Preparation method of heat-resistant yolk liquid

Abstract

The invention discloses a preparation method of heat-resistant yolk liquid, relates to improvement of the sterilization temperature and the sterilization time of the yolk liquid, maintenance or improvement of emulsification characteristics and prolonging of the shelf life, and belongs to the technical field of agricultural product processing and storage. The original sterilization condition of the egg yolk liquid is 68 DEG C for 4 minutes, and the sterilization condition of the egg yolk liquid is improved to 76 DEG C for 8 minutes by adopting a low-temperature plasma assisted enzyme and amino acid technology. The thermal denaturation temperature of the egg yolk liquid is effectively improved, the thermal aggregation of the egg yolk liquid is inhibited, and the thermal solidification of the egg yolk liquid is delayed. The problems of pipeline blockage and reduced emulsibility caused by pasteurization heat treatment of the egg yolk liquid in the food industry are solved, and an important technical support is provided for the egg product industry.

Description

Technical Field

[0001] The invention provides a method for preparing heat-resistant egg yolk liquid, and belongs to the technical field of agricultural product processing and storage. Background Art

[0002] Since shell eggs are fragile and have the risk of reducing benefits during transportation, replacing shell eggs with liquid egg products has great market application prospects. Egg yolk liquid is widely used in baked products, convenience foods and other fields because of its rich nutritional value and good emulsification. In order to ensure the standardization of egg yolk liquid products, pasteurization is often required before entering the market. The thermal coagulation temperature of egg yolk liquid is relatively close to the pasteurization temperature (about 65°C), and the pasteurization process is prone to cause pipeline blockage and other problems. Therefore, the thermal instability of egg yolk liquid has become a problem that needs to be solved in the current food industry. In addition, improving the heat resistance of egg yolk liquid can make full use of its emulsification and provide a theoretical basis for broadening the application of egg yolk liquid in food. At present, the research on the thermal aggregation of egg liquid mainly introduces exogenous substances such as salt, sugar, and enzymes to inhibit its thermal aggregation. Based on the public's pursuit of healthy food and flavor, high-sugar or high-salt foods no longer meet the dietary needs of most people. Therefore, it is of great significance to explore more scientific, healthy and effective ways to improve the heat resistance of egg yolk liquid.

[0003] As a new type of green modification technology, low-temperature plasma can be applied to various operations in food processing. Its main principle is to use a carrier gas system such as air and nitrogen, and generate various chemical reactions through different discharge methods such as dielectric barrier and microwave, so as to achieve the modification of protein structure. Currently, there is no patent that uses low-temperature plasma to assist enzymes and amino acids to improve the heat resistance of egg yolk liquid, so the inventor filed this application. Summary of the invention

[0004] 1. The present invention provides a method for preparing heat-resistant egg yolk liquid, and the technical scheme is as follows:

[0005] (1) selecting commercially available fresh eggs with no surface damage, cleaning and disinfecting the eggshell surface, beating the eggs to remove the egg white, ligaments and yolk membrane, and stirring the obtained egg yolk liquid in a stirrer at 300-400 r / min for 15-20 min to obtain a uniform egg yolk liquid;

[0006] (2) subjecting the egg yolk liquid obtained in step (1) to low-temperature plasma pretreatment;

[0007] (3) adding enzyme to the egg yolk liquid obtained in step (2) above, stirring in a stirrer at 300-400 rpm for 10 min until the enzyme is completely dissolved and mixed evenly;

[0008] (4) placing the enzyme-added egg yolk solution obtained in step (3) above in a 50° C. water bath for enzymatic hydrolysis for 20-50 min (at a rotation speed of 140 rpm), and then rapidly cooling in an ice water bath to inhibit enzymatic hydrolysis;

[0009] (5) adding amino acids to the enzymatically hydrolyzed egg yolk solution obtained in step (4) above, stirring in a stirrer at 300-400 r / min for 15-20 min until the amino acids are completely dissolved;

[0010] (6) pasteurizing the egg yolk liquid obtained in step (5) at 76° C. for 8 min;

[0011] (7) cooling the pasteurized egg yolk liquid obtained in step (6) to room temperature in an ice water bath;

[0012] (8) The egg yolk liquid obtained in the above step (7) is subjected to quality inspection, and the egg yolk liquid without impurity contamination and with microbial content meeting the standard is a qualified product.

[0013] 2. The method for preparing a heat-resistant egg yolk liquid according to claim 1, characterized in that the low-temperature plasma voltage in step (2) is set to 60-100 kV and the processing time is 30-60 s.

[0014] 3. The method for preparing a heat-resistant egg yolk liquid according to claim 1, characterized in that the enzyme added in the enzymatic hydrolysis treatment in step (3) is a neutral protease, and the added amount is 0.2-0.5%.

