A method for preparing a special-purpose egg yolk liquid for spreading by using a complex enzyme hydrolysis technology

Abstract

The application discloses a method for preparing a special egg yolk liquid for smearing by using a composite enzyme hydrolysis technology and belongs to the technical field of food processing. The preparation method comprises the following steps: raw material pretreatment: egg yolk raw materials are diluted and dissolved by adding water to prepare an egg yolk solution; phosphate addition: phosphate is added to the egg yolk solution and then ultrasonic dissolution is performed; lipase hydrolysis: lipase is added to the ultrasonic solubilized egg yolk solution for hydrolysis; protease hydrolysis: composite protease is added to the egg yolk solution after the lipase hydrolysis for hydrolysis; heat-aroma reaction: the egg yolk solution after the composite protease hydrolysis is subjected to heat reaction; blending and calibration: an oligosaccharide solution is added to the egg yolk solution after heat preservation; pasteurization: the egg yolk solution after the addition of the oligosaccharide solution is subjected to sterilization treatment; sterile filling: the sterilized egg yolk solution is filled to prepare the special egg yolk liquid for smearing. The prepared egg yolk liquid has appropriate viscosity and aroma.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food processing, and in particular to a method for preparing egg yolk liquid for special coating by using a complex enzyme hydrolysis technology. BACKGROUND

[0002] Egg yolk is a common food raw material and is widely used in the production of pastries, bread, cakes, biscuits and other foods. However, the traditional egg yolk liquid preparation method has some limitations, such as inaccurate viscosity control, which affects the coating use of egg yolk liquid in food processing, and poor odor of egg yolk liquid product, which affects the coating effect.

[0003] In the prior art, patent CN117568308B proposes a method for preparing modified egg yolk liquid by using a complex enzyme preparation. The complex enzyme preparation is prepared by physically mixing phospholipase, glutaminease and a carrier, and the egg yolk liquid is modified to improve its storage stability and taste. Patent CN116076675A provides a low-gel egg yolk liquid, a preparation method and an application. The method modifies the fresh egg yolk liquid by adding methylcyclohexyl carboxylate, dissolves five-carbon sugars, and combines homogenization and sterilization processes to make the odor temperature and odor concentration of the obtained egg yolk liquid consistent with those of fresh egg yolk liquid, and prolongs the shelf life of the egg yolk liquid during normal temperature preservation and cold storage. However, these technologies do not focus on the coating application of egg yolk liquid, and there is no egg yolk liquid with good brushing characteristics and rich aroma to meet the processing needs of different foods. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] The traditional egg yolk liquid preparation process has the problems of high viscosity of egg yolk liquid which is not conducive to coating, and poor odor of the product, so it is necessary to provide an egg yolk liquid with good brushing characteristics and rich aroma.

[0006] TECHNICAL CONTENT

[0007] To solve the above problems, the present application provides a method for preparing an egg yolk liquid for special coating, which comprises the following steps:

[0008] (1) Raw material pretreatment: dilute and dissolve the egg yolk raw material with water to obtain an egg yolk solution with a protein concentration of 13-18wt%;

[0009] (2) Phosphate addition: add phosphate to the egg yolk solution and then ultrasonically dissolve it;

[0010] (3) Lipase hydrolysis: add lipase to the ultrasonically solubilized egg yolk solution for hydrolysis;

[0011] (4) Protease hydrolysis: adding complex protease to the egg yolk solution after lipase hydrolysis for hydrolysis;

[0012] (5) Thermal flavor-enhancing reaction: subjecting the egg yolk solution after complex protease hydrolysis to thermal reaction;

[0013] (6) Formulation calibration: adding oligosaccharide solution to the egg yolk solution after thermal reaction;

[0014] (7) Pasteurization: subjecting the egg yolk solution after adding oligosaccharide solution to sterilization treatment to obtain egg yolk liquid for special application.

[0015] Further, the egg yolk raw material in step (1) includes fresh egg yolk, egg yolk powder or concentrated egg yolk liquid.

[0016] Further, the protein content of the egg yolk raw material in step (1) is 20-50wt%.

[0017] Further, the amount of phosphate added in step (2) is 0.01-0.05wt% of the mass of the egg yolk solution.

