Stinky tofu and preparation process thereof

Abstract

The present invention provides stinky tofu and a preparation technology thereof, and belongs to the technical field of food processing, and the preparation technology comprises the following steps: S1, preparation of acid water: taking Chinese yams, jujubes and radix puerariae for enzymolysis saccharification to obtain an enzymolysis product, taking poria cocos, dried orange peels and honeysuckles for water extraction to obtain a water extract, mixing the enzymolysis product with the water extract, inoculating a complex microbial inoculant, and performing fermentation to obtain the acid water; performing temperature-controlled fermentation to obtain acid water; the complex microbial inoculants are lactobacillus plantarum, streptococcus thermophilus and candida utilis; s2, preparing bean curd: cleaning, soaking and grinding soybeans, then filtering to obtain soybean milk, heating the soybean milk, adding acid water, and carrying out curdling, blank pressing and cutting to obtain bean curd blocks; s3, preparation of the stinky tofu: preparing brine, soaking the tofu blocks in the brine for standing, draining the soaked tofu blocks, frying, seasoning and packaging to obtain the stinky tofu. The invention provides the stinky tofu and the preparation process thereof, and aims of shortening the process period and increasing the flavor level of the stinky tofu are fulfilled.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to stinky tofu and a preparation process thereof. Background Art

[0002] Tofu is a nutritious food with a long history. It contains a variety of trace elements necessary for the human body and is rich in high-quality protein. Therefore, tofu is a healthy and nutritious food that is deeply loved by the public. In order to extend the shelf life of tofu, processed foods such as tofu puffs, dried tofu, stinky tofu, and fermented tofu have also been extended to increase the richness of tofu products. Among them, stinky tofu is obtained by fermenting tofu. The fermentation process mainly uses molds and yeasts to decompose and transform proteins, fats, carbohydrates and other substances in tofu to produce substances with special flavors. Therefore, it has the characteristics of "smelling stinky, but tasting delicious". At the same time, after fermentation, stinky tofu converts protein into more easily absorbed polypeptides and amino acids, retains the mineral elements in the raw soybeans, and is beneficial to maintaining the body's acid-base balance and water-electrolyte balance.

[0003] The traditional stinky tofu preparation process mainly includes tofu preparation, brine soaking, frying and other processes. Calcium sulfate (gypsum) or magnesium chloride (bitter) is used as a brine agent in the tofu preparation process. The use of different brine agents determines the basic taste of stinky tofu. The brine soaking time is long, otherwise the flavor is weak. The brine soaking determines the basic flavor of stinky tofu. The whole traditional process is not only complicated, but also time-consuming. In addition, the market is in urgent need of stinky tofu with new flavors. Summary of the invention

[0004] In view of this, the present invention provides a stinky tofu and a preparation process thereof, so as to achieve the purpose of shortening the process cycle and increasing the flavor levels of the stinky tofu.

[0005] To achieve the above object, the present invention provides a process for preparing stinky tofu, comprising the following steps: S1. Preparation of acid water: enzymatic saccharification of yam, jujube and kudzu root to obtain an enzymatic hydrolyzate, water extraction of Poria cocos, tangerine peel and honeysuckle to obtain an aqueous extract, mixing the enzymatic hydrolyzate with the aqueous extract, inoculating a composite bacterial agent, and fermenting under controlled temperature to obtain acid water; the composite bacterial agent is Lactobacillus plantarum, Streptococcus thermophilus and Candida utilis; S2. Preparation of tofu: washing, soaking, grinding and filtering soybeans to obtain soy milk, heating the soy milk, adding acid water to make the milk, pressing embryos, cutting, and obtaining tofu blocks; S3. Preparation of stinky tofu: prepare brine, soak tofu blocks in the brine and let them stand, drain the tofu blocks after soaking, fry, season and package to obtain stinky tofu.

