CN112042763B

CN112042763B - Method and device for preparing soft bean curd by using secondary hot spot slurry

Info

Publication number: CN112042763B
Application number: CN202010816233.4A
Authority: CN
Inventors: 蔡水埼; 赵大勇; 吴彩珍
Original assignee: ZUMING BEAN PRODUCTS CO Ltd
Current assignee: ZUMING BEAN PRODUCTS CO Ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2023-05-23
Anticipated expiration: 2040-08-14
Also published as: CN112042763A

Abstract

The invention discloses a method and a device for preparing soft bean curd by secondary hot spot slurry, and aims to solve the defects of poor toughness and easy rotten long-time boiling of bean curd prepared by the prior art. The invention adopts the secondary hot spot slurry technology to fully utilize the solidification characteristics of each coagulant in the preparation process of the soft bean curd, has good gel effect, and makes the soft bean curd with good toughness, elasticity, good water retention, smoothness and fineness. The bean curd after the first hot spot pulp is immediately subjected to the second pulp flushing type pulp-dropping, so that the synergistic action of the coagulators of the first and second pulp-dropping is ensured, and the effect of the first pulp-dropping is not damaged by the second pulp-dropping. The soft bean curd prepared by the process of the invention improves the toughness, hardness and fineness of the bean curd, and is not rotten after long-term boiling.

Description

Method and device for preparing soft bean curd by using secondary hot spot slurry

Technical Field

The invention relates to the technical field of food processing, in particular to a method and a device for preparing soft bean curd by secondary hot spot slurry.

Background

Bean curd is food with soybean as main material, and has been popular with people in China and world. The bean curd has rich nutrition, high protein content, low fat content, iron, calcium, phosphorus, magnesium and other trace elements necessary for human body, and is called as vegetable meat. Bean curd is a food for invigorating, clearing heat and promoting health, and can tonify spleen and replenishing qi, clear heat and moisten dryness, promote salivation and quench thirst, and clean intestines and stomach when being eaten frequently. Modern medicine proves that the bean curd has the functions of increasing nutrition, helping digestion and stimulating appetite, and is also beneficial to the growth and development of teeth and bones; the bean curd does not contain cholesterol, is a medicated diet delicacy for patients with hypertension, hyperlipidemia, hypercholesterolemia and arteriosclerosis and coronary heart disease, and is a good food therapy product for children, weak and the elderly to supplement nutrition.

Bean curd originates from China, and Han dynasty is Wang Liuan to invent bean curd, so far, 2000 years old. The tofu has long history, wide spread range and is popular with people.

The bean curd sold in the market at present mainly comprises three types of gypsum bean curd, brine bean curd and lactone bean curd. There are different eating habits, including the classification of north and south bean curd. The south bean curd is gypsum bean curd, and is high in water content, good in water retention, fine in texture, but insufficient in bean fragrance, and slightly bitter. North bean curd, namely marinated bean curd, has relatively low water content, firm texture, coarse mouthfeel, more internal pores, better mouthfeel and flavor, natural bean flavor and sweet flavor of bean curd, and is usually prepared by adding magnesium chloride to the bean curd, namely the aged bean curd and the hard bean curd. In the 60 th century, glucono-delta-lactone is first used as coagulant in Japan to produce lactone bean curd with raised water holding capacity, white color, toughness, tenderness and convenient shape, but the lactone bean curd has less flavor and gel strength than bittern (gypsum) bean curd and has the phenomena of sour flavor, fragile firing, poor toughness, etc. The three bean curd have the common defects of poor toughness, easy rotting after long-time boiling and the like.

Disclosure of Invention

The invention overcomes the defects of poor toughness and easy rotting after long-time boiling of the bean curd prepared by the prior art, and provides the method and the device for preparing the soft bean curd by using the secondary hot spot slurry, which improve the toughness, hardness and fineness of the bean curd and avoid rotting after long-time boiling.

