Egg white fermented yogurt and method for preparing the same

Abstract

The application belongs to the technical field of food processing, and particularly relates to an egg liquid fermented yogurt and a preparation method thereof. First, the egg liquid is subjected to protease hydrolysis treatment, sugar addition and dispersion treatment to obtain high-temperature-resistant egg liquid, so as to improve the sterilization temperature of the egg liquid and ensure that the egg liquid does not form gel and does not produce fishy smell. Then, the high-temperature-resistant egg liquid is fully mixed with milk, and after high-temperature short-time sterilization, fermentation is performed. The inactivation rate of lysozyme in the egg liquid is more than 95%, so that the egg liquid fermented yogurt prepared through fermentation has good organization state and good flavor and taste.

Description

Technical Field

[0001] This invention belongs to the field of food processing, specifically relating to a fermented yogurt made from egg liquid and its preparation method. Background Technology

[0002] Egg liquid, made from crushed and processed eggshells, is packaged as a substitute for fresh eggs. It is rich in essential amino acids, minerals, vitamins, folic acid, and other bioactive substances, offering a comprehensive range of nutrients. In the food industry, egg liquid is frequently used as a raw material in the production of various foods such as dairy products, baked goods, pastries, and beverages. The development of various functional egg-based snacks is receiving increasing attention. However, egg liquid has a high moisture content and is highly susceptible to microbial contamination and spoilage at room temperature. Therefore, heating is often used to sterilize it during production. However, temperatures above 60°C cause the proteins in egg liquid to denature and form a gel. Temperatures above 70°C not only cause gel formation but also decompose sulfur-containing proteins, producing hydrogen sulfide, which slowly develops a fishy odor. This not only impairs its processing properties but also severely reduces its sensory quality, limiting its application in food processing. To ensure the quality and processing performance of egg liquid, existing technologies generally use a temperature of 60-65℃ to sterilize the egg liquid for 2-3 minutes. After sterilization, the egg liquid has a short shelf life at room temperature and a high lysozyme content. When used to prepare fermented yogurt, the fermentation time is long and the product has high acidity, poor texture, and low overall quality. Summary of the Invention

[0003] Based on the above reasons, the purpose of this invention is to provide an egg-based fermented yogurt and its preparation method. First, the egg liquid is hydrolyzed, sugar is added, and dispersion treatment is performed to obtain a heat-resistant egg liquid, which improves the heat resistance of the egg liquid and does not produce gel or fishy smell. Then, the heat-resistant egg liquid is mixed with milk and sterilized at high temperature for a short time to destroy the lysozyme in the egg liquid. After fermentation, an egg-based fermented yogurt with good texture, flavor, and taste is obtained.

[0004] To achieve the above objectives, this invention discloses a method for preparing egg-fermented yogurt, which utilizes heat-resistant egg liquid mixed with milk for fermentation.

[0005] Furthermore, the preparation of the heat-resistant egg liquid includes: adding sugar to the egg liquid and then dispersing it.

[0006] Furthermore, the addition of sugar includes a protease hydrolysis process.

[0007] Furthermore, the protease includes one or more of papain, bromelain, flavor protease, trypsin, pepsin, cathepsin, Bacillus subtilis protease, and aspartic protease.

[0008] Furthermore, the sugar is one or more of tetracarbon sugars, pentose sugars, and their sugar alcohols.

[0009] Furthermore, the tetracarbon sugar and its sugar alcohol include erythritol, threose, and erythritol.

[0010] Furthermore, the pentose sugars and their sugar alcohols include xylose, arabinose, ribose, and xylitol.

[0011] Furthermore, the dispersion treatment is one or more of the following: microfluidic homogenization treatment, ultrasonic treatment, colloid milling treatment, high-shear emulsification treatment, and high-voltage electric field treatment.

[0012] Furthermore, the fermentation process also includes a high-temperature short-time sterilization treatment.

[0013] And, the egg-based fermented yogurt prepared according to the above preparation method.