[0018] Further, the phosphate is a mixture of sodium pyrophosphate and sodium dihydrogen phosphate with a mass ratio of 1:1-2.

[0019] Further, the frequency of the ultrasound in step (2) is 40-100Hz.

[0020] Further, the lipase in step (3) includes triglyceride lipase, phospholipase or galactolipase.

[0021] Further, the enzyme activity of the lipase in step (3) is 3000-10000U / g.

[0022] Further, the amount of lipase added in step (3) is 0.05-1wt% of the egg yolk solution after ultrasonic solubilization.

[0023] Further, the hydrolysis temperature in step (3) is 50-60 degrees, and the hydrolysis time is 2-4h.

[0024] Further, the complex protease in step (4) is a mixture of flavor enzyme, papain and neutral protease; the mass ratio of flavor enzyme, papain and neutral protease is 1:1-2:1-2.

[0025] Further, the enzyme activity of the flavor enzyme is 4000-8000U / g.

[0026] Further, the enzyme activity of the papain is 2000-5000U / g.

[0027] Further, the enzyme activity of the neutral protease is 6000-10000 U / g.

[0028] Further, the addition amount of the complex protease in step (4) is 0.1-2 wt% of the egg yolk solution after the lipase hydrolysis.

[0029] Further, the hydrolysis pH in step (4) is 5.0-7.0, the hydrolysis temperature is 50-55℃, and the hydrolysis time is 3-4h.

[0030] Further, the heat reaction in step (5) is to incubate the egg yolk solution after the complex protease hydrolysis at a temperature of 50-60℃, and the incubation time is 20-28h.

[0031] Further, the oligosaccharide in step (6) includes konjac oligosaccharide or isomalto-oligosaccharide.

[0032] Further, the concentration of the oligosaccharide in the oligosaccharide solution in step (6) is 0.1-0.2 wt%.

[0033] Further, the addition amount of the oligosaccharide solution in step (6) is 0.1-0.5 wt% of the egg yolk solution after the heat reaction.

[0034] Further, the sterilization temperature in step (7) is 125-135 degrees, and the sterilization time is 4-6s.

[0035] The application provides a special egg yolk liquid for spreading prepared by the above method.

[0036] The application provides the application of the special egg yolk liquid for spreading in the field of food processing, cooking or baking.

[0037] The application has the following advantages:

[0038] (1) The viscosity is suitable: the viscosity of the egg yolk liquid is controlled in a desired range (150-200 Pa.s) by adjusting multiple preparation processes, and the egg yolk liquid is suitable for spreading and other food processing, and the surface of the egg yolk liquid has good film-forming property, the thickness is 1-1.5 mm, and the texture is uniform, while the film-forming thickness of the ordinary egg yolk liquid is usually 2-4 mm, which is too thick and it is difficult to control the uniformity of the liquid film thickness.

[0039] (2) The flavor of the egg yolk liquid is improved: the enzyme hydrolysis and heat flavor-enhancing reaction promote the disintegration of the egg yolk globule structure, the release of free amino acids and fatty acids, and the oxidation and Maillard reaction of protein and lipid molecules, so that the egg yolk liquid can greatly increase the food aroma after being spread, and the food, especially the baked products, is more delicious. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Viscosity of the egg yolk liquid obtained for the examples and comparative examples.

[0041] Figure 2 Flavor profile for the electronic nose test.

[0042] Detailed Implementation

[0043] Raw material sources

[0044] Triglyceride lipase, enzyme activity 3000 U / g; phospholipase, enzyme activity 10000 U / g; flavor protease, enzyme activity 6000 U / g; papain, enzyme activity 3000 U / g; neutral protease, enzyme activity 8000 U / g; all the above enzymes are ordinary commercially available enzymes. Egg yolk powder is made by selecting fresh egg yolk and then spray drying, wherein the detected protein concentration is 32wt%, and the fat content is 65wt%.

[0045] Example 1

[0046] (1) Raw material pretreatment: select egg yolk powder, add water and stir to dilute to obtain an egg yolk solution, wherein the protein concentration is 16wt%.