In order to solve the technical problems, the invention adopts the following technical scheme: a method for preparing soft bean curd by using secondary hot spot slurry comprises the following steps: a. soaking, namely soaking the screened soybeans; b. pulping, namely cleaning soaked soybeans, pulping, and separating bean dregs in the ground paste to obtain soybean milk; c. burning soybean milk, namely placing the soybean milk into a soybean milk burning cylinder to burn the soybean milk; d. sieving the soybean milk, and sieving the cooked soybean milk with a sieve; e. heating the soybean milk at 70-80 ℃ at one time, adding the soybean milk into a soybean milk stirring barrel, and adding an emulsified magnesium coagulant while stirring, wherein the adding amount is 0.5% -0.7%; releasing the emulsified magnesium coagulant embedded in the grease, mixing with the soybean milk, and rapidly carrying out secondary hot spot slurry before the emulsified magnesium coagulant is not completely combined; f. the secondary hot spot slurry is stirred at 60-70 ℃ to finish the synchronous flushing of the soybean milk of the primary hot spot slurry and the secondary spot slurry coagulant into a flushing barrel for flushing type spot slurry, and the addition amount of the secondary spot slurry coagulant is 1.5-2.5%; g. packaging and sealing the film, namely quickly flushing the bean curd after the secondary hot spot paste is finished into a packaging box, and performing heat sealing on the film; h. sterilizing, warehousing, preserving the heat of the packaged and film-sealed product for a period of time at 60-65 ℃, heating to 85-90 ℃ for sterilization, cooling after sterilization, and finally transferring into a refrigeration house.

The secondary hot spot slurry technology is adopted in the preparation process of the soft bean curd, the solidification characteristics of all coagulants are fully utilized, the gel effect is good, and the soft bean curd is made into the soft bean curd which is tough, tender, good in elasticity, good in water retention, smooth and fine, and the process is high in automation degree, sanitary and safe in product, good in water retention, tough and tender in taste, fine in tissue, not rotten after long-time boiling, stable in quality, convenient to store and transport and suitable for long-distance sales. The bean curd after the first hot spot pulp is immediately subjected to the second pulp flushing type pulp-dropping, so that the synergistic action of the coagulators of the first and second pulp-dropping is ensured, and the effect of the first pulp-dropping is not damaged by the second pulp-dropping. The soft bean curd prepared by the process of the invention improves the toughness, hardness and fineness of the bean curd, and is not rotten after long-term boiling.

Preferably, the emulsified magnesium coagulant is prepared by mixing and emulsifying the following components in percentage by weight: 50% of magnesium chloride, 30% of vegetable oil, 15% of water and 5% of glyceryl monostearate. The emulsified magnesium coagulant has good curdling effect and is beneficial to ensuring the toughness and hardness of the bean curd.

Preferably, the secondary slurry setting agent comprises the following components in percentage by weight: 69.2% of water, 2.5% of calcium sulfate, 22% of glucono-delta-lactone, 5.5% of TG enzyme and 0.8% of edible salt. The secondary curdling coagulant is beneficial to ensuring the fineness of the bean curd.

Preferably, in the step e, the stirring speed of the soybean milk is 500 rpm for 1-2 seconds when the emulsified magnesium coagulant is added, the speed is increased to 3000-4000 rpm after the emulsified magnesium coagulant is added, the temperature is kept for 30-35 seconds, and then the temperature is adjusted to 1000-2000 rpm, and the temperature is kept for 2-10 seconds. The process aims at releasing magnesium chloride coagulant embedded in grease to mix with soybean milk.

Preferably, in the step h, the product after packaging and sealing the film is preserved for 30 minutes at 60-65 ℃, is heated to 85-90 ℃ for pasteurization for 30 minutes, is precooled for 20-40 minutes after sterilization, is placed into an ice water tank at 4-15 ℃ for cooling for 40-60 minutes, and is discharged from the tank and transferred into a refrigeration house. The bean curd products have good sterilization effect.

Preferably, in the step b, the soybean milk is ground according to the ratio of soybean to water of 1:4-1:5, the ground paste is subjected to high-speed centrifugation through 2-3 times of circulation, and bean dregs are thrown out, so that the soybean milk is obtained. And the bean dregs in the soybean milk are separated, so that the quality of the bean curd is improved.

