阅读说明：本技术 采用二次熟浆工艺制备包浆豆腐的方法 (Method for preparing slurry-coated bean curd by adopting secondary slurry cooking process ) 是由 张胤 李肯 江振桂 于 2021-02-06 设计创作，主要内容包括：本发明提供了采用二次熟浆工艺制备包浆豆腐的方法,具体包括如下步骤：浸泡、去皮、磨浆、一次煮浆、一次过滤、二次煮浆、二次过滤、混合煮浆、三次过滤、豆清发酵液点浆、蹲脑、压榨、冷藏、浸泡、清洗、装盒、速冻。通过上述方法制备的包浆豆腐不仅能有效消除豆腥味、涩味及不良风味,显著提高产品品质,使豆香味浓郁,浆汁爽滑细嫩,呈流动状态,而且还能提高蛋白质、脂肪和多糖的溶出率,从而提高包浆豆腐的产量与营养价值及企业的经济效益与市场竞争力,促进行业转型升级。(The invention provides a method for preparing slurry-coated bean curd by adopting a secondary slurry cooking process, which specifically comprises the following steps: soaking, peeling, grinding into thick liquid, boiling thick liquid once, filtering once, boiling thick liquid twice, filtering twice, mixing and boiling thick liquid, filtering for three times, curdling by using a soy bean jelly fermentation liquid, squatting, squeezing, refrigerating, soaking, cleaning, boxing and quick-freezing. The slurry-coated bean curd prepared by the method not only can effectively eliminate beany flavor, astringent taste and bad flavor, remarkably improve the product quality, make the bean fragrant, and the slurry juice smooth and tender and in a flowing state, but also can improve the dissolution rate of protein, fat and polysaccharide, thereby improving the yield and the nutritional value of the slurry-coated bean curd, improving the economic benefit and market competitiveness of enterprises, and promoting the transformation and upgrading of industries.)

1. The method for preparing the slurry-coated bean curd by adopting the secondary slurry cooking process is characterized by comprising the following steps of:

(1) soaking: according to the dry bean: soaking bean water in a ratio of 1:3 at room temperature for 4-12 h;

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1: 3-5 to obtain bean paste for later use;

(4) primary pulp boiling: boiling the pulp at 102-110 ℃ and keeping the temperature for 3-10 min;

(5) primary filtration: filtering the bean paste after boiling to obtain a residue and a paste;

(6) secondary pulp boiling: adding deionized water with the weight of 1-5 of that of the dry beans into the first residue, uniformly stirring, continuously boiling the pulp, wherein the pulp boiling temperature is 100-108 ℃, and preserving heat for 1-10 min;

(7) secondary filtration: filtering the bean paste after the secondary soybean milk cooking to obtain secondary slag and secondary soybean milk;

(8) mixing and boiling the pulp: by mass, according to a slurry: mixing the two pulps 1-5: 1, stirring uniformly, continuously boiling the pulps at the temperature of 100-105 ℃, and preserving heat for 1-10 min for later use;

(9) and (3) filtering for three times: filtering with a vibrating screen to obtain soybean milk for later use;

(10) curdling a soy bean whey fermentation liquid: adding 15-50% of whey fermentation liquor while stirring according to the volume fraction of the soybean milk until a large amount of brain flowers are generated, and stopping stirring after a light yellow supernatant is separated out;

(11) squatting: preserving the temperature for 3-30 min, sucking out supernatant and breaking the brain;

(12) squeezing: putting the encephalopathy into a box, and squeezing for 3-30 min;

(13) and (3) refrigerating: cutting the squeezed bean curd into blocks, and refrigerating at 4 ℃ for 8-20 h;

(14) soaking: soaking the refrigerated bean curd in a mixed solution of 0.1-0.5% of sodium bicarbonate and 0.1-0.3% of edible salt for 3-20 h;

(15) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(16) boxing and quick freezing: and (4) boxing the slurry-coated bean curd, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

2. The method of claim 1, wherein the soy material has a crude protein content of not less than 40.0%.

3. The method according to claim 1, wherein in the step (1), the soaking time of the soybeans in summer is 4-6 h, the soaking time of the soybeans in winter is 8-12 h, the soaking time of the soybeans in spring and autumn is 6-10 h, the soaked soybeans are full, the cross section of the soybeans does not have obvious hard center, and the weight of wet soybeans is about 2-3 times that of dry soybeans.

