Method for preparing special egg yolk liquid for smearing by using compound enzyme hydrolysis technology

Abstract

The invention discloses a method for preparing special egg yolk liquid for smearing by using a compound enzyme hydrolysis technology, and belongs to the technical field of food processing. The preparation method comprises the following steps: pretreatment of raw materials: adding water to dilute and dissolve yolk raw materials to prepare a yolk solution; adding phosphate: adding phosphate into the yolk solution, and then performing ultrasonic dissolution; lipase hydrolysis: adding lipase into the yolk solution subjected to ultrasonic solubilization for hydrolysis; protease hydrolysis: adding compound protease into the egg yolk solution subjected to lipase hydrolysis for hydrolysis; performing thermal aroma enhancement reaction, namely performing thermal reaction on the yolk solution hydrolyzed by the compound protease; blending and calibrating: adding an oligosaccharide solution into the egg yolk solution subjected to heat preservation; performing pasteurization: performing sterilization treatment on the egg yolk solution added with the oligosaccharide solution; and performing sterile canning: performing canning on the sterilized yolk solution to prepare the special yolk liquid for smearing. And the prepared yolk liquid is appropriate in viscosity and has fragrance.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a method for preparing egg yolk liquid for spreading by utilizing composite enzyme hydrolysis technology. Background Art

[0002] Egg yolk is a common food raw material, widely used in the production of pastries, bread, cakes, biscuits and other foods. However, the traditional method of preparing egg yolk liquid has some limitations, such as the viscosity control is not precise enough, which affects the application of egg yolk liquid in food processing, and the odor of egg yolk liquid products affects the application effect.

[0003] In the prior art, patent publication CN117568308B proposes a method for preparing a modified egg yolk liquid with a composite enzyme preparation, in which phospholipase, glutaminase and a carrier are physically mixed to prepare a composite enzyme preparation, and the egg yolk liquid is modified to improve its storage stability and taste. Patent publication CN116076675A provides a low-gelling egg yolk liquid, a preparation method and an application, which is modified by adding methyl cyclohexylcarboxylate to fresh egg yolk liquid, dissolving it with pentose, and combining homogenization and sterilization processes, so that the obtained egg yolk liquid has the same fishy smell generation temperature and fishy smell concentration as the fresh egg yolk liquid, and extends the shelf life of the egg yolk liquid when stored at room temperature and refrigerated. However, these technologies have not yet been applied to the smearing of egg yolk liquid, and have not yet provided an egg yolk liquid with good slurry brushing properties and a strong aroma to meet the processing needs of different foods. Summary of the invention

[0004] Technical issues

[0005] In the traditional preparation process of egg yolk liquid, there are problems such as the high viscosity of the egg yolk liquid, which is not conducive to coating, and the product has a poor odor. Therefore, it is necessary to provide an egg yolk liquid with good brushing properties and a strong aroma.

[0006] Technical content

[0007] In order to solve the above problems, the present invention provides a method for preparing egg yolk liquid for spreading, the preparation method comprising the following steps:

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

[0009] (2) Phosphate addition: adding phosphate to the egg yolk solution and then dissolving it by ultrasonication;

[0010] (3) Lipase hydrolysis: lipase is added to the egg yolk solution after ultrasonic solubilization for hydrolysis;

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

[0012] (5) Thermal flavor enhancement reaction: subjecting the egg yolk solution hydrolyzed by the composite protease to a thermal reaction;

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

[0014] (7) Pasteurization: The egg yolk solution to which the oligosaccharide solution is added is sterilized to obtain the egg yolk liquid for coating.

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

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

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

[0018] Furthermore, the phosphate is a mixture of sodium pyrophosphate and sodium dihydrogen phosphate in a mass ratio of 1:1 to 2.

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

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

[0021] Furthermore, the lipase activity in step (3) is 3000 to 10000 U / g.

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

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

[0024] Furthermore, the composite 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] Furthermore, the enzyme activity of the flavor enzyme is 4000-8000 U / g.

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

[0027] Furthermore, the enzymatic activity of the neutral protease is 6000 to 10000 U / g.

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

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

[0030] Furthermore, in step (5), the thermal reaction is to keep the egg yolk solution after being hydrolyzed by the composite protease at a temperature of 50-60° C. for 20-28 hours.