Preferably, in the step c, the temperature of the roasted soybean milk is controlled to be 98-100 ℃, the roasted soybean milk is kept for 3-5 minutes, and the concentration of the roasted soybean milk is controlled to be 12-14 ℃. The nutritive value of the bean curd is ensured.

The device for preparing the soft bean curd by the secondary hot spot slurry comprises a controller, a soybean milk barrel, a stirring barrel and a slurry flushing barrel, wherein the soybean milk barrel is arranged above the stirring barrel, the stirring barrel is arranged above the slurry flushing barrel, a primary slurry-dropping coagulant barrel is arranged above the stirring barrel, a secondary slurry-dropping coagulant barrel is arranged above the slurry flushing barrel, the lower end of the soybean milk barrel is connected with a soybean milk control valve, the soybean milk control valve is connected with a soybean milk conveying pipe for conveying soybean milk to the stirring barrel, the lower end of the primary slurry-dropping coagulant barrel is connected with a primary slurry-dropping control valve, the primary slurry-dropping control valve is connected with a primary slurry-dropping pipe for conveying emulsified magnesium coagulant to the stirring barrel, the lower end of the stirring barrel is connected with a slurry flushing control valve, the lower end of the secondary slurry-dropping coagulant barrel is connected with the secondary slurry-dropping control valve, and a slurry flushing pipe is connected between the slurry flushing control valve and the secondary slurry-dropping control valve, and the slurry flushing pipe is connected with a slurry outlet pipe arranged towards the slurry flushing barrel; the lower end of the pulp flushing barrel is connected with a bean curd control valve for conveying bean curd into the packaging box; a stirring rod driven by a stirring motor to rotate is arranged in the stirring barrel; the soybean milk control valve, the primary soybean milk dispensing control valve, the flushing control valve, the secondary soybean milk dispensing control valve, the bean curd control valve and the stirring motor are controlled by a controller.

And (3) placing the screened soybean milk into a soybean milk barrel for storage, and opening a soybean milk control valve and a primary soybean milk-dropping control valve when primary soybean milk is dropped into the soybean milk barrel, so that the soybean milk and the emulsified magnesium coagulant in the primary soybean milk-dropping coagulant barrel are fed into a stirring barrel, and a stirring motor drives a stirring rod to rotate. After primary hot spot slurry is finished, a slurry flushing control valve and a secondary slurry flushing control valve are opened, and the soybean milk of the primary hot spot slurry and the secondary slurry flushing coagulant in the secondary slurry flushing coagulant barrel are synchronously flushed into the slurry flushing barrel to perform slurry flushing type slurry flushing. After the secondary curdling is completed, the bean curd control valve is opened, and the bean curd falls into the packaging box. The soymilk barrel, the stirring barrel and the soymilk barrel are sequentially arranged from top to bottom, so that fluid flows downwards under the gravity, power is not needed, and the cost is reduced. The automatic control of the soybean milk control valve, the primary soybean milk dispensing control valve, the flushing control valve, the secondary soybean milk dispensing control valve, the bean curd control valve and the stirring motor is realized through the controller, so that the automation degree is high, and the working efficiency is high.

Preferably, an installation table is arranged above the stirring barrel, a lifting piston cylinder is installed on the installation table, a telescopic rod of the lifting piston cylinder is connected with a lifting plate, a stirring motor is installed on the lifting plate, and stirring blades are installed at the lower end of the stirring rod. The stirring rod is driven to lift up and down through the lifting piston cylinder, so that soybean milk at each position in the stirring barrel is stirred, the stirring effect is improved, the soybean milk and the coagulant are fully mixed, and the milk-dropping effect is improved.