4. The method as claimed in claim 1, wherein the index requirement of the whey fermentation liquid in the step (10) is that the whey fermentation liquid is heated to 35-70 ℃, and then a sample is taken to measure the total acid of the whey fermentation liquid, so as to ensure that the total acid of the whey fermentation liquid is 3-5.5 g/L, and the specific preparation method comprises the following steps: the viable count of Lactobacillus casei, Lactobacillus plantarum, Lactobacillus rhamnosus and Streptococcus thermophilus is 1.0 × 10⁸CFU/mL was measured at 1: 1: 1: 1, fermenting by adopting periodic temperature change and segmentation, and culturing for 10-36 hours in a ventilating way.

5. The method according to claim 4, wherein the operation of the periodic temperature-variable staged fermentation in the step (10) is that the fermentation time is 0-4 h, and the fermentation temperature is 42 ℃; the fermentation time is 4-10 or 4-36 h, and the fermentation temperature is 36 ℃.

6. The method according to claim 1, wherein before the soaking in the step (14), the temperature of deionized water is adjusted to 10-30 ℃, and then 0.1-0.5% of sodium bicarbonate and 0.1-0.3% of edible salt are respectively added into the deionized water in terms of volume fraction, and the mixture is mixed and dissolved, so that the temperature of the soaking water is ensured to be 10-30 ℃.

7. The method according to claim 1, wherein in the step (16), liquid nitrogen is adopted for quick freezing, a tunnel storehouse body is further included besides liquid nitrogen deep-freezing equipment, liquid nitrogen spray pipes are sequentially arranged from a discharge port to a feed port of the tunnel storehouse body, the rotating speed of a nozzle is 100-600 r/min, and the bean curd runs for 3-8 min in an environment of-50-40 ℃. The finished product can be preserved for 6 months under the condition that the freezing preservation temperature is-18 to-20 ℃.

Technical Field

The invention relates to the field of bean product processing, in particular to a method for preparing slurry-coated bean curd by adopting a secondary slurry cooking process.

Background

The slurry-coated bean curd is rich in vitamins, plant proteins, trace elements, mineral substances and the like, has the effects of enriching blood and supplementing calcium, and tonifying spleen and nourishing stomach, is particularly suitable for old people, women, children and people with high blood pressure, high blood sugar and high blood sugar, has the digestibility of more than 95 percent, is fresh, tender and delicious in taste, and is deeply loved by people.

At present, the production process of the bean curd covered with soybean milk adopts a raw soybean milk process, namely a process method of firstly grinding soybean milk, then separating and filtering soybean dregs to obtain soybean milk, and then boiling the soybean milk. The slurry production method has the advantages of less equipment investment, production at normal temperature, low requirement on production environment and relatively low microorganism propagation speed. However, the raw slurry method also has a lot of process short plates: firstly, the pulping process has a plurality of control points, which is not beneficial to controlling the product quality and the food safety; secondly, the soybean is ground into pulp and then exposed in the air for a long time, and under the action of soybean endogenous enzymes such as lipoxygenase and glucosidase, the product has heavier beany flavor and bitter taste and poor mouthfeel; thirdly, the bean dregs separated and filtered after the pulping are not suitable for being directly processed into food or used as food raw materials, and waste or pollution exists.

Chinese patent 'A coated bean curd and its preparation method' (patent application No. 201810987166.5) discloses a coated bean curd and its preparation method, which adopts raw milk process to grind into slurry, and uses citric acid, underground well water and water as coagulator to make curdling to prepare the coated bean curd. The method is simple to operate, but the soybean milk prepared by the raw milk process has heavier beany flavor and bitter taste, and the product is additionally provided with chemical additives by using citric acid and underground well water, so that the flavor and taste of the product are easily influenced.

