Processing method of low-purine bean curd

Abstract

The invention relates to the technical field of food processing, in particular to a low-purine bean curd processing method. Soybean milk is subjected to ultrasonic-assisted enzymolysis treatment based on two reaction conditions to obtain modified soybean milk, and the modified soybean milk subjected to soybean milk boiling treatment is subjected to soybean milk solidification treatment through an emulsion coagulant to obtain the low-purine bean curd gel. Wherein the first reaction condition and the second reaction condition have different first reaction enzyme and second reaction enzyme which are respectively used for reducing micro cellulose in the soybean milk, increasing the content of soy isoflavone in the soybean milk and inhibiting a xanthine-uric acid metabolic pathway. The processing method provided by the invention can obviously improve the activity of the bean curd, and the bean curd has low purine.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a low-purine tofu processing method. Background Art

[0002] Beans and their processed bean products are rich in nutrients, rich in high-quality protein and bioactive ingredients that are beneficial to the human body, which gives them high nutritional value. However, bean products have a high purine content, and excessive intake of such foods poses a greater health risk to people with abnormal uric acid. At present, limiting purine intake is an important means of auxiliary treatment of hyperuricemia, but plant protein is the recommended protein intake for auxiliary treatment of hyperuricemia. Therefore, the development of low-purine and high-nutrition bean products has very important practical significance. Summary of the invention

[0003] In order to solve the above problems, the embodiment of the present application provides a low-purine tofu processing method, which can reduce the purine content in the finished tofu product and improve the nutritional value of tofu by increasing the content of soy isoflavones during the tofu processing process.

[0004] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows: In a first aspect, an embodiment of the present application provides a method for processing low-purine tofu, wherein the method obtains modified soy milk by subjecting soy milk to ultrasound-assisted enzymatic hydrolysis based on first reaction conditions and second reaction conditions, and obtains low-purine tofu by subjecting the modified soy milk after the boiling treatment to solid slurry treatment using an emulsion coagulant; the first reaction condition and the second reaction condition contain different first reaction enzymes and second reaction enzymes, which are respectively used to reduce the high cellulose content in the soy milk and increase the soy isoflavone content in the soy milk; the emulsion coagulant is an oil-in-water type ionic sustained-release coagulant.

[0005] In some specific implementations, the first reaction enzyme is cellulase, and the second reaction enzyme is β-glucosidase.

[0006] In some specific implementations, the soy milk is subjected to ultrasound-assisted enzymatic hydrolysis based on the first reaction conditions, including: adding a first reaction enzyme accounting for a total amount of 0.5~1U / 10mL to the soy milk, and performing ultrasonic water bath treatment based on a first enzymatic hydrolysis temperature and a first ultrasonic reaction time to obtain an initial modified soy milk.

[0007] In some specific implementations, the soy milk is subjected to ultrasound-assisted enzymatic hydrolysis based on the second reaction condition, comprising: heating the reaction environment under the first reaction condition to a second enzymatic hydrolysis temperature and adding a second reaction enzyme accounting for a total amount of 0.5~1U / 10mL to the initial modified soy milk, and performing an ultrasonic water bath treatment based on the second enzymatic hydrolysis temperature and a second ultrasonic reaction time to obtain the modified soy milk.

[0008] In some specific implementations, the method further comprises adding ferulic acid oligomers in a total amount of 0.1-0.3 U / 10 mL to the initial modified soy milk under the second reaction conditions to inhibit xanthine oxidase in the initial modified soy milk.

[0009] In some specific implementations, the first enzymatic hydrolysis temperature is 35°C, and the second enzymatic hydrolysis temperature is 45°C.

[0010] In some specific implementations, the soy milk is obtained by grinding and filtering soybeans and purified water in a weight ratio of 1:6.

[0011] In some specific implementations, the first ultrasonic reaction time and the second ultrasonic reaction time are respectively determined based on the amount of soybeans, specifically including: updating the basic first ultrasonic reaction time and the basic second ultrasonic reaction time based on the proportional relationship between the amount of soybeans and the unit amount of soybeans, and obtaining the first ultrasonic reaction time and the second ultrasonic reaction time corresponding to the current amount of soybeans; the unit amount of soybeans is 500g, the basic first ultrasonic reaction time is 20min, and the second basic reaction time is 30min.

[0012] In some specific implementations, the emulsion coagulant is an oil-in-water type magnesium ion sustained-release coagulant, and the ratio of the water phase to the oil phase is: 2~8:8~2; the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase includes soybean oil.

[0013] In some specific implementations, the mass fraction of the low-methoxy pectin accounts for 0.06-0.16% of the mixed solution, and the mass fraction of the magnesium chloride accounts for 2-16% of the mixed solution.

[0014] In the technical solution provided in the embodiment of the present application, the activity of tofu can be significantly improved and the tofu has low purine content by adding the first reaction enzyme, the second reaction enzyme and the emulsion coagulant and performing ultrasound-assisted enzymatic treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a flow chart of the low-purine tofu processing method provided in the embodiments of the present application. DETAILED DESCRIPTION

[0019] To make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. The embodiments described below are some embodiments of the present invention, rather than all embodiments. In conjunction with the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention.