[0031] Furthermore, in step (6), the oligosaccharide comprises konjac oligosaccharide or isomaltooligosaccharide.

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

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

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

[0035] The invention provides an egg yolk liquid for spreading prepared by the method.

[0036] The egg yolk liquid for spreading provided by the present invention is used in the fields of food processing, cooking or baking.

[0037] Beneficial effects of the present invention:

[0038] (1) Appropriate viscosity: The present invention controls the viscosity of the egg yolk liquid within an ideal range (150-200 Pa.s) through the adjustment of multiple preparation processes. The egg yolk liquid is suitable for coating and other food processing. When used for brushing, the egg yolk liquid has good film-forming property on the surface, a thickness of 1-1.5 mm, and a uniform texture. The film thickness of ordinary egg yolk liquid for brushing is usually 2-4 mm, which is too thick and it is difficult to control the uniformity of the liquid film thickness.

[0039] (2) Enhancement of egg yolk liquid flavor: The enzymatic hydrolysis and thermal aroma enhancement reactions adopted by the present invention promote the disintegration of the egg yolk globules structure and the release of free amino acids and fatty acids, thereby promoting the oxidation and Maillard reaction of protein and lipid molecules, producing a rich baked egg yolk aroma, so that the egg yolk liquid can greatly enhance the aroma of food after being applied, making the food, especially baked products, more delicious. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The viscosity of the egg yolk liquid obtained in the embodiment and the comparative example is compared.

[0041] Figure 2 Flavour profile tested for electronic nose.

[0042] Specific implementation part

[0043] Source of raw materials

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

[0045] Example 1

[0046] (1) Raw material pretreatment: egg yolk powder was selected, and water was added and stirred to dilute it to obtain an egg yolk solution, in which the protein concentration was 16 wt%.

[0047] (2) Phosphate addition: Sodium pyrophosphate and sodium dihydrogen phosphate are added to the egg yolk solution at a ratio of 1:1, accounting for 0.2 wt% of the egg yolk solution. After addition, a low-frequency ultrasonic disruptor (frequency of 60 Hz) is used for ultrasonic solubilization to promote the dissolution of lipoprotein particles and yolk phosphoprotein.

[0048] (3) Lipase hydrolysis: The egg yolk solution after ultrasound was hydrolyzed using triglyceride lipase. The amount of triglyceride lipase added was 0.05 wt % of the egg yolk solution. The pH of the hydrolysis was 8, the temperature of the hydrolysis was 50° C., and the hydrolysis time was 4 h.

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

[0050] (5) Thermal aroma enhancement reaction: The egg yolk solution hydrolyzed in steps (3) and (4) is placed in a heat preservation tank and kept at 55° C. for 24 hours to induce lipid oxidation, protein oxidation, and the formation of Maillard reaction flavor.

[0051] (6) Preparation and calibration: add 0.1 wt % of isomaltooligosaccharide solution (wherein the concentration of isomaltooligosaccharide is 0.1 wt %) to the egg yolk solution and mix to obtain egg yolk liquid.

[0052] (7) Ultra-high temperature pasteurization: Ultra-high temperature pasteurization technology is used for sterilization, with a sterilization temperature of 125°C and a sterilization time of 4-6 seconds, ensuring its extended shelf life.

[0053] (8) Aseptic canning: The sterilized egg yolk liquid is aseptically filled and tested for nutritional content, viscosity and microbiological indicators to ensure that the product meets food safety standards.

[0054] Example 2

[0055] The lipase used in step (4) of Example 1 was adjusted to phospholipase, and the addition amount was 0.1wt%. The other steps were kept consistent with Example 1 to obtain a flavored egg yolk liquid specially used for baking batter brushing.

[0056] Example 3

[0057] The ratio of the protease in step (5) of Example 1 was adjusted to 1:1.5:1.5, and the other steps were kept consistent with Example 1 to obtain a flavored egg yolk liquid specifically for baking batter brushing.

[0058] Example 4

[0059] The temperature of the heat aromatization reaction in step (6) of Example 1 is adjusted to 60° C., and the other steps are kept consistent with Example 1 to obtain an aromatized egg yolk liquid specifically for baking batter brushing.