[0015] 4. The method for preparing a heat-resistant egg yolk liquid according to claim 1, characterized in that the amino acids in step (5) are betaine and proline, and the added amount is 0.5-3%.

[0016] Analytical methods:

[0017] Observation of egg yolk fluidity: Take 25mL of egg yolk liquid sample and place it in a 50mL sample bottle. Pasteurize it at 76℃ for 8min, cool it to room temperature in an ice water bath, and observe the fluidity of the egg yolk liquid.

[0018] Rheological temperature scanning measurement: Select a 35mm flat plate and set a 0.3mm gap for measurement. Place a certain amount of egg yolk liquid sample on the flat plate, scrape off the excess sample and apply silicone oil around the flat plate to prevent water evaporation during heating. Before heating, the sample is balanced at 25℃ for 1min, and the temperature is raised from 25℃ to 90℃ at a heating rate of 3℃ / min.

[0019] Viscosity determination: Place 30 mL of egg yolk liquid sample in a 50 mL sample bottle and use the No. 63 rotor of a digital viscometer to measure its viscosity at different speeds.

[0020] Emulsification property determination: Use deionized water to dilute the egg yolk solution to 5 mg / mL, add 5 mL of soybean oil and homogenize at 10000 r / min for 1 min to prepare an emulsion. 50 μL of the homogenate was taken at 0 min and 10 min after homogenization and mixed with 5 mL of SDS (0.1%, w / v). The absorbance value of the SDS solution was used as a blank, and the absorbance of the sample was measured at 500 nm. The emulsification activity and emulsification stability were calculated according to the following formula.

[0021]

[0022] In the formula, T = 2.303; N is the dilution factor, 101; C is the concentration of the protein solution before the emulsion is formed (g / mL); is the volume fraction of the oil phase in the emulsion, 0.2; A0 is the absorbance at 0 min, ΔT is the time difference, 10 min.

[0023] Color difference measurement: Place equal amounts of samples in sample bottles and measure using a colorimeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Observation of the fluidity of untreated heated egg yolk liquid and treated group heated egg yolk liquid.

[0025] As can be seen from the figure, the egg yolk liquid in the treatment group still has good fluidity after being pasteurized at 76°C for 8 minutes. In order to further explore the effects of low-temperature plasma-assisted enzymes and amino acids on the rheological properties and fluidity of heated egg yolk liquid, the temperature scan and viscosity in the rheology were measured.

[0026] Figure 2 It is the gel formation temperature and viscosity of fresh egg yolk liquid and treated group egg yolk liquid.

[0027] The storage modulus in rheology shows an upward trend with temperature, which can reflect the aggregation and gelation process of egg yolk liquid with increasing temperature. The inflection point in the figure is the formation temperature of egg yolk liquid gel. The gelation temperature of the egg yolk liquid in the treated group (80.29℃) is significantly higher than that of the fresh egg yolk liquid (75.66℃). And the fluidity of the egg yolk liquid in the treated group is significantly lower than that of the fresh egg yolk liquid. This shows that low-temperature plasma-assisted enzyme and amino acid treatment can significantly improve the heat resistance of egg yolk liquid and effectively inhibit the thermal aggregation of egg yolk.

[0028] Figure 3 It is the emulsification activity and emulsification stability of fresh egg yolk liquid, pasteurized egg yolk liquid (68℃, 4min) and treatment group pasteurized egg yolk liquid (76℃, 8min).

[0029] The emulsification of egg yolk liquid is one of its important functional properties. Emulsification activity reflects the ability of protein to adsorb to the interface, and emulsification stability reflects the ability of protein to form a strong emulsion. It can be seen from the figure that the egg yolk liquid treated with low-temperature plasma assisted enzymes and amino acids still exceeds the emulsification activity of fresh egg yolk liquid and pasteurized egg yolk liquid (68°C, 4min) after heating at 76°C for 8min. In terms of emulsification stability, the emulsification stability (19.02min) of the egg yolk liquid treated with low-temperature plasma assisted enzymes and amino acids (76°C, 8min) is significantly higher than that of fresh egg yolk liquid (10.42min) and pasteurized egg yolk liquid (68°C, 4min) (10.49min). This shows that low-temperature plasma assisted enzyme and amino acid treatment can improve the emulsification properties of egg yolk liquid.

[0030] Figure 4 It is the color difference between fresh egg yolk liquid, pasteurized egg yolk liquid (68℃, 4min) and pasteurized egg yolk liquid in the treatment group (76℃, 8min).

