Preparation method of galactomannan structure-oriented soybean protein isolate emulsion

Abstract

The invention discloses a preparation method of a galactomannan structure-oriented soybean protein isolate emulsion, and belongs to the field of production and application of soybean protein products. The method comprises the following steps: (1) preparing a soybean protein isolate-galactomannan mixed solution; (2) preparing a soybean protein isolate-galactomannan compound; and (3) preparing the galactomannan structure-oriented soybean protein isolate emulsion. The invention clarifies the influence of the structure of galactomannan in the preparation of the soybean protein isolate emulsion, and determines that the emulsion with high solubility, stronger emulsion stability and better emulsion activity can be prepared under better conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of developing soy protein-galactomannan emulsion, and mainly relates to a method for preparing a galactomannan structure-oriented soy protein isolate emulsion. BACKGROUND

[0002] Soy protein isolate has a protein content of more than 90%, and is one of the protein forms with the highest nutritional value and the strongest functionality among plant proteins. Soy protein isolate exhibits excellent functionality in food processing characteristics, has excellent emulsifying properties, can stabilize the oil-water interface, and is widely used in meat products, dairy products and sauces. However, the exposed hydrophobic groups in the soy protein isolate molecules are relatively few or buried inside the structure, and the interaction with oil is weak, which leads to larger and uneven emulsion droplets initially formed, and compared with emulsifiers such as sodium caseinate, the stability of pure soy protein isolate emulsion is poorer in long-term storage, and is prone to delamination or precipitation.

[0003] Galactomannan is a natural water-soluble polysaccharide formed by the connection of galactose and mannose through β-1,4 glycosidic bond, and widely exists in the seeds of leguminous plants (such as guar beans, locust beans, sesame, etc.). In the emulsion system, it mainly plays the roles of thickening, stabilizing and structure strengthening. In the soy protein isolate-galactomannan composite emulsion system, the long chains of galactomannan are adsorbed on the surface of protein-coated oil droplets or form a continuous network structure, effectively preventing the aggregation, flocculation and osterization of droplets through physical barrier effect. At the same time, the increase of galactomannan polysaccharide in the continuous phase viscosity delays the floating or sinking of oil droplets, inhibits delamination or precipitation, and improves the long-term storage stability. The ratio of galactose side chain to mannose backbone in different galactomannans is different, and this ratio is called the branching degree of galactomannan, which is the core determinant of its functional properties. The difference in branching degree directly affects the molecular conformation, solubility, rheological behavior and interaction with other components, and then determines its application effect in emulsion.

[0004] The present application improves the stability of soy protein isolate emulsion by forming a complex of galactomannan and soy protein isolate. Different galactomannan structures have differences, and by utilizing these structural differences, the preparation method of soy protein isolate-galactomannan emulsion is optimized, and a method for preparing a galactomannan structure-oriented soy protein isolate emulsion is provided. This invention provides a theoretical basis for the development of new plant-based foods with higher nutritional value. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide a method for preparing a galactomannan structure-oriented soy protein isolate emulsion, so as to greatly enhance the stability of the soy protein isolate emulsion and improve the emulsifying activity.

[0006] The technical problem to be solved by the present application is realized by the following technical scheme:

[0007] A preparation method of a galactomannan structure-oriented soybean protein isolate emulsion, characterized in that the method comprises the following steps: (1) mixing soybean protein isolate and water at room temperature to prepare a 2% (w / v) soybean protein isolate solution. After magnetic stirring for 1 h, three different galactomannans, guar gum, tara gum and locust bean gum, are added to ensure that the concentration of galactomannan in the system is 0.5% (w / v), and the mixture is stirred magnetically for 2 h and placed at 4 ℃ overnight to prepare a soybean protein isolate-galactomannan mixed solution; (2) heating the soybean protein isolate-galactomannan mixed solution in a water bath at 80 ℃ for 30 min, and then cooling the mixture to room temperature in an ice water bath to prepare a soybean protein isolate-galactomannan compound; and (3) mixing the compound with sunflower oil at a ratio of 3:1, 4:1 or 5:1 (v / v) and homogenizing the mixture using a high-speed dispersion homogenizer at a speed of 6000-12000 r / min for 2 min.

[0008] The preparation method of a galactomannan structure-oriented soybean protein isolate emulsion according to claim 1, characterized in that the preferred type of galactomannan in the soybean protein isolate-galactomannan compound solution is guar gum.

[0009] The preparation method of a galactomannan structure-oriented soybean protein isolate emulsion according to claim 1, characterized in that the preferred ratio of the compound to sunflower oil is 4:1 (v / v).

[0010] The preparation method of a galactomannan structure-oriented soybean protein isolate emulsion according to claim 1, characterized in that the optimal homogenization speed for preparing the emulsion is 12000 r / min. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The process route of the present application.

[0012] Figure 2 The emulsion picture of the embodiment.

[0013] Figure 3 The emulsion particle size of the embodiment.

[0014] Figure 4 The emulsion emulsification activity of the embodiment.

[0015] Figure 5 The emulsion emulsification stability of the embodiment. DETAILED DESCRIPTION

[0016] The present application will be described in detail below with reference to the accompanying drawings.

