CN117204501A - A method for improving the functional properties of soybean protein by combining thermal denaturation and high-pressure homogenization - Google Patents

Abstract

The invention belongs to the field of food processing, and particularly relates to a method for improving the functional properties of soybean protein by combining thermal denaturation and high-pressure homogenization. The invention is realized by the following method: first, prepare a soybean protein dispersion at room temperature, adjust the pH value, stir thoroughly to fully disperse, and then divide the processed soybean protein dispersion into two parts; one part of the soybean protein dispersion is thermally denatured. Then perform high-pressure homogenization treatment; another part is subjected to heat denaturation treatment after high-pressure homogenization treatment; and can be combined after treatment. The treatment method provided by the invention increases the hydrophobicity of the protein surface, induces the formation of soluble aggregates, and ultimately improves the solubility and emulsification properties, providing important technical support for the industrial production of high-solubility and high-emulsification soybean protein. .

Description

A method of combining thermal denaturation and high-pressure homogenization to improve the functional properties of soybean protein method

Technical field

The invention belongs to the field of food processing, and particularly relates to a method for improving the functional properties of soybean protein by combining thermal denaturation and high-pressure homogenization.

Background technique

Soy protein isolate (SPI) contains over 90% protein, consisting primarily of globulin (11S) and conglycinin (7S). SPI is widely used in foods due to its excellent nutritional value and health benefits (containing physiological components beneficial for reducing cholesterol, hyperlipidemia and cardiovascular disease risk). However, due to its compact structure, soy protein usually exhibits poor functional properties. Therefore, appropriate SPI modification has the potential to improve its functional properties, especially its emulsifying properties.

Physical treatment methods such as heat treatment and high-pressure homogenization (HPH) have been widely used in industrial production of soy protein processing. HPH is a non-thermal technology that is widely used in the food industry to improve the emulsifying properties of food proteins. HPH can induce the synthesis and destruction of chemical bonds and molecular interactions by generating high shear forces, turbulence and cavitation, thereby improving the functional properties of soy protein. Liu et al. also found that HPH treatment led to an increase in solubility, which caused protein aggregation at the oil-water interface and reduced the surface tension of the protein, thereby improving emulsification. Bi et al. reported that HPH helps form a stable three-dimensional network structure in the gel, thereby improving the functionality of latex gels. HPH reduces the particle size of hazelnut protein, increases solubility, and improves the emulsification and rheological properties of the protein. In addition, heat treatment is one of the most common modification and pretreatment methods for proteins and has been shown to be effective in improving emulsification capabilities. Peng et al. studied the effect of heat treatment on the emulsification properties of pea protein and showed that heat treatment increased the protein adsorption rate in the protein emulsion, thereby improving the emulsification activity. Dissanayake and Vasiljevic showed that heat treatment unfolds some proteins, improving their interfacial properties and thus improving emulsification. After heating soy protein to 95°C for 30 minutes, the adsorption of protein at the oil/water interface was enhanced and the emulsification performance was significantly improved.

Although heat treatment and HPH treatment alone improved the functional properties of soy protein, their effects on protein structure were relatively limited. For example, high-pressure treatment mainly affects non-covalent bonds such as hydrogen bonds, ionic bonds, and hydrophobic interactions. HPH treatment breaks or forms these bonds, improving functional properties by changing the hydrophobic groups. In contrast, heat treatment causes violent movements of molecules, leading to the breaking or formation of covalent and non-covalent bonds. In the current state of the art, there is limited research on how the sequence of high-pressure homogenization and heat treatment affects the conformation and emulsification properties of soy proteins.

Contents of the invention

In view of the technical gaps existing in the prior art, the present invention provides a method for improving the functional properties of soybean protein by combining thermal denaturation and high-pressure homogenization.

The technical solutions adopted by the present invention to achieve the above objects are:

The invention provides a method for improving the functional properties of soybean protein through combined heat denaturation and high-pressure homogenization treatment, which includes the following steps:

(1) Prepare soy protein dispersion at room temperature, adjust the pH value, stir thoroughly to fully disperse, and then divide the processed soy protein dispersion into two parts;

(2) A portion of the soy protein dispersion is heated and then insulated, followed by high-pressure homogenization and cooled to room temperature;

(3) Another part of the soy protein dispersion is subjected to high-pressure homogenization treatment, followed by heating and insulation treatment, and then cooled to room temperature;

(4) Combine the two processed soy protein dispersions.

Further, in step (1), the concentration of the soy protein dispersion prepared at room temperature is 4%-9% (w/v); the pH value is 7; and the stirring is at 1000-2000r/min. Stir under the conditions for 30-60min.

Further, in step (1), the pH value is determined by using 2 mol/L hydrochloric acid or 2 mol/L sodium hydroxide solution.

Further, in step (2), the heat preservation treatment is maintained at 90-100°C for 5-15 minutes.

Further, in step (2), the high-pressure homogenization treatment is 1-2 times of homogenization under the condition of 10-90MPa.

Further, in step (3), the high-pressure homogenization treatment is 1-2 times of homogenization under the condition of 10-90MPa.

Further, in step (3), the heat preservation treatment is maintained at 90-100°C for 5-15 minutes.

The beneficial effects of the present invention are:

(1) The processing method provided by the present invention provides a new option for the industrial manufacturing of highly emulsifiable soybean protein;

(2) The treatment method provided by the present invention increases the hydrophobicity of the protein surface, induces the formation of soluble aggregates, and ultimately improves the solubility and emulsification properties, providing important solutions for the industrial production of high-solubility and high-emulsification soybean proteins. technical support.

