials, auxiliary materials and formulas for preparing the fermented bean curds, brewing process, surface color, flavor and the like, wherein the flavor, appearance and texture of the finished fermented bean curds are key factors for determining the quality of the fermented bean curds.

Fermented soya bean, ancient called "YouShu", is another characteristic fermented bean product flavoring in China. The beans are generally cooked and then fermented by mucor, aspergillus or bacteria, and five major products of aspergillus oryzae type, rhizopus type, mucor type, bacterial type and neurospora type are used for seasoning. The fermented soybean is rich in protein, fat and carbohydrate, contains various amino acids required by human body, and also contains various mineral substances, vitamins and other nutrient substances, and has various physiological functions. The fermented soya beans increase appetite and promote absorption by virtue of the special aroma of the fermented soya beans, and can be used for seasoning and serving as a medicine. According to the traditional Chinese medicine, the fermented soya beans are mild in nature, sweet and slightly bitter in taste, have the effects of sweating, relieving exterior syndrome, clearing heat, promoting eruption, relieving epigastric distention, relieving restlessness, dispersing stagnation and detoxifying, and can be used for treating cold, headache, chest distress, vexation, vomiting, typhoid fever, cold and heat, food poisoning and other diseases.

The bean fermented food is the focus of attention of researchers and consumers due to the special nutritive value and health care function of the bean fermented food, and the fermented bean curd and the fermented soya beans are taken as two excellent bean fermented appetizers, so that people have been constantly researching on the aspects of mature process improvement, action mechanism, microbiology and the like of the fermented bean curd and the fermented soya beans for years. Chinese patent publication No. CN107183207A discloses a process for preparing fermented bean curd, which is characterized in that soy sauce type fermented bean curd with unique flavor and uniform quality is prepared by secondary fermentation of bean curd, however, the bean curd of the process is prepared by natural mildew, the required fermentation period is longer, and the prepared fermented bean curd has single flavor.

Disclosure of Invention

The invention relates to a fermented bean curd making method by utilizing fermented bean prepared by soy sauce koji, which aims to develop novel fermented bean curd and develop soybean fermented health-care food with Chinese characteristics by researching a novel compound seasoning process for fermented bean curd brewing.

The invention aims to provide a method for making fermented bean curd, which comprises the following steps:

(1) preparing yeast powder: mixing soy sauce koji and starch adjuvant at a certain proportion to obtain koji powder;

(2) preparing fermented soya beans: selecting high-quality broad beans, peeling and cleaning, soaking, steaming, cooling, adding yeast powder according to a proportion, and uniformly mixing; ventilating the broad beans inoculated with the yeast powder to prepare yeast until the inside and outside of the broad beans are yellow green;

(3) preparing a salted bean curd blank: draining water from bean curd, cutting into blocks, salting, and collecting the brine; exposing the bean curd in the sun in the daytime, withdrawing the bean curd blocks at night, immersing the bean curd blocks in the collected brine overnight, and repeatedly exposing the bean curd blocks in the sun for stewing until the bean curd is yellow and hard;

(4) sealing the bottle and fermenting: taking a clean container, filling fermented soya beans and the salted bean curd blank layer by layer, adding 3% saline water to submerge the salted bean curd blank and the fermented soya beans, covering and sealing, and placing the container outdoors for solarization fermentation;

(5) and (3) maturing: fermenting the fermented bean curd to be basically mature, and after the fermented bean curd is qualified, finishing fermentation to obtain a fermented bean curd finished product.

Preferably, the mass ratio of the soy sauce koji to the starch auxiliary materials in the step (1) is 1: 40-1: 50, and the mass ratio of the koji powder to the broad beans in the step (2) is 1: 3-1: 4.

