An egg powder and a method of making the same

Abstract

The application belongs to the technical field of food processing, and particularly relates to an egg powder and a preparation method thereof. In view of the problems of low protein content and poor brewing performance of the egg powder prepared by the prior art, the egg liquid is first 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 acid substance is added to the high-temperature-resistant egg liquid, and the high-temperature-resistant egg liquid is subjected to spray drying treatment after high-temperature short-time sterilization, so as to avoid the increase of the viscosity of the high-temperature-resistant egg liquid after sterilization, and the protein content and the brewing performance of the prepared egg powder are both significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of food processing, specifically relating to an egg powder 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. The sterilized egg liquid is then used to prepare egg powder. The product obtained by spray drying has a significantly reduced protein content and decreased reconstitution performance. Summary of the Invention

[0003] Based on the above reasons, the purpose of this invention is to provide an egg powder 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, an acidic substance is added to the heat-resistant egg liquid and it is sterilized at high temperature to avoid the increase in viscosity of the heat-resistant egg liquid after sterilization. The egg powder obtained by spray drying has a significantly increased protein content and good reconstitution properties.

[0004] To achieve the above objectives, this invention discloses an egg powder and its preparation method, which is obtained by spray drying after sterilizing high-temperature resistant egg liquid.

[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 high-temperature resistant egg liquid is sterilized by adding an acidic substance.

[0013] And the egg powder prepared according to the above preparation method.

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

[0015] This invention addresses the problems of low sterilization temperatures in existing egg liquids, resulting in low protein content and poor reconstitution properties in the prepared egg powder. 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 any fishy odor. Then, an acidic substance is added to the heat-resistant egg liquid before a short-time high-temperature sterilization process. This avoids the increase in viscosity caused by the increased sterilization temperature and sugar addition during sterilization, ensuring the dispersibility of molecules within the heat-resistant egg liquid system. Consequently, the egg powder obtained after spray drying has a high protein content and good reconstitution properties. 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 discloses a method for preparing egg powder, which involves sterilizing high-temperature resistant egg liquid and then spray drying it.

[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 national standard GB / T 42237-2022, "General Rules for the Quality of Egg Powder," specifies the moisture content requirements for egg powder: whole egg powder ≤ 4.5%, egg yolk powder ≤ 4.0%, and egg white powder ≤ 9.0%. Generally, the lower the moisture content of egg powder, the better its storage performance. Existing technology utilizes spray drying to prepare egg powder from egg liquid. Spray drying parameters of 110-120℃ inlet air temperature, 70-80℃ outlet air temperature, and 4-5 hours ensure good quality of the egg powder while maintaining a moisture content below 2%, thus providing good storage performance. Even though the improved heat resistance of the high-temperature resistant egg liquid in this application can reduce the degree of protein denaturation caused by the above-mentioned spray drying parameters, the viscosity of the dried material will increase significantly even after short-term sterilization of 2-3 minutes due to the increased sterilization temperature and the addition of sugar. In order to make the moisture content of the final egg powder less than 2%, the inlet and outlet air temperatures need to be increased to a certain extent or the drying time needs to be significantly extended based on the above-mentioned spray drying parameters. This will easily cause protein denaturation and reduce the reconstitution performance of the egg powder.

[0028] In this embodiment, an acidic substance is added to the heat-resistant egg liquid before sterilization. This is to prevent the viscosity of the heat-resistant egg liquid from increasing after sterilization, ensuring the dispersion of molecules in the sterilized heat-resistant egg liquid, and ensuring the drying efficiency of the egg powder in a shorter drying time. Existing technologies generally use water dilution to reduce the viscosity of the solution. However, water dilution can damage the protective film formed by sugars on the surface of the protein in the heat-resistant egg liquid of this application to some extent, still resulting in protein loss and decreased reconstitution performance. The applicant has discovered that adding an acidic substance to the sterilized heat-resistant egg liquid can effectively reduce its viscosity while preventing damage to the protective film on the protein surface. This may be because the acidic substance molecules reduce the adhesion between the protective films on the protein surface.

[0029] It is understood that the acidic substance described in this application is an organic acid that does not react with sugar. In some specific embodiments, the acidic substance includes, but is not limited to, citric acid, malic acid, and lactic acid; in some specific embodiments, the amount of the acidic substance added is 0.5%-0.8% of the mass of the heat-resistant egg liquid.