[0047] (2) Phosphate addition: add 0.2wt% of sodium pyrophosphate and sodium dihydrogen phosphate salt to the egg yolk solution, the ratio of the two phosphates is 1:1, after adding, use a low-frequency ultrasonic disruptor (frequency is 60Hz) for ultrasonic solubilization, to promote the dissolution of lipoprotein particles and phosvitin.

[0048] (3) Lipase hydrolysis: use triglyceride lipase for hydrolysis of the ultrasonic egg yolk solution, the addition amount of triglyceride lipase is 0.05wt% of the egg yolk solution, the hydrolysis pH is 8, the hydrolysis temperature is 50℃, and the hydrolysis time is 4h.

[0049] (4) Protease hydrolysis: add a complex protease to the egg yolk solution after lipase hydrolysis for hydrolysis, the complex protease is a mixture of flavor enzyme, papain and neutral protease, the ratio of the three proteases is 1:1:1, the total addition amount is 0.5wt% of the egg yolk solution, the hydrolysis pH is 6.0, the hydrolysis temperature is 50℃, and the hydrolysis time is 3h.

[0050] (5) Heat flavoring reaction: put the egg yolk solution after steps (3) and (4) hydrolysis into a heat incubator, incubate at 55℃ for 24h, to induce lipid oxidation, protein oxidation and formation of Maillard reaction flavor.

[0051] (6) Formulation calibration: add 0.1wt% of oligoisomaltose solution (the concentration of oligoisomaltose is 0.1wt%) to the egg yolk solution to obtain an egg yolk liquid.

[0052] (7) Ultra-high temperature pasteurization: The egg yolk liquid is subjected to sterilization treatment by using the ultra-high temperature pasteurization technology, the sterilization temperature is 125℃, and the sterilization time is 4-6s, so as to ensure the extended shelf life.

[0053] (8) Aseptic packaging: The sterilized egg yolk liquid is subjected to aseptic filling, and the nutritional ingredients, viscosity and microbial indicators are detected to ensure that the product meets the food safety standards.

[0054] Example 2

[0055] In the step (4) of Example 1, the lipase used is adjusted to phospholipase, and the addition amount is 0.1wt%, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0056] Example 3

[0057] In the step (5) of Example 1, the ratio of protease is adjusted to 1:1.5:1.5, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0058] Example 4

[0059] In the step (6) of Example 1, the temperature of the thermal flavoring reaction is adjusted to 60℃, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0060] Comparative Example 1

[0061] In the step (2) of Example 1, the addition of phosphate is deleted, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0062] Comparative Example 2

[0063] In the step (3) of Example 1, the lipase hydrolysis is deleted, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0064] Comparative Example 3

[0065] In the step (4) of Example 1, the compound protease used is adjusted to a single neutral protease, and the addition amount of the neutral protease is the same as the total addition amount of the compound protease, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0066] Comparative Example 4

[0067] In the step (4) of Example 1, the compound protease used is adjusted to a single alkaline protease, and the addition amount of the alkaline protease is the same as the total addition amount of the compound protease, and the other steps remain the same as Example 1, to obtain a special flavoring egg yolk liquid for baking brushing.

[0068] Comparative Example 5

[0069] The time of the thermal flavor-enhancing reaction in step (5) was changed to 12 h to obtain a baked brushing special flavor-enhancing egg yolk solution.

[0070] Comparative Example 6

[0071] The egg yolk solution of step (2) was taken without subsequent processing.

[0072] Test Method

[0073] I. Determination of apparent viscosity

[0074] A rheometer (Discovery HR-3) was used to characterize the rheological properties of the samples. An aluminum plate with a diameter of 40 mm and a gap of 1.0 mm was selected as the probe. The egg yolk samples were tested at 25°C. The steady shear mode of the rheometer was used to determine the flowability of the samples. The shear rate was set to 0.1 s -1 ~ 100 s -1 The obtained curve of apparent viscosity versus shear rate was fitted by a power law equation:

[0075] η = K x ε n-1

[0076] where η represents the apparent viscosity (Pa s); ε represents the shear rate (s -1 ); K is the viscosity coefficient (Pa s n ); and n is the flow index.

[0077] II. Determination of the thickness of the dough brushing

[0078] A container with a mass of M0 was filled with distilled water, and the total mass was recorded as M1. After emptying the container, it was filled with dough, and the total mass was recorded as M2. The specific gravity of the batter was calculated by knowing the specific gravity of distilled water (1 g / cm 3 ).