[0020] In a specific embodiment of the present invention, the present invention provides a low-purine tofu processing method, which is used to reduce the purine content in tofu and increase the soy isoflavone content in tofu.

[0021] Among them, purine is a heterocyclic aromatic compound formed by the hybridization of a pyrimidine ring and an imidazole ring. It is colorless and odorless, easily soluble in water, methanol and other organic reagents. It mainly exists in the human body in the form of nucleotides. It is an important component base of nucleic acid. In nucleic acid, purine and ribose are closely linked by glycosidic bonds. After the glycosidic bond is broken, free purine bases and purine-free sites will be produced. This process is called depurination. Purine bases mainly include adenine and guanine. Xanthine and hypoxanthine are also produced in a series of anabolism and catabolism in the body. Generally, nucleic acids, nucleotides and free purine bases are collectively referred to as purine substances. The presence of purine can induce ventilation. Generally, according to the level of purine content in food, food can be divided into three categories, namely high-purine food (≥150mg / 100g), medium-purine food (25-150mg / 100g) and low-purine food (≤25mg / 100g). The total purine content in some aquatic and livestock products is the highest, especially xanthine, such as fish eggs, goose, soy products, sardines, sea bream, anchovies and beef liver. Tofu, as the main soy product in life, can reduce purine and is more suitable for consumption by many people.

[0022] Moreover, the nutritional value of tofu is mainly reflected in the various nutrients, multiple mineral elements and rich dietary fiber it contains. These nutrients not only help regulate gastrointestinal function, but are also well preserved in the process of making tofu. In addition to the basic nutrients, tofu is also rich in a variety of physiologically active ingredients, including soy isoflavones, soy oligosaccharides, soy lecithin and soy dietary fiber. These ingredients have multiple benefits for human health, such as anti-oxidation, reducing the risk of cardiovascular disease, etc., showing good medical and health care effects. Due to the widespread problem of lactose intolerance, lactose-containing dairy products are difficult for many people to digest and absorb, and tofu or soy milk have become high-quality substitutes. Among them, beans and soy products are the main sources of soy isoflavones. However, among the soy products currently on the market, fermented soy products are rich in soy isoflavone aglycones, and non-fermented soy products are mainly soy isoflavone glycosides, containing a small amount of soy isoflavone aglycones. In the human and animal bodies, the functional activity of soy isoflavone aglycones is better than that of soy isoflavone glycosides, with better digestion and absorption rate and greater nutritional value.

[0023] Therefore, in view of the technical problems in the above-mentioned research and development background, in order to obtain tofu of better quality, the embodiment of the present application provides a low-purine tofu processing method, through which the soy isoflavone content in tofu can be increased during the processing process, and the content of soy isoflavone aglycones in non-fermented soy products can be correspondingly increased, thereby enhancing the activity of tofu; and it can also reduce the purine content in the molded tofu, which can be more suitable for consumption by multiple groups of people, and reduce the metabolic pressure of the consumer and the occurrence of symptoms such as wind.

[0024] The present invention provides a method for processing low-purine tofu, which includes at least three steps. Figure 1 The process shown specifically includes: Step S1. subjecting soy milk to ultrasound-assisted enzymatic hydrolysis based on the first reaction condition and the second reaction condition to obtain modified soy milk.

[0025] Step S2: boiling the modified soy milk.

[0026] Step S3: solidifying the modified soybean milk after boiling with an emulsion coagulant to obtain tofu.

[0027] It is worth noting that step S1 to step S3 are key steps in the complete processing technology, but it does not mean that the tofu processing and molding process only includes the above three steps. In other embodiments, the above steps are also provided with a soy milk processing process and a molding process.

[0028] The soymilk processing process includes a pulping process before step S1, including but not limited to soaking soybeans and then grinding them to obtain the soymilk in step S1. Specifically, the soybeans are soaked for 12 hours and the soaked soybeans are washed; and distilled water 6 times the weight of the soybeans is mixed with the soybeans and then ground, and filtered using a 100-mesh screen to obtain the soymilk in step S1.

[0029] The tofu molding process is performed by pressing the tofu after step S3.

[0030] Furthermore, the above steps S1 to S3 are described in detail.

[0031] Among them, the first reaction condition and the second reaction condition in this embodiment are respectively used to enzymolyze soybean milk so that the soybean milk meets the target needs. In this embodiment, the target needs for soybean milk include reducing the purine content and increasing the soybean isoflavone content, especially the content of soybean isoflavone aglycones. In addition, during the tofu processing, because there are more large particle fibers in the soybean milk, the protein gel network is damaged. This damage will cause nutrients such as protein and soybean isoflavones to be lost along with the removed water during the tofu pressing process. Therefore, in this embodiment, it is necessary to make the structure of the protein gel network more stable.