Chinese patent 'a coated bean curd and its preparation method' (patent application No. 201910971360.9) discloses a coated bean curd and its preparation method, which adopts raw pulp process to grind into pulp while reducing the temperature of the machine. The method avoids protein denaturation caused by over-high temperature and soybean endogenous enzymes such as soybean lipoxygenase and glucosidase activated by high temperature, so that the product has heavy beany flavor and bitter taste, poor mouthfeel, poor quality and the like. However, the method is unstable, temperature control is difficult, and product quality cannot be guaranteed.

Chinese patent 'A quick-frozen slurry-coated bean curd and its preparation method' (patent application No. 201910971021.0) discloses a quick-frozen slurry-coated bean curd and its preparation method, which adopts raw slurry process to grind slurry while reducing the temperature of the machine. The method avoids protein denaturation caused by over-high temperature and phenomena of heavy beany flavor, bitter taste, poor mouthfeel, poor quality and the like of products caused by activation of soybean endogenous enzyme. However, the method is unstable, temperature control is difficult, and product quality cannot be guaranteed.

Chinese patent 'drink a dendrobium pulp-coated bean curd and its preparation technology' (patent application No. 202010496839.4) discloses a dendrobium pulp-coated bean curd and its preparation technology, which adopts a once-cooked pulp process to prepare pulp, and adds dendrobium juice in the production process, so that the product is light green, not only the appearance is more beautiful, but also the nutritive value can be improved. However, the utilization rate of nutrient substances in the process needs to be improved, the bean dregs still contain a large amount of nutrient substances such as protein and the like, resources are wasted, the environment is polluted, meanwhile, citric acid water is used for coagulation forming with the alarm water, chemical additives are additionally introduced, the flavor and the taste of the product are easily influenced, the alarm water is naturally fermented, the fermentation process is uncontrollable, the quality is unstable, and potential safety hazards exist due to pollution.

In view of the above, the invention adopts the '2-extraction-3-boiling' of the secondary pulp cooking process, which can effectively eliminate the beany flavor and the bitter taste of the pulp-coated beancurd, improve the quality and the flavor of the product, and improve the protein, the fat, the polysaccharide and the K⁺And Na⁺The content and the utilization rate of the substances are improved, so that the yield, the quality and the nutritive value of the slurry-coated bean curd are improved, the economic benefit and the market competitiveness of an enterprise are improved, and the transformation and the upgrade of the industry are promoted.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the method for preparing the slurry-coated bean curd by adopting the secondary slurry cooking process, which can effectively eliminate the beany flavor and the bitter taste of the slurry-coated bean curd, improve the quality and the flavor of the product, and improve the protein, the fat, the polysaccharide and the K⁺And Na⁺The content and the utilization rate of the substances are improved, so that the yield, the quality and the nutritive value of the slurry-coated bean curd are improved, the economic benefit and the market competitiveness of an enterprise are improved, and the transformation and the upgrade of the industry are promoted.

The invention provides a method for preparing slurry-coated bean curd by adopting a secondary slurry cooking process, which specifically comprises the following steps:

(1) soaking: according to the dry bean: soaking bean water in a ratio of 1:3 at room temperature for 4-12 h;

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1: 3-5 to obtain bean paste for later use;

(4) primary pulp boiling: boiling the pulp at 102-110 ℃ and keeping the temperature for 3-10 min;

(5) primary filtration: filtering the bean paste after boiling to obtain a residue and a paste;

(6) secondary pulp boiling: adding deionized water with the weight of 1-5 of that of the dry beans into the first residue, uniformly stirring, continuously boiling the pulp, wherein the pulp boiling temperature is 100-108 ℃, and preserving heat for 1-10 min;

(7) secondary filtration: filtering the bean paste after the secondary soybean milk cooking to obtain secondary slag and secondary soybean milk;