[0006] Optionally, the enzymatic saccharification in the preparation of the acid water includes the following steps: cutting the yam and kudzu root into pieces, removing the core of the jujube, and steaming the three together at 90-100°C for 0.5-1h, adding α-amylase and cellulase after cooling, and performing enzymolysis at 55-65°C for 2-3h, and obtaining an enzymolysis product after inactivating the enzymes; the total weight of the α-amylase and cellulase accounts for 0.3% of the total weight of the yam, kudzu root and jujube, and the mass ratio of the α-amylase to the cellulase is 2:1.

[0007] Optionally, the water extraction in the preparation of the acid water includes the following steps: mixing Poria cocos, dried tangerine peel and honeysuckle with water, decocting and extracting at 75-85° C. for 0.5-1 h, and filtering to obtain a water extract.

[0008] Optionally, the inoculation amount of the composite bacterial agent is 4-5% of the total weight of the enzymatic hydrolysate and the water extract, and the weight ratio of Lactobacillus plantarum, Streptococcus thermophilus and Candida utilis is 2:1:1.

[0009] Optionally, the temperature-controlled fermentation includes aerobic fermentation and static fermentation, and firstly the fermentation is carried out under stirring at 35-37°C for 10-12 hours with a stirring speed of 100-150 rpm; then the fermentation is carried out under static condition at 28-32°C for 10-12 hours to obtain sour water.

[0010] Optionally, the preparation of the acid water includes the following raw materials in parts by weight: 20-30 parts of yam, 5-8 parts of poria, 10-15 parts of jujube, 3-6 parts of kudzu root, 1-2 parts of tangerine peel, 1-3 parts of honeysuckle, and 120-150 parts of water.

[0011] Optionally, the acid water accounts for 6-8% of the mass of the soy milk.

[0012] Optionally, the preparation of the tofu includes heating soy milk to 90-92° C. by steam, draining the soy milk, adding acid water, stirring for 10-15 seconds, and allowing the soy milk to stand until flocculent tofu curd appears.

[0013] Optionally, the frying includes placing the drained tofu cubes into an oil pan heated to 130±5°C and frying them for 5-6 minutes, then placing them into an oil pan heated to 165±5°C and continuing to fry them for 5-6 minutes to obtain fried tofu cubes.

[0014] In order to achieve the above object, the present invention also provides stinky tofu prepared by the above stinky tofu preparation process.

[0015] The above technical solution of the present invention includes at least the following beneficial effects: The stinky tofu preparation process provided by the present invention uses sour water obtained by fermenting specific ingredients in foods with medicinal and edible properties, such as mucus protein in yam, Poria cocos polysaccharide and other substances, to brines soy milk, avoiding the introduction of chemical brining agents such as gypsum or magnesium chloride, and has health-care effects and is safe and assured. In the sour water prepared by the present invention, jujube is used to provide natural sugars to neutralize the sour taste; Pueraria root is rich in Pueraria isoflavones, which has an antioxidant effect and improves the texture of tofu; limonene and other ingredients in tangerine peel inhibit bacteria and give a special flavor; chlorogenic acid in honeysuckle is an antibacterial ingredient that extends the shelf life of sour water. The sour water is obtained by fermentation of a composite strain, in which Lactobacillus plantarum produces acid to inhibit bacteria, Streptococcus thermophilus synthesizes extracellular polysaccharides to improve the water retention of tofu, and Candida utilis produces ester flavor substances, and the symbiosis of the three bacteria improves the fermentation efficiency. The tofu formed by sour water brine has high elasticity and a porous network structure is formed inside the tofu, which makes it easier to absorb the flavor during the later soaking process in the brine and shortens the soaking time. The sour water combines with the brine to form rich flavor layers, providing stinky tofu with a new flavor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a graph showing the flavor substance content of stinky tofu in Examples 1 to 3 of the present invention; Figure 2 The TPA analysis results of stinky tofu of Examples 1 to 3 of the present invention and Comparative Example 1 are shown; Figure 3 The sensory evaluation diagram of stinky tofu of Examples 1 to 3 of the present invention and Comparative Example 1 is shown.