[0079] Dough specific gravity = (M2 - M0) / (M1 - M0)

[0080] The height of the dough before brushing was measured and recorded as H1. After brushing the dough twice, the height of the dough was measured and recorded as H2. The height of the dough can be measured with a vernier caliper, and the brushing thickness of the dough surface = H2 (mm) - H1 (mm).

[0081] III. Flavor evaluation (electronic nose)

[0082] Accurately weigh 3 grams of sample and transfer it to a sealed 20 mL headspace vial. Detection conditions were achieved using two DB-5 and DB-1701 (10 m - 0.18 mm) columns of different polarities, and two flame ionization detectors. The headspace extraction temperature was set to 60 °C, and the injection temperature was maintained at 200 °C. The following temperature program was used: first, increasing the temperature from 50 °C to 80 °C at a rate of 1 °C / s, then increasing it to 250 °C at a rate of 2 °C / s.

[0083] IV. Sensory Evaluation

[0084] The sensory evaluation panel for the egg yolk liquid consisted of 15 judges, all of whom received sensory evaluation training before the formal experiment. This experiment evaluated the flavor of the egg yolk liquid, with a maximum score of 10 points for each parameter. Specific evaluation criteria are shown in Table 1. During the testing period, the order in which the samples were placed was randomized.

[0085] Table 1 Sensory Evaluation Criteria for Egg Yolk Liquid

[0086] Excellent (8-10) Average (5-7) Poor (0-4) Flavor Stronger roasted egg flavor Lighter flavor, no off notes No flavor

[0087] 1. Viscosity Comparison

[0088] from Figure 1 The viscosity comparison data shows that the viscosity of the egg yolk hydrolysate samples treated according to Examples 1-4 is generally lower than 150 Pa·s. However, in Comparative Examples 1-4, the degree of hydrolysis of egg yolk protein decreased after deleting steps (2) and (3) or changing the hydrolysis conditions in step (4), resulting in higher viscosity, all above 150 Pa·s. It can be seen that the use of phosphate in step (2) can promote the depolymerization of egg yolk lipoprotein, thereby increasing the degree of hydrolysis of egg yolk protein. The use of lipase in step (3) to hydrolyze and promote the disintegration of the yolk globule structure is also conducive to promoting protein solubilization and hydrolysis. Furthermore, the combined hydrolysis of protease in step (4) also shows that the combined enzyme used is the key to egg yolk hydrolysis.

[0089] 2. Thickness of the batter brushed onto the dough surface

[0090] As can be seen from the brushing characteristics of the egg yolk liquid samples in each embodiment and comparative example on the dough surface in Table 1, the brushing thickness is directly related to the viscosity of the egg yolk liquid. The higher the viscosity, the greater the brushing thickness. Comparative examples 1-4 have increased viscosity due to decreased protein hydrolysis, resulting in brushing film thickness exceeding the target value, all greater than 1.5 mm, which is obviously unsuitable for application. Among them, comparative example 2 has the highest brushing film thickness due to the removal of the lipase hydrolysis step. Comparative example 5 only changed step (5) of the heat-enhancing reaction, so the brushing thickness still meets the requirements.

[0091] Table 1

[0092]

[0093] 3. Flavor evaluation (electronic nose) + sensory score

[0094] from Figure 2 The flavor profiles of the egg yolk samples from the various embodiments and comparative examples, as measured by electronic nose (E-nose) testing, show that Examples 1-3 exhibit a high degree of similarity in flavor. Example 4, due to its enhanced heat-enhancing reaction, possesses a richer roasted egg yolk aroma, resulting in a slight difference in flavor profile. Comparative Examples 4 and 5, however, differ significantly from the flavor profiles of the embodiments, indicating substantial differences in overall flavor characteristics. This is primarily because Comparative Example 4 utilizes alkaline protease, which is not beneficial for the release of umami and aromatic amino acids. Therefore, the proposed method of protein hydrolysis using a combination of papain, neutral enzymes, and flavor enzymes is more conducive to enhancing the flavor of egg yolks. Comparative Example 5, by shortening the heat-enhancing reaction time, suffers from insufficient lipid oxidation, free amino acid oxidation, and Maillard reaction in the egg yolk, leading to inadequate flavor and a marked difference in flavor compared to the embodiments.

