Egg white gel suspension and its preparation method and application

Abstract

The present invention discloses an egg white gel suspension, its preparation method, and its application. The egg white is physically treated to alter the interactions between the egg white proteins. The pretreated egg white solution is then heated to produce a milky, free-flowing egg white gel suspension. The egg white gel suspension produced by the present invention significantly expands the application range of egg white thermogels. It can be used for the encapsulation, delivery, and sustained release of water-soluble active ingredients, as micro-nano protein particles for the preparation of Pickering emulsions, as a protein-based fat substitute, and in the preparation of pre-cooked egg white powder.

Description

Technical Field

[0001] The invention belongs to the field of egg product production, and specifically relates to an egg white gel suspension and a preparation method and application thereof. Background Art

[0002] As one of the most common raw materials in food processing, egg white has diverse protein functions, among which gel properties play an important role in food manufacturing. At present, the research on egg white thermal gel is mainly focused on solid gel, and there is a lack of systematic research on fluid gel. In addition, the existing process for preparing egg white gel suspension is relatively simple. There are usually two methods. One is to dilute the egg white liquid before heating to form a fluid gel; the other is to heat the egg white liquid while shearing it to form a gel suspension. Among them, the first method significantly reduces the protein concentration due to the dilution treatment, and the nutritional value is reduced accordingly; the second method is difficult to operate and has low feasibility, which is not convenient for large-scale industrial production. Therefore, the present invention discloses a method for preparing egg white suspension by ultrasonic pretreatment. Summary of the Invention

[0003] The present invention provides an egg white gel suspension, a preparation method and an application thereof. The method for preparing a milky white flowable egg white hot gel by inducing egg white through ultrasonic (or homogenization) treatment lays a foundation for the industrial production of the egg white gel suspension.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] An egg white gel suspension is a heat-denatured gel suspension formed by sequentially treating fresh egg white with physical treatment and heating. The egg white gel suspension has a viscosity of 20-90 cp, is free-flowing, and has a particle size distribution range of 100-1200 nm. The physical treatment is ultrasonication or homogenization.

[0006] Preferably, the egg white gel suspension is obtained by the following preparation method, comprising the following steps:

[0007] Step 1: Physically treating the egg white, such as ultrasonication or homogenization;

[0008] Step 2: Heat the physically treated egg white in a water bath to denature it and form a milky white flowable egg white gel suspension (fluid gel).

[0009] Further preferably, in step 1, the ultrasonic power density is 0.2-0.8 W / mL and the ultrasonic treatment time is not less than 150 seconds.

[0010] Further preferably, in the step 1, the homogenization pressure is not less than 2 Mpa, and the number of homogenization times is not less than 3 times.

[0011] Further preferably, in step 2, the water bath temperature is not higher than 76° C., and the water bath heating time is not more than 16 minutes.

[0012] A method for preparing an egg white gel suspension, comprising the following steps:

[0013] Step 1: Physically treat the egg white, wherein the physical treatment is ultrasound;

[0014] Step 2: Heat the physically treated egg white in a water bath to denature it and form a milky white, flowable egg white hot gel (fluid gel).

[0015] Preferably, in step 1, the ultrasonic power density is 0.2-0.8 W / mL, and the ultrasonic treatment time is not less than 150 seconds.

[0016] Preferably, in step 2, the water bath temperature is not higher than 76° C., and the water bath heating time is not more than 16 min.

[0017] A method for preparing an egg white gel suspension, comprising the following steps:

[0018] Step 1: Physically treat the egg white to homogenize it;

[0019] Step 2: Heat the physically treated egg white in a water bath to denature it and form a milky white, flowable egg white hot gel (fluid gel).

[0020] Preferably, in step 1, the homogenization pressure is not less than 2 Mpa, and the homogenization times are not less than 3 times.

[0021] Preferably, in step 2, the water bath temperature is not higher than 76° C., and the water bath heating time is not more than 16 min.

