Ultrasonic preparation method of protein-based emulsion gel with high water binding capacity

Abstract

The invention discloses an ultrasonic preparation method of protein-based emulsion gel with high water holding capacity, belongs to the technical field of food gel preparation, and can solve the technical problems of low gel strength, poor water holding capacity and the like of the existing protein-based emulsion gel. The preparation method comprises the following steps: 1, preparation of a protein solution: dissolving protein in water, and carrying out ultrasonic emulsification treatment to obtain the protein solution; 2, preparing a protein emulsion, namely adding vegetable oil into the protein solution, and performing emulsification ultrasonic treatment to obtain the protein emulsion. 3, preparation of protein matrix liquid: dissolving protein in water, and then carrying out ultrasonic emulsification treatment to obtain the protein matrix liquid; and 4, preparation of protein-based emulsion gel: mixing the protein emulsion with the protein matrix liquid. And heating the uniformly mixed liquid to obtain the protein-based emulsion gel. The technical problems that protein-based emulsion gel is low in gel strength, poor in water holding performance and the like can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of food gel preparation, and particularly relates to an ultrasonic preparation method for high water-holding protein-based emulsion gels. Background Art

[0002] With the development of productivity and the continuous improvement of living standards, people are now gradually inclined to high-fat and high-calorie diets. Long-term excessive intake of oil is likely to cause many health problems, such as obesity, diabetes, hypertension, cardiovascular diseases, etc. In order to reduce the risks brought by high-fat diets to human health, reducing oil intake is a safe and effective strategy. However, simply removing the oil in food will reduce the sensory qualities such as the flavor, taste, and texture of the food. Emulsion gels are gel-like solids with a spatial network structure formed on the basis of emulsions, and the oil is dispersed as a filler in the gel network. It is a fat substitute and delivery carrier that can simulate the sensory and functional characteristics of oil.

[0003] Proteins have excellent nutritional value, high surface activity, and good emulsion stability. Emulsion gels prepared from proteins have good rheological properties. However, technical problems such as low gel strength and poor water-holding performance of protein-based emulsion gels limit the application of protein-based emulsion gels. Recently, ultrasonic treatment has been used to improve the material properties of protein-based emulsion gels. However, different proteins are suitable for different ultrasonic treatment conditions, and the process of defining ultrasonic treatment conditions is complex, and ultrasound cannot play a role widely and effectively. Therefore, developing a new preparation method that is easy to operate and has wide adaptability to improve the physicochemical properties of protein-based emulsion gels by ultrasound is the key to solving the above problems. Summary of the Invention

[0004] In view of the technical problems such as low gel strength and poor water-holding performance of existing protein-based emulsion gels, the present invention proposes a new preparation method that is easy to operate and has wide adaptability to improve the physicochemical properties of protein-based emulsion gels by ultrasound.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] Preparation of protein solution: Dissolve the protein in water and then perform ultrasonic emulsification treatment to obtain a protein solution.

[0007] Preparation of protein emulsion: Add vegetable oil to the protein solution and perform emulsification ultrasonic treatment to obtain a protein emulsion.

[0008] Preparation of protein matrix solution: Dissolve the protein in water and then perform ultrasonic treatment to obtain a protein matrix solution.

[0009] Preparation of protein-based emulsion gel: Mix the protein emulsion with the protein matrix solution. The uniformly mixed liquid is subjected to heat treatment to obtain the protein-based emulsion gel.

[0010] Preferably, the vegetable oil is any one of sunflower oil, peanut oil, soybean oil, and olive oil.

[0011] Preferably, the protein is any one of soy protein, ovalbumin, whey protein, and myofibrillar protein.

[0012] Preferably, in the protein solution, the protein concentration is 40 - 120 mg / mL, preferably 80 - 100 mg / mL.

[0013] Preferably, in the protein emulsion, the concentration of the vegetable oil is 10% - 50% (v / v), preferably 20% - 35% (v / v).

[0014] Preferably, in the protein matrix solution, the protein concentration is 40 - 120 mg / mL, preferably 80 - 100 mg / mL.

[0015] Preferably, the volume ratio of the protein emulsion to the protein matrix solution is any one of 5:1, 5:2, 5:3, 5:4, and 5:5.

[0016] Preferably, the ultrasonic treatment parameters of the protein solution are time and frequency. The time is 1 - 10 min, preferably 2 - 5 min, and the frequency is any one of 20 kHz, 40 kHz, and 70 kHz.

[0017] Preferably, the emulsification time of the protein emulsion is 0.5 - 6 min, preferably 1 - 3 min. The emulsification rotation speed is 6000 - 20000 rpm, preferably 10000 - 15000 rpm.

