阅读说明：本技术 一种大豆蛋白热聚集体及其在凝胶制备中的应用 (Soybean protein heat aggregate and application thereof in gel preparation ) 是由 郑志 季扶云 李兴江 杨雪飞 穆冬冬 罗水忠 赵妍嫣 姜绍通 于 2019-09-30 设计创作，主要内容包括：一种大豆蛋白热聚集体及其在凝胶制备中的应用,包括以下技术步骤：(1)大豆蛋白热聚集体的制备,(2)制备大豆蛋白和大豆蛋白热聚集体的均匀体系溶液,(3)葡萄糖酸-δ-内酯诱导凝胶的制备。本发明制备的凝胶,其硬度为41.4-119.8g,弹性为0.817-0.965mm,持水率为54.4%-67.0%。(A soybean protein heat aggregate and application thereof in gel preparation comprise the following technical steps: (1) preparing a soybean protein heat aggregate, (2) preparing a uniform system solution of the soybean protein and the soybean protein heat aggregate, and (3) preparing gluconic acid-delta-lactone induced gel. The gel prepared by the invention has the hardness of 41.4-119.8g, the elasticity of 0.817-0.965mm and the water retention rate of 54.4-67.0%.)

1. A soybean protein heat aggregate and application thereof in gel preparation are characterized in that: comprises the following steps:

step 1: mixing the soybean protein and deionized water according to the mass ratio of 3-5:100, and uniformly stirring to obtain a soybean protein dispersion liquid;

step 2: standing the soybean protein dispersion liquid for 10-15h at the temperature of 3-5 ℃, and carrying out hydration treatment to obtain a hydrated soybean protein dispersion liquid;

and step 3: adjusting the pH value of the soybean protein dispersion liquid after hydration treatment to 2.5-3.5, adding NaCl to adjust the sodium ion strength of the soybean protein dispersion liquid after hydration treatment to 150-300mM, then heating to 85-95 ℃, keeping the temperature for 2-10h, and then cooling to room temperature to obtain the soybean protein dispersion liquid after heating treatment;

and 4, step 4: centrifuging the heated soybean protein dispersion liquid, and collecting supernatant;

and 5: freeze-drying the supernatant to obtain a soluble soybean protein hot aggregate;

step 6: putting the soybean protein heat aggregate and the soybean protein into a resonance acoustic mixer according to the mass ratio of 1:2.5-10, and treating for 300 plus 500s under the conditions of frequency of 80-120Hz and amplitude of 1.5-2.0mm to obtain a mixture;

and 7: mixing the mixture with deionized water according to the mass ratio of 6.5-11:100, and stirring for 20-30min at the temperature of 20-25 ℃ and the rotating speed of 400-; then placing the stirred solution into an ultrasonic environment at an ultrasonic frequency of 25-35KHz and a power density of 0.35-0.45w/cm²Treating for 10-15min under the condition to obtain a uniform system solution of the soybean protein and the soybean protein heat aggregate;

and 8: adjusting the pH value of the uniform system solution of the soybean protein and the soybean protein heat aggregate to 7.0-7.5, then heating to 85-95 ℃, and uniformly adding a gluconic acid-delta-lactone solution with the mass fraction of 0.5-0.8% into the uniform system solution of the soybean protein and the soybean protein heat aggregate within 3-5min to ensure that the mass concentration of the gluconic acid-delta-lactone in the uniform system solution of the soybean protein and the soybean protein heat aggregate is 5-12% of the mass concentration of the soybean protein; then stirring for 90-150s at the rotating speed of 50-100r/min, preserving heat for 25-30min, placing in a quick cooling environment, and cooling to form gel.

2. The soy protein thermal aggregate and its use in gel preparation according to claim 1, characterized in that: the soybean protein is dry powder soybean protein isolate, the protein content is more than or equal to 90 percent, and the water content is less than or equal to 5.0 percent.