[0095] Table 2

[0096]

[0097] The sensory evaluation results further validated the flavor profile test results of the electronic nose. As shown in Table 2, the flavor scores of each embodiment were relatively high. Example 4 had the highest overall flavor score because of the increased degree of aroma enhancement reaction, resulting in a richer baked egg flavor. Comparative Examples 1-3 had slightly lower aroma scores than the embodiments because the degree of protein hydrolysis was reduced, leading to a decrease in the degree of egg yolk increase reaction. The sample of Comparative Example 4, which used alkaline protease hydrolysis, had an even lower aroma score of only 7.9 points, indicating that the choice of enzyme has an important impact on the product aroma. Comparative Example 5 had the lowest overall aroma score because the shortened heat reaction time for aroma enhancement resulted in insufficient lipid oxidation, free amino acid oxidation, and Maillard reaction in the egg yolk liquid, leading to insufficient flavor. This shows that step (5) of the heat aroma enhancement reaction in this invention is the key step in determining the aroma of the brushed egg yolk liquid, while other steps can also affect the heat aroma enhancement reaction process by changing the degree of egg yolk protein hydrolysis, thereby weakening the aroma.

[0098] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing an egg yolk liquid for painting, characterized by, The preparation method comprises the following steps: (1) raw material pretreatment: dilute and dissolve the egg yolk raw material with water to obtain an egg yolk solution with an egg white concentration of 13-18 wt%; (2) phosphate addition: add a phosphate to the egg yolk solution, and then ultrasonically dissolve it; (3) lipase hydrolysis: add a lipase to the ultrasonically solubilized egg yolk solution for hydrolysis; (4) protease hydrolysis: add a complex protease to the egg yolk solution after lipase hydrolysis for hydrolysis; (5) heat-enhanced flavor reaction: perform a heat reaction on the egg yolk solution after complex protease hydrolysis; (6) formulation calibration: add an oligosaccharide solution to the egg yolk solution after heat preservation; (7) ultrahigh-temperature pasteurization: perform sterilization treatment on the egg yolk solution to which the oligosaccharide solution is added, to obtain a special egg yolk liquid for spreading; The amount of the phosphate added in step (2) is 0.01-0.05 wt% of the mass of the egg yolk solution; the phosphate is a mixture of sodium pyrophosphate and sodium dihydrogen phosphate with a mass ratio of 1:1-2; The lipase in step (3) includes a triglyceride lipase, a phospholipase, or a galactose lipase, and the amount of addition is 0.05-1 wt% of the ultrasonically solubilized egg yolk solution; the hydrolysis temperature is 50-60℃, and the hydrolysis time is 2-4 h; The complex protease in step (4) is a mixture of a flavor enzyme, a papain, and a neutral protease, with a mass ratio of the flavor enzyme, the papain, and the neutral protease being 1:1-2:1-2, and the amount of addition is 0.1-2 wt% of the egg yolk solution after lipase hydrolysis; the hydrolysis pH is 5.0-7.0, the hydrolysis temperature is 50-55℃, and the hydrolysis time is 3-4 h; The heat reaction in step (5) is heat preservation of the egg yolk solution after complex protease hydrolysis at a temperature of 50-60℃, and the heat preservation time is 20-28 h; The concentration of the oligosaccharide in the oligosaccharide solution in step (6) is 0.1-0.2 wt%, and the amount of addition of the oligosaccharide solution is 0.1-0.5 wt% of the egg yolk solution after heat preservation; the oligosaccharide includes a konjac oligosaccharide or an isomalto-oligosaccharide.

2. The preparation method according to claim 1, characterized in that, The egg yolk raw material in step (1) includes fresh egg yolk, egg yolk powder, or concentrated egg yolk liquid.

3. The production method as claimed in claim 1, characterized in that, The sterilization temperature in step (7) is 125-135℃, and the sterilization time is 4-6 s.

4. A special egg yolk liquid for spreading prepared by the preparation method in any one of claims 1-3.

5. Application of the special egg yolk liquid for spreading in claim 4 in the field of cooking or baking.

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