[0018] Preferably, the ultrasonic treatment parameters of the protein emulsion are time and frequency. The time is 1 - 10 min, preferably 2 - 5 min, and the frequency is any one of 20 kHz, 40 kHz, and 70 kHz.

[0019] Preferably, the ultrasonic treatment parameters of the protein matrix solution are time and frequency. The time is 1 - 10 min, preferably 2 - 5 min, and the frequency is any one of 20 kHz, 40 kHz, and 70 kHz.

[0020] Preferably, the heating temperature of the protein-based emulsion gel is 60 - 100 °C, preferably 80 - 90 °C, and the heating time is 0.2 - 1 h, preferably 0.5 - 0.8 h.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are as follows: 1. The present invention provides an ultrasonic preparation method for a highly water-holding protein-based emulsion gel. The emulsion gel obtained by this method has good gel properties, texture properties, and environmental stability, which is an effective way to solve technical problems such as low gel strength and poor water-holding performance of protein-based emulsion gels. 2. The ultrasonic preparation method for a highly water-holding protein-based emulsion gel provided by the present invention is different from improving the material properties of protein-based emulsion gels by changing the frequency and time of ultrasonic treatment. By ultrasonic treating different components in the protein-based emulsion gel, it is convenient to operate and has wide adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a macroscopic photograph of the emulsion gel provided by an embodiment of the present invention;

[0023] Figure 2 It is a graph showing the relationship between the hardness of the emulsion gel provided by an embodiment of the present invention and the ultrasonic treatment;

[0024] Figure 3 It is a graph showing the relationship between the centrifugal water-holding rate of the emulsion gel provided by an embodiment of the present invention and the ultrasonic treatment;

[0025] Figure 4 It is a Fourier transform infrared spectroscopy diagram of the emulsion gel provided by an embodiment of the present invention;

[0026] Figure 5 It is a scanning electron microscopy image of the emulsion gel provided by an embodiment of the present invention;

[0027] Figure 6 It is a laser scanning confocal microscopy image of the emulsion gel provided by an embodiment of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solutions in the embodiments of the present invention will be described in detail and accurately below. Obviously, the embodiments described below are only some embodiments of the present invention, rather than all embodiments. For the numerical ranges in the following embodiments of the present invention, it should be understood that each intermediate numerical range between the upper limit and the lower limit of the addition amount range of the present invention is specifically disclosed. The upper and lower limits of these numerical ranges can be independently included or excluded within the range. Regarding the words "comprising", "including", "having", "containing", etc. used in the specification of the present invention, they are all open terms, which mean including but not limited to. Based on the embodiments of the present invention, all other embodiments obtained by any ordinary person skilled in the relevant art without making explicit creative efforts belong to the scope of protection of the present invention.

[0029] An embodiment of the present invention provides an ultrasonic preparation method for a highly water-holding protein-based emulsion gel, including the following steps:

[0030] Preparation of the S1 protein solution: The protein is dissolved in water and then subjected to ultrasonic emulsification treatment to obtain the protein solution.

[0031] Preparation of the S2 protein emulsion: Vegetable oil is taken and added to the protein solution for emulsification ultrasonic treatment to obtain the protein emulsion.

[0032] Preparation of the S3 protein matrix solution: The protein is dissolved in water and then subjected to ultrasonic treatment to obtain the protein matrix solution.

[0033] Preparation of the S4 protein-based emulsion gel: The protein emulsion is mixed with the protein matrix solution. The uniformly mixed liquid is subjected to heat treatment to obtain the protein-based emulsion gel.

[0034] In a preferred embodiment, the vegetable oil is any one of sunflower oil, peanut oil, soybean oil, and olive oil.

[0035] In a preferred embodiment, the protein is any one of soybean protein, ovalbumin, whey protein, and myofibrillar protein.

[0036] In a preferred embodiment, in the protein solution, the protein concentration is 40 - 120 mg / mL, preferably 80 - 100 mg / mL.

[0037] In a preferred embodiment, in the protein emulsion, the concentration of the vegetable oil is 10% - 50% (v / v), preferably 20% - 35% (v / v).

[0038] In a preferred embodiment, in the protein matrix solution, the protein concentration is 40 - 120 mg / mL, preferably 80 - 100 mg / mL.

[0039] In a preferred embodiment, the volume ratio of the protein emulsion to the protein matrix solution is 5:1, 5:2, 5:3, 5:4, 5:5, or any value within the above-defined range falls within the protection scope of the present invention.