Preferably, the stirring rod is connected with an anti-rotating seat near the upper part, the anti-rotating seat and the stirring rod can rotate mutually, a liquid passing cavity is arranged in the stirring rod, the liquid passing cavity is arranged between the stirring blade and the anti-rotating seat, a liquid outlet hole which is radially arranged is arranged on the stirring blade, a liquid outlet hole is arranged on the outer wall of the lower end of the stirring rod, and the liquid outlet holes are communicated with the liquid passing cavity; the inner wall of the anti-rotation seat is provided with a liquid passing ring cavity, the stirring rod is provided with a liquid passing hole for communicating the liquid passing ring cavity with the liquid passing cavity, the anti-rotation seat is provided with a coagulant inlet and a slurry inlet which are communicated with the liquid passing ring cavity, the coagulant inlet and the slurry inlet are both provided with one-way valves, the coagulant inlet is connected with a metering pump, the primary slurry-dropping pipe is a flexible pipe, and the metering pump is connected with the primary slurry-dropping pipe; the anti-rotation seat is connected with a piston pipe, a piston is arranged in the piston pipe, a piston rod is connected with the piston, a fixed plate is connected with the stirring barrel, the upper end of the piston rod is connected with the fixed plate, a positioning rod is arranged on the anti-rotation seat, a positioning hole is formed in the fixed plate, and the positioning rod is movably inserted into the positioning hole; the lower end of the piston tube is provided with a liquid suction port and a liquid discharge port, the liquid suction port is connected with a liquid suction tube, the lower end of the liquid suction tube is provided with a filter cover, the liquid discharge port is connected with a liquid discharge tube, the liquid discharge tube is connected with a slurry inlet, and the liquid suction port and the liquid discharge port are both provided with one-way valves.

The emulsified magnesium coagulant in the primary slurry-dropping coagulant barrel is conveyed into the stirring barrel through the metering pump, the stirring rod moves up and down while rotating, and the emulsified magnesium coagulant is conveyed. The metering pump pumps the emulsified magnesium coagulant in the one-time slurry-dropping coagulant barrel and conveys the emulsified magnesium coagulant into the liquid-passing cavity, and when the stirring rod moves downwards, the emulsified magnesium coagulant outwards flows into the stirring barrel from the liquid outlet hole, and the emulsified magnesium coagulant is outwards thrown out along with the stirring blade. When the stirring blade descends to the lowest position, the metering pump just completes quantitative extraction of the emulsified magnesium coagulant, and at the moment, the quantitative pump is closed. The piston moves upward relative to the piston tube, which withdraws the bean pulp through the pipette, due to the anti-swivel base moving downward with the stirring rod during the downward movement of the stirring rod. In the process that the stirring rod rotates and moves upwards, the piston moves downwards relative to the piston tube, and bean pulp in the piston tube is discharged from the liquid discharge tube and conveyed into the liquid passing ring cavity, so that the residual emulsified magnesium coagulant in the liquid passing cavity is extruded outwards, and the accurate dosage of the emulsified magnesium coagulant is ensured. And the emulsified magnesium coagulant is discharged along with the downward movement of the stirring rod, so that the emulsified magnesium coagulant is output to different positions in the soybean milk, uniform mixing of the emulsified magnesium coagulant and the soybean milk is facilitated, and the soybean milk spot effect is improved.

Compared with the prior art, the invention has the beneficial effects that: the secondary hot spot slurry technology is adopted in the preparation process of the soft bean curd, the solidification characteristics of all coagulants are fully utilized, the gel effect is good, and the soft bean curd is made into the soft bean curd which is tough, tender, good in elasticity, good in water retention, smooth and fine, and the process is high in automation degree, sanitary and safe in product, good in water retention, tough and tender in taste, fine in tissue, not rotten after long-time boiling, stable in quality, convenient to store and transport and suitable for long-distance sales.

Drawings

Fig. 1 is a schematic structural view of embodiment 1 of the present invention;

fig. 2 is a schematic structural view of embodiment 2 of the present invention;

in the figure: 1. the soybean milk bucket, 2, the stirring bucket, 3, the pulp flushing bucket, 4, the primary pulp-dropping coagulant bucket, 5, the secondary pulp-dropping coagulant bucket, 6, the soybean milk control valve, 7, the soybean milk conveying pipe, 8, the primary pulp-dropping control valve, 9, the primary pulp-dropping pipe, 10, the pulp flushing control valve, 11, the secondary pulp-dropping control valve, 12, the pulp flushing pipe, 13, the pulp outlet pipe, 14, the bean curd control valve, 15, the stirring motor, 16, the stirring rod, 17, the mounting table, 18, the lifting piston cylinder, 19, the lifting plate, 20, the stirring blade, 21, the guide rod, 22, the anti-rotating seat, 23, the liquid passing cavity, 24, the liquid outlet hole, 25, the liquid passing cavity, 26, the liquid passing hole, 27, the coagulant inlet, 28, the pulp inlet, 29, the metering pump, 30, the piston pipe, 31, the piston, 32, the piston rod, 33, the fixing plate, 34, the positioning rod, 35, the liquid suction port, 36, the liquid suction port, 37, the liquid suction pipe, 38, the filter positioning block cover, 39, the liquid discharge pipe, 40, the upper part, 41 and lower part.