3. The soy protein thermal aggregate and its use in gel preparation according to claim 1, characterized in that: in the step 1, stirring is carried out at a stirring speed of 400-.

4. The soy protein thermal aggregate and its use in gel preparation according to claim 1, characterized in that: in the step 4, the centrifugal speed is 6000-.

5. The thermal soybean protein aggregate and the use thereof in the preparation of a gel according to claim 1, wherein in step 5, the thermal soybean protein aggregate is freeze-dried at a temperature of-60 ~ -35 ℃ under an environmental condition of-0.09 to-0.10 MPa in vacuum gauge until the water content is 5.0% or less.

6. The soy protein thermal aggregate and its use in gel preparation according to claim 1, characterized in that: the quick cooling environment is one of ice water bath and air conditioner quick cooling.

Technical Field

The invention belongs to the technical field of food processing, and relates to a soybean protein heat aggregate and application thereof in gel preparation.

Background

Thermal aggregation of proteins refers to the phenomenon of dissociation or polymerization of proteins under heating. Aggregation of various proteins to form aggregates occurs as long as conditions are appropriate. Aggregation of proteins has adverse aspects such as reduced protein solubility and activity, adverse effects on the quality of the protein product, etc.; aggregation of proteins also has a beneficial aspect, and suitable aggregation may improve product stability, improve product texture, and even bring new properties. Researches show that through regulating and controlling various external conditions such as temperature, pH value, ionic strength and the like, the same protein subunit can form aggregates with different types, different structures and forms and different properties.

Natural proteins are biological macromolecules with amino acids as basic units, and protein molecules maintain the stability of the structure through intramolecular disulfide bonds, ionic salt bonds, hydrogen bonds, hydrophobic bonds, van der waals forces and the like. Thermal processing and heat treatment are the most common methods and procedures for processing various proteins in food, such as cooking, maillard flavoring, high temperature sterilization, inactivation of anti-nutritional factors, spray drying, etc. In the heat treatment process, the closely and orderly tertiary structure of the protein is firstly destroyed along with the rise of the temperature, the tertiary structure of the protein molecule is unfolded to expose a large number of hydrophobic amino acid groups, and the molecules are easily associated together through hydrophobic interaction; meanwhile, protein molecules can generate sulfydryl/disulfide bond exchange reaction to form intermolecular disulfide bonds. Therefore, with the increase of the external temperature, the structure of the natural protein is changed, and the hot aggregate of the protein is formed, thereby having important influence on the functional property and the application value of the protein.

The soybean protein is a plant protein with rich nutrition, wide source and low price, and is a substitute source of high-quality animal protein. The superiority of the soybean protein is mainly reflected in the following three aspects: (1) the soybean protein has reasonable proportion of amino acid, the content of essential amino acid is close to the recommended value of FAO/WHO organization, and the soybean protein is high-quality full-value plant protein; (2) the soybean protein contains a certain amount of physiological active ingredients, and has the functions of reducing cholesterol, reducing blood fat, reducing the risk of cardiovascular diseases and the like; (3) the soybean protein has good functional characteristics, such as gel property, emulsifying property, water and oil retention property and the like.

Under proper conditions, the viscosity of a polymer solution or sol with a certain concentration gradually increases, and finally the fluidity is lost, so that the whole system becomes an elastic semisolid which has uniform appearance and keeps a certain shape, and the elastic semisolid is called gel. Protein molecules aggregate, and attractive and repulsive forces are balanced to form a highly ordered three-dimensional network structure or matrix capable of holding a large amount of water, namely protein gel. Gels and gelling processes play an important role in food processing, enabling the formation of the texture required for food products, enabling designability of food product manufacture.

Disclosure of Invention

The invention aims to provide a soybean protein thermal aggregate and application thereof in gel preparation.