(8) mixing and boiling the pulp: by mass, according to a slurry: mixing the two pulps 1-5: 1, stirring uniformly, continuously boiling the pulps at the temperature of 100-105 ℃, and preserving heat for 1-10 min for later use;

(9) and (3) filtering for three times: filtering with a vibrating screen to obtain soybean milk for later use;

(10) curdling a soy bean whey fermentation liquid: adding 15-50% of whey fermentation liquor while stirring according to the volume fraction of the soybean milk until a large amount of brain flowers are generated, and stopping stirring after a light yellow supernatant is separated out;

(11) squatting: preserving the temperature for 3-30 min, sucking out supernatant and breaking the brain;

(12) squeezing: putting the encephalopathy into a box, and squeezing for 3-30 min;

(13) and (3) refrigerating: cutting the squeezed bean curd into blocks, and refrigerating at 4 ℃ for 8-20 h;

(14) soaking: soaking the refrigerated bean curd in a mixed solution of 0.1-0.5% of sodium bicarbonate and 0.1-0.3% of edible salt for 3-20 h;

(15) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(16) boxing and quick freezing: and (4) packing the slurry-coated bean curd into boxes, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

Furthermore, the content of crude protein of the soybean raw material is not less than 40.0%, the soybeans which are full, free of worm damage and mildew and deterioration are selected, impurities are removed, and then the soybeans are cleaned by deionized water.

Further, in the step (1), the soaking time of the soybeans in summer is 4-6 h, the soaking time of the soybeans in winter is 8-12 h, the soaking time of the soybeans in spring and autumn is 6-10 h, the soaked soybeans are full, the section of the soybeans does not have obvious hard center, and the weight of wet soybeans is 2-3 times of that of dry soybeans.

Further, the index requirement of the whey fermentation liquor in the step (10) is that after the whey fermentation liquor is heated to 35-70 ℃, a sample is taken to measure the total acid of the whey fermentation liquor, and the total acid of the whey fermentation liquor is ensured to be 3-5.5 g/L, and the specific preparation method comprises the following steps: the viable count of Lactobacillus casei, Lactobacillus plantarum, Lactobacillus rhamnosus and Streptococcus thermophilus is 1.0 × 10⁸CFU/mL was measured at 1: 1: 1: 1, fermenting by adopting periodic temperature change and segmentation, and culturing for 10-36 hours in a ventilating way.

Further, the operation steps of periodic temperature-changing and sectional fermentation in the step (10) are that the fermentation time is 0-4 h, and the fermentation temperature is 42 ℃; the fermentation time is 4-10 or 4-36 h, and the fermentation temperature is 36 ℃.

Further, before the soaking in the step (14), the temperature of the deionized water is adjusted to 10-30 ℃, then 0.1-0.5% of sodium bicarbonate and 0.1-0.3% of edible salt are added into the deionized water according to volume fraction, and the mixture is mixed and dissolved, so that the soaking water temperature is 10-30 ℃.

Further, in the step (16), liquid nitrogen is adopted for quick freezing, besides liquid nitrogen deep-freezing equipment, a tunnel warehouse body is further included, liquid nitrogen spray pipes are sequentially arranged from a discharge port to a feed port of the tunnel warehouse body, the rotating speed of a nozzle is 100-600 r/min, and bean curd runs for 3-8 min under the environment of-50 to-40 ℃. The finished product can be preserved for 6 months under the condition that the freezing preservation temperature is-18 to-20 ℃.

Technical effects

1. The '2-extraction-3-boiling' technology of the secondary slurry cooking process is adopted to prepare the slurry-coated bean curd, the beany flavor and the bitter taste of the slurry-coated bean curd can be effectively eliminated, the quality and the flavor of the product are improved, and the protein, the fat, the polysaccharide and the K are improved⁺And Na⁺The dissolution rate of the substances is reduced, and the nutrients in the bean dregs are reducedThe quality content reduces resource waste and environmental pollution.