[0022] The egg white gel suspension or the egg white gel suspension obtained by the preparation method is used for egg tart core or egg white powder.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention uses an ultrasonic cell disruptor (or high-pressure homogenizer) to ultrasonically treat egg white, disrupting the structure of larger-scale egg white proteins and changing their initial interactions. The modified egg white solution is then heated to produce an egg white thermal gel. After pretreatment with an ultrasonic power density of 0.2-0.8 W / mL and an ultrasonic treatment time of at least 150 seconds (or a homogenization pressure of 2 MPa or higher and at least three homogenizations), and then heating the egg white in a water bath at a temperature not exceeding 76°C for no more than 16 minutes, the gel formation rate slows. As the heating time increases, a milky white suspension gradually forms, ultimately forming a milky white egg white gel with a partially flocculent gel and good fluidity.

[0025] 2. It greatly expands the application scope of egg white thermal gel, which can be used for the embedding, delivery and sustained release of water-soluble active ingredients, as micro-nano protein particles for the preparation of Pickering emulsions, as a protein-based fat substitute, and for the preparation of pre-cooked egg white powder.

[0026] 3. Compared with the traditional "heating-crushing-homogenization" technical route to form fluid gel, the fluid gel prepared by this method has smaller particle size and is more stable. In addition, this method is simple to operate, has a short preparation cycle, low energy consumption and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The effects of different ultrasonic power densities on the formation process and state of egg white gel suspension are shown;

[0028] Figure 2 The results show the differences in the formation process, fluidity and homogeneity of egg white gel suspension in water at different ultrasound times;

[0029] Figure 3 The effects of different water bath temperatures on the formation process and state of egg white gel suspension are shown;

[0030] Figure 4 The effects of different water bath heating times on the formation process and state of egg white gel suspension are shown;

[0031] Figure 5 The microstructure of egg white and gel is shown;

[0032] Figure 6 The particle size distribution (A), zeta potential (B), hardness (C), and viscosity (D) of fresh egg white (FEW), ultrasound-induced egg white (UEW), and egg white thermogel (UEFG or EWSG) are shown. Different letters in the figure indicate significant differences (p < 0.05);

[0033] Figure 7The macroscopic changes of egg white gel suspension during storage under different pH systems are shown;

[0034] Figure 8 Shows the effects of different pH systems on the properties of egg white gel suspension: A: particle size distribution; B: zeta potential; C: turbidity; D: absorbance. Different letters represent significant differences between the groups ( p <0.05) p The value is defined as p <0.05(*) , p <0.01(**), p <0.001(***) and p <0.0001(****);

[0035] Figure 9 Shows the difference comparison of the upper, middle and lower layers of egg white gel suspension solutions under different pH systems, A: particle size distribution; B: zeta potential; C: turbidity; D: absorbance;

[0036] Figure 10 The macroscopic changes of egg white gel suspensions in different solution systems during storage are shown;

[0037] Figure 11 The effects of different concentrations of salt solution on the properties of egg white gel suspension are shown. A: particle size distribution; B: zeta potential; C: turbidity; D: absorbance. Different letters represent significant differences between the groups ( p <0.05);

[0038] Figure 12 The effect of different concentrations of sucrose solution on the properties of egg white gel suspension is shown. A: particle size distribution; B: zeta potential; C: turbidity; D: absorbance. Different letters represent significant differences between the groups ( p <0.05);

[0039] Figure 13 The macroscopic and microscopic structures of pre-cooked egg white powder are shown;

[0040] Figure 14 Effects of different pressure treatments on egg white gel suspension. A: 0-10 Mpa; B: 0-140 Mpa; C: viscosity. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0043] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0044] Example 1:

[0045] A preparation process for an egg white gel suspension comprises:

[0046] (1) Ultrasonic treatment

[0047] Separate the egg white from the egg yolk and remove impurities such as the ligament, mix them evenly with a magnetic stirrer, and then perform ultrasonic treatment or homogenization;

[0048] The speed of the magnetic stirrer was 500 r / min, and the stirring time was 15 min;

[0049] The power density of the ultrasonic treatment was 0.25 W / mL, and the ultrasonic time was 4 min (under the condition that the ultrasonic treatment and the interval time were both set to 3 s).

[0050] (2) Water bath heating

[0051] The ultrasonically treated egg white is heated in a water bath to denature it and form a milky white flowable egg white hot gel (fluid gel);

[0052] The water bath heating temperature is 72° C., and the water bath heating time is 10 min.