[0032] Generally speaking, in conventional scenarios, in order to solve the problem of unstable protein gel network structure, coagulants are usually used for improvement. Among them, commonly used coagulants can be divided into three types according to the main ingredients: salt coagulants, acid coagulants and enzyme coagulants. According to the usage classification, they are mainly divided into single coagulants and compound coagulants. Although the above-mentioned coagulants can solve the problem of protein gel network destruction to a certain extent, the above-mentioned types of coagulants also have the problems of uneven protein gel network and poor taste of tofu products. In addition, because there is a high content of insoluble dregs of soybean milk, the above-mentioned coagulant method cannot achieve the micronization of dregs of soybean fiber, so that the final tofu cannot guarantee the stability of molding and the guarantee of taste and nutrition.

[0033] Therefore, in order to solve this problem, in this embodiment, the high cellulose content in the process is improved and the coagulant is improved so that the influence of dregs fiber on the overall structure and taste of the tofu after it is formed is reduced, and the overall integrity and texture of the tofu are made better, thereby improving the overall appearance, taste and nutritional value of the tofu products as a whole.

[0034] Therefore, in the present embodiment, the first reaction condition in step S1 is used to reduce the high cellulose in the soy milk, that is, the first reaction condition corresponds to the first reaction process. Among them, the first reaction condition for reducing the cellulose in the soy milk is realized by increasing the first reaction enzyme, and the micro cellulose in the soy milk is decomposed by the enzymatic method and removed based on the subsequent process. In general, the enzymatic process is usually carried out under a certain temperature condition and the enzyme is fed and reacted by stirring, but the reaction time of this process is long in large-scale production. In order to improve the overall reaction efficiency, the reflection is more in-depth in a short time. In this embodiment, the enzymatic reaction is carried out by ultrasound-assisted method. Moreover, for the use of ultrasound-assisted method, the cell wall can be broken by cavitation effect, thereby effectively accelerating the release and dissolution of the effective components in the cell. Moreover, in this process, the physical field of ultrasound can accurately destroy the molecular structure of macromolecular substances, and even change its molecular spatial configuration, thereby making the macromolecular substances easier to be degraded. Among them, cellulose is a typical macromolecular polysaccharide structure, so the enzymatic hydrolysis of micro cellulose in the enzymatic reaction can be accelerated by ultrasound-assisted method, so that the reaction process is more efficient.

[0035] Specifically, for the first reaction process, 0.5-1 U / 10 mL of cellulase is added to the soy milk, and an ultrasonic water bath treatment is performed based on a first enzymatic hydrolysis temperature and a first ultrasonic reaction time to obtain the initial modified soy milk.

[0036] The first enzymatic hydrolysis temperature is 35°C. That is, in the first reaction process, the initial temperature of the soy milk is 35°C and the reaction temperature is maintained at 35°C by means of an ultrasonic water bath. By adding cellulase to the soy milk and assisting with ultrasound, the microcellulose in the soy milk is decomposed, so that only large cellulose exists in the soy milk, thereby avoiding the destruction of the protein network structure by more microcellulose to a certain extent.

[0037] The main purpose of the reaction process under the first reaction condition is to increase the content of large cellulose in soybean milk, so that the tofu after molding can ensure high cellulose content while also reducing the damage to the tofu structure. But it is worth noting that the application of cellulase can reduce the content of microcellulose in soybean milk and reduce the risk of tofu protein network being destroyed, but only this improvement cannot solve the problem of tofu protein network structure being destroyed. In addition to the reason of microcellulose, the tofu protein network structure is destroyed, and other reasons are also included. Therefore, in this embodiment, it is also necessary to introduce a coagulant to make the molded structure of tofu in a stable state.

[0038] Furthermore, the first reaction is used to reduce microcellulose, and the second reaction is used to increase the content of soy isoflavones in soy milk, especially the content of soy isoflavone aglycones.

[0039] Specifically, the second reaction condition for increasing the content of soy isoflavones is also achieved by adding the corresponding reaction enzyme to the soy milk based on the enzymatic method. The difference from the first reaction is that the enzyme used in the second reaction process is the second reaction enzyme, specifically β-glucosidase. Among them, soy isoflavones are commonly found in beans and soy products. However, in the tofu making process, because the pressing and molding process is involved, the water in the tofu will be discharged, but the applicant has found that a large amount of soy isoflavone glycosides are discharged along with the discharged water, so that the content of soy isoflavones in the final tofu is less. The reason for this result is that the soy isoflavone glycosides in the soy isoflavones have good water solubility. In the tofu making process, a large amount of soy isoflavone glycosides will dissolve in water and be discharged along with the discharged water, thereby reducing the content of soy isoflavones in the final formed tofu.

[0040] In order to solve this technical problem and prevent the loss of soy isoflavone glycosides, the current method mainly involves adding coagulants to increase the water holding rate of tofu so that the soy isoflavone glycosides dissolved in water can be preserved and enriched. However, the use of coagulants alone still cannot solve the problem of a large amount of water being discharged, because the soybean content is relatively small relative to the amount of water used during tofu processing, and a large amount of water will still be discharged. Therefore, in actual scenarios, the soy isoflavone content in tofu cannot be significantly increased by using coagulants.