[0014] The beneficial effects of this invention are as follows:

[0015] This invention addresses the problems of existing technologies where egg liquid has a low sterilization temperature, high lysozyme content, long fermentation time, and low product quality when used to prepare fermented yogurt. First, through protease hydrolysis, sugar addition, and dispersion treatment, the sterilization temperature of the prepared heat-resistant egg liquid is increased to 77-82℃, preventing gel formation and the generation of a fishy odor. Then, the heat-resistant egg liquid is mixed with milk and subjected to short-time sterilization. The lysozyme in the egg liquid is inactivated at a rate significantly higher than 95% in the presence of milk protein. The resulting fermented yogurt has good coagulation properties, low acidity, and a harmonious egg and milk flavor, resulting in better overall quality. Detailed Implementation

[0016] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention.

[0017] To achieve the above objectives, the first embodiment of the present invention provides a method for preparing egg-fermented yogurt, which is prepared by mixing and fermenting heat-resistant egg liquid with milk.

[0018] In some specific embodiments, the preparation of the heat-resistant egg liquid includes: adding sugar to the egg liquid and then dispersing it.

[0019] In some specific embodiments, the addition of sugar is further complicated by protease hydrolysis.

[0020] It should be noted that the egg liquid mentioned in this application includes egg white liquid, egg yolk liquid, or whole egg liquid.

[0021] It should be noted that the main reason for the gel formation and fishy smell in egg liquid during high-temperature sterilization is the denaturation and decomposition of proteins during heating. Existing technologies include adding proteases or sucrose to increase the sterilization temperature of the egg liquid. However, while adding proteases breaks down the proteins in the egg liquid into peptides and amino acids, thereby improving the stability of the egg liquid components and increasing its sterilization temperature, ensuring heat resistance requires thorough hydrolysis of the proteins. This necessitates specific enzyme combinations, continuous monitoring of the egg liquid's pH during enzymatic hydrolysis, and excessive hydrolysis can lead to a noticeable bitter taste, requiring subsequent bitterness removal treatment. Adding sucrose works by reacting with the denatured proteins caused by heat, thus protecting the undenatured proteins and increasing the temperature required for gel formation. However, adding up to 8% sucrose only raises the sterilization temperature of the egg liquid to around 70°C. Increasing the amount of sucrose might further increase the sterilization temperature, but excessive sucrose will inevitably lead to an excessively high sugar content in the egg liquid, affecting its quality and limiting its further processing and application in food.

[0022] In this embodiment, protease is first used to hydrolyze some of the proteins in the egg liquid into polypeptides and amino acids, improving the heat resistance of the egg liquid, delaying the formation of gel and fishy odor, and ensuring that no bitterness is produced. Then, sugar is added to the hydrolyzed egg liquid. The purpose is to utilize the hydroxyl groups of the sugar to form hydrogen bonds with the polar groups of the unhydrolyzed proteins in the egg liquid, replacing the water molecules surrounding the protein polar groups, forming a protective film on the protein surface, ensuring protein stability, maintaining its complete structure and function at high temperatures, and preventing denaturation and decomposition, thus further increasing its sterilization temperature. However, the mutual attraction between proteins and water molecules in the egg liquid makes it difficult for sugar to fully bind with the proteins. Simultaneously, the amino acid molecules produced by hydrolysis also attract the undecomposed proteins, further hindering the binding of sugar and protein. Therefore, this application disperses the sugar-containing egg liquid to separate the proteins from water molecules and hydrolyzed amino acid molecules. The proteins exist in the form of tiny particles, facilitating the binding of sugar hydroxyl groups with their polar groups, forming a protective film on the protein surface, and ensuring the protection of the proteins.

[0023] Furthermore, in this embodiment, the added sugars are tetracarbon sugars, pentose sugars, and their sugar alcohols. These sugars can fully contact the small protein particles during dispersion treatment, forming a dense protective film on the protein surface and ensuring the structure and function of the protein at higher sterilization temperatures. In the prior art, sucrose is generally added, but due to its large molecular weight, even when added in large quantities to the egg liquid of this application, it is difficult for sucrose to fully contact and bind with the protein to form a dense protective film on the protein surface, and its effect on improving the heat resistance of the egg liquid is not particularly significant. Moreover, the applicant has found that the addition of tetracarbon sugars, pentose sugars, and their sugar alcohols has a significant effect on extending the shelf life of the egg liquid at room temperature. This may be because, compared with sucrose or other large-molecule sugars (such as hexoses), or even small-molecule sugars (trioses), tetracarbon sugars, pentose sugars, and their sugar alcohols are difficult for microorganisms to utilize rapidly. At room temperature, they cannot quickly provide sufficient carbon and energy sources for the growth and reproduction of microorganisms, thereby effectively improving the stability and processing performance of the egg liquid at room temperature and extending its shelf life at room temperature. Compared with existing technologies, the high-temperature resistant egg liquid prepared in this application can increase the sterilization temperature of the egg liquid from 60-65℃ to 77-82℃ while ensuring the quality and processing performance of the egg liquid at room temperature.