Preferably, the method for making the fermented soya beans in the step (2) comprises the following specific steps:

selecting high-quality broad beans, peeling and cleaning, soaking for 1-2 hours, steaming, cooling to 25-35 ℃, adding yeast powder, uniformly mixing, placing the inoculated broad beans on bamboo split discs, paving 1.0-2.5 kg of the broad beans on each disc, stacking the bamboo split discs in a fermentation room, covering wet cloth, culturing for 60-72 hours at 28 ℃, turning the discs up and down for 3-5 times according to the product temperature and the growth trend of the aspergillus during the period, opening the fermentation room for ventilation every 12 hours during the whole fermentation period, replenishing water in the space of the fermentation room after turning the discs for 36 hours of fermentation, starting opening the door to remove the cloth after fermenting for 36 hours, carrying out forced ventilation, and obtaining the mature fermented soya beans after the yeast becomes yellow green and has obvious spore growth.

Preferably, the specific method for preparing the salty blank of bean curd in the step (3) comprises the following steps:

selecting high-quality bean curd, draining, and cutting into bean curd blocks of 3 × 3 × 3 cm-4 × 4 × 4 cm; putting the cut bean curd blocks into salt grains, turning to make the surface fully adhered with the salt grains, putting the salt grains on a rice sieve in order and in a staggered way, and collecting bean curd brine exuded in the salt rolling process for later use; exposing the bean curd in the sun in the daytime, turning over bean curd blocks, taking back the bean curd at night, drying until the surface of the bean curd is dry and has a micro volume, and putting the bean curd into bean curd brine collected in a salt rolling process for standing overnight; and (4) placing the bean curd on a rice sieve for insolating the bean curd the next day, and repeatedly insolating the bean curd for stewing until the bean curd is yellow, the volume is obviously reduced, and the texture is hard, so that the salty blank of the bean curd is obtained.

Preferably, in the step (4), the concentration of the saline water is 3%, and the bottle sealing fermentation time is 30-90 days.

The invention also aims to provide fermented soya bean curd prepared by the preparation method.

After fermented for one month, the fermented soybean fermented bean curd can show slight red expansion of salty blanks of the bean curd. The bottle is opened, the bean curd blocks are slightly twisted into mud, the texture is fine, and the taste is remained after eating, so that the finished product is obtained. The salty blank of the fermented bean curd with fermented soya beans has low water content, can be subjected to long-time after-fermentation, and is more aromatic and delicious after being placed for 3 years.

Advantageous effects：

(1) The fermented bean curd is prepared by fermented bean prepared from the soy sauce koji, and is sealed and solarized under the fermentation effect of the soy sauce koji, so that the fermented bean and the fermented bean are mutually fused and supplement each other, and the prepared fermented bean curd has the fragrance of both the fermented bean and the fermented bean, and the flavor of the traditional fermented bean curd is enriched.

(2) The soy sauce koji used in the invention contains aspergillus, yeast, lactobacillus and other microorganisms, wherein the aspergillus comprises aspergillus oryzae, aspergillus niger, sweet potato aspergillus and the like, the aspergillus secretes a large amount of enzyme systems for enzymolysis of proteins in bean curd, and the enzyme systems are fermented together with the yeast and the lactobacillus in the fermented bean curd after fermentation, so that the obtained fermented bean curd has more unique flavor, has obvious advantages compared with the conventional products, is especially obvious in sauce flavor, and has more exquisite, dry and soft mouthfeel.

(3) The salty blanks of the bean curd are repeatedly dried in the sun and marinated in the night, so that the water content is low, on one hand, the fermented bean curd has a more ideal appearance and is not easy to break, and the fermented bean curd is prevented from breaking and loosening or becoming fermented bean curd milk in the transportation process; on the other hand, the fermentation period is longer, the higher quality can be kept for a longer time, and the micro-fermentation can be kept for a long time, so that the more savory and mellow taste and fragrance can be obtained.

(4) The invention adopts the process of dehydration and fermentation, and the microorganism is added after the bean curd is dehydrated, so that the requirement of the fermentation process on the surrounding environment is reduced, and better convenience and possibility are provided for large-scale and industrialization.

Drawings

FIG. 1 is a volatile matter detection diagram of fermented soybean curd prepared in example 1.