[0017] In the figure: both the control and the control group represent Comparative Example 1. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described in combination with the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0019] Example 1 A preparation process of stinky tofu comprises the following steps: Take the following raw materials by weight: 30 parts of yam, 5 parts of Poria cocos, 15 parts of jujube, 3 parts of Pueraria root, 2 parts of dried orange peel, 1 part of honeysuckle, and 150 parts of water. Cut yam, Pueraria root and Poria cocos into pieces, and remove the core of the jujube for later use. Steam yam, Pueraria root and jujube at 90℃ for 1h, add α-amylase and cellulase after cooling to room temperature, and enzymolyze at 55℃ for 3h. The total weight of α-amylase and cellulase accounts for 0.3% of the total weight of yam, Pueraria root and jujube, and the mass ratio of α-amylase and cellulase is 2:1. After the enzymolysis is completed, the enzyme is inactivated to obtain the enzymolysis product. Poria cocos, dried orange peel and honeysuckle are decocted and extracted with water at 85℃ for 0.5h, and filtered to obtain the water extract. The enzymatic hydrolysate and the water extract were mixed and inoculated with a composite bacterial agent, the inoculation amount of which was 5% of the total weight of the enzymatic hydrolysate and the water extract, and the weight ratio of Lactobacillus plantarum, Streptococcus thermophilus and Candida utilis was 2:1:1. After inoculation with the composite bacterial agent, aerobic fermentation was carried out in a fermentation tank, the temperature was maintained at 35°C, the fermentation was stirred, the fermentation time was 10h, and the stirring speed was 150rpm; after the aerobic fermentation was completed, the fermentation was allowed to stand at 28°C for 10h to obtain acid water.

[0020] The soybeans were washed twice, cleaned, and mixed with water in a mass ratio of 1:8, and soaked in water at 15°C for 12 hours. After soaking, the soybeans increased in weight to 2.4 times; the soybeans and water were poured into a pulping machine (the screen in the pulping machine was 100 mesh), and the pulp was polished twice. The mixed soybean milk was passed through an 80-mesh screen, and the soybean milk concentration was 9 Brix; after filtering the soybean milk, the soybean milk was heated to 92°C with steam, and the steam was stopped, and the pulp was discharged. After cooling to room temperature, the above-mentioned acid water was added for pulping. The mass of the acid water was 8% of the mass of the soybean milk. The soybean milk was stirred up and down while adding. When flocculent bean curd appeared in 10 seconds, the stirring was stopped immediately, and the bean curd was allowed to stand for 3 minutes. The bean curd was broken by scooping from the bottom to the top to precipitate the yellow water; the bean curd was transferred to a molding frame covered with gauze and evenly spread on the molding frame; a 60 kg pressure (52.5 * 52.5 cm 2 The tofu was pressed on a forming frame for 3 min; the weight was increased to 130 kg and the pressing was continued for 4 min, the embryo thickness was 1.4 cm; the tofu was then cut into blocks, each block was 2.7 cm long and 7 cm wide, with a moisture content of 75±2% and a weight of 22±2 g.

[0021] The brine is prepared in a traditional way, and the tofu blocks are soaked in the brine and allowed to stand for 4 hours. After the soaking, the tofu blocks are allowed to stand and drain the surface water. The drained tofu blocks are then put into an oil pan heated to 130°C and fried for 6 minutes. Then, the tofu blocks are put into an oil pan heated to 165°C and fried for another 6 minutes to obtain fried tofu blocks. The seasoning is stir-fried, the fried tofu blocks and the seasoning are mixed evenly, and the blocks are packed in bags. The stinky tofu is obtained after sterilization.