[0040] In a preferred embodiment, the ultrasonic treatment parameters of the protein solution are time and frequency. The time is 1 - 10 min, preferably 2 - 5 min, and the frequency is any one of 20 kHz, 40 kHz, 70 kHz, or any value within the above-defined range falls within the protection scope of the present invention.

[0041] In a preferred embodiment, the emulsification time of the protein emulsion is 0.5 - 6 min, preferably 1 - 3 min. The emulsification rotation speed is 6000 - 20000 rpm, preferably 10000 - 15000 rpm.

[0042] In a preferred embodiment, the ultrasonic treatment parameters of the protein emulsion are time and frequency. The time is 1 - 10 min, preferably 2 - 5 min, and the frequency is any one of 20 kHz, 40 kHz, 70 kHz or any value within the above - defined range, and all fall within the protection scope of the present invention.

[0043] In a preferred embodiment, the ultrasonic treatment parameters of the protein matrix solution are time and frequency. The time is 1 - 10 min, preferably 2 - 5 min, and the frequency is any one of 20 kHz, 40 kHz, 70 kHz or any value within the above - defined range, and all fall within the protection scope of the present invention.

[0044] In a preferred embodiment, the heating temperature of the protein - based emulsion gel is 60 - 100 °C, preferably 80 - 90 °C, and the heating time is 0.2 - 1 h, preferably 0.5 - 0.8 h.

[0045] In order to introduce more clearly and in detail a method for ultrasonic preparation of a high - water - holding - capacity protein - based emulsion gel provided by the embodiments of the present invention, the following will be described in combination with specific embodiments.

[0046] Example 1

[0047] This example provides a method for ultrasonic preparation of a high - water - holding - capacity protein - based emulsion gel, and the specific steps are as follows:

[0048] (1) Preparation of ovalbumin solution: Dissolve ovalbumin in water, and after magnetic stirring treatment, an ovalbumin solution with a concentration of 100 mg / mL is obtained without ultrasonic treatment.

[0049] (2) Preparation of ovalbumin emulsion: Add sunflower seed oil to the above - mentioned ovalbumin solution, emulsify at a speed of 12000 rpm for 1 min to obtain an ovalbumin emulsion, where the concentration of sunflower seed oil is 20% (v / v). Ultrasonically treat the ovalbumin emulsion, and the treatment conditions are time and frequency. The time is 5 min and the frequency is 40 kHz.

[0050] (3) Preparation of ovalbumin matrix solution: Dissolve ovalbumin in water, and after magnetic stirring treatment, an ovalbumin matrix solution with a concentration of 100 mg / mL is obtained without ultrasonic treatment.

[0051] (4) Preparation of emulsion gel (Post - E): Mix the ovalbumin emulsion and the ovalbumin matrix solution in a ratio of 5:4 and heat at 80 °C for 0.5 h.

[0052] Example 2

[0053] This example provides a method for ultrasonic preparation of a high - water - holding - capacity protein - based emulsion gel, and the specific steps are as follows:

[0054] (1) Preparation of ovalbumin solution: Dissolve ovalbumin in water, and after magnetic stirring treatment, an ovalbumin solution with a concentration of 100 mg / mL is obtained. Subject the ovalbumin solution to ultrasonic treatment, and the treatment conditions are time and frequency. The time is 5 min and the frequency is 40 kHz.

[0055] (2) Preparation of ovalbumin emulsion: Add sunflower seed oil to the above ovalbumin solution and emulsify at a speed of 12000 rpm for 1 min to obtain an ovalbumin emulsion, where the concentration of sunflower seed oil is 20% (v / v).

[0056] (3) Preparation of ovalbumin matrix solution: Dissolve ovalbumin in water, and after magnetic stirring treatment, an ovalbumin matrix solution with a concentration of 100 mg / mL is obtained without ultrasonic treatment.

[0057] (4) Preparation of emulsion gel (Pre-E): Mix the ovalbumin emulsion and the ovalbumin matrix solution in a ratio of 5:4 and heat at 80 °C for 0.5 h.

[0058] Example 3

[0059] This example provides a method for ultrasonic preparation of a highly water-holding protein-based emulsion gel, and the specific steps are as follows:

[0060] (1) Preparation of ovalbumin solution: Dissolve ovalbumin in water, and after magnetic stirring treatment, an ovalbumin solution with a concentration of 100 mg / mL is obtained without ultrasonic treatment.

[0061] (2) Preparation of ovalbumin emulsion: Add sunflower seed oil to the above ovalbumin solution and emulsify at a speed of 12000 rpm for 1 min to obtain an ovalbumin emulsion, where the concentration of sunflower seed oil is 20% (v / v).