[0024] It is understood that the type and amount of protease added, as well as the protease hydrolysis temperature and time, can be conventionally selected by those skilled in the art based on the composition and degree of hydrolysis of the egg liquid, and do not exceed the scope of knowledge in the art. This invention does not impose any particular limitations, but only provides some preferred reference ranges. In some specific embodiments, the protease includes one or more of papain, bromelain, flavor protease, trypsin, pepsin, cathepsin, Bacillus subtilis protease, and aspartic protease; in some specific embodiments, the amount of protease added is 0.8%-1% of the egg liquid mass; in some specific embodiments, the protease hydrolysis temperature is 45-50℃, and the time is 3-4 hours.

[0025] It is understood that the sugars added in this application are tetracarbon sugars, pentose sugars, and their sugar alcohols, which have small molecular weights and cannot be rapidly utilized by microorganisms at room temperature. The type and amount of sugar added can be conventionally selected by those skilled in the art based on specific needs such as the sweetness of the egg liquid, and this does not exceed the scope of knowledge in the field. This application does not impose any particular limitations, but only provides some preferred reference ranges. In some specific embodiments, the amount of sugar added is 1.5%-2.5% of the egg liquid mass; in some specific embodiments, the tetracarbon sugars and their sugar alcohols include erythrose, thorose, and erythritol; in some specific embodiments, the pentose sugars and their sugar alcohols include xylose, arabinose, ribose, and xylitol.

[0026] It should be noted that the dispersion treatment described in this application adopts conventional solution dispersion technology. Those skilled in the art can make general adjustments to the dispersion process and parameters according to the specific conditions of the egg liquid. This application does not impose any particular limitations, but only provides some preferred embodiments. In some specific embodiments, the dispersion treatment is one or more of microfluidic homogenization, ultrasonic treatment, colloid milling, high-shear emulsification, and high-voltage electric field treatment. In some specific embodiments, the microfluidic homogenization parameters are: homogenization pressure 10-60 MPa, time 1-10 min; in some specific embodiments, the ultrasonic treatment parameters are: power 100-600 W, time 5-20 min; in some specific embodiments, the colloid milling parameters are: film mixing time 1-2 h, temperature 20-30℃; in some specific embodiments, the high-shear emulsification parameters are: rotation speed 10000-10800 r / min, time 5-10 min; in some specific embodiments, the high-voltage electric field treatment parameters are: electric field strength 800-1000 V / cm, time 60-90 min.

[0027] It should be noted that the current yogurt fermentation time is generally 8-12 hours. This fermentation time ensures that the resulting yogurt has a good set, suitable acidity, and a good taste. The fermentation time should not exceed 14 hours, as excessive fermentation time will lead to excessively high acidity and an unpleasant taste. When the above-mentioned heat-resistant egg liquid is used to prepare fermented yogurt, the lysozyme in the egg liquid will inhibit the growth of lactic acid bacteria, causing the yogurt to remain in a semi-solid state even after 24 hours of fermentation. Furthermore, the excessively long fermentation time results in a noticeably sour taste.