[0022] Example 2 A preparation process of stinky tofu comprises the following steps: Take the following raw materials by weight: 20 parts of yam, 8 parts of Poria cocos, 10 parts of jujube, 6 parts of Pueraria root, 1 part of dried orange peel, 3 parts of honeysuckle, and 140 parts of water. Cut yam, Pueraria root and Poria cocos into pieces, and remove the pits of jujube for later use. Steam yam, Pueraria root and jujube at 100℃ for 0.5h, add α-amylase and cellulase after cooling to room temperature, and enzymolyze at 65℃ for 2h. The total weight of α-amylase and cellulase accounts for 0.3% of the total weight of yam, Pueraria root and jujube, and the mass ratio of α-amylase and cellulase is 2:1. After the enzymolysis is completed, the enzyme is inactivated to obtain the enzymolysis product. Poria cocos, dried orange peel and honeysuckle are decocted and extracted with water at 75℃ for 1h, and the water extract is filtered. The enzymatic hydrolysate and the water extract were mixed and inoculated with a composite bacterial agent, the inoculation amount of which was 4% of the total weight of the enzymatic hydrolysate and the water extract, and the weight ratio of Lactobacillus plantarum, Streptococcus thermophilus and Candida utilis was 2:1:1. After inoculation with the composite bacterial agent, aerobic fermentation was carried out in a fermentation tank, the temperature was maintained at 37°C, the fermentation was stirred, the fermentation time was 12h, and the stirring speed was 100rpm; after the aerobic fermentation was completed, the fermentation was allowed to stand at 32°C for 11h to obtain acid water.

[0023] The soybeans were washed twice, cleaned, and mixed with water in a mass ratio of 1:8, and soaked in water at 19°C for 13 hours; the soybeans and water were poured into a pulping machine (the screen in the pulping machine was 100 mesh), and the pulp was polished twice, and the mixed soybean milk was passed through an 80-mesh screen, and the soybean milk concentration was 8.5 Brix; after filtering the soybean milk, the soybean milk was heated to 90°C with steam, and the steam was stopped, and the pulp was discharged. After cooling to room temperature, the above-mentioned acid water was added for pulping. The mass of the acid water was 7% of the mass of the soybean milk. The soybean milk was stirred up and down while adding. When flocculent bean curd appeared in 12 seconds, the stirring was stopped immediately, and the bean curd was allowed to stand for 5 minutes. The bean curd was scooped from the bottom to the top to break the bean curd and precipitate the yellow water; the bean curd was transferred to a molding frame covered with gauze and evenly spread on the molding frame; a 60 kg pressure (52.5 * 52.5 cm 2 The tofu was pressed for 3 min on a forming frame; the weight was increased to 130 kg and the pressing was continued for 4 min, the embryo thickness was 1.4 cm; the tofu was then cut into blocks, each block was 2.7 cm long and 7 cm wide, with a moisture content of 73±2% and a weight of 21±2 g.

[0024] The brine is prepared in a traditional way, and the tofu blocks are soaked in the brine and allowed to stand for 5 hours. After the soaking, the tofu blocks are allowed to stand and drain the surface water. The drained tofu blocks are then put into an oil pan heated to 135°C and fried for 5 minutes. Then, the tofu blocks are put into an oil pan heated to 170°C and fried for another 5 minutes to obtain fried tofu blocks. The seasoning is stir-fried, the fried tofu blocks and the seasoning are mixed evenly, and the blocks are packed in bags. The stinky tofu is obtained after sterilization.

[0025] Example 3 A preparation process of stinky tofu comprises the following steps: The following raw materials are taken in parts by weight: 25 parts of yam, 7 parts of poria, 13 parts of jujube, 5 parts of kudzu root, 2 parts of tangerine peel, 2 parts of honeysuckle, and 130 parts of water; the yam, kudzu root and poria are cut into pieces, and the jujube is pitted for later use; the yam, kudzu root and jujube are steamed at 95°C for 0.8h, and after cooling to room temperature, α-amylase and cellulase are added, and enzymolysis is performed at 60°C for 2.5h, the total weight of α-amylase and cellulase accounts for 0.3% of the total weight of the yam, kudzu root and jujube, and the mass ratio of α-amylase to cellulase is 2:1; after the enzymolysis is completed, the enzyme is inactivated to obtain an enzymolysis product. Boil Poria cocos, dried tangerine peel and honeysuckle with water at 80°C for 1 hour, and filter to obtain a water extract; mix the enzymatic hydrolysate and the water extract, and inoculate a composite bacterial agent, the inoculation amount of the composite bacterial agent is 4.5% of the total weight of the enzymatic hydrolysate and the water extract, and the weight ratio of Lactobacillus plantarum, Streptococcus thermophilus and Candida utilis is 2:1:1; after inoculation of the composite bacterial agent, aerobic fermentation is carried out in a fermentation tank, the temperature is maintained at 36°C, and fermentation is carried out while stirring. The fermentation time is 12 hours and the stirring speed is 120rpm; after the aerobic fermentation is completed, it is allowed to ferment at 30°C for 12 hours to obtain acid water.