In order to achieve the above objects and other related objects, the present invention provides the following technical solutions: a soy protein thermal aggregate and its use in gel preparation comprising the steps of:

step 1: mixing the soybean protein and deionized water according to the mass ratio of 3-5:100, and uniformly stirring to obtain a soybean protein dispersion liquid;

step 2: standing the soybean protein dispersion liquid for 10-15h at the temperature of 3-5 ℃, and carrying out hydration treatment to obtain a hydrated soybean protein dispersion liquid;

and step 3: adjusting the pH value of the soybean protein dispersion liquid after hydration treatment to 2.5-3.5, adding NaCl to adjust the sodium ion strength of the soybean protein dispersion liquid after hydration treatment to 150-300mM, then heating to 85-95 ℃, keeping the temperature for 2-10h, and then cooling to room temperature to obtain the soybean protein dispersion liquid after heating treatment;

and 4, step 4: centrifuging the heated soybean protein dispersion liquid, and collecting supernatant;

and 5: freeze-drying the supernatant to obtain a soluble soybean protein hot aggregate;

step 6: putting the soybean protein heat aggregate and the soybean protein into a resonance acoustic mixer according to the mass ratio of 1:2.5-10, and treating for 300 plus 500s under the conditions of frequency of 80-120Hz and amplitude of 1.5-2.0mm to obtain a mixture;

and 7: mixing the mixture with deionized water according to the mass ratio of 6.5-11:100, and stirring for 20-30min at the temperature of 20-25 ℃ and the rotating speed of 400-; then placing the stirred solution into an ultrasonic environment at an ultrasonic frequency of 25-35KHz and a power density of 0.35-0.45w/cm²Treating for 10-15min under the condition to obtain a uniform system solution of the soybean protein and the soybean protein heat aggregate;

and 8: adjusting the pH value of the uniform system solution of the soybean protein and the soybean protein heat aggregate to 7.0-7.5, then heating to 85-95 ℃, and uniformly adding a gluconic acid-delta-lactone solution with the mass fraction of 0.5-0.8% into the uniform system solution of the soybean protein and the soybean protein heat aggregate within 3-5min to ensure that the mass concentration of the gluconic acid-delta-lactone in the uniform system solution of the soybean protein and the soybean protein heat aggregate is 5-12% of the mass concentration of the soybean protein; then stirring for 90-150s at the rotating speed of 50-100r/min, preserving heat for 25-30min, placing in a quick cooling environment, and cooling to form gel.

The preferable technical scheme is as follows: the soybean protein is dry powder soybean protein isolate, the protein content is more than or equal to 90 percent, and the water content is less than or equal to 5.0 percent.

The preferable technical scheme is as follows: in the step 1, stirring is carried out at a stirring speed of 400-.

The preferable technical scheme is as follows: in the step 4, the centrifugal speed is 6000-.

In the step 5, under the environmental conditions of-60 ℃ below zero 60 ~ -35 ℃ and vacuum gauge pressure of-0.09 to-0.10 MPa, the freeze drying is carried out until the water content is less than or equal to 5.0 percent.

The preferable technical scheme is as follows: the quick cooling environment is one of ice water bath and air conditioner quick cooling.

Due to the application of the technical scheme, compared with the prior art, the invention has the advantages that:

1. the invention modifies the soy protein isolate to form the soy protein thermal aggregate, adds the soy protein thermal aggregate into the soy protein isolate, and uses gluconic acid-delta-lactone to induce and form the cold gel, thereby obtaining the protein gel with excellent hardness, elasticity and water retention.

2. The invention realizes the uniform mixing of the soybean protein and the soybean protein heat aggregate by the modes of resonance sound mixing and ultrasonic treatment, and obtains a uniform system solution.

3. The gel prepared by the invention has the hardness of 41.4-119.8g, the elasticity of 0.817-0.965mm and the water retention rate of 54.4-67.0%.

Drawings

Figure 1 soy protein gel micro-morphology without added soy protein thermal aggregates.

FIG. 2 micro-morphology of gel formed with a soy protein thermal aggregate and soy protein isolate ratio of 1: 9.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Please refer to fig. 1-2. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.