[0028] In this embodiment, a short-time high-temperature sterilization treatment is included before the above-mentioned heat-resistant egg liquid and milk are fully mixed and fermented. The purpose is to improve the inactivation rate of lysozyme in the heat-resistant egg liquid. Lysozyme is heat-stable under acidic conditions, and its stability only decreases when the pH value is greater than 6. Although the pH of egg liquid is greater than 6, the pH value of alkaline egg white is only up to 8, and the pH value of egg yolk is as low as about 6.5. In the prior art, the lysozyme inactivation rate is only about 30% when egg white is sterilized at 65°C for 3 minutes. Although increasing the sterilization temperature can increase the destruction of lysozyme, the heat-resistant egg liquid of this application is heated at 77-82°C for 2-3 minutes, or even extended to 10 minutes, and the increase in lysozyme inactivation rate is not significant. Moreover, the excessive heating time has a certain impact on the quality of the egg liquid. Existing technologies also increase the inactivation rate of lysozyme during heating by raising the pH value of the egg liquid. However, heating at 60°C or higher for at least 10 minutes at pH 8.5-9.0 is required to achieve an inactivation rate of approximately 90% for lysozyme. Although the heat-resistant egg liquid used in this application can achieve an inactivation rate of approximately 90% after sterilization for 2-3 minutes, adjusting the pH value will also have a certain impact on the quality of the egg liquid. In this application, the heat-resistant egg liquid is mixed with milk and then sterilized at 77-82°C for 2-3 minutes. The inactivation rate of lysozyme in the egg liquid exceeds 95%. This may be because the -SH groups in the milk reduce the -SS- bonds of lysozyme, making it easier to inactivate during heating. At the same time, it avoids the generation of a noticeable milk odor due to whey protein at high temperatures and does not affect the main protein in milk, casein, thus ensuring the coagulation properties of the fermented yogurt.

[0029] In this embodiment, the mass of heat-resistant egg liquid added accounts for 10%-20% of the total mass of the fermentation system.

[0030] It is understood that the amount of heat-resistant egg liquid added in the fermentation system of this application can be adjusted by those skilled in the art according to the requirements of product flavor and taste. For example, if a richer egg liquid fermentation flavor is required, the amount of egg liquid added can be appropriately increased, but not exceeding 50%. If the amount added is greater than 50%, the yogurt fermentation time will exceed 14 hours, and the acidity of the product will gradually become obvious.

[0031] In this embodiment, the fermentation process is a conventional yogurt fermentation process. The types and amounts of fermentation bacteria, as well as the fermentation parameters, can be conventionally selected by those skilled in the art based on the specific product, and do not exceed the scope of knowledge in the field. This application does not impose any special limitations, but only provides some preferred reference ranges. In some specific embodiments, the fermentation bacteria are one or more of Lactobacillus bulgaricus, Lactobacillus plantarum, Lactobacillus rhamnosus, Bifidobacterium, Streptococcus thermophilus, and Lactobacillus casei; in some specific embodiments, the added mass of the fermentation bacteria accounts for 1.5%-2.5% of the total mass of the fermentation system; in some specific embodiments, the fermentation temperature is 37-42℃, and the fermentation time is 8-10 hours.

[0032] The second embodiment of this application provides egg-based fermented yogurt prepared by the above-described preparation method.

[0033] The following will disclose specific embodiments for implementing this application, along with corresponding comparative examples to demonstrate the relevant technical effects of this application.

[0034] Example 1: Preparation of High-Temperature Resistant Egg Liquid

[0035] Add 0.08 kg of papain to 10 kg of whole egg liquid and hydrolyze at 45℃ for 4 hours;

[0036] Add 0.15 kg of erythrose to the hydrolyzed whole egg liquid and mix well;

[0037] The sugared whole egg liquid is subjected to microfluidic homogenization at a pressure of 10-60 MPa for 1-10 minutes to obtain a heat-resistant whole egg liquid.

[0038] Example 2: Preparation of High-Temperature Resistant Egg Liquid

[0039] Add 0.1 kg of Bacillus subtilis protease to 10 kg of egg white solution and hydrolyze at 48°C for 3.5 h;

[0040] Add 0.25 kg of xylitol to the hydrolyzed egg white solution and mix well;

[0041] The sugared egg white solution was subjected to colloid milling, with a mixing time of 1-2 hours and a temperature of 20-30℃, to obtain a heat-resistant egg white solution.

[0042] Example 3: Preparation of High-Temperature Resistant Egg Liquid

[0043] Add 0.045 kg of flavor protease and 0.045 kg of aspartic protease to 10 kg of egg yolk liquid, and hydrolyze at 50°C for 3 hours;

[0044] Add 0.1 kg of erythritol and 0.1 kg of arabinose to the hydrolyzed egg yolk liquid and mix well;

[0045] The sugared egg yolk liquid is subjected to a high-voltage electric field treatment with an electric field strength of 800-1000V / cm for 60-90 minutes to obtain a heat-resistant egg yolk liquid.