[0041] In view of this, the applicant adopts another technical idea in this embodiment. The applicant found that the absorption efficiency and absorption amount of soybean isoflavone aglycones by the human body are higher than those of soybean isoflavone glycosides, and aglycones have higher physiological activity, and the water solubility of soybean isoflavone aglycones is poor, so that soybean isoflavone aglycones will not be fully combined with water, so as not to cause the soybean isoflavone aglycones to be discharged due to the pressing and drainage process of tofu. Therefore, for this embodiment, by converting soybean isoflavone glycosides into soybean isoflavone aglycones, and enriching the soybean isoflavone glycosides that have not been converted again by means of a coagulant, the content of soybean isoflavones in tofu is increased, and the human body is fully absorbed by soybean isoflavone aglycones.

[0042] Furthermore, the purpose of the second reaction condition is to convert soybean isoflavone glycosides into soybean isoflavone aglycones. Specifically, the second reaction process is to add 0.5-1U / 10mL of the first reaction enzyme to the soybean milk after the first reaction process, and perform ultrasonic water bath treatment based on the first enzymolysis temperature and the first ultrasonic reaction time to obtain the initial modified soybean milk.

[0043] Among them, the second enzymatic hydrolysis temperature is 45°C.

[0044] Because the second enzymolysis temperature is higher than the reaction temperature in the first enzymolysis process, in order to enable the reaction to proceed, the soymilk after the first reaction needs to be heated before the enzymolysis. Specifically, the reaction environment under the first reaction condition is heated to the second enzymolysis temperature, and the second reaction enzyme accounting for a total amount of 0.5~1U / 10mL is added to the initial modified soymilk, and the ultrasonic water bath treatment is performed based on the second enzymolysis temperature and the second ultrasonic reaction time to obtain the modified soymilk.

[0045] Since only cellulase was added in the first reaction process and did not have a significant impact on the weight of the soymilk itself, for the convenience of calculation and feeding, the total amount mentioned in this embodiment may refer to the total amount of soymilk before the reaction.

[0046] The role of the second reaction enzyme in this embodiment is to convert the soybean isoflavone glycosides in soybean milk into soybean isoflavone aglycones. Specifically, the second reaction enzyme is β-glucosidase, which has the ability to hydrolyze the glycosidic bonds in soybean isoflavone glycosides to release soybean isoflavone aglycones and glucose.

[0047] Furthermore, in order to further improve the release and dissolution of the effective ingredients, namely the release of soybean isoflavone glycosides, ultrasound-assisted enzymolysis was also used in this embodiment to perform the enzymolysis reaction.

[0048] In summary, in this embodiment, by adding the reaction enzyme in the above two reaction processes, the microcellulose can be decomposed, which reduces the problem of more dregs caused by the microcellulose, making the tofu more stable and full. In addition, the content of soy isoflavones in soy milk is increased by converting the glycosides and aglycones in soy isoflavones. In addition, the above two reaction processes are reused, which can optimize the above two effects as a whole.

[0049] Moreover, soy isoflavones have high antioxidant and anti-inflammatory properties, and have a greater effect on reducing the occurrence of gout. The cause of gout is mainly based on uric acid precipitation, and the cause of uric acid precipitation is that the purine content dissolved in food is high, and the purine content in soybeans accounts for a high proportion in daily food. Therefore, in order to reduce the gout caused by eating tofu, the possibility of gout occurrence can be reduced by anti-inflammatory means by increasing the soy isoflavone content in tofu. Specifically, soy isoflavones belong to flavonoid compounds, and their components can inhibit the activity of xanthine oxidase, thereby reducing the synthesis of uric acid by the human body, and ultimately play a role in preventing uric acid deposition and preventing gout. However, the effect of uric acid deposition inhibition only by the effect of soy isoflavones is limited. In order to further improve the inhibitory effect on uric acid deposition, the amount of uric acid deposition is reduced by increasing ferulic acid oligomers in this embodiment, thereby reducing the possibility of gout generation.

[0050] Among them, the purines in the human body must exist in the form of purine nucleotides, mainly including adenine, guanine, hypoxanthine and xanthine. Among them, the above purines are mainly degraded at three levels in the human body, the upstream products include adenine ribonucleic acid, hypoxanthine ribonucleic acid, xanthine ribonucleic acid and guanine ribonucleic acid, the midstream products are adenosine, inosine, xanthine, guanosine, and the downstream products include adenine, hypoxanthine, xanthine and guanine, and finally generate uric acid. In the above decomposition process of the human body, the starting purine bases are mainly adenine and guanine. As the fermentation proceeds, adenine and guanine are continuously consumed, and the content of hypoxanthine and xanthine gradually increases. The increase in the content of hypoxanthine is small, and the increase in the content of xanthine is large. The final purine content is mainly xanthine.