Detailed Description

The technical scheme of the invention is further specifically described by the following specific embodiments with reference to the accompanying drawings:

example 1: a method for preparing soft bean curd by using secondary hot spot slurry comprises the following steps: a. soaking, namely soaking the screened soybeans; b. pulping, namely cleaning soaked soybeans, pulping, and separating bean dregs in the ground paste to obtain soybean milk; c. burning soybean milk, namely placing the soybean milk into a soybean milk burning cylinder to burn the soybean milk; d. sieving the soybean milk, and sieving the cooked soybean milk with a sieve; e. heating the soybean milk at 70-80 ℃ at one time, adding the soybean milk into a soybean milk stirring barrel, and adding an emulsified magnesium coagulant while stirring, wherein the adding amount is 0.5-0.7% by weight percent; releasing the emulsified magnesium coagulant embedded in the grease, mixing with the soybean milk, and rapidly carrying out secondary hot spot slurry before the emulsified magnesium coagulant is not completely combined; f. the secondary hot spot slurry is stirred at 60-70 ℃ to finish synchronous flushing of the soybean milk of the primary hot spot slurry and the secondary spot slurry coagulant into a flushing barrel for flushing type spot slurry, wherein the adding amount of the secondary spot slurry coagulant is 1.5-2.5 percent by weight percent; g. packaging and sealing the film, namely quickly flushing the bean curd after the secondary hot spot paste is finished into a packaging box, and performing heat sealing on the film; h. sterilizing, warehousing, preserving the heat of the packaged and film-sealed product for a period of time at 60-65 ℃, heating to 85-90 ℃ for sterilization, cooling after sterilization, and finally transferring into a refrigeration house.

The emulsified magnesium coagulant is prepared by mixing and emulsifying the following components in percentage by weight: 50% of magnesium chloride, 30% of vegetable oil, 15% of water and 5% of glyceryl monostearate. The secondary curdling coagulant comprises the following components in percentage by weight: 69.2% of water, 2.5% of calcium sulfate, 22% of glucono-delta-lactone, 5.5% of TG enzyme and 0.8% of edible salt.

In the step e, the stirring speed of the soybean milk is 500 rpm for 1-2 seconds when the emulsified magnesium coagulant is added, the speed is increased to 3000-4000 rpm after the emulsified magnesium coagulant is added, the temperature is kept for 30-35 seconds, and then the temperature is adjusted to 1000-2000 rpm, and the temperature is kept for 2-10 seconds.

In the step h, the product after packaging and film sealing is preserved for 30 minutes at 60-65 ℃, is heated to 85-90 ℃ for pasteurization for 30 minutes, is precooled for 20-40 minutes after sterilization, is placed into an ice water tank at 4-15 ℃ for cooling for 40-60 minutes, and is discharged from the tank and transferred into a refrigeration house.

In the step b, grinding the soybean and water in a ratio of 1:4-1:5, and centrifuging the ground paste at a high speed through 2-3 times of circulation to throw out the bean dregs to obtain the soybean milk.

In the step c, the temperature of the roasted soybean milk is controlled to be 98-100 ℃, the roasted soybean milk is kept for 3-5 minutes, and the concentration of the roasted soybean milk is controlled to be 12-14 ℃.