[0026] Wash the soybeans twice, clean them, mix them with water in a mass ratio of 1:8, and soak them at 17℃ for 11h; pour the soybeans and water into a pulper (100 mesh screen in the pulper), grind them twice, and pass the mixed soybean milk through an 80-mesh screen to a soybean milk concentration of 9.5 Brix; after filtering the soybean milk, heat the soybean milk to 91℃ with steam, stop steaming, start draining, cool to room temperature, add the above-mentioned acid water for pulping, the mass of the acid water is 6% of the mass of the soybean milk, stir the soybean milk up and down while adding, and stop stirring immediately when flocculent bean curd appears in 15s, let it stand for 5 minutes, and scoop from bottom to top to destroy the bean curd and precipitate the yellow water; transfer the bean curd to a molding frame covered with gauze and evenly spread it on the molding frame; press 60 kg pressure (52.5 * 52.5 cm 2 The tofu was pressed for 3 min on a forming frame; the weight was increased to 130 kg and the pressing was continued for 4 min, the embryo thickness was 1.4 cm; the tofu was then cut into blocks, each block was 2.7 cm long and 7 cm wide, with a moisture content of 73±2% and a weight of 21±2 g.

[0027] The brine is prepared in a traditional way, and the tofu blocks are soaked in the brine and allowed to stand for 6 hours. After the soaking, the tofu blocks are allowed to stand and drain the surface water. The drained tofu blocks are then put into an oil pan heated to 125°C and fried for 5 minutes. Then, the tofu blocks are put into an oil pan heated to 160°C and fried for another 6 minutes to obtain fried tofu blocks. The seasoning is stir-fried, the fried tofu blocks and the seasoning are mixed evenly, and the blocks are packed in bags. The stinky tofu is obtained after sterilization.

[0028] Example 4 Compared with Example 1, the only difference is that the following raw materials are taken in parts by weight: 28 parts of yam, 6 parts of poria, 12 parts of jujube, 4 parts of kudzu root, 2 parts of tangerine peel, 3 parts of honeysuckle, and 120 parts of water; the yam, kudzu root and poria are cut into pieces, the jujube is pitted for later use, the yam, kudzu root and jujube are steamed at 92° C. for 1 hour, and after cooling to room temperature, α-amylase and cellulase are added, and enzymolysis is carried out at 58° C. for 3 hours, the total weight of α-amylase and cellulase accounts for 0.3% of the total weight of the yam, kudzu root and jujube, and the mass ratio of α-amylase to cellulase is 2:1; after the enzymolysis is completed, the enzyme is inactivated to obtain an enzymolysis product. Poria cocos, dried orange peel and honeysuckle were decocted and extracted with water at 82°C for 0.8h, and the water extract was filtered to obtain the water extract; the enzymatic hydrolysate and the water extract were mixed, and the composite bacterial agent was inoculated, the inoculation amount of the composite bacterial agent was 4% of the total weight of the enzymatic hydrolysate and the water extract, and the weight ratio of plant lactobacillus, thermophilic streptococcus and utilis candida was 2:1:1; after the composite bacterial agent was inoculated, aerobic fermentation was carried out in a fermentation tank, the temperature was maintained at 35°C, and the fermentation was stirred while fermenting, the fermentation time was 10h, and the stirring speed was 140rpm; after the aerobic fermentation was completed, the fermentation was allowed to stand at 28°C for 12h to obtain acid water. The remaining steps and operations were consistent with those in Example 1.