[0051] Uric acid is produced through the oxidation of hypoxanthine and xanthine to xanthine metabolites catalyzed by xanthine oxidase, and the mechanism of inhibiting uric acid production is to inhibit the activity of xanthine oxide so that the metabolic pathways of xanthine and hypoxanthine cannot be formed, thereby not producing uric acid that can accumulate. As for ferulic acid, it can dock with xanthine oxidase. When ferulic acid oligomers enter the isoalloxazine ring pocket of xanthine oxidase, molecular oxygen is reduced to superoxide anion or H2O2, and interacts with amino acid residues LYS433, ILE358, THR345 and GLU263 to form hydrogen bonds, making O2- unable to diffuse, and electrons are transferred from FADH2 to O2-, further generating H2O2, and ultimately reducing uric acid production overall.

[0052] Therefore, the reduction of purine content in this embodiment does not refer to directly reducing the content of purine in the overall composition, but rather inhibiting xanthine oxidase, thereby preventing the passage of uric acid formation. Specifically, the content of ferulic acid oligomers in this embodiment is 0.1-0.3U / 10mL in the initial modified soy milk. In addition, the feeding of ferulic acid oligomers is also carried out under the second reaction condition.

[0053] Further, for the ferulic acid oligomer, it is mainly ferulic acid dimer, ferulic acid trimer and ferulic acid tetramer.Wherein, for the above-mentioned configuration, it can be obtained by the mode of prior art, and no longer repeats in the present embodiment.Wherein, ferulic acid dimer, trimer and tetramer are docked with xanthine oxidase, and dimer can enter the isoalloxazine ring active region in xanthine oxidase, hinder the diffusion of O2-, reduce the reduction of molecular oxygen, and under the effect of these two main driving forces of hydrogen bond and hydrophobic bond, dimer and xanthine oxidase form stable complex, make it lose activity thereby suppress the metabolic pathway of xanthine oxidase.But for above-mentioned different oligomers, the applicant finds that the binding energy for ferulic acid dimer is the highest, the binding energy of trimer is lower, and the binding energy of tetramer is the lowest, based on the binding energy, its structure is more stable, then explain that the xanthine oxidase inhibition effect is poorer, then preferentially select ferulic acid dimer in the above-mentioned compounds.

[0054] In summary, the embodiments of the present application add the first reaction enzyme, the second reaction enzyme and ferulic acid oligomers under the first reaction conditions and the second reaction conditions, and treat the soy milk by ultrasound-assisted enzymatic hydrolysis, so that the protein network structure in the soy milk is more stable, has a stable large fiber structure, and enzymatically hydrolyzes the soy isoflavone aglycones with a high content and ferulic acid oligomers for inhibiting purine metabolism.

[0055] It is worth noting that the first ultrasonic reaction time and the second ultrasonic reaction time in this embodiment are determined based on the amount of soybeans input, respectively. It can be understood that when the amount of soybeans input is different, the reaction time is different.

[0056] Specifically, the ultrasonic reaction time is determined based on the basic reaction time and the amount of soybeans input. The basic reaction time corresponds to the basic soybean amount, wherein the basic soybean amount is the unit soybean amount. In the present embodiment, the specific value for the unit soybean amount is 500g, and the basic ultrasonic reaction time is updated by the proportional relationship between the amount of soybeans input and the unit soybean amount, and the ultrasonic reaction corresponding to the current soybean amount is obtained. Among them, the basic ultrasonic reaction is different for the first ultrasonic reaction and the second ultrasonic reaction, which can be understood as the basic first ultrasonic reaction time in the first reaction is different from the basic second ultrasonic reaction time in the second reaction. Specifically, the basic first ultrasonic reaction time is 20min, and the second basic ultrasonic reaction time is 30min. The above-mentioned basic first ultrasonic reaction time and the second basic ultrasonic reaction time are updated by the ratio of the amount of soybeans input to the basic soybean amount. For example, when the amount of soybeans input is 1000g, the current first ultrasonic reaction time is 40min, and the second ultrasonic reaction time is 60min.

[0057] This method can finely control the soymilk reaction process, but it is worth noting that the increase in the amount of soybeans input is not linear with the reaction time. Therefore, in order to further accurately control the reaction, in this embodiment, the coefficient of the reaction process is processed by fitting, and a function of the actual reaction time is obtained. This function is used to determine the first reaction time and the second reaction time, which is expressed based on the following formula: , where T1 is the first reaction time, T2 is the second reaction time, G1 is the actual amount of soybean input, G0 is the unit amount of soybean, R1 is the first reaction coefficient, and R2 is the second reaction coefficient. R1 is determined to be 0.5 by fitting, and R2 is determined to be 0.7 by fitting. Through this process, compared with the above-mentioned proportional linear increase in reaction time, the overall reaction is more refined, thereby improving the precipitation and activity retention of soymilk reactants.

[0058] The modified soymilk obtained in step S1 is boiled. In this process, the boiling process can adopt any process method in the prior art, which will not be described in detail in this embodiment.