2. The clear bean liquid is fermented by the cooperation of multiple strains of probiotics and periodic temperature-changing segmentation to obtain clear bean liquid fermentation liquid, so that the clear bean liquid fermentation liquid is rich in nutrient substances such as organic acid, extracellular polysaccharide, gamma-aminobutyric acid, free soybean isoflavone, B vitamins, polypeptide and the like, and the yield, the quality and the nutritional value of the slurry-coated bean curd are improved.

3. The method not only can reduce the discharge of the soybean clear liquid, relieve the environmental protection pressure of enterprises, reduce the environmental pollution and protect the environment, but also can realize the comprehensive utilization of the soybean clear liquid, change waste into valuable, improve the quality of the slurry-coated bean curd products and the core competitiveness of the enterprises and promote the transformation and upgrading of the industry.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments.

Evaluation indexes are as follows:

1. the yield is as follows: weighing the soaked, cleaned and drained slurry-coated bean curd, and calculating the mass of the wet slurry-coated bean curd obtained per 100g of dry soybeans, namely the yield of the wet slurry-coated bean curd.

2. Fuzzy sensory evaluation: the same in-situ frying/roasting was performed on the slurry-coated tofu prepared in the following examples 1 to 3 and control groups 1 to 2, while 1000 sensory evaluators were randomly invited. Wherein 200 persons are 8-18 years old, 400 persons are 19-30 years old, 300 persons are 31-50 years old, and 100 persons are 51 years old or older. Before sensory evaluation, samples are numbered, and sensory evaluation is respectively carried out on the color, smell, taste and texture of the bean curd by adopting a double-blind method, each index is divided into 3 grades of superior, good and poor, and the sensory evaluation table is shown in table 1.

TABLE 1 sensory evaluation chart

The color (U) of the bean curd was used for this comparison₁) And fragrance (U)₂) And taste (U)₃) And juice (U)₄) The fuzzy sensory analysis factor set of the obtained bean curd is U ═ U as sensory evaluation index₁,U₂,U₃,U₄}. The evaluation set is a set of ratings to which the evaluated index belongs. The bean curd is determined to have excellent evaluation grade (V) through the discussion of an evaluation group₁) Good (V)₂) A, a (V)₃) Obtaining the comment set V ═ V of the bean curd₁,V₂,V₃{90,70,50 }; determining the weight set of the sensory index of the bean curd as R ═ { R₁,R₂,R₃,R₄0.15,0.25,0.3 and 0.3, namely, the color and luster accounts for 0.15, the fragrance accounts for 0.25, the mouthfeel accounts for 0.30 and the juice accounts for 0.3. And the fuzzy mathematics comprehensive evaluation is that Y is Ry, wherein R is a weight set, Y is a fuzzy mathematics matrix, and Y is obtained by dividing the number of persons corresponding to each evaluation standard and each evaluation result by the total number of appraisers.

Example 1

(1) Soaking: according to the dry bean: soaking bean water at a ratio of 1:3 at room temperature for 4h (summer);

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1:3 for later use;

(4) primary pulp boiling: boiling the pulp at 108 deg.C, and keeping the temperature for 3 min;

(5) primary filtration: filtering the bean paste after boiling to obtain a residue and a paste;

(6) secondary pulp boiling: adding deionized water with the weight of 5 of the dry beans into the first residue, uniformly stirring, continuously boiling the pulp at 105 ℃, and keeping the temperature for 5 min;

(7) secondary filtering, namely filtering the bean paste subjected to secondary soybean milk cooking to obtain secondary slag and secondary soybean milk;

(8) mixing and boiling the pulp, wherein the mass ratio of the pulp is as follows: mixing the two pastes 5:1, stirring uniformly, continuously boiling the paste at the temperature of 102 ℃, and preserving heat for 3min for later use;

(9) and (3) filtering for three times: filtering with a vibrating screen to obtain soybean milk for later use;

(10) curdling: adding 35% of soy whey fermentation liquor while stirring according to the volume fraction of the soy milk until a large amount of brain flowers are generated, and stopping stirring after a light yellow supernatant is separated out;