The device (see figure 1) for preparing soft bean curd by using secondary hot spot slurry comprises a controller, a soybean milk barrel 1, a stirring barrel 2 and a slurry flushing barrel 3, wherein the soybean milk barrel is arranged above the stirring barrel, the stirring barrel is arranged above the slurry flushing barrel, a primary slurry-flushing coagulant barrel 4 is arranged above the stirring barrel, a secondary slurry-flushing coagulant barrel 5 is arranged above the slurry flushing barrel, the lower end of the soybean milk barrel is connected with a soybean milk control valve 6, the soybean milk control valve is connected with a soybean milk conveying pipe 7 for conveying soybean milk to the stirring barrel, the lower end of the primary slurry-flushing coagulant barrel is connected with a primary slurry-flushing control valve 8, the primary slurry-flushing control valve is connected with a primary slurry-flushing pipe 9 for conveying emulsified magnesium coagulant to the stirring barrel, the lower end of the stirring barrel is connected with a slurry flushing control valve 10, the lower end of the secondary slurry-flushing coagulant barrel is connected with a slurry flushing control valve 11, a slurry flushing pipe 12 is connected between the slurry flushing control valve and the secondary slurry-flushing control valve, and a slurry outlet pipe 13 arranged towards the slurry flushing barrel is connected on the slurry flushing pipe; the lower end of the pulp flushing barrel is connected with a beancurd jelly control valve 14 for conveying beancurd jelly into the packaging box; a stirring rod 16 driven by a stirring motor 15 to rotate is arranged in the stirring barrel; the soybean milk control valve, the primary soybean milk dispensing control valve, the flushing control valve, the secondary soybean milk dispensing control valve, the bean curd control valve and the stirring motor are controlled by a controller. The agitator top sets up mount table 17, installs lift piston cylinder 18 on the mount table, and lift piston cylinder telescopic link connects lifter plate 19, and the agitator motor is installed on the lifter plate, and stirring vane 20 is installed to the puddler lower extreme. The primary soymilk dropping pipe is connected in parallel with the soymilk conveying pipe, and the soymilk conveying pipe is downwards arranged towards the stirring barrel. The lifting plate is provided with a guide rod 21 which is movably inserted on the mounting table. The soybean milk control valve, the primary soybean milk dispensing control valve, the flushing control valve, the secondary soybean milk dispensing control valve and the bean curd control valve are all electromagnetic valves.

Example 2: the device for preparing soft bean curd by secondary hot pulp (see fig. 2) has a structure similar to that of the embodiment 1, and is mainly characterized in that an anti-rotating seat 22 is connected to the upper part of a stirring rod in the embodiment, the anti-rotating seat and the stirring rod can mutually rotate, a liquid through cavity 23 is arranged in the stirring rod, the liquid through cavity is arranged between a stirring blade and the anti-rotating seat, a radially arranged liquid outlet hole 24 is arranged on the stirring blade, a liquid outlet hole is arranged on the outer wall of the lower end of the stirring rod, and the liquid outlet holes are all communicated with the liquid through cavity; the inner wall of the anti-rotation seat is provided with a liquid passing ring cavity 25, the stirring rod is provided with a liquid passing hole 26 for communicating the liquid passing ring cavity with the liquid passing cavity, the anti-rotation seat is provided with a coagulant inlet 27 and a slurry inlet 28 which are communicated with the liquid passing ring cavity, the coagulant inlet and the slurry inlet are respectively provided with a one-way valve, the coagulant inlet is connected with a metering pump 29, the primary slurry-dropping pipe is a flexible pipe, and the metering pump is connected with the primary slurry-dropping pipe; the anti-rotation seat is connected with a piston pipe 30, a piston 31 is arranged in the piston pipe, a piston rod 32 is connected to the piston, a fixed plate 33 is connected to the stirring barrel, the upper end of the piston rod is connected to the fixed plate, a positioning rod 34 is arranged on the anti-rotation seat, a positioning hole is formed in the fixed plate, and the positioning rod is movably inserted into the positioning hole; the lower end of the piston tube is provided with a liquid suction port 35 and a liquid discharge port 36, the liquid suction port is connected with a liquid suction tube 37, the lower end of the liquid suction tube is provided with a filter cover 38, a plurality of filter holes are densely distributed on the filter cover, the liquid discharge port is connected with a liquid discharge tube 39, the liquid discharge tube is connected with a slurry inlet, and the liquid suction port and the liquid discharge port are both provided with one-way valves. The upper positioning block 40 and the lower positioning block 41 are respectively connected above and below the anti-rotation seat on the stirring rod, and the anti-rotation seat is limited between the upper positioning block and the lower positioning block, so that the anti-rotation seat is ensured to move up and down along with the stirring rod, and the positioning rod on the anti-rotation seat is inserted into the positioning hole on the fixing plate, so that the anti-rotation seat can be ensured not to rotate along with the stirring rod. Other structures are the same as those of embodiment 1.