[0030] The second embodiment of this application provides egg powder prepared by the above preparation method.

[0031] The following will disclose specific embodiments for implementing this application, along with corresponding comparative examples to demonstrate the relevant technical effects of this application.

[0032] Example 1: Preparation of High-Temperature Resistant Egg Liquid

[0033] Add 0.08 kg of papain to 10 kg of whole egg liquid and hydrolyze at 45℃ for 4 hours;

[0034] Add 0.15 kg of erythrose to the hydrolyzed whole egg liquid and mix well;

[0035] 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.

[0036] Example 2: Preparation of High-Temperature Resistant Egg Liquid

[0037] Add 0.1 kg of Bacillus subtilis protease to 10 kg of egg white solution and hydrolyze at 48°C for 3.5 h;

[0038] Add 0.25 kg of xylitol to the hydrolyzed egg white solution and mix well;

[0039] 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.

[0040] Example 3: Preparation of High-Temperature Resistant Egg Liquid

[0041] 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;

[0042] Add 0.1 kg of erythritol and 0.1 kg of arabinose to the hydrolyzed egg yolk liquid and mix well;

[0043] 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.

[0044] Experimental Example 1: Heat Resistance Test of Egg Liquid

[0045] 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.

[0046] Test method:

[0047] ① Determination of the temperature at which egg liquid forms a gel

[0048] 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.

[0049] ② Determination of the temperature at which the egg liquid produces a fishy smell

[0050] 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.

[0051] Test results: See Table 1.

[0052] Table 1. Egg liquid forming a gel, producing a fishy smell, and the highest sterilization temperature.

[0053] 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.

[0054] Experiment Example 4: Preparation of Egg Powder

[0055] Take 1 kg of the high-temperature resistant whole egg liquid obtained in Example 1, add 0.005 kg of citric acid and mix thoroughly. Sterilize at 80°C for 3 min, and then spray dry. The spray drying parameters are: spray flow rate of 20 mL / min, inlet air temperature of 110°C, outlet air temperature of 80°C, and drying time of 4.5 h.

[0056] Example 5: Preparation of Egg Powder

[0057] Take 1 kg of the high-temperature resistant whole egg liquid obtained in Example 2 and mix it thoroughly with 0.007 kg of lactic acid. Sterilize it at 77°C for 3 min, and then spray dry it. The spray drying parameters are: spray flow rate of 22 mL / min, inlet air temperature of 115°C, outlet air temperature of 77°C, and drying time of 5 h.

[0058] Experiment Example 6: Preparation of Egg Powder

[0059] Take 1 kg of the high-temperature resistant whole egg liquid obtained in Example 3 and mix it thoroughly with 0.008 kg of malic acid. Sterilize it at 82°C for 2 min and then spray dry it. The spray drying parameters are: spray flow rate of 25 mL / min, inlet air temperature of 120°C, outlet air temperature of 82°C, and drying time of 4 h.

[0060] Comparative Example 1: Preparation of Egg Powder

[0061] The preparation method is the same as in Example 4, except that Comparative Example 1 uses ordinary egg liquid and the sterilization temperature is 65°C.

[0062] Comparative Example 2: Preparation of Egg Powder

[0063] The preparation method is the same as in Example 4, except that the addition of citric acid was omitted in Comparative Example 2.

[0064] Comparative Example 3: Preparation of Egg Powder

[0065] The preparation method is the same as in Example 4, except that in Comparative Example 3, water is used instead of citric acid and the amount added is 10% of the egg liquid.

[0066] Experimental Example 2: Determination of Moisture Content

[0067] The moisture content of the egg powders in Examples 4-6 and Comparative Examples 1-3 was determined according to the national standard GB5009.3-2016 "Determination of Moisture in Food". The results are shown in Table 2.

[0068] Table 2 Results of moisture content determination of egg powder

[0069]

[0070] As can be seen from the data in Table 2, the moisture content of the egg powder in Examples 4-6 is all below 2%, indicating that the egg powder prepared in this application has a low moisture content. Compared with Comparative Example 4, Comparative Examples 1 and 3 also have lower moisture content, while Comparative Example 2 has a significantly higher moisture content due to the increased viscosity of the dried material.