FIG. 2 is a volatile matter detection diagram of salty Henry white fermented bean curd sold on the market.

Detailed Description

The present invention will be described in more detail with reference to examples. It is to be understood that the practice of the invention is not limited to the following examples, and that any variations and/or modifications may be made thereto without departing from the scope of the invention.

In the invention, all parts and percentages are weight units, and all equipment, raw materials and the like can be purchased from the market or are commonly used in the industry, if not specified. Unless otherwise indicated, the examples employ methods that are within the ordinary skill in the art.

The soy sauce koji used in the invention is produced by Shanghai brewing factory.

Example 1

Preparing yeast powder: 1000g of flour and 20g of soy sauce koji are evenly stirred to prepare the koji powder.

Preparing fermented soya beans: 3000g of selected peeled broad beans are cleaned, soaked for 1 hour, steamed and cooled. When the temperature of the cooked broad beans is reduced to 35 ℃, 1000g of yeast powder is uniformly scattered on the broad beans and uniformly stirred, then the inoculated broad beans are placed on clean bamboo split discs, the quantity of the broad beans laid on each disc is 1.0kg, the bamboo split discs are stacked and placed in a fermentation room, wet cloth is covered, the broad beans are cultured for 60 hours at 28 ℃, the discs are inverted up and down for 3-5 times according to the product temperature and the growth situation of the aspergillus, the fermentation room is opened for ventilation every 12 hours in the whole fermentation period, water mist is sprayed on the fermentation room for supplementing water after each turning, the humidity of the fermentation room is not lower than 80% in 36 hours of fermentation, the door is opened to remove the cloth for forced ventilation after 36 hours of fermentation, the yeast material is changed into yellow green, and obvious spore growth is taken as the fermentation end point, and the cooked fermented soya beans are obtained.

Preparing a salted bean curd blank: selecting 5kg of bittern bean curd, draining off water, and cutting into 4cm bean curd blocks. Slightly putting the cut bean curd blocks into the coarse salt particles, turning to make the surfaces fully adhered with the salt particles, neatly and staggerly opening the bean curd blocks on a bamboo rice sieve, and collecting bean curd brine exuded in the salt rolling process for later use; when the weather is fine, the bean curd and the rice sieve are placed in the sun for insolation, bean curd blocks cannot be turned over, the bean curd is retracted at night, and is placed in bean curd brine collected in the salt rolling process after being sunned until the surface of the bean curd is dry and the volume is micro-reduced; and (4) placing the bean curd on a rice sieve for insolating the bean curd the next day, and repeatedly insolating the bean curd for stewing until the bean curd is yellow, the volume is obviously reduced, the texture is as hard as a stone, and the bean curd is a salty blank when the iron clanger is knocked and clanded.

Sealing the bottle and fermenting: taking a clean and dry glass bottle, laying a layer of fermented soya beans below the glass bottle, putting a salted bean blank into the glass bottle, orderly stacking the layers of the salted bean blank, staggering the layers, laying a layer of fermented soya beans on the top layer, adding 3% saline water until the fermented soya beans and the fermented soya beans are submerged, and screwing a bottle cover. And placing the sealed glass bottle outdoors for solarization fermentation.

And (3) maturing: after fermenting for 50 days, the salty blank of the bean curd turns red and slightly rises, the bottle opening attempt has obvious fragrance, the bean curd blocks are slightly twisted into mud, the texture is fine, after eating, the taste is fragrant, and the fermentation is finished.

Example 2

Preparing yeast powder: 1000g of flour and 25g of soy sauce koji are evenly stirred to prepare the koji powder.