[0053] Experimental Example 1 Effect of different ultrasonic power densities on egg white thermal gelation

[0054] The difference from Example 1 is that in this embodiment:

[0055] The ultrasonic power density is 0, 0.2, 0.4, 0.6, 0.8, and 1.0 W / mL;

[0056] Specific results such as Figure 1As shown, Figure A compares the thermal gel formation process of untreated egg white and egg white treated with different ultrasonic power densities, and Figure B compares the fluidity of thermal gel of untreated egg white and egg white treated with different ultrasonic power densities.

[0057] The results showed that untreated and 1 W / mL ultrasonically treated egg whites formed solid gels, while egg whites treated at 0.2-0.8 W / mL ultrasonically formed fluid gels upon heating. With increasing heating time, the gel gradually formed from the outside to the center and settled at the bottom of the untreated and 1 W / mL ultrasonically treated egg whites, with a rapid formation rate and good gel stability. However, with increasing heating time, the ultrasonically treated egg whites gradually formed a milky white suspension and eventually formed a partially flocculent gel. The gel formation rate was slow, with good fluidity.

[0058] Ultrasonic treatment can induce egg white to form milky white and fluid egg white thermogel, but the increase of ultrasonic power density can lead to changes in the morphology and type of egg white thermogel.

[0059] Experimental Example 2 Effect of Different Ultrasonic Treatment Times on Egg White Thermal Gel

[0060] The difference from Example 1 is that in this embodiment:

[0061] The ultrasonic treatment time is set to three gradients, including:

[0062] (1) 0, 2, 4, 6, 8, 10, 12 minutes;

[0063] (2) 0, 1, 2, 3, 4, 5, 6 minutes;

[0064] (3) 0, 60, 90, 120, 150, 180 s.

[0065] Figure 2 shows the formation process of egg white thermal gel under the three time gradients mentioned above, its fluidity, and the uniformity of the solution after adding an equal amount of deionized water. Figure A is gradient (1), Figure B is gradient (2), and Figure C is gradient (3). It was observed that when the ultrasonic treatment time was less than 150 s, a solid gel tended to form. The gel formed earlier, and the gel gradually formed from the outside to the center and deposited at the bottom. The formation rate was faster, the gel state was stable, and it had no fluidity. After dilution with water in equal proportions, the solution was not uniform and had obvious phase separation.

[0066] When the ultrasonic treatment time is higher than 150 s, a fluid gel tends to form, and the gel formation rate is slow. As the heating time increases, a milky suspension gradually forms. The longer the ultrasonic treatment time, the more obvious the turbidity, and finally a partial flocculent gel is formed with poor stability and good fluidity. After dilution with water, the solution is uniform and not stratified.

[0067] Experimental Example 3 Effect of different water bath temperatures on egg white thermal gelation

[0068] The difference from Example 1 is that in this embodiment:

[0069] The water bath temperatures are 68, 70, 72, 74, 76, 78, and 80°C, respectively.

[0070] Specific results such as Figure 3 As shown, Figure A shows the difference in the thermal gel state of egg white treated with different water bath temperatures, and Figure B shows the difference in the thermal gel formation process of egg white treated with different water bath temperatures.

[0071] The results showed that when the water bath temperature was in the range of 68-80 ℃, as the temperature increased, the fluidity of egg white thermal gel decreased, the gel formation speed accelerated, the gel stability increased, and the fluidity decreased. When the water bath temperature was not lower than 76 ℃, a solid gel was formed.

[0072] When the water bath temperature is not higher than 68℃, the egg white thermal gel cannot be formed. It is speculated that the degree of denaturation of the egg white is too low to form a flocculent "gel skeleton", and the color is light yellow-green instead of milky white.

[0073] Experimental Example 4 Effect of Different Water Bath Heating Times on Egg White Thermal Gel

[0074] The difference from Example 1 is that in this embodiment:

[0075] The water bath heating time is set to three gradients, including:

[0076] (1) 0, 10, 20, 30 minutes;

[0077] (2) 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 minutes;

[0078] (3) 0, 9, 10, 11, 12, 13, 14, 15, 16 minutes.

[0079] The test results of the three gradients (1), (2), and (3) correspond to Figure 4 Figures A, B, and C in Figure 4 and Figure D show the state of the egg white and the equal-ratio dilution of egg white hot gel and water in Test Example 4 (3) under strong light.

[0080] The experiment found that after the egg white thermogel was heated in a water bath for 14 minutes, the state of the egg white thermogel began to change from fluid to solid, the gel fluidity decreased, and the "gel skeleton" increased significantly. After heating for 16 minutes, the egg white thermogel became a solid gel.