[0029] Comparative Example 1 Stinky tofu prepared by traditional method purchased from the market.

[0030] The following tests were performed on the embodiments and comparative examples: 1. Flavor substance detection Detection method: Headspace fixed microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) to determine flavor compounds: (1) Extraction conditions: Weigh 2 g of homogenized stinky tofu sample into a 20 ml headspace bottle. Place it in the injection device of the ZESTE fully automatic solid phase microextraction, and use a 50 / 30 μm DVB / CAR / PDMS extraction head. Equilibrium time: 10 min, extraction temperature: 60 ℃, extraction time: 30 min, desorption temperature: 250 ℃, desorption time: 5 min.

[0031] (2) Chromatographic conditions: Agilent HP-5MS UI (30 m× 0.25 mm×0.25 μm) chromatographic column was used for separation. The initial temperature was 40°C, maintained for 2 min, then raised to 180°C at a rate of 3°C / min, then raised to 190°C at a rate of 3°C / min, maintained for 2 min, and finally raised to 280°C at a rate of 10°C / min; the carrier gas (He, purity above 99.999%) flow rate was 1.6 mL / min; the injection port temperature was 250°C, and the injection was non-split.

[0032] (3) Mass spectrometry conditions: electron impact (EI) ion source; electron energy 70 eV; transfer line temperature 280 °C; ion source temperature 230 °C; quadrupole temperature 150 °C. SCAN scanning range: 33-450 m / z.

[0033] (4) Qualitative analysis of volatile compounds: Comparison was performed based on the standard spectral library NIST20 Library, and the components were preliminarily characterized according to the degree of match (positive and negative matching degree ≥ 80%).

[0034] The flavor substances of the stinky tofu of Examples 1 to 3 were detected, and the results shown in Table 1 and Figure 1 .

[0035] Table 1 Composition of flavor compounds in stinky tofu of Examples 1 to 3 (numbers are peak areas measured by chromatogram)

[0036] Combination Figure 1 As shown in Table 1, Examples 1 to 3 of the present invention not only have fermented acidic aroma substances (such as ethyl acetate and propyl caproate) in the sour bean curd water, but also have flavor substances unique to stinky tofu (such as p-cresol, 2-pentylfuran, indole, butyric acid), and have a complex aroma. In addition, the ester compounds in Example 2 are significantly higher than those in other samples, which is a typical feature of fermentation aroma.

[0037] 2. Total Texture Analysis (TPA) TPA analysis method of stinky tofu: Use TA.XT Plus100C texture analyzer to perform TPA test on stinky tofu. Cut fresh stinky tofu into 2*2*2 cm 3 The standard square was placed on the test platform, and the ICL500 probe was used. The initial scanning speed was set to 2 mm / s, the speed during the test was 1 mm / s, the trigger force was 2 g, and the test distance was 5 mm. Six samples at different positions were selected for each sample and the average value was taken.

[0038] TPA test was performed on Examples 1 to 3 and Comparative Example 1. The results are shown in Figure 2 .

[0039] Depend on Figure 2 It can be seen that the stinky tofu prepared by the present invention has hardness, chewiness and adhesiveness similar to those of the stinky tofu prepared by the traditional process.

[0040] 3. Sensory evaluation Sensory evaluation method of stinky tofu: A sensory evaluation team consisting of 10 expert sensory evaluators with long-term sensory analysis experience was formed. The sensory evaluation scoring criteria are shown in Table 2 below. The full score for each indicator is 10 points. The scoring results are shown in Figure 3 .

[0041] Table 2 Sensory analysis score table of stinky tofu

[0042] Combined with Table 2 and Figure 3 It can be seen that the stinky tofu prepared by the present invention has certain advantages in overall acceptability, apparent structure, flavor, etc. compared with the stinky tofu prepared by the traditional process.