[0059] With respect to step S3, it is used to solidify the soybean milk so that the tofu is initially formed. In the prior art, this process can be generally described as "adding brine" to solidify the liquid soybean milk into a solid structure. This process is an important environment in the tofu production process, which can directly affect the texture, taste and other physical properties of the tofu. In the prior art, this process usually uses brine as a coagulant for solidification. Although this coagulant is the most commonly used method, when brine is used as a coagulant, the coagulation process of soy protein is violent and difficult to control. In addition, rapid coagulation can also cause problems such as hardness, uneven texture, poor water retention and low product yield of the tofu, and during the pressing and molding process, nutrients such as protein and soy isoflavones will also be lost along with the discharged water.

[0060] Therefore, in this embodiment, a coagulant that can slow down the coagulation reaction needs to be provided during the solidification process to increase the yield and nutritional value of tofu.

[0061] Specifically, the coagulant in this embodiment is an oil-in-water type ionic slow-release coagulant. The slow-release coagulant is an oil-in-water type ionic slow-release coagulant, which is composed of an aqueous phase and an oil phase, and the ratio of the aqueous phase to the oil phase is 2-8:8-2. The aqueous phase in this embodiment includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil.

[0062] In this embodiment, the mass fraction of low methoxyl pectin accounts for 0.06-0.16% of the mixed solution, and the mass fraction of magnesium chloride accounts for 2-16% of the mixed solution.

[0063] For the corrosion-inhibiting coagulant in this embodiment, magnesium ions can be embedded in the emulsion to achieve slow release of magnesium ions. Among them, for low-methoxy pectin, a cross-linked structure can be formed with divalent or polyvalent metal cations to form a gel. Specifically, low-methoxy pectin and magnesium ions undergo gel reaction to form a three-dimensional network structure, which can absorb and retain a large amount of water, thereby increasing the water holding capacity of tofu. In addition, magnesium ions can also promote gel formation during the reaction. In the synergistic low-methoxy pectin process induced by magnesium ions, magnesium ion bridges promote the formation of gel structure by connecting pectin aggregates, and oxidize the gel network by forming hydrogen bonds. The two hydrogen bonds cooperate with each other to produce a strong interaction between pectin peaks. In addition, the affinity of magnesium ions to water is very high, and gel can be formed with pectin by polycondensation.

[0064] The water-in-oil type magnesium ion sustained-release coagulant in this embodiment is prepared by using low methoxy pectin as a surfactant, dissolving low methoxy pectin in an oxidase solution to form a mixed solution, adding the aqueous phase to soybeans under high-speed shearing using a high-speed disperser in a water bath, and stirring to obtain the mixed solution. The mass fraction of low methoxy pectin accounts for 0.06-0.16% of the mixed solution, and the mass fraction of magnesium chloride accounts for 2-16% of the mixed solution.

[0065] In this embodiment, the modified soybean milk is solidified by the above-mentioned slow-release coagulant to obtain a semi-finished tofu product, and the semi-finished tofu product is pressed and molded to obtain the final tofu product.

[0066] The low-purine tofu processing method of the present invention is further illustrated by specific examples below.

[0067] Example 1 The present embodiment provides a low-purine tofu processing method, comprising the following steps: Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.5U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 0.5U / 10mL of β-glucosidase and 0.1U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0068] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0069] Step S3. Adding 0.16% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 2:8, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.06% of the mixed solution, and the mass fraction of magnesium chloride accounts for 2% of the mixed solution.

[0070] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.06% low methoxy pectin in a 2% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0071] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0072] Example 2 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.6U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 0.6U / 10mL of β-glucosidase and 0.2U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0073] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0074] Step S3. Adding 0.18% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 4:4, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.1% of the mixed solution, and the mass fraction of magnesium chloride accounts for 4% of the mixed solution.

[0075] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.1% low methoxy pectin in a 4% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0076] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0077] Example 3 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.7U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 0.7U / 10mL of β-glucosidase and 0.2U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0078] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0079] Step S3. Adding 0.20% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 4:4, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.12% of the mixed solution, and the mass fraction of magnesium chloride accounts for 6% of the mixed solution.

[0080] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.12% low methoxy pectin in a 6% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0081] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0082] Example 4 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.8U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 0.8U / 10mL of β-glucosidase and 0.3U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0083] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0084] Step S3. Adding 0.20% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 4:6, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.14% of the mixed solution, and the mass fraction of magnesium chloride accounts for 8% of the mixed solution.

[0085] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.14% low methoxy pectin in a magnesium chloride solution in a 8% magnesium chloride solution, adding the aqueous phase to soybean oil in a 30°C water bath using a high-speed disperser at a high shear rate of 14500 r / min, and stirring for 120 seconds.

[0086] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0087] Example 5 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.9U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 0.9U / 10mL of β-glucosidase and 0.3U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0088] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0089] Step S3. Adding 0.18% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 4:8, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.16% of the mixed solution, and the mass fraction of magnesium chloride accounts for 10% of the mixed solution.