[0017] Example 1:

[0018] (1) Soybean protein isolate and water were mixed at room temperature to prepare a 2% (w / v) soybean protein isolate solution. After magnetic stirring for 1 h, locust bean gum was added to ensure that the concentration of galactomannan in the system was 0.5% (w / v), and magnetic stirring was performed for 2 h. The mixture was placed at 4 ℃ overnight to prepare a soybean protein isolate-galactomannan mixed solution; (2) The soybean protein isolate-galactomannan mixed solution was heated in a water bath at 80 ℃ for 30 min, and then cooled to room temperature in an ice water bath after heating to prepare a soybean protein isolate-galactomannan complex; (3) The complex was mixed with sunflower oil at a ratio of 5:1 (v / v), and homogenized using a high-speed dispersion homogenizer for 2 min at a speed of 6000 r / min. The particle size of the sample was 783.6 nm, the solubility was poor, the emulsion stability was good but the emulsifying activity was poor.

[0019] Example 2:

[0020] (1) Soybean protein isolate and water were mixed at room temperature to prepare a 2% (w / v) soybean protein isolate solution. After magnetic stirring for 1 h, tara gum was added to ensure that the concentration of galactomannan in the system was 0.5% (w / v), and magnetic stirring was performed for 2 h. The mixture was placed at 4 ℃ overnight to prepare a soybean protein isolate-galactomannan mixed solution; (2) The soybean protein isolate-galactomannan mixed solution was heated in a water bath at 80 ℃ for 30 min, and then cooled to room temperature in an ice water bath after heating to prepare a soybean protein isolate-galactomannan complex; (3) The complex was mixed with sunflower oil at a ratio of 3:1 (v / v), and homogenized using a high-speed dispersion homogenizer for 2 min at a speed of 12000 r / min. The particle size of the sample was 614.2 nm, the solubility was poor, the emulsion stability was poor but the emulsifying activity was good.

[0021] Example 3:

[0022] (1) Soybean protein isolate and water were mixed at room temperature to prepare a 2% (w / v) soybean protein isolate solution. After magnetic stirring for 1 h, guar gum was added to ensure that the concentration of galactomannan in the system was 0.5% (w / v), and magnetic stirring was performed for 2 h. The mixture was placed at 4 ℃ overnight to prepare a soybean protein isolate-galactomannan mixed solution; (2) The soybean protein isolate-galactomannan mixed solution was heated in a water bath at 80 ℃ for 30 min, and then cooled to room temperature in an ice water bath after heating to prepare a soybean protein isolate-galactomannan complex; (3) The complex was mixed with sunflower oil at a ratio of 4:1 (v / v), and homogenized using a high-speed dispersion homogenizer for 2 min at a speed of 6000 r / min. The particle size of the sample was 571.9 nm, the solubility was good, the emulsion stability was poor but the emulsifying activity was good.

[0023] Example 4:

[0024] (1) Soybean protein isolate and water were mixed at room temperature to prepare a 2% (w / v) soybean protein isolate solution. After magnetic stirring for 1 h, guar gum was added to ensure that the concentration of galactomannan in the system was 0.5% (w / v), and the system was stirred magnetically for 2 h and then placed at 4 ℃ overnight to prepare a soybean protein isolate-galactomannan mixed solution; (2) The soybean protein isolate-galactomannan mixed solution was heated in a water bath at 80 ℃ for 30 min, and then cooled to room temperature in an ice water bath to prepare a soybean protein isolate-galactomannan complex; (3) The complex was mixed with sunflower oil at a ratio of 4:1 (v / v), and homogenized using a high-speed dispersion homogenizer at a speed of 12,000 r / min for 2 min. The sample particle size reached 564.3 nm, and the solubility, emulsion stability and emulsifying activity were good.

Claims

1. A galactomannan structure directed soybean The preparation method of the isolated protein emulsion is characterized in that, The method comprises the following steps: (1) Mix soybean protein isolate and water at room temperature to prepare a 2% (w / v) soybean protein isolate solution. After magnetic stirring for 1 h, three different galactomannans, guar gum, tara gum and locust bean gum, are added to ensure the concentration of galactomannan in the system is 0.5% (w / v), and magnetic stirring is performed for 2 h. The system is placed at 4°C overnight to prepare a soybean protein isolate-galactomannan mixed solution; (2) The soybean protein isolate-galactomannan mixed solution is heated in a water bath at 80°C for 30 min, and then cooled to room temperature in an ice water bath after heating to prepare a soybean protein isolate-galactomannan complex; (3) The complex is mixed with sunflower oil at a ratio of 3:1, 4:1 and 5:1 (v / v), and homogenized in a high-speed dispersion homogenizer for 2 min at a speed of 6000-12000 r / min.

2. The method for preparing a galactomannan structure-directed soy protein isolate emulsion according to claim 1, characterized in that: The preferred type of galactomannan in the soybean protein isolate-galactomannan complex solution is guar gum.

3. The method for preparing a galactomannan-structure-directed soybean protein isolate emulsion according to claim 1, characterized in that: The preferred ratio of the complex to sunflower oil is 4:1 (v / v).

4. A galactomannan structure-oriented soybean protein isolate according to claim 1 Process for the preparation of a protein isolate emulsion, characterized in that: The optimal homogenization speed for preparing the emulsion is 12000 r / min.

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