[0043] In summary, the stinky tofu prepared by the present invention not only has potential functional properties, but also simplifies the process flow and has high consumer acceptance.

[0044] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A process for preparing stinky tofu, characterized in that: The following steps are involved: S1. Preparation of acid water: enzymatic saccharification of yam, jujube and kudzu root to obtain an enzymatic hydrolyzate, water extraction of Poria cocos, tangerine peel and honeysuckle to obtain an aqueous extract, mixing the enzymatic hydrolyzate with the aqueous extract, inoculating a composite bacterial agent, and fermenting under controlled temperature to obtain acid water; the composite bacterial agent is Lactobacillus plantarum, Streptococcus thermophilus and Candida utilis; S2. Preparation of tofu: washing, soaking, grinding and filtering soybeans to obtain soy milk, heating the soy milk, adding acid water to make the milk, pressing embryos, cutting, and obtaining tofu blocks; S3. Preparation of stinky tofu: prepare brine, soak tofu blocks in the brine and let them stand, drain the tofu blocks after soaking, fry, season and package to obtain stinky tofu.

2. The process for preparing stinky tofu according to claim 1, characterized in that: The enzymatic saccharification in the preparation of the acid water comprises the following steps: cutting yam and kudzu root into pieces, removing the core of jujube, steaming the three together at 90-100° C. for 0.5-1 hour, adding α-amylase and cellulase after cooling, performing enzymolysis at 55-65° C. for 2-3 hours, and obtaining an enzymolysis product after inactivating the enzymes; the total weight of the α-amylase and cellulase accounts for 0.3% of the total weight of the yam, kudzu root and jujube, and the mass ratio of the α-amylase to the cellulase is 2:

1.

3. The process for preparing stinky tofu according to claim 1, characterized in that: The water extraction in the preparation of the acid water comprises the following steps: mixing Poria cocos, dried orange peel and honeysuckle with water, decocting and extracting at 75-85° C. for 0.5-1 h, and filtering to obtain a water extract.

4. The process for preparing stinky tofu according to claim 1, characterized in that: The inoculation amount of the composite bacterial agent is 4-5% of the total weight of the enzymatic hydrolysate and the water extract, and the weight ratio of plant lactobacillus, thermophilic streptococcus and utilis candida is 2:1:

1.

5. The process for preparing stinky tofu according to claim 1, characterized in that: The temperature-controlled fermentation includes aerobic fermentation and static fermentation. First, stirring fermentation is carried out at 35-37° C. for 10-12 hours with a stirring speed of 100-150 rpm; then static fermentation is carried out at 28-32° C. for 10-12 hours to obtain sour water.

6. The process for preparing stinky tofu according to claim 1, characterized in that: The preparation of the acid water comprises the following raw materials in parts by weight: 20-30 parts of yam, 5-8 parts of poria, 10-15 parts of jujube, 3-6 parts of kudzu root, 1-2 parts of tangerine peel, 1-3 parts of honeysuckle, and 120-150 parts of water.

7. The process for preparing stinky tofu according to claim 1, characterized in that: The acid water accounts for 6-8% of the mass of the soy milk.

8. The process for preparing stinky tofu according to claim 1, characterized in that: The preparation of the tofu comprises the steps of heating soy milk to 90-92° C. by steam, draining the milk, cooling the milk, adding acid water, stirring the mixture for 10-15 seconds, and allowing the mixture to stand for 10-15 seconds after flocculent tofu curd appears.

9. The process for preparing stinky tofu according to claim 1, characterized in that: The frying process comprises putting the drained tofu blocks into an oil pan heated to 130±5° C. and frying them for 5-6 minutes, then putting them into an oil pan heated to 165±5° C. and continuing to fry them for 5-6 minutes to obtain fried tofu blocks.

10. Stinky tofu prepared by the process for preparing stinky tofu according to any one of claims 1 to 9.

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