The above-described embodiments are merely preferred embodiments of the present invention, and the present invention is not limited in any way, and other variations and modifications may be made without departing from the technical aspects set forth in the claims.

Claims

1. The device for preparing the soft bean curd by the secondary hot spot slurry is characterized by being used in a method for preparing the soft bean curd by the secondary hot spot slurry, and the method for preparing the soft bean curd by the secondary hot spot slurry comprises the following steps of: a. soaking, namely soaking the screened soybeans; b. pulping, namely cleaning soaked soybeans, pulping, and separating bean dregs in the ground paste to obtain soybean milk; c. burning soybean milk, namely placing the soybean milk into a soybean milk burning cylinder to burn the soybean milk; d. sieving the soybean milk, and sieving the cooked soybean milk with a sieve; e. heating the soybean milk at 70-80 ℃ at one time, adding the soybean milk into a soybean milk stirring barrel, and adding an emulsified magnesium coagulant while stirring, wherein the adding amount is 0.5% -0.7%; releasing the emulsified magnesium coagulant embedded in the grease, mixing with the soybean milk, and rapidly carrying out secondary hot spot slurry before the emulsified magnesium coagulant is not completely combined; f. the secondary hot spot slurry is stirred at 60-70 ℃ to finish the synchronous flushing of the soybean milk of the primary hot spot slurry and the secondary spot slurry coagulant into a flushing barrel for flushing type spot slurry, and the addition amount of the secondary spot slurry coagulant is 1.5-2.5%; g. packaging and sealing the film, namely quickly flushing the bean curd after the secondary hot spot paste is finished into a packaging box, and performing heat sealing on the film; h. sterilizing, warehousing, preserving the heat of the packaged and film-sealed product for a period of time at 60-65 ℃, heating to 85-90 ℃ for sterilization, cooling after sterilization, and finally transferring to a refrigeration house; the device for preparing the tender bean curd by the secondary hot spot slurry comprises a controller, a soybean milk barrel, a stirring barrel and a slurry flushing barrel, wherein the soybean milk barrel is arranged above the stirring barrel, the stirring barrel is arranged above the slurry flushing barrel, a primary slurry-dropping coagulant barrel is arranged above the stirring barrel, a secondary slurry-dropping coagulant barrel is arranged above the slurry flushing barrel, the lower end of the soybean milk barrel is connected with a soybean milk control valve, the soybean milk control valve is connected with a soybean milk conveying pipe for conveying soybean milk to the stirring barrel, the lower end of the primary slurry-dropping coagulant barrel is connected with a primary slurry-dropping control valve, the primary slurry-dropping control valve is connected with a primary slurry-dropping pipe for conveying emulsified magnesium coagulant to the stirring barrel, the lower end of the stirring barrel is connected with a slurry flushing control valve, the lower end of the secondary slurry-dropping coagulant barrel is connected with a slurry flushing pipe between the slurry flushing control valve and the secondary slurry-dropping control valve, and the slurry outlet pipe arranged towards the slurry flushing barrel is connected on the slurry flushing pipe; the lower end of the pulp flushing barrel is connected with a bean curd control valve for conveying bean curd into the packaging box; a stirring rod driven by a stirring motor to rotate is arranged in the stirring barrel; the soybean milk control valve, the primary soybean milk dispensing control valve, the flushing control valve, the secondary soybean milk dispensing control valve, the bean curd control valve and the stirring motor are controlled by a controller; the lower end of the stirring rod is provided with a stirring blade; the stirring rod is connected with an anti-rotation seat near the upper part, the anti-rotation seat and the stirring rod can rotate mutually, a liquid passing cavity is arranged in the stirring rod, the liquid passing cavity is arranged between the stirring blade and the anti-rotation seat, a liquid outlet hole which is radially arranged is arranged on the stirring blade, a liquid outlet hole is arranged on the outer wall of the lower end of the stirring rod, and the liquid outlet holes are all communicated with the liquid passing cavity; the inner wall of the anti-rotation seat is provided with a liquid passing ring cavity, the stirring rod is provided with a liquid passing hole for communicating the liquid passing ring cavity with the liquid passing cavity, the anti-rotation seat is provided with a coagulant inlet and a slurry inlet which are communicated with the liquid passing ring cavity, the coagulant inlet and the slurry inlet are both provided with one-way valves, the coagulant inlet is connected with a metering pump, the primary slurry-dropping pipe is a flexible pipe, and the metering pump is connected with the primary slurry-dropping pipe; the anti-rotation seat is connected with a piston pipe, a piston is arranged in the piston pipe, a piston rod is connected with the piston, a fixed plate is connected with the stirring barrel, the upper end of the piston rod is connected with the fixed plate, a positioning rod is arranged on the anti-rotation seat, a positioning hole is formed in the fixed plate, and the positioning rod is movably inserted into the positioning hole; the lower end of the piston tube is provided with a liquid suction port and a liquid discharge port, the liquid suction port is connected with a liquid suction tube, the lower end of the liquid suction tube is provided with a filter cover, the liquid discharge port is connected with a liquid discharge tube, the liquid discharge tube is connected with a slurry inlet, and the liquid suction port and the liquid discharge port are both provided with one-way valves.