[0062] (3) Preparation of ovalbumin matrix solution: Dissolve ovalbumin in water, and after magnetic stirring treatment, an ovalbumin matrix solution with a concentration of 100 mg / mL is obtained. Subject the ovalbumin matrix solution to ultrasonic treatment, and the treatment conditions are time and frequency. The time is 5 min and the frequency is 40 kHz.

[0063] (4) Preparation of emulsion gel (Ss): Mix the ovalbumin emulsion and the ovalbumin matrix solution in a ratio of 5:4 and heat at 80 °C for 0.5 h.

[0064] Example 4

[0065] This example provides a method for ultrasonic preparation of a highly water-holding protein-based emulsion gel, and the specific steps are as follows:

[0066] (1) Preparation of ovalbumin solution: Ovalbumin was dissolved in water, and after magnetic stirring treatment, an ovalbumin solution with a concentration of 100 mg / mL was prepared without ultrasonic treatment.

[0067] (2) Preparation of ovalbumin emulsion: Sunflower seed oil was added to the above ovalbumin solution and emulsified at a speed of 12000 rpm for 1 min to obtain an ovalbumin emulsion, where the concentration of sunflower seed oil was 20% (v / v).

[0068] (3) Preparation of ovalbumin matrix solution: Ovalbumin was dissolved in water, and after magnetic stirring treatment, an ovalbumin matrix solution with a concentration of 100 mg / mL was prepared without ultrasonic treatment.

[0069] (4) Preparation of emulsion gel (control): The ovalbumin emulsion and the ovalbumin matrix solution were mixed at a ratio of 5:4 and heated at 80 °C for 0.5 h.

[0070] Example 5

[0071] This example provides a method for ultrasonic preparation of a high water-holding protein-based emulsion gel, and the specific steps are as follows:

[0072] (1) Preparation of ovalbumin solution: Ovalbumin was dissolved in water, and after magnetic stirring treatment, an ovalbumin solution with a concentration of 100 mg / mL was prepared. The ovalbumin solution was subjected to ultrasonic treatment, and the treatment conditions were time and frequency. The time was 5 min and the frequency was 40 kHz.

[0073] (2) Preparation of ovalbumin emulsion: Sunflower seed oil was added to the above ovalbumin solution and emulsified at a speed of 12000 rpm for 1 min to obtain an ovalbumin emulsion, where the concentration of sunflower seed oil was 20% (v / v).

[0074] (3) Preparation of ovalbumin matrix solution: Ovalbumin was dissolved in water, and after magnetic stirring treatment, an ovalbumin matrix solution with a concentration of 100 mg / mL was prepared. The ovalbumin matrix solution was subjected to ultrasonic treatment, and the treatment conditions were time and frequency. The time was 5 min and the frequency was 40 kHz.

[0075] (4) Preparation of emulsion gel (ESs): The ovalbumin emulsion and the ovalbumin matrix solution were mixed at a ratio of 5:4 and heated at 80 °C for 0.5 h.

[0076] Testing of physicochemical properties of emulsion gel

[0077] The present invention respectively tested the macroscopic appearance, hardness, centrifugal water-holding rate (WHC) and infrared spectrum (FTIR) of the emulsion gels prepared in each example. The specific test methods and measurement results are as follows:

[0078] (1) Physicochemical property experiments

[0079] In this experiment, a texture analyzer, a centrifuge, and FTIR were used to test the hardness, WHC, and FTIR of the emulsion gels prepared in each example.

[0080] (2) Result analysis

[0081] Figure 1 The macroscopic photographs of the emulsion gels prepared in each example are shown. Each gel sample was cut into 5 cm in height and placed vertically on the same horizontal plane. The emulsion gels in all groups formed white opaque gels with no difference in color. Among all groups, the emulsion gel (Pre-E) formed by ultrasonic treatment followed by emulsification of the protein in the protein emulsion had the smallest inclination. Figure 2 The hardness diagram of the emulsion gels prepared in each example is shown. The emulsion gel (Pre-E) formed by ultrasonic treatment followed by emulsification of the protein in the protein emulsion had the highest hardness. Figure 3 The WHC diagram of the emulsion gels prepared in each example is shown. The emulsion gel (Pre-E) formed by ultrasonic treatment followed by emulsification of the protein in the protein emulsion had the highest WHC. Figure 4 The FTIR diagram of the emulsion gels prepared in each example is shown. The hydrophobic region and hydrogen bond in the emulsion gel (Pre-E) formed by ultrasonic treatment followed by emulsification of the protein in the protein emulsion were stronger than those in the other two groups (Post-E, Ss).