[0081] Four key parameters in the preparation process of egg white gel suspension were determined through Example 1 and Test Examples 1-4: ultrasonic power density of 0.2-0.8 W / mL, ultrasonic treatment time of not less than 150 seconds, water bath heating temperature not higher than 76°C, and heating time not more than 16 min.

[0082] Example 2: Characterization of egg white gel suspension, including:

[0083] Based on the egg white gel suspension obtained by the preparation method of the egg white gel suspension described in Example 1, the present invention performs characterization and measurement on the egg white gel suspension, including:

[0084] (1) Dry and wet weight ratio of gel particles

[0085] Weigh the sample and record the mass as m. Add it to a 25 mL beaker and weigh the total mass as m1. After centrifugation, pour out the supernatant and weigh it as m2. Dry it in an oven at 105°C to constant weight and weigh it as m3. Repeat three times. The calculation formula is: gel wet weight percentage = [1-(m1-m2) / m]×100%, gel wet weight percentage = [1-(m1-m3) / m]×100%. The specific results are shown in Table 1:

[0086] Table 1 Dry and wet weight ratio of gel particles

[0087]

[0088] (2) pH of egg white gel suspension

[0089] Weigh 70 mL of sample into a 100 mL beaker and measure the pH of the sample using a pH meter. The experimental results show that the pH of the egg white gel suspension is 8.9-9.0.

[0090] (3) Microstructure of egg white and gel

[0091] The sample was diluted with distilled water to a dry matter content of 0.02 mg / mL, and then 15 μL of the diluted liquid gel solution was applied to a glass slide and allowed to dry naturally. The sample coated with the glass slide was cut into appropriate sizes and then attached to a metal stage. Gold was sprayed onto the sample and observed by scanning electron microscopy at an accelerating voltage of 2 kV. Representative images were obtained, as shown in Figure 2. Figure 5 shown.

[0092] The samples included fresh egg white (FWE), ultra-sonicated egg white (UEW), and egg white gel suspension (UEFG) prepared as described in Example 1.

[0093] Figure 5The results showed that there were large molecular weight egg white protein aggregates and a large number of small spherical particles in FWE. The loose and porous structure of the aggregates could be clearly seen at a magnification of 100 KX. At a magnification of 10 KX, it was found that after ultrasonic treatment of egg white, a large number of beaded spherical particles appeared in UEW, the porous protein aggregates in FWE disappeared, and the molecular weight difference between protein aggregates was significantly reduced. A large number of nano-scale spherical particles appeared in EWFG, and suspected nano-scale microbubbles also appeared.

[0094] (4) Particle size distribution and Zeta potential of egg white and gel

[0095] The samples were diluted to 0.1% (v / v) with phosphate buffer (10 mM, pH 7.4) at room temperature and measured at 25°C using a nanoparticle size analyzer.

[0096] The sample is the same as in Example 2. (3), and the test results are as follows Figure 6 (A, B) shown:

[0097] Proteins and their aggregates in the egg white sample were primarily distributed within the particle size ranges of 1-10 nm, 10-100 nm, and 100-1000 nm. These are hypothesized to correspond to small-molecular-weight egg white proteins, large-molecular-weight egg white proteins, and egg white protein aggregates, respectively. Compared to stirred egg white, the egg white treated with ultrasonic power shifted toward smaller particle sizes in Peak 3, indicating a reduction in the size of egg white protein aggregates after ultrasonic treatment. After heating in a water bath, ovalbumin, ovotransferrin, lysozyme, ovomucin α-subunit (Mucin 5B), and ovomucin β-subunit (Mucin 6) participated in the formation of the egg white gel suspension. Numerous protein aggregates appeared in the UEFG, with particle sizes confined to approximately 200-400 nm and unable to further aggregate. This is hypothesized to be due to the rapid structural unfolding of the heat-sensitive proteins in the egg white, exposing hydrophobic and charged groups within the proteins. This significantly increased the absolute value of the zeta potential and led to electrostatic repulsion between the proteins.

[0098] (5) Hardness of egg white and gel

[0099] An appropriate amount of each sample was placed in a cylinder of 12 mm × 12 mm (diameter × height), and the sample properties were measured using a texture analyzer.