[0046] Experimental Example 1: Heat Resistance Test of Egg Liquid

[0047] When egg liquid is heated for sterilization, the proteins in the egg liquid gradually form a gel and produce a fishy smell as the temperature rises. In this experiment, the change in storage modulus G' with temperature was measured to determine the sterilization temperature at which the egg liquid forms a gel. At the same time, the sterilization temperature at which the egg liquid produces a fishy smell was determined through sensory evaluation of the fishy smell, thus obtaining the highest sterilization temperature for the samples in Examples 1-3.

[0048] Test method:

[0049] ① Determination of the temperature at which egg liquid forms a gel

[0050] A rheometer was used with a dynamic temperature scanning program to determine the change of egg liquid storage modulus G' with temperature. The sample scanning temperature range was selected as 60-85℃, and the heating rate was 1℃ / min.

[0051] ② Determination of the temperature at which the egg liquid produces a fishy smell

[0052] Sensory evaluation was conducted using 15 food professionals with normal sense of smell. The egg liquid from Examples 1-3 was evaluated for its fishy smell by smelling, and the temperature at which the fishy smell was produced was recorded.

[0053] Test results: See Table 1.

[0054] Table 1. Egg liquid forming a gel, producing a fishy smell, and the highest sterilization temperature.

[0055]

[0056] Results analysis: The high-temperature resistant egg liquid obtained in the above examples does not form a gel or produce a fishy smell when heated and sterilized at 77-82℃ for 2-3 minutes, and has good quality and processing performance at room temperature.

[0057] Experiment Example 4: Preparation of Egg-Fermented Yogurt

[0058] 1 kg of the heat-resistant whole egg liquid obtained in Example 1 was mixed with 8.85 kg of milk and sterilized at 80°C for 3 min. Then, 0.15 kg of Lactobacillus plantarum was added and fermented at 40°C for 9 h to obtain egg liquid fermented yogurt.

[0059] Example 5: Preparation of Egg-Fermented Yogurt

[0060] 1.5 kg of the heat-resistant egg white liquid obtained in Example 2 was mixed with 8.3 kg of milk and sterilized at 77°C for 3 min. Then, 0.2 kg of Lactobacillus bulgaricus was added and fermented at 37°C for 10 h to obtain egg-based fermented yogurt.

[0061] Example 6: Preparation of Egg-Fermented Yogurt

[0062] 2 kg of the heat-resistant egg yolk liquid obtained in Example 3 was mixed with 7.75 kg of milk and sterilized at 82°C for 2 min. Then, 0.1 kg of Lactobacillus rhamnosus and 0.15 kg of Bifidobacterium were added, and the mixture was fermented at 42°C for 8 h to obtain egg liquid fermented yogurt.

[0063] Comparative Example 1: Preparation of Egg-Fermented Yogurt

[0064] The preparation method is the same as in Example 4, except that the sterilization treatment was omitted in Comparative Example 1.

[0065] Comparative Example 2: Preparation of Egg-Fermented Yogurt

[0066] The preparation method is the same as in Example 4, except that in Comparative Example 2, the heat-resistant egg liquid was sterilized and then mixed with milk for fermentation.

[0067] The preparation method is the same as in Example 4, except that the sterilization time of the heat-resistant egg liquid in Comparative Example 3 is 10 minutes, and it is then mixed with milk for fermentation after sterilization.

[0068] Comparative Example 4: Preparation of Egg-Fermented Yogurt

[0069] The preparation method is the same as in Example 4, except that in Comparative Example 4, fresh egg liquid is used instead of heat-resistant egg liquid, and the sterilization temperature is 65°C.

[0070] Comparative Example 5: Preparation of Egg-Fermented Yogurt

[0071] The preparation method is the same as in Example 4, except that in Comparative Example 5, sodium hydroxide, an acidity regulator, was used to adjust the pH of the heat-resistant egg liquid to 9, and after sterilization, it was mixed with milk for fermentation.

[0072] Test Example 2: Lysozyme inactivation rate test

[0073] Lysozyme in egg liquid inhibits the growth of lactic acid bacteria during yogurt fermentation, reducing fermentation efficiency, significantly prolonging fermentation time, and resulting in poor yogurt coagulation and high acidity. In this experiment, the enzyme activity of lysozyme in the egg liquids of Examples 4-6 and Comparative Examples 2-5 before and after sterilization was tested according to the national standard GB / T 25879-2010 "Determination of Lysozyme in Egg White by Spectrophotometry," to obtain the inactivation rate of lysozyme in the sterilized egg liquid. The test results are shown in Table 2.