[0071] Experimental Example 3: Determination of Protein Content

[0072] The protein content of the egg powders from Examples 4-6 and Comparative Examples 1-3 was determined according to the national standard GB5009.5-2016 "Determination of Protein in Food". The results are shown in Table 3.

[0073] Table 3 Results of protein content determination in egg powder

[0074]

[0075] As shown in Table 3, the protein content of the egg powder in Examples 4-6 is all above 50%, indicating that the process of this application can effectively prevent protein loss caused by high-temperature sterilization and spray drying, and increase the protein content of the egg powder. Compared with Example 4, Comparative Example 1 has the lowest protein content because ordinary egg liquid has low heat resistance, and the excessively high drying temperature during spray drying causes serious protein loss. In Comparative Example 2, the viscosity of the dried material increases significantly due to the sterilization process, which reduces the spray drying efficiency, resulting in a high water content and low protein content in the egg powder. The protein content in Comparative Example 3 is also low because although the addition of water reduces the viscosity of the dried material, it damages the protective film on the surface of the protein in the high-temperature resistant egg liquid to a certain extent, reducing the heat resistance of the high-temperature resistant egg liquid, and thus increasing the protein loss during spray drying.

[0076] Experimental Example 3: Egg Powder Reconstitution Performance Test

[0077] The reconstitution performance of the egg powders in Examples 4-6 and Comparative Examples 1-3 was tested, including the determination of egg powder flowability, dispersibility, hydration capacity and solubility.

[0078] Test method:

[0079] Flowability: The angle of repose was determined by the injection method to examine the flowability of the egg powder. The larger the angle of repose, the greater the coefficient of friction, and the worse the flowability of the egg powder on the surface.

[0080] Dispersibility: Accurately weigh 5g of egg powder and dissolve it in 50mL of deionized water. Stir the mixture at a certain speed on a constant temperature magnetic stirrer and record the time required from the start of stirring until the egg powder clumps are completely dispersed. Repeat the test 3 times and take the average value as the dispersion time (s). The longer the dispersion time, the worse the dispersibility of the egg powder.

[0081] Hydration capacity: Weigh 0.5g of egg powder and place it in a pre-weighed centrifuge tube. Add water gradually, stirring with a glass rod until the egg powder is fully dissolved. Centrifuge at 4500 rpm for 15 minutes and discard the supernatant. If there is no supernatant, add water again, stir, and centrifuge until a small amount of supernatant remains. Calculate the mass of water absorbed per gram of egg powder, which is the hydration capacity of the egg powder (mL / g). The calculation formula is as follows:

[0082]

[0083] The higher the hydration capacity, the stronger the powder's ability to adsorb water.

[0084] Solubility: The determination was made in accordance with the national standard GB 5413.29-2010 "Determination of solubility in infant food and dairy products".

[0085] Test results: See Table 4.

[0086] Table 4 Results of Egg Powder Mixing Performance Test

[0087]

[0088] As shown in Table 4, Example 4 exhibits the best flowability, dispersibility, hydration capacity, and solubility, indicating that the egg powder prepared by the process described in this application has good reconstitution properties. This is because the egg powder particles prepared by this process have smooth and uniform surfaces, a high total diffusion rate, low protein denaturation, strong interaction between proteins and water molecules, and strong water adsorption capacity. Compared to Example 4, Comparative Example 1 has the worst reconstitution performance. This is because the egg liquid in Comparative Example 1 undergoes the most severe protein denaturation during spray drying, leading to a significant decrease in all aspects of the egg powder particle indicators. Comparative Example 2 has a higher water content in its egg powder particles, resulting in greater cohesion between particles and thus reduced reconstitution performance. Comparative Example 3 suffers from reduced reconstitution performance due to the destruction of the protective film on the protein surface in the high-temperature resistant egg liquid, leading to increased protein denaturation.

[0089] 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 powder, characterized in that, include: Add 0.5%-0.8% of an acidic substance by weight to the heat-resistant egg liquid, sterilize, and then spray dry. The acidic substance is citric acid, malic acid, or lactic acid; 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 subjecting it to high-voltage electric field treatment, 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. An egg powder prepared by the preparation method according to claim 1.

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