Preparing fermented soya beans: 4000g of selected peeled broad beans are cleaned, soaked for 2 hours, steamed and cooled. When the temperature of the cooked broad beans is reduced to 27 ℃, 1000g of yeast powder is uniformly scattered on the broad beans and uniformly stirred, then the inoculated broad beans are placed on clean bamboo split discs, the quantity of the broad beans laid on each disc is 1.0kg, the bamboo split discs are stacked and placed in a fermentation room, wet cloth is covered, the broad beans are cultured for 72 hours at 28 ℃, the discs are inverted up and down for 3-5 times according to the product temperature and the growth condition of the aspergillus, the fermentation room is opened for ventilation every 12 hours in the whole fermentation period, water mist is sprayed in the fermentation room for supplementing water after each turning, the humidity of the fermentation room is not lower than 80% in 36 hours of fermentation, the door is opened to remove the cloth for forced ventilation after 36 hours of fermentation, the yeast material is changed into yellow green, and obvious spore growth is taken as the fermentation end point, and the cooked fermented soya beans are obtained.

Preparing a salted bean curd blank: selecting 5kg of bittern bean curd, draining off water, and cutting into bean curd blocks of 3cm square. Slightly putting the cut bean curd blocks into the coarse salt particles, turning to make the surfaces fully adhered with the salt particles, neatly and staggerly opening the bean curd blocks on a bamboo rice sieve, and collecting bean curd brine exuded in the salt rolling process for later use; when the weather is fine, the bean curd and the rice sieve are placed in the sun for insolation, bean curd blocks cannot be turned over, the bean curd is retracted at night, and is placed in bean curd brine collected in the salt rolling process after being sunned until the surface of the bean curd is dry and the volume is micro-reduced; and (4) placing the bean curd on a rice sieve for insolating the bean curd the next day, and repeatedly insolating the bean curd for stewing until the bean curd is yellow, the volume is obviously reduced, the texture is as hard as a stone, and the bean curd is a salty blank when the iron clanger is knocked and clanded.

Sealing the bottle and fermenting: taking a clean and dry glass bottle, laying a layer of fermented soya beans below the glass bottle, putting a salted bean blank into the glass bottle, orderly stacking the layers of the salted bean blank, staggering the layers, laying a layer of fermented soya beans on the top layer, adding 3% saline water until the fermented soya beans and the fermented soya beans are submerged, and screwing a bottle cover. And placing the sealed glass bottle outdoors for solarization fermentation.

And (3) maturing: after fermenting for 90 days, the salty blank of the bean curd turns red slightly and expands, the bottle opening attempt has obvious fragrance, the bean curd blocks are slightly twisted into mud, the texture is fine, after eating, the taste is fragrant, and the fermentation is finished.

Comparative example 1

Salty Henry white fermented bean curd (available from Shaoxing salty Henry food Co., Ltd.) sold on the market was used as comparative example 1.

Comparative example 2

1000g of flour and 20g of Aspergillus oryzae were mixed and made into yeast powder, and the other procedures were as described in example 1 to obtain fermented bean curd of comparative example 2.

Example 3

And (3) detecting volatile flavor substances in the fermented bean curd by adopting sweeping and trapping combined with a gas chromatography-mass spectrometry method, and determining the relative content (%) of each volatile substance.

1. Sampling of fermented bean curd samples

And (3) removing a needle of a 5mL medical syringe, connecting the syringe with a water phase needle filter, filtering the fermented bean curd soup base, collecting 20mL of the filtered fermented bean curd soup base in a headspace bottle, adding 20mL of ultrapure water, and fully and uniformly mixing. 20mL of commercially available salty Henry white fermented bean curd was sampled in a headspace bottle according to the same method as described above, and 20mL of ultrapure water was added thereto and sufficiently mixed.

2. Purge trap conditions

The trapping temperature is 30 ℃; purging for 20 min; blowing for 1 min; the pre-desorption temperature is 185 ℃; the desorption temperature is 190 ℃; the desorption time is 2 min; the baking temperature is 210 ℃; baking for 10 min.

3. Gas chromatography-mass spectrometry conditions

Chromatographic conditions are as follows: column TG-WAXMS (30 m.times.0.25. mu.m.times.0.25 mm); the temperature of a sample inlet is 250 ℃; temperature rising procedure: the initial temperature is 32 ℃, and the temperature is kept for 5 min; then heating to 130 ℃ at the speed of 4 ℃/min; finally, heating to 200 ℃ at the speed of 10 ℃/min; the flow rate of the carrier gas (He) was 10 mL/min.