[0074] Table 2 Results of lysozyme inactivation rate test in sterilized egg liquid

[0075]

[0076] As shown in Table 2, the lysozyme inactivation rate of the sterilized egg liquid in Examples 4-6 was all above 95%, indicating that the sterilization process of the heat-resistant egg liquid of this application can effectively destroy the lysozyme in the egg liquid. The lysozyme inactivation rate of the sterilized egg liquid in Comparative Examples 2-4 was significantly lower than that in Example 4, indicating that only high-temperature short-time sterilization after mixing the heat-resistant egg liquid of this application with milk can significantly improve the lysozyme inactivation rate. Mixing ordinary egg liquid with milk (Comparative Example 2) and extending the sterilization time of the heat-resistant egg liquid (Comparative Example 4) cannot increase the lysozyme inactivation rate to above 95%. The lysozyme inactivation rate of the egg liquid in Comparative Example 5 was not much different from that in Example 4, indicating that adjusting the pH value of the egg liquid to 9 can also significantly improve the degree of lysozyme inactivation during the sterilization process.

[0077] Experiment Example 3: Sensory Evaluation of Egg Yogurt

[0078] Sensory evaluations were conducted on the egg-fermented yogurts from Experiments 4-6 and Comparative Examples 1-5 to analyze the overall quality of products prepared by each process.

[0079] Test method: A sensory evaluation panel of 30 food professionals with comprehensive training was selected. Sensory evaluation standards for egg-fermented yogurt were formulated (as shown in Table 3). The sensory evaluation panel evaluated the egg-fermented yogurts prepared in Examples 4-6 and Comparative Examples 1-5 in terms of color, taste, aroma and texture according to the evaluation standards. The results are shown in Table 4.

[0080] Table 3 Sensory Evaluation Standards for Egg-Fermented Yogurt

[0081]

[0082] Table 4 Sensory Evaluation Results of Egg-Fermented Yogurt

[0083]

[0084] As shown in Tables 1 and 2, the sensory scores of Examples 4-6 were all above 95 points, indicating that the egg-fermented yogurt prepared by the process of this application is light yellow, uniform in color, with a harmonious aroma and taste of egg liquid and milk, a distinct egg aroma, a delicate texture, and good coagulation. Compared with Example 4, the sensory scores of Comparative Examples 1-4 were all lower, indicating that the heat-resistant egg liquid of this application contains more lysozyme (Comparative Example 1), which significantly inhibits the growth of lactic acid bacteria during yogurt fermentation, resulting in lower scores in all aspects of the yogurt and a serious reduction in product quality. Comparative Examples 2-4 degraded the lysozyme in the egg liquid, and as the lysozyme inactivation rate increased, the sensory scores of the yogurt increased, and the overall quality improved. Compared with Example 4, the sensory score of Comparative Example 5 was lower. This is because although the increase in pH value enhanced the degradation of lysozyme in the egg liquid, the use of acidity regulators reduced the edible quality of the egg liquid, thereby reducing the taste and texture of the yogurt and lowering the overall quality.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing egg-based fermented yogurt, characterized in that, include: Mix heat-resistant egg liquid with milk, sterilize at 77-82℃ for 2-3 minutes, and then ferment according to the conventional yogurt fermentation process to obtain egg liquid fermented yogurt. The method for preparing the heat-resistant egg liquid is as follows: After hydrolyzing the egg liquid with papain, erythrosine is added and the mixture is homogenized by microfluidic jet to obtain a heat-resistant egg liquid. Alternatively, after hydrolyzing the egg liquid with Bacillus subtilis protease, xylitol is added and the mixture is then subjected to colloid milling to obtain heat-resistant egg liquid. Alternatively, after hydrolyzing the egg liquid with flavor protease and aspartic protease, adding erythritol and arabinose and then treating it with a high-voltage electric field, a heat-resistant egg liquid can be obtained. The above-mentioned heat-resistant egg liquid will not form a gel or produce a fishy smell after being sterilized by heating at 77-82℃.

2. A fermented yogurt made from egg liquid according to the preparation method of claim 1.

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