[0100] The samples include the samples tested in Example 2. (3) and solid gel (EWSG). The test results are as follows. Figure 6 (C) shows:

[0101] The average hardness of fresh egg white liquid was 13.23 ± 1.52 gf, the average hardness of sonicated egg white was 11.76 ± 0.25 gf, the average hardness of the egg white gel suspension was 15.24 ± 1.47 gf, and the average hardness of the solid gel was 515.39 ± 1.35 gf. The hardness decreased slightly after sonication, but there was no significant difference. However, the hardness increased significantly after heating in a water bath to form an egg white gel suspension. Once the egg white gel transitioned from a fluid to a solid, the hardness showed a significant difference, increasing by hundreds of times.

[0102] (6) Viscosity of egg white and gel

[0103] At room temperature, an appropriate amount of each sample was placed in a 20 mm × 70 mm (diameter × height) cylinder, and the liquid properties of the sample were measured using a digital rotational viscometer.

[0104] The sample is the same as in Example 2. (3), and the test results are as follows Figure 6 (D) shows:

[0105] The average viscosity of fresh egg white liquid was 112.28 ± 3.18 cp, the average viscosity of sonicated egg white was 37.33 ± 0.82 cp, and the average viscosity of the egg white gel suspension was 79.48 ± 1.60 cp. After the shearing effect of ultrasonic pretreatment, the initial interactions of fresh egg white were destroyed, and the viscosity dropped significantly. Heating in a water bath, however, caused the ovalbumin, ovotransferrin, and lysozyme in the egg white to polymerize, causing the viscosity to recover somewhat, but still lower than the viscosity of the original egg white liquid.

[0106] Example 3: Stability evaluation of egg white gel suspension

[0107] Based on the egg white gel suspension prepared by the method for preparing the egg white gel suspension described in Example 1, the present invention performs a stability assessment on the egg white gel suspension, comprising:

[0108] (1) Stability of egg white gel suspension under different pH systems

[0109] Under aseptic operation, 5 ml of egg white gel suspension and an equal amount of water were added to a 12 ml transparent sample bottle for isocratic dilution. The pH was measured as the control group (CK). The experimental group was diluted with water at a ratio of 1:0.8, and then the pH value was adjusted to 2, 4, 6, 8, 10, and 12 with 3 mol / L hydrochloric acid and sodium hydroxide. Finally, the volume was replenished to 1:1 and the lid was closed. After completion, the sample bottle was placed in a constant temperature refrigerator at 4 °C for 28 days. The measurement indicators, including macroscopic changes (photographs), particle size, zeta potential, absorbance, and turbidity, were taken out on the 1st, 7th, 14th, 21st, and 28th days.

[0110] Test results:

[0111] Based on Example 2.(2), the pH value of CK is 8.9-9.0.

[0112] Figure 7 The results showed that under storage conditions of 4°C and a pH range of 6-10, the egg white gel suspension had good stability and no obvious macroscopic changes during the 28-day test period. At a pH of 2, the egg white gel suspension began to stratify on the third day, and the upper layer gradually became clear as the storage time increased. At a pH of 4, the egg white gel suspension was extremely unstable, with stratification occurring on the first day and obvious stratification on the third day, with the protein obviously aggregating and sinking. It is speculated that this may be because the isoelectric point of most proteins in egg white is around pH 4.5, leading to protein aggregation and sinking. When the pH of the egg white gel suspension was adjusted to 12, the color of the egg white gel suspension changed from milky white to light yellow-green, and the transparency was significantly improved. After storage for 7 days, an obvious odor of protein deterioration appeared.

[0113] Figure 8 A shows that when the pH value of the egg white gel suspension is 6-10, the protein and its aggregates are mainly distributed in the range of 100-2000 nm, with a very small part distributed in the range of 10-100 nm and 2000-10000 nm; when the pH value is 2 and 4, all the protein aggregates are distributed in the range of 1000-10000 nm. Figure 8 B It can be found that the absolute value of the Zeta potential at the corresponding pH value is significantly reduced, and the electrostatic repulsion in the solution is reduced, which may be the reason for protein aggregation; when the pH value is 12, the protein and its aggregates are all distributed in the range of 100-2000 nm. Figure 8 In C, the turbidity of the egg white gel suspension decreased under both strong acid and strong alkaline environments, and was more significant under strong alkaline conditions. In an environment with a pH close to the isoelectric point of egg white protein, the turbidity increased significantly.