Mass spectrum conditions: the ion source temperature is 230 ℃; the interface temperature is 250 ℃; an ionization mode: an Electron Ionization (EI) source; electron energy 70 eV; the mass scanning range is 40-350 m/z. The results are shown in the following table and in fig. 1 and 2.

TABLE 1 fermented soya beans and test results of comparative example volatile substances

From the results in table 1, the total relative content of 14 kinds of volatile flavor substances in the fermented soybean curd of example 1 is 66.190%, including 3 alcohol compounds, 3 aldehyde compounds, 3 acid compounds, 2 ketone compounds and 3 ester compounds. Wherein the relative contents of 2, 3-butanediol, 5-methylfuran aldehyde, formic acid and pyran-4-ketone are 26.266%, 7.146%, 8.892% and 7.518% respectively, which are obviously higher than other flavor substances, and the main components forming the main flavor of the fermented bean curd with fermented beans. The fermented bean curd of example 2 has similar detection results. The total relative content of volatile flavor substances in the savory white beancurd milk in the comparative example 1 is 7.343%, wherein the relative content of 3 alcohol compounds, 3 aldehyde compounds, 3 acid compounds, 2 ketone compounds and 2 ester compounds is 4.545%, 0.789%, 0.543% and 0.506% of glycerol, 5-methylfuran aldehyde, acetic acid and ethyl acetate respectively. The fermented bean curd of comparative example 2 has a total relative content of volatile flavor components of 18.41%, wherein 3 alcohol compounds, 2 aldehyde compounds, 2 acid compounds, 2 ketone compounds, and 3 ester compounds, wherein the relative contents of 2, 3-butanediol, 5-methylfuran aldehyde, glycerol, diethyl succinate, and ethyl acetate are 8.305%, 3.051%, 2.325%, 2.149%, and 1.201%, respectively, which shows that the fermented bean curd prepared by fermenting a single aspergillus oryzae has a flavor inferior to that of fermented bean curd prepared by soy sauce koji used in the present invention, and further shows that the synergistic fermentation of various microbial components in soy sauce koji makes the flavor of the obtained product more abundant. Comparative examples 1 and 2 have significantly lower volatile matter content than fermented bean curds of examples 1 and 2. The above results show that the fermented bean curd prepared by the invention has richer flavor and richer fragrance compared with the traditional white fermented bean curd.

Example 4

25 professionally trained researchers were invited to form an assessment panel to score the color, aroma, taste and texture of the fermented bean curd of example 1 and comparative example, respectively, and the average was taken by scoring. The evaluation criteria and the evaluation results are shown in tables 2 and 3.

TABLE 2 sensory evaluation criteria for fermented bean curd

TABLE 3 sensory evaluation results of fermented bean curd

Sample (I)	Color and luster	Fragrance	Taste of the product	Texture of	Total score
						Example 1	9.12	26.35	27.50	24.95	97.92
Comparative example 1	9.30	15.16	22.64	18.43	65.53
						Comparative example 2	9.08	18.50	24.05	26.10	77.73

From the above results, the sensory evaluation results of fermented bean curd prepared by the method of the present invention are significantly higher than those of comparative example 1 and comparative example 2, especially significantly better in aroma and texture than comparative example 1 and significantly better in aroma than comparative example 2. The fermented bean curd with fermented soya beans provided by the invention is fermented by utilizing the cooperation of the aspergillus, the yeast, the lactobacillus and other microorganisms in the soy sauce koji, and compared with fermented bean curd fermented by utilizing single microorganism, the fermented bean curd with fermented soya beans provided by the invention has the advantages of richer and purer fragrance, unique fermented bean curd flavor, and finer, smoother, more comfortable and more soft mouthfeel. In addition, the fermented bean curd prepared by the method has richer flavor by fermenting in a sealed and solarization manner. In addition, the salty blank of the bean curd is repeatedly dried in the sun and marinated in the night in the manufacturing process, and the water content is low, so that the preserved bean curd has a more ideal appearance, is not easy to break, and has uniform and good texture.