(11) squatting: keeping the temperature for 10min, sucking out the supernatant and breaking the brain;

(12) squeezing: putting the encephalopathy into a box, and squeezing for 20 min;

(13) and (3) refrigerating: cutting the squeezed bean curd into blocks, and refrigerating at 4 ℃ for 16 h;

(14) soaking: soaking the refrigerated bean curd in a mixed solution of 0.3% sodium bicarbonate and 0.1% edible salt for 10 h;

(15) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(16) boxing and quick freezing: and (4) packing the slurry-coated bean curd into boxes, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

Example 2

(1) Soaking: according to the dry bean: soaking bean water at a ratio of 1:3 at room temperature for 12h (winter);

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1:5 for later use;

(4) primary pulp boiling: boiling the pulp at 105 deg.C, and keeping the temperature for 3 min;

(5) primary filtration: filtering the bean paste after boiling to obtain a residue and a paste;

(6) secondary pulp boiling: adding deionized water with the weight of 3 of the dry beans into the first residue, uniformly stirring, continuously boiling the pulp at the temperature of 103 ℃, and keeping the temperature for 3 min;

(7) secondary filtering, namely filtering the bean paste subjected to secondary soybean milk cooking to obtain secondary slag and secondary soybean milk;

(8) mixing and boiling the pulp, wherein the mass ratio of the pulp is as follows: mixing the two pastes 3:1, stirring uniformly, continuously boiling the paste at the temperature of 102 ℃, and preserving heat for 1min for later use;

(9) and (3) filtering for three times: filtering with a vibrating screen to obtain soybean milk for later use;

(10) curdling: adding 25% of soy whey fermentation liquor while stirring according to the volume fraction of the soy milk until a large amount of brain flowers are generated, and stopping stirring when a light yellow supernatant is separated out;

(11) squatting: keeping the temperature for 15min, sucking out the supernatant and breaking the brain;

(12) squeezing: putting the encephalopathy into a box, and squeezing for 10 min;

(13) and (3) refrigerating: cutting the squeezed bean curd into blocks, and refrigerating at 4 ℃ for 10 h;

(14) soaking: soaking the refrigerated bean curd in a mixed solution of 0.2% sodium bicarbonate and 0.3% edible salt for 16 h;

(15) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(16) boxing and quick freezing: and (4) packing the slurry-coated bean curd into boxes, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

Example 3

(1) Soaking: according to the dry bean: soaking bean water at a ratio of 1:3 at room temperature for 12h (winter);

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1:4 for later use;

(4) primary pulp boiling: boiling the pulp at 103 deg.C, and keeping the temperature for 5 min;

(5) primary filtration: filtering the bean paste after boiling to obtain a residue and a paste;

(6) secondary pulp boiling: adding deionized water with the weight of 4 of the dry beans into the first residue, uniformly stirring, continuously boiling the pulp at the temperature of 102 ℃, and preserving heat for 3 min;

(7) secondary filtering, namely filtering the bean paste subjected to secondary soybean milk cooking to obtain secondary slag and secondary soybean milk;

(8) mixing and boiling the pulp, wherein the mass ratio of the pulp is as follows: mixing the two pastes 4:1, stirring uniformly, continuously boiling the paste at the temperature of 102 ℃, and keeping the temperature for 2min for later use;

(9) and (3) filtering for three times: filtering with a vibrating screen to obtain soybean milk for later use;

(10) curdling: adding 45% of the whey fermentation liquor while stirring according to the volume fraction of the soybean milk until a large amount of brain flowers are generated, and stopping stirring after a light yellow supernatant is separated out;

(11) squatting: keeping the temperature for 3min, sucking out supernatant and breaking the brain;

(12) squeezing: putting the encephalopathy into a box, and squeezing for 30 min;

(13) and (3) refrigerating: cutting the squeezed bean curd into pieces, and refrigerating at 4 deg.C for 18 h;