[0114] When stored for 21 days, the egg white gel suspension with a pH of 6-10 showed subtle stratification that was difficult to distinguish with the naked eye, and was divided into three layers: upper, middle and lower. Figure 11 The results show the differences in the upper, middle and lower layers of the egg white gel suspension solution under different pH systems. In the system with a pH of 4, the solution is only divided into two layers, the upper and lower layers, and in the system with a pH of 12, the solution is not separated. Figure 9 As shown in A, when pH is 2, the particle size of the lower layer is the smallest among the three layers, followed by the upper layer, and both exceed 4000 nm, far exceeding other systems. Figure 9 Turbidity in C and Figure 7 This indicates that the protein in the egg white gel suspension further aggregates under a strong acidic environment, and a small amount of macromolecular aggregates also exist in the supernatant; Figure 9B shows that at pH values ​​of 2 and 4, the absolute value of Zeta-potential is significantly lower than that of other systems, which is one of the reasons why the egg white gel suspension solution is unstable; Figure 9 C and D correspond to the turbidity and absorbance of the solution, respectively. The turbidity and absorbance of the upper, middle and lower layers of the egg white gel suspension solution under each pH system all showed an upward trend, and the upper, middle and lower layers were significantly different from the lower layer.

[0115] The test results show that the egg white gel suspension has good stability when the pH is 6-10. Strong acid, strong alkaline and pH environment close to the isoelectric point of egg white protein are not suitable for the storage of egg white gel suspension.

[0116] (2) Stability of egg white gel suspension in different solution systems

[0117] Aseptically add 5 ml of egg white gel suspension to a 12 ml transparent sample bottle, and then dilute in equal proportions with equal amounts of water, saline solution, and sucrose solution. Cover the bottle and store it in a 4°C refrigerator for 28 days. Measure the parameters on days 1, 7, 14, 21, and 28, including macroscopic changes (photographs), particle size, zeta potential, absorbance, and turbidity.

[0118] The concentrations of the saline solutions were 0.01 mg / ml and 0.02 mg / ml, respectively; the concentrations of the sucrose solutions were 0.05 mg / ml and 0.1 mg / ml, respectively.

[0119] Test results: Figure 10 、 11 , 12 showed that under storage conditions of 4 °C, during the test period of 28 days, the egg white gel suspension did not show significant macroscopic changes in the salt solution and sucrose solution systems, and there was no significant difference in particle size, zeta potential, absorbance, turbidity and CK, indicating that the egg white gel suspension had good stability in the salt solution and sucrose solution systems.

[0120] Example 4: Preparation of an egg white gel suspension egg tart core

[0121] Based on the egg white gel suspension obtained by the preparation method of the egg white gel suspension described in Example 1, the present invention prepares an egg white gel suspension egg tart core, comprising:

[0122] (1) Preparation of egg tart liquid

[0123] Weigh corresponding weight portions of 200 parts of pure milk, 60 parts of egg yolk, 40 parts of egg white gel suspension, and 15 parts of fine sugar in a container, stir and mix, and filter through a 60-mesh sieve.

[0124] (2) Degassing treatment

[0125] Degassing of egg tart liquid by ultrasonic water bath;

[0126] The ultrasonic power is 150 W and the time is 5 min.

[0127] (3) Baking

[0128] Pour the egg tart liquid into the mold and bake it in the oven;

[0129] The oven temperature is 210° C., and the baking time is 30 minutes.

[0130] Test Example 5: Preparation of Ordinary Egg Tart Core

[0131] The difference from Example 4 is the preparation of the egg tart liquid. In this test example:

[0132] Weigh 100 parts of pure milk, 100 parts of light cream, 60 parts of egg yolks, 40 parts of condensed milk and 15 parts of fine sugar in corresponding parts by weight, put them into a container, stir and mix, and filter through a 60-mesh sieve.

[0133] The nutritional substances of the egg tart cores in Example 4 and Test Example 5 were measured, and the specific results are shown in Table 2:

[0134] Table 2 Comparison of nutrient content of two egg tart cores

[0135]

[0136] As can be seen from Table 2 above, although the egg tart core prepared by the present invention has a slightly lower protein content, the calorie and fat content are less than half of those in the test example, which proves that the egg white gel suspension has good application prospects as a protein-based fat substitute.