[0031] Color is the most intuitive indicator for evaluating products and may affect consumers' judgment of products. As shown in the figure, the color difference of egg yolk liquid treated with low-temperature plasma assisted enzyme and amino acid is similar to that of fresh egg yolk liquid and pasteurized egg yolk liquid (68℃, 4min). This shows that low-temperature plasma assisted enzyme and amino acid treatment can maintain the original color of egg yolk liquid.

[0032] Beneficial effects achieved by the present invention:

[0033] (1) Using low-temperature plasma-assisted enzyme and amino acid technology, the pasteurization conditions of egg yolk liquid were increased from 68°C and 4 min to 76°C and 8 min, resulting in a heat-resistant egg yolk liquid product.

[0034] (2) By using low-temperature plasma-assisted enzyme and amino acid technology, the emulsification stability of egg yolk liquid was increased from 10.49 min to 19.02 min, and the emulsification of egg yolk liquid was significantly improved. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments, but the scope of protection claimed by the present invention is not limited to the scope described in the embodiments.

[0036] Example 1

[0037] (1) selecting commercially available fresh eggs with no surface damage, cleaning and disinfecting the eggshell surface, beating the eggs to remove the egg white, ligaments and yolk membrane, and stirring the obtained egg yolk liquid in a stirrer at 300-400 r / min for 15-20 min to obtain a uniform egg yolk liquid;

[0038] (2) subjecting the egg yolk liquid obtained in the above step (1) to a low-temperature plasma pretreatment at a voltage of 80 kV for 30 seconds;

[0039] (3) adding 0.2% neutral protease to the egg yolk liquid obtained in step (2) above, stirring at 300-400 r / min for 10 min in a stirrer until the enzyme is completely dissolved and mixed evenly;

[0040] (4) placing the enzyme-added egg yolk solution obtained in step (3) above in a 50° C. water bath for enzymatic hydrolysis for 20-50 min (at a rotation speed of 140 rpm), and then rapidly cooling in an ice water bath to inhibit enzymatic hydrolysis;

[0041] (5) adding 2% betaine and proline to the enzymatically hydrolyzed egg yolk solution obtained in step (4) above, stirring in a stirrer at 300-400 r / min for 15-20 min until the amino acids are completely dissolved;

[0042] (6) pasteurizing the egg yolk liquid obtained in step (5) at 76° C. for 8 min;

[0043] (7) cooling the pasteurized egg yolk liquid obtained in step (6) to room temperature in an ice water bath;

[0044] (8) The egg yolk liquid obtained in the above step (7) is subjected to quality inspection, and the egg yolk liquid without impurity contamination and with microbial content meeting the standard is a qualified product.

[0045] The above embodiments are only specific descriptions of the technical solutions of the present invention, and are not intended to be limiting. Those skilled in the art should recognize that all changes, additions and substitutions made around the spirit and scope of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing heat-resistant egg yolk liquid, characterized in that Follow these steps: (1) selecting commercially available fresh eggs with no surface damage, cleaning and disinfecting the eggshell surface, beating the eggs to remove the egg white, ligaments and yolk membrane, and stirring the obtained egg yolk liquid in a stirrer at 300-400 r / min for 15-20 min to obtain a uniform egg yolk liquid; (2) subjecting the egg yolk liquid obtained in step (1) to low-temperature plasma pretreatment; (3) adding enzyme to the egg yolk liquid obtained in step (2) above, stirring in a stirrer at 300-400 rpm for 10 min until the enzyme is completely dissolved and mixed evenly; (4) placing the enzyme-added egg yolk solution obtained in step (3) above in a 50° C. water bath for enzymatic hydrolysis for 20-50 min (at a rotation speed of 140 rpm), and then rapidly cooling in an ice water bath to inhibit enzymatic hydrolysis; (5) adding amino acids to the enzymatically hydrolyzed egg yolk solution obtained in step (4) above, stirring in a stirrer at 300-400 r / min for 15-20 min until the amino acids are completely dissolved; (6) pasteurizing the egg yolk liquid obtained in step (5) at 76° C. for 8 min; (7) cooling the pasteurized egg yolk liquid obtained in step (6) to room temperature in an ice water bath; (8) The egg yolk liquid obtained in the above step (7) is subjected to quality inspection, and the egg yolk liquid without impurity contamination and with microbial content meeting the standard is a qualified product.

2. The method for preparing a heat-resistant egg yolk liquid according to claim 1, characterized in that In step (2), the low-temperature plasma voltage is set to 60-100 kV, and the processing time is 30-60 s.

3. The method for preparing a heat-resistant egg yolk liquid according to claim 1, characterized in that The enzyme added in the enzymatic hydrolysis treatment in step (3) is neutral protease, and the added amount is 0.2-0.5%.

4. The method for preparing a heat-resistant egg yolk liquid according to claim 1, characterized in that The amino acids in step (5) include betaine and proline, and the added amount is 0.5-3%.

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