2. The device for preparing soft bean curd from the secondary hot spot slurry according to claim 1, wherein the emulsified magnesium coagulant is prepared by mixing and emulsifying the following components in percentage by weight: 50% of magnesium chloride, 30% of vegetable oil, 15% of water and 5% of glyceryl monostearate.

3. The apparatus for preparing soft bean curd from the secondary hot spot slurry according to claim 1, wherein the secondary spot slurry coagulant comprises the following components in percentage by weight: 69.2% of water, 2.5% of calcium sulfate, 22% of glucono-delta-lactone, 5.5% of TG enzyme and 0.8% of edible salt.

4. The apparatus for preparing soft bean curd from the secondary hot spot slurry according to claim 1, wherein in the step e, the stirring speed of the soybean milk is 500 rpm for 1-2 seconds when the emulsified magnesium coagulant is added, the stirring speed is increased to 3000-4000 rpm after the emulsified magnesium coagulant is added, the temperature is maintained for 30-35 seconds, and then the temperature is adjusted to 1000-2000 rpm, and the temperature is maintained for 2-10 seconds.

5. The device for preparing soft bean curd by using the secondary hot spot slurry according to claim 1, wherein in the step h, the product after packaging and sealing is preserved for 30 minutes at 60-65 ℃, is heated to 85-90 ℃ for pasteurization for 30 minutes, is precooled for 20-40 minutes after sterilization, is placed into an ice water tank at 4-15 ℃ for cooling for 40-60 minutes, and is discharged from the tank and transferred into a refrigeration house.

6. The apparatus for preparing soft bean curd from the secondary hot spot slurry according to any one of claims 1 to 5, wherein in the step b, the soybean milk is prepared by grinding the soybean and water in a ratio of 1:4-1:5, and centrifuging the ground soybean paste at a high speed by 2-3 cycles, and throwing out the bean dregs.

7. The apparatus for preparing soft bean curd from the secondary hot spot slurry according to any one of claims 1 to 5, wherein in the step c, the slurry burning temperature is controlled to 98-100 ℃, the temperature is maintained for 3-5 minutes, and the concentration of the burned soybean milk is controlled to 12-14 ℃.

8. The device for preparing soft bean curd by using the secondary hot spot slurry according to claim 1, wherein a mounting table is arranged above the stirring barrel, a lifting piston cylinder is mounted on the mounting table, a telescopic rod of the lifting piston cylinder is connected with a lifting plate, and the stirring motor is mounted on the lifting plate.