[0060] Comparative Example 1

[0061] The addition of phosphate in step (2) is deleted, and the other steps are kept the same as in Example 1 to obtain a flavored egg yolk liquid specially used for baking batter brushing.

[0062] Comparative Example 2

[0063] The lipase hydrolysis in step (3) was deleted, and the other steps were kept the same as those in Example 1 to obtain a flavored egg yolk liquid specially used for baking batter brushing.

[0064] Comparative Example 3

[0065] The composite protease used in step (4) of Example 1 is changed to a single neutral protease, and the amount of neutral protease added is the same as the total amount of composite protease added. The other steps are consistent with Example 1 to obtain a special flavored egg yolk liquid for baking batter brushing.

[0066] Comparative Example 4

[0067] The composite protease used in step (4) of Example 1 was changed to a single alkaline protease. The amount of alkaline protease added was the same as the total amount of composite protease added. The other steps were kept the same as in Example 1 to obtain a flavored egg yolk liquid for baking batter brushing.

[0068] Comparative Example 5

[0069] The heat aromatization reaction time in step (5) is changed to 12 hours to obtain the aromatized egg yolk liquid specially used for baking batter brushing.

[0070] Comparative Example 6

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

[0072] Test Method

[0073] 1. Determination of apparent viscosity

[0074] The rheological properties of the samples were characterized using a rheometer (Discovery HR-3). 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 flowability of the samples was determined using the steady-state shear mode of the rheometer. The shear rate was set to 0.1 s -1 ~100s -1 , the obtained curve of apparent viscosity changing with shear rate is fitted by the power law equation:

[0075] η=K×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 ); n is the flow index.

[0077] 2. Determination of dough brushing thickness

[0078] Take a container with a mass of M0, fill it with distilled water, the total mass is recorded as M1, empty the container and fill it with dough, the total mass is recorded as M2. 3 ) Calculate the specific gravity of equal volume of batter.

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

[0080] Measure the height of the dough before applying the paste, record it as H1, and measure the height of the dough after applying the paste twice, record it as H2. The height of the dough can be measured with a vernier caliper, the thickness of the paste applied on the dough surface = H2 (mm) - H1 (mm).

[0081] 3. Flavor evaluation (electronic nose)

[0082] 3 grams of accurately weighed sample was transferred to a sealed 20 ml headspace bottle. The detection conditions were two chromatographic columns of different polarities, DB-5 and DB-1701 (10m-0.18mm), and two flame ionization detectors. The headspace extraction temperature was set at 60°C and the injection temperature was maintained at 200°C. The following program temperature increase was used: first from 50°C to 80°C at a rate of 1°C / S, and then to 250°C at a rate of 2°C / S.

[0083] 4. Sensory Evaluation

[0084] The sensory evaluation panel for egg yolk liquid was composed of 15 judges, all of whom received sensory evaluation training before the formal experiment. This experiment evaluated the flavor of egg yolk liquid, with a full score of 10 points for the parameter. The specific evaluation criteria are shown in Table 1. During the test, the order of sample placement was random.

[0085] Table 1 Sensory evaluation standards for egg yolk liquid

[0086] Excellent (8-10 points) Average (5-7 points) Poor (0-4 points) Flavor Has a strong roasted egg aroma Light fragrance, no odor No fragrance

[0087] 1. Viscosity comparison

[0088] from Figure 1 It can be seen from the viscosity comparison data that the viscosity of the egg yolk hydrolyzate samples treated according to Examples 1 to 4 is generally lower than 150 Pa·s, while in Comparative Examples 1-4, after deleting step (2), step (3) or changing the hydrolysis conditions of step (4), the degree of hydrolysis of the egg yolk protein decreased, resulting in a high viscosity, all higher than 150 Pa·s. It can be seen that the use of phosphate in step (2) can promote the depolymerization of egg yolk lipoprotein and thus increase the degree of hydrolysis of egg yolk protein, the use of lipase in step (3) to promote the disintegration of the yolk ball structure is also conducive to promoting protein solubilization and hydrolysis, and the protease complex hydrolysis in step (4) also shows that the complex enzyme used is the key to egg yolk hydrolysis.