(14) soaking: soaking the refrigerated bean curd in a mixed solution of 0.5% sodium bicarbonate and 0.3% edible salt for 7 h;

(15) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(16) boxing and quick freezing: and (4) packing the slurry-coated bean curd into boxes, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

Comparative example 1

A raw slurry process:

(1) soaking: according to the dry bean: soaking bean water at a ratio of 1:3 at room temperature for 12h (winter);

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1:5 for later use;

(4) and (3) filtering: separating and filtering the bean paste to obtain bean dregs and soybean milk;

(5) boiling the soybean milk: boiling the pulp at 108 deg.C, and keeping the temperature for 3 min;

(6) curdling: adding 35% of soy whey fermentation liquor while stirring according to the volume fraction of the soy milk until a large amount of brain flowers are generated, and stopping stirring after a light yellow supernatant is separated out;

(7) squatting: keeping the temperature for 5min, sucking out the supernatant and breaking the brain;

(8) squeezing: putting the encephalopathy into a box, and squeezing for 20 min;

(9) and (3) refrigerating: cutting the squeezed bean curd into blocks, and refrigerating at 4 ℃ for 16 h;

(10) soaking: soaking the refrigerated bean curd in a mixed solution of 0.2% sodium bicarbonate and 0.2% edible salt for 6 h;

(11) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(12) boxing and quick freezing: and (4) packing the slurry-coated bean curd into boxes, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

Comparative example 2

The primary pulp cooking process comprises the following steps:

(1) soaking: according to the dry bean: soaking bean water at a ratio of 1:3 at room temperature for 12h (winter);

(2) peeling: peeling the soaked soybeans by using a peeling machine, and cleaning the soybeans for later use;

(3) grinding: according to the dry bean: grinding the bean paste according to the bean water ratio of 1:5 for later use;

(4) boiling the soybean milk: boiling the pulp at 108 deg.C, and keeping the temperature for 3 min;

(5) and (3) filtering: separating and filtering the bean paste to obtain bean dregs and soybean milk;

(6) curdling: adding 40% of soy whey fermentation liquor while stirring according to the volume fraction of the soy milk until a large amount of brain flowers are generated, and stopping stirring after a light yellow supernatant is separated out;

(7) squatting: keeping the temperature for 5min, sucking out the supernatant and breaking the brain;

(8) squeezing: putting the encephalopathy into a box, and squeezing for 20 min;

(9) and (3) refrigerating: cutting the squeezed bean curd into blocks, and refrigerating at 4 ℃ for 16 h;

(10) soaking: soaking the refrigerated bean curd in a mixed solution of 0.2% sodium bicarbonate and 0.2% edible salt for 6 h;

(11) cleaning: washing the soaked slurry-coated bean curd with deionized water, and draining off the surface water;

(12) boxing and quick freezing: and (4) packing the slurry-coated bean curd into boxes, quickly freezing by adopting liquid nitrogen, and preserving under a freezing condition for half a year after the quick freezing is finished.

Example 4

The comparison results of the slurry-coated tofu prepared in examples 1, 2 and 3 and comparative examples 1 and 2 are shown in Table 2.

TABLE 2 comparison of results table

According to the results in table 2, the sensory score and the yield of the slurry-coated tofu prepared by the '2-to-3 cooking' of the secondary slurry cooking process are obviously higher than those of the raw slurry process and the primary slurry cooking process, which shows that the slurry-coated tofu provided by the embodiment of the invention has higher yield and better comprehensive quality and is more favored by consumers. In conclusion, the method can effectively eliminate beany flavor and bitter taste of the slurry-coated beancurd, improve the quality and flavor of the product, improve the dissolution rate of protein, fat, polysaccharide, K +, Na + and other substances, reduce the content of nutrient substances in the bean dregs, and reduce resource waste and environmental pollution, thereby improving the yield, quality and nutritional value of the slurry-coated beancurd, further improving the economic benefit and market competitiveness of enterprises, and promoting the transformation and upgrading of the industry.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.