Detailed ways

The present invention will be further described in detail with reference to the examples, but the protection scope of the present invention is not limited to the described contents.

Example 1

(1) Prepare a soy protein dispersion with a concentration of 7% (w/v) at room temperature, adjust the pH to 7.0, stir with a mechanical stirrer at 1500r/min for 45 minutes to fully disperse, and then divide it into equal parts. two servings;

(2) First heat one part of the soy protein dispersion to 90°C for 10 minutes, then homogenize it twice under 20MPa and cool to room temperature;

(3) Another soy protein dispersion was homogenized twice at 20MPa, then heated to 90°C for 10 minutes, and then cooled to room temperature;

(4) Combine the two processed soy protein dispersions.

Example 2

(1) Prepare a soy protein dispersion with a concentration of 4% (w/v) at room temperature and adjust the pH to 7.0. Use a mechanical stirrer to stir at 1500r/min for 30 minutes to fully disperse.

(2) First heat the above soy protein dispersion to 95°C for 15 minutes, and then homogenize it twice under 50MPa. Cool to room temperature;

(3) Another soy protein dispersion was homogenized twice under 50MPa conditions, then heated to 95°C for 15 minutes and cooled to room temperature;

(4) Combine the two processed soy protein dispersions.

Example 3

(1) Prepare a soy protein dispersion with a concentration of 9% (w/v) at room temperature and adjust the pH to 7.0. Use a mechanical stirrer to stir for 60 minutes at 1500r/min to fully disperse.

(2) Divide the above soy protein dispersion into two parts, heat one part to 90°C for 5 minutes, and then homogenize once at 90MPa. Cool to room temperature.

(3) The other part is homogenized once at 90MPa, then heated to 90°C for 5 minutes, and cooled to room temperature.

Comparative example 1

(1) Prepare a soy protein dispersion with a concentration of 7% (w/v) at room temperature, and adjust its pH to 7.0 with 2 mol/L hydrochloric acid or 2 mol/L sodium hydroxide solution. Use a mechanical stirrer to stir for 45 minutes at 1000-2000r/min to fully disperse.

(2) The above soy protein dispersion is first homogenized twice under 20MPa conditions, then heated to 90°C for 10 minutes, and cooled to room temperature.

Comparative example 2:

(1) Prepare a soy protein dispersion with a concentration of 4% (w/v) at room temperature, and adjust its pH to 7.0 with 2 mol/L hydrochloric acid or 2 mol/L sodium hydroxide solution. Use a mechanical stirrer to stir for 30 minutes at 1000-2000r/min to fully disperse.

(2) The above soy protein dispersion is first homogenized twice under 50MPa conditions, then heated to 95°C for 15 minutes, and cooled to room temperature.

Comparative example 3

(1) Prepare a soy protein dispersion with a concentration of 9% (w/v) at room temperature, and adjust its pH to 7.0 with 2 mol/L hydrochloric acid or 2 mol/L sodium hydroxide solution. Use a mechanical stirrer to stir for 60 minutes at 1000-2000r/min to fully disperse.

(2) Homogenize the above soy protein dispersion once at 90MPa, then heat to 90°C for 5 minutes and cool to room temperature.

Effect Example

Take the products prepared in Examples 1-3 and Comparative Examples 1-3 and measure their solubility and emulsification respectively.

Solubility was measured according to the method provided in the literature "Structural and emulsifying properties of soy proteinisolate subjected to acid and alkaline pH-shifting processes";

The emulsifying activity index and emulsifying stability index were measured according to the method provided in the literature "Effect of enzymatic hydrolysis followed after extrusion pretreatment on the structure and emulsibility of soybean protein".

The results are recorded in Table 1.

Table 1 Solubility and emulsification properties of soy protein

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Claims (7)

1. A method for improving the functional characteristics of soy protein by heat denaturation and high-pressure homogenization combined treatment, which is characterized by comprising the following steps:

(1) Preparing soybean protein dispersion liquid at room temperature, regulating the pH value, fully stirring to fully disperse the soybean protein dispersion liquid, and then equally dividing the processed soybean protein dispersion liquid into two parts;

(2) Heating and preserving heat of one part of soybean protein dispersion liquid, then carrying out high-pressure homogenization treatment, and cooling to room temperature;

(3) Carrying out high-pressure homogenization treatment on the other part of soybean protein dispersion liquid, heating, then carrying out heat preservation treatment, and cooling to room temperature;

(4) Combining the two treated soy protein dispersions.

2. The method of claim 1, wherein in step (1), the concentration of the soy protein dispersion formulated at room temperature is 4% -9% (w/v); the pH value is 7; the stirring is carried out for 30-60min under the condition of 1000-2000 r/min.

3. The process according to claim 1 or 2, characterized in that in step (1) the pH is carried out with 2mol/L hydrochloric acid or 2mol/L sodium hydroxide solution.

4. The method according to claim 1 or 2, wherein in step (2), the incubation is carried out at 90-100 ℃ for 5-15 minutes.

5. The method according to claim 1 or 4, wherein in the step (2), the high-pressure homogenizing treatment is homogenizing 1 to 2 times under 10 to 90 MPa.

6. The method according to claim 1 or 2, wherein in step (3), the high-pressure homogenizing treatment is homogenizing 1 to 2 times under 10 to 90 MPa.

7. The method according to claim 1 or 6, wherein in step (3), the incubation is carried out at 90-100 ℃ for 5-15 minutes.