[0090] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.16% low methoxy pectin in a 10% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0091] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0092] Example 6 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 1.0U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 1.0U / 10mL of β-glucosidase and 0.3U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0093] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0094] Step S3. Adding 0.20% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 6:8, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.16% of the mixed solution, and the mass fraction of magnesium chloride accounts for 10% of the mixed solution.

[0095] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.16% low methoxy pectin in a 12% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0096] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0097] Example 7 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.7U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 1.0U / 10mL of β-glucosidase and 0.3U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0098] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0099] Step S3. Adding 0.20% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 4:6, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.1% of the mixed solution, and the mass fraction of magnesium chloride accounts for 10% of the mixed solution.

[0100] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.1% low-methoxy pectin in a 10% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0101] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0102] Example 8 Step S1. Obtain the amount of soybean added, and determine the first ultrasonic reaction time and the second ultrasonic reaction time based on the amount of soybean added, and add a total amount of 0.7U / 10mL of cellulase to the soy milk, and perform ultrasonic water bath treatment based on 35°C and the first ultrasonic reaction time to obtain initial modified soy milk; and increase the temperature to 45°C, add 1.2U / 10mL of β-glucosidase and 0.2U / 10mL of ferulic acid dimer to the initial modified soy milk, and perform ultrasonic water bath treatment based on 45°C and the second ultrasonic reaction time to obtain modified soy milk.

[0103] Step S2: boiling the modified soy milk to obtain cooked soy milk.

[0104] Step S3. Adding 0.20% of the total amount of cooked soy milk to the oil-in-water type magnesium ion slow-release coagulant to solidify the cooked soy milk to obtain tofu gel; wherein the ratio of the water phase to the oil phase of the oil-in-water type magnesium ion slow-release coagulant is 8:8, wherein the water phase includes a mixed solution composed of low-methoxy pectin and magnesium chloride solution, and the oil phase is soybean oil. The mass fraction of low-methoxy pectin accounts for 0.1% of the mixed solution, and the mass fraction of magnesium chloride accounts for 10% of the mixed solution.

[0105] The water-in-oil type magnesium ion sustained-release coagulant is prepared by dissolving 0.1% low-methoxy pectin in a 10% magnesium chloride solution, adding the aqueous phase to soybean oil at a high shear rate of 14500 r / min in a 30°C water bath using a high-speed disperser, and stirring for 120 seconds.

[0106] Step S4. The formed tofu gel is placed in a water bath at 85° C. to keep warm to ensure that the gel structure is fully formed; after the tofu gel structure is stable, it is lightly broken up and poured into a tofu mold and pressed to form the final tofu.

[0107] Experimental Example 1 This experimental example is used to measure the moisture content of tofu. The tofu prepared in Examples 1 to 8 is sliced ​​and weighed to obtain a wet weight M1. The tofu blocks are placed in an oven and dried to a constant temperature. The final dry weight of the tofu is recorded as M2. The moisture content in Examples 1 to 8 is calculated based on the following formula: Moisture content (%) = (M1-M2) × 100 / M1.

[0108] Experimental Example 2 This experimental example is used to measure the texture characteristics of tofu, by sampling the middle area of ​​the tofu in Example 1 to Example 8, and using a probe to measure the texture in the above sample. The following parameters are set: the test rate and return rate are both set to 1mm / s, the deformation of the sample is set to 75%, the starting distance is set to 30.00mm, and the number of cycles is 3 times to increase the reliability and repeatability of the measurement; the test time is set to 5s, the starting pressure is set to 5g, and the hardness and elasticity of the sample are recorded.

[0109] Experimental Example 3 In this experimental example, the content of soybean isoflavones in the dried tofu base in Examples 1 to 8 was determined by high performance liquid chromatography according to the national standard GB / T26625-2011.

[0110] The experimental data in Examples 1 to 3 are described based on Table 1.

[0111] Moisture content Soy isoflavone content (μg / g) Hardness(N) elasticity Example 1 88% 957 297.84 0.91 Example 2 86% 972 357.85 0.91 Example 3 85% 1016 448.66 0.92 Example 4 81% 1062 451.75 0.93 Example 5 84% 1034 417.26 0.91 Example 6 82% 1043 463.94 0.94 Example 7 78% 1085 492.66 0.96 Example 8 80% 1045 477.51 0.94 Table 1. Results of the first experiment Comparative Example 4 In this experimental example, the inhibitory effect of modified soy milk on the metabolites of xanthine was measured by setting up a blank control group, wherein the blank control group was the soy milk that had not been subjected to the above-mentioned modification treatment and the modified soy milk corresponding to Examples 1 to 8, and xanthine oxidase were mixed to obtain a mixed solution, which was centrifuged for 30 minutes to take the supernatant as the reaction solution, and the CD spectrum data was measured by CD spectroscopy. Among them, the parameters of the CD spectroscopy method were a scanning wavelength of 200-240nm and a scanning speed of 60nm / min, and the secondary structure content of xanthine oxidase before and after adding the modified soy milk was calculated by online software, wherein the secondary structure included the content of α-helix, parallel structure, β-turn, and no curl.