[0082] Microstructure test of emulsion gel

[0083] In the present invention, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to test the emulsion gels prepared in each example respectively. The specific test methods and measurement results are as follows:

[0084] (1) Microstructure experiment

[0085] In this experiment, SEM and CLSM were used to observe the microstructure of the emulsion gels prepared in each example respectively.

[0086] (2) Result analysis

[0087] Figure 5 The SEM diagram of the emulsion gels prepared in each example is shown. The pores in the emulsion gel (Pre-E) formed by ultrasonic treatment followed by emulsification of the protein in the protein emulsion were significantly smaller than those in the other two groups (Post-E, Ss). Figure 6CLSM images of the emulsion gels prepared in each example are shown. The oil droplets in the emulsion gel (Pre-E) formed by first ultrasonically treating and then emulsifying the protein in the protein emulsion are evenly dispersed, while the oil droplets in the emulsion gel (Ss) formed by ultrasonically treating the protein in the protein matrix solution are unevenly dispersed and show obvious aggregation.

[0088] As can be seen from the above, the emulsion gels prepared by using the ultrasonic preparation method of a high water-holding protein-based emulsion gel provided in the embodiments of the present invention have good gel properties, texture properties and environmental stability, can solve technical problems such as low gel strength and poor water-holding performance of existing protein-based emulsion gels, and are beneficial to the high-value utilization of protein-based emulsion gels. In addition, the novel preparation method provided in the embodiments of the present invention is convenient to operate, has wide adaptability, and has broad application prospects.

Claims

1. A method for ultrasonically preparing a high water-holding protein-based emulsion gel, characterized in that: The steps include: Preparation of protein solution: The protein was dissolved in water and then subjected to ultrasonic emulsification to obtain a protein solution. Preparation of protein emulsion: vegetable oil is added into the protein solution for emulsification and ultrasonic treatment to obtain protein emulsion. Preparation of protein matrix solution: The protein is dissolved in water and then subjected to ultrasonic treatment to obtain the protein matrix solution. Preparation of protein-based emulsion gel: protein emulsion liquid is mixed with protein matrix liquid, and the liquid after uniform mixing is heated to obtain protein-based emulsion gel.

2. The method for preparing the emulsion gel according to claim 1, characterized in that: The protein is any one of soy protein, egg albumin, whey protein and myofibrillar protein; the vegetable oil is any one of sunflower oil, peanut oil, soybean oil and olive oil.

3. The method for preparing the emulsion gel according to claim 1, characterized in that: In the protein solution, the protein concentration is 40-120 mg / mL, preferably 80-100 mg / mL, and the concentration of the vegetable oil is 10%-50% (v / v), preferably 20%-35% (v / v).

4. The method for preparing the emulsion gel according to claim 1, characterized in that: In the protein matrix solution, the protein concentration is 40-120 mg / mL, preferably 80-100 mg / mL.

5. The method for preparing the emulsion gel according to claim 1, characterized in that: The volume ratio of the protein emulsion to the protein matrix liquid is any one of 5:1, 5:2, 5:3, 5:4, and 5:

5.

6. The method for preparing the emulsion gel according to claim 1, characterized in that: The ultrasonic treatment parameters of the protein solution are time and frequency. The time is 1-10 min, preferably 2-5 min, and the frequency is any one of 20 kHz, 40 kHz, and 70 kHz.

7. The method for preparing the emulsion gel according to claim 1, characterized in that: The emulsification time of the protein emulsion is 0.5-6 min, preferably 1-3 min, and the emulsification rotation speed is 6000-20000 rpm, preferably 10000-15000 rpm.

8. The method for preparing the emulsion gel according to claim 1, characterized in that: The ultrasonic treatment parameters of the protein emulsion and protein matrix liquid are time and frequency. The time is 1-10 min, preferably 2-5 min, and the frequency is any one of 20 kHz, 40 kHz, and 70 kHz.

9. The method for preparing the emulsion gel according to claim 1, characterized in that: The heating temperature of the protein-based emulsion gel is 60-100° C., preferably 80-90° C., and the heating time is 0.2-1 h, preferably 0.5-0.8 h.

10. The ultrasonic preparation method of a high water-holding protein-based emulsion gel according to any one of claims 1 to 9, characterized in that: Through ultrasonic treatment, the gel properties, texture properties and environmental stability of protein-based emulsion gels are improved, the technical problems of low gel strength and poor water holding capacity of protein-based emulsion gels are solved, the potential application value of protein-based emulsion gels in food and medicine and other fields is increased, and it is applied to the field of food gel preparation technology.

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