While the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (6)

1. The method for preparing fermented bean curd is characterized by comprising the following steps:

(1) preparing yeast powder: mixing soy sauce koji and starch adjuvant at a certain proportion to obtain koji powder;

(2) preparing fermented soya beans: selecting high-quality broad beans, peeling and cleaning, soaking, steaming, cooling, adding yeast powder according to a proportion, and uniformly mixing; ventilating the broad beans inoculated with the yeast powder to prepare yeast until the inside and outside of the broad beans are yellow green;

(3) preparing a salted bean curd blank: draining water from bean curd, cutting into blocks, salting, and collecting the brine; exposing the bean curd in the sun in the daytime, withdrawing the bean curd blocks at night, immersing the bean curd blocks in the collected brine overnight, and repeatedly exposing the bean curd blocks in the sun for stewing until the bean curd is yellow and hard;

(4) sealing the bottle and fermenting: taking a clean container, filling fermented soya beans and the salted bean curd blank layer by layer, adding salt water to submerge the salted bean curd blank and the fermented soya beans, covering and sealing, and placing the container outdoors for solarization fermentation;

(5) and (3) maturing: fermenting the fermented bean curd to be basically mature, and after the fermented bean curd is qualified, finishing fermentation to obtain a fermented bean curd finished product.

2. The manufacturing method according to claim 1, wherein the mass ratio of soy sauce koji to the starchy auxiliary material in the step (1) is 1: 40-1: 50, and the mass ratio of koji powder to broad bean in the step (2) is 1: 3-1: 4.

3. The manufacturing method of claim 1 or 2, wherein the specific method of manufacturing the fermented soybeans in the step (2) is as follows:

selecting high-quality broad beans, peeling and cleaning, soaking for 1-2 hours, steaming, cooling to 27-35 ℃, adding yeast powder, uniformly mixing, placing the inoculated broad beans on bamboo split discs, paving 1.0-2.5 kg of the broad beans on each disc, stacking the bamboo split discs in a fermentation room, covering wet cloth, culturing for 60-72 hours at 28 ℃, turning the discs up and down for 3-5 times according to the product temperature and the growth trend of the aspergillus during the period, opening the fermentation room for ventilation every 12 hours during the whole fermentation period, replenishing water in the space of the fermentation room after turning the discs for 36 hours of fermentation, starting opening the door to remove the cloth after fermenting for 36 hours, carrying out forced ventilation, and obtaining the mature fermented soya beans after the yeast becomes yellow green and has obvious spore growth.

4. The manufacturing method according to claim 1 or 2, wherein the step (3) is a specific method for manufacturing the salty blank of bean curd:

selecting high-quality bean curd, draining, and cutting into bean curd blocks of 3 × 3 × 3 cm-4 × 4 × 4 cm; putting the cut bean curd blocks into salt grains, turning to make the surface fully adhered with the salt grains, putting the salt grains on a rice sieve in order and in a staggered way, and collecting bean curd brine exuded in the salt rolling process for later use; exposing the bean curd in the sun in the daytime, turning over bean curd blocks, taking back the bean curd at night, drying until the surface of the bean curd is dry and has a micro volume, and putting the bean curd into bean curd brine collected in a salt rolling process for standing overnight; and (4) placing the bean curd on a rice sieve for insolating the bean curd the next day, and repeatedly insolating the bean curd for stewing until the bean curd is yellow, the volume is obviously reduced, and the texture is hard, so that the salty blank of the bean curd is obtained.

5. The preparation method according to claim 1, wherein the concentration of the saline water in the step (4) is 3%, and the bottle-sealing fermentation time is 30-90 days.

6. Fermented soybean fermented bean curd prepared by the preparation method according to claim 1.

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