[0137] Example 5: Preparation of pre-cooked egg white powder based on egg white gel suspension

[0138] Based on the egg white gel suspension obtained by the method for preparing an egg white gel suspension described in Example 1, the present invention prepares a pre-cooked egg white powder, comprising:

[0139] (1) Ultrasonic spray dried egg white powder (USD)

[0140] The egg white gel suspension was spray dried.

[0141] The spray drying process had an air inlet temperature of 140°C, an air outlet temperature of 80°C, and a feed liquid rate of 0.45 mL / h.

[0142] (2) Ultrasonic vacuum freeze-dried egg white powder (UFD)

[0143] The egg white gel suspension was vacuum freeze-dried.

[0144] The vacuum freeze drying has a cold trap temperature of approximately -80°C, a drying chamber temperature of approximately -55°C, a final vacuum degree of 10-20 Pa, and a drying time of 36 h.

[0145] Test Example 6: Preparation of pre-cooked egg white powder based on non-sonicated egg white

[0146] Compared with Example 5, the difference in this test example is:

[0147] (1) Spray-dried egg white powder (SD)

[0148] The unsonicated egg white was heated in a water bath at 52°C for 30 min and then spray-dried.

[0149] (2) Vacuum freeze-dried egg white powder (FD)

[0150] The unsonicated egg white was directly subjected to vacuum freeze-drying.

[0151] A macro and micro comparison of SD, FD, USD, and UFD is shown below. Figure 13 As shown:

[0152] The results showed that the color of the pre-cooked egg white powder prepared based on fluid gel was similar to that of the egg white powder prepared from fresh egg white, but the average particle size was smaller and the egg white powder formed was finer, especially the contrast between USD and SD was extremely obvious.

[0153] Example 6: Preparation of egg white gel suspension based on ultrahigh pressure homogenization

[0154] The method for preparing an egg white gel suspension based on the above-mentioned Example 1 is different from Example 1 in that this embodiment uses ultrahigh pressure averaging treatment instead of ultrasonic treatment, comprising:

[0155] (1) Ultra-high pressure homogenization treatment

[0156] Separate the egg white and yolk and remove impurities such as ligaments, mix them evenly with a magnetic stirrer, and homogenize them using an ultra-high pressure homogenizer;

[0157] The speed of the magnetic stirrer was 500 r / min, and the stirring time was 15 min;

[0158] The pressure of the ultra-high pressure equalizer is not less than 2 MPa, the single flow rate is 8.80 mL, the extension speed is 71 Time / Min, and the egg white liquid is circulated for 3 times.

[0159] (2) Water bath heating

[0160] The homogenized egg white is heated in a water bath to denature it and form a milky white flowable egg white hot gel (fluid gel);

[0161] The water bath heating temperature is 72° C., and the water bath heating time is 10 min.

[0162] The results are as follows Figure 14 As shown, ultrahigh-pressure homogenization can replace ultrasonic treatment to produce an egg white gel suspension. When the pressure is not less than 2 MPa and the homogenization is repeated at least three times, the viscosity of the resulting egg white gel suspension is significantly lower than the average viscosity of FEW and lower than the average viscosity of UEFG, indicating that the resulting egg white gel suspension has better fluidity, which also reflects the decrease in the gel skeleton content in the egg white gel suspension. As the pressure increases, the viscosity of the egg white gel suspension first decreases and then increases.

[0163] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The embodiments and features in the embodiments of this application may be arbitrarily combined with each other unless they conflict. The scope of protection of the present invention shall be the technical solutions described in the claims, including equivalent alternatives to the technical features of the technical solutions described in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A free-flowing egg white gel suspension for egg tart core or egg white powder, characterized in that: The egg white gel suspension is a heat-denatured gel microparticle formed by sequentially treating fresh egg white with physical treatment and heat treatment. The egg white gel suspension has a viscosity of 20-90 cp, is free-flowing, and has a particle size distribution range of 100-1200 nm. The physical treatment is homogenized. The egg white gel suspension is prepared by the following preparation method, comprising the following steps: Step 1: Homogenize the egg white at a pressure of 20-140 MPa and for at least 3 times; Step 2: Heat the physically treated egg white in a water bath to denature it and form a milky white, flowable egg white gel suspension; the water bath temperature is 72°C and the water bath heating time is 10 minutes.

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