[0112] α-helix (%) Parallel structure (%) β-turn angle (%) No curl (%) Blank control group 22.4 13.7 17.6 52.4 Example 1 24.6 12.6 17.8 46.1 Example 2 24.8 12.3 17.8 45.4 Example 3 24.8 12.4 17.7 45.6 Example 4 25.1 11.7 17.6 43.4 Example 5 25.3 11.5 17.7 43.1 Example 6 25.4 11.5 17.8 43.2 Example 7 25.5 11.3 17.9 42.6 Example 8 24.6 12.4 17.8 45.3 Table 2. Second Experiment Table It can be seen from Table 2 that the α-helix content of Examples 1 to 8 gradually changes correspondingly from that of the blank control group, the β-turn content remains basically unchanged, and the other contents decrease, indicating that the modified soymilk binds and interacts with xanthine oxidase, inducing a part of the parallel structure and the non-curled structure in the secondary structure of the enzyme to be converted into an α-helix structure, thereby affecting the compactness of the secondary structure of xanthine oxidase and inhibiting the enzymatic reaction of xanthine oxidase to xanthine.

[0113] From Table 1 and Table 2, it can be clearly seen that the tofu prepared according to Examples 1 to 8 has better tofu quality, and the corresponding soy isoflavones content is higher, and the metabolic inhibition of xanthine is better, and the effect corresponding to Example 7 is the best and most optimal embodiment among the above embodiments.

[0114] In summary, the low-purine tofu processing method provided in the embodiments of the present application can significantly improve the activity of tofu and make it low-purine by adding the first reaction enzyme, the second reaction enzyme and the emulsion coagulant and performing ultrasound-assisted enzymatic treatment.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing low-purine tofu, characterized in that: The method obtains modified soy milk by subjecting soy milk to ultrasound-assisted enzymatic hydrolysis based on first reaction conditions and second reaction conditions, and obtains low-purine tofu gel by subjecting the modified soy milk after boiling to solidification through an emulsion coagulant; the first reaction condition and the second reaction condition contain different first reaction enzymes and second reaction enzymes, which are respectively used to reduce the microcellulose in the soy milk and increase the soy isoflavone content in the soy milk; the emulsion coagulant is an oil-in-water type ionic slow-release coagulant.

2. The low-purine tofu processing method according to claim 1, characterized in that: The first reaction enzyme is cellulase, and the second reaction enzyme is β-glucosidase.

3. The low-purine tofu processing method according to claim 2, characterized in that: The method comprises: adding a first reaction enzyme accounting for a total amount of 0.5-1U / 10mL into the soy milk, and performing an ultrasonic water bath treatment based on a first enzymatic hydrolysis temperature and a first ultrasonic reaction time to obtain an initial modified soy milk.

4. The low-purine tofu processing method according to claim 3, characterized in that: The soy milk is subjected to an ultrasonic-assisted enzymatic hydrolysis treatment based on a second reaction condition, comprising: heating the reaction environment under the first reaction condition to a second enzymatic hydrolysis temperature, adding a second reaction enzyme accounting for a total amount of 0.5 to 1 U / 10 mL to the initial modified soy milk, and performing an ultrasonic water bath treatment based on the second enzymatic hydrolysis temperature and a second ultrasonic reaction time to obtain the modified soy milk.

5. The low-purine tofu processing method according to claim 4, characterized in that: The method further comprises adding ferulic acid oligomers in a total amount of 0.1-0.3 U / 10 mL to the initial modified soy milk under the second reaction condition to inhibit xanthine oxidase in the initial modified soy milk.

6. The low-purine tofu processing method according to claim 4, characterized in that: The first enzymolysis temperature is 35°C, and the second enzymolysis temperature is 45°C.

7. The low-purine tofu processing method according to claim 4, characterized in that: The soy milk is obtained by grinding and filtering soybeans and purified water in a weight ratio of 1:

6.

8. The low-purine tofu processing method according to claim 7, characterized in that: The first ultrasonic reaction time and the second ultrasonic reaction time are respectively determined based on the amount of soybeans, specifically including: updating the basic first ultrasonic reaction time and the basic second ultrasonic reaction time based on the proportional relationship between the amount of soybeans and the unit amount of soybeans, and obtaining the first ultrasonic reaction time and the second ultrasonic reaction time corresponding to the current amount of soybeans; the unit amount of soybeans is 500g, the basic first ultrasonic reaction time is 20min, and the basic second reaction time is 30min.

9. The low-purine tofu processing method according to claim 1, characterized in that: The emulsion coagulant is a water-in-oil type magnesium ion slow-release coagulant, and the ratio of the water phase to the oil phase is 2-8:8-2; the water phase comprises a mixed solution of low-methoxy pectin and magnesium chloride solution, and the oil phase comprises soybean oil.

10. The low-purine tofu processing method according to claim 9, characterized in that: The mass fraction of the low methoxyl pectin accounts for 0.06-0.16% of the mixed solution, and the mass fraction of the magnesium chloride accounts for 2-16% of the mixed solution.

Images