[0089] 2. Thickness of the paste on the dough surface

[0090] From the brushing characteristics of egg yolk liquid samples of each embodiment and comparative example on the dough surface in Table 1 below, it can be seen that the brushing thickness is directly correlated with the viscosity of the egg yolk liquid. The greater the viscosity, the greater the brushing thickness. Comparative Examples 1-4 have a lowered degree of protein hydrolysis, resulting in an increase in viscosity, which causes the brushing liquid film thickness to exceed the target value, all greater than 1.5 mm, and are obviously not suitable for coating. Among them, Comparative Example 2 has the highest brushing liquid film thickness due to the deletion of the lipase hydrolysis step. Comparative Example 5 only changes the thermal flavoring reaction in step (5), so the brushing thickness can still meet the requirements.

[0091] Table 1

[0092]

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

[0094] from Figure 2 It can be seen from the flavor profiles of the electronic nose (E-nose) test of the egg yolk samples of each embodiment and the comparative example that embodiments 1-3 have a high degree of similarity in flavor. Because the intensity of the heat aroma enhancement reaction is enhanced, Example 4 has a stronger roasted egg yolk aroma, so there is a slight difference in the flavor profile. However, the flavor profiles of Comparative Examples 4 and 5 are far different from those of the embodiments, indicating that the overall flavor characteristics show a great difference. This is mainly because Comparative Example 4 uses alkaline protease, which is not beneficial for the release of umami and aromatic amino acids. Therefore, the composite hydrolysis of papaya enzyme, neutral enzyme, and flavor enzyme proposed in the present invention is also a protein hydrolysis method that is beneficial to egg yolk aroma enhancement. Comparative Example 5 shortens the aroma enhancement heat reaction time, resulting in insufficient flavor due to lipid oxidation, free amino acid oxidation, and Maillard reaction in the egg yolk liquid, which is significantly different from the flavor of the embodiments.

[0095] Table 2

[0096]

[0097] The results of the sensory evaluation further verified the flavor profile test results of the electronic nose. From the scores in Table 2, the flavor scores of each embodiment are relatively high. Embodiment 4 has a higher degree of flavor enhancement reaction, so it produces a richer baked egg flavor and has the highest overall flavor score. However, since the degree of protein hydrolysis is reduced, the degree of egg yolk enhancement reaction is reduced in Comparative Examples 1-3, and the aroma score is slightly lower than that of the embodiments; and the aroma score of the sample hydrolyzed by alkaline protease in Comparative Example 4 is even lower, only 7.9 points, indicating that the selection of enzymes has an important influence on the aroma of the product; Comparative Example 5 shortens the aroma enhancement heat reaction time, resulting in insufficient flavor due to lipid oxidation, free amino acid oxidation, and Maillard reaction in the egg yolk liquid, resulting in the lowest overall aroma score. It is shown that the thermal aroma enhancement reaction in step (5) of the present invention is the key step in determining the aroma of the egg yolk liquid, and other steps will also affect the progress of the thermal aroma enhancement reaction 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 present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing egg yolk liquid for spreading, characterized in that: The preparation method comprises the following steps: (1) Raw material pretreatment: diluting and dissolving the egg yolk raw material with water to prepare an egg yolk solution with a protein concentration of 13-18 wt%; (2) Phosphate addition: adding phosphate to the egg yolk solution and then dissolving it by ultrasonication; (3) Lipase hydrolysis: lipase is added to the egg yolk solution after ultrasonic solubilization for hydrolysis; (4) Protease hydrolysis: adding composite protease to the egg yolk solution after lipase hydrolysis for hydrolysis; (5) Thermal flavor enhancement reaction: subjecting the egg yolk solution hydrolyzed by the composite protease to a thermal reaction; (6) Preparation and calibration: adding the oligosaccharide solution to the egg yolk solution after the thermal reaction; (7) Pasteurization: sterilizing the egg yolk solution to which the oligosaccharide solution is added to obtain the egg yolk solution for coating; The amount of phosphate added in step (2) is 0.01-0.05wt% of the egg yolk solution; In step (3), the lipase includes triglyceride lipase, phospholipase or galactose lipase, and the added amount is 0.05-1wt% of the egg yolk solution after ultrasonic solubilization; In step (4), the composite protease 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, and the added amount is 0.1-2wt% of the egg yolk solution after lipase hydrolysis; In step (6), the oligosaccharide concentration in the oligosaccharide solution is 0.1-0.2 wt %, and the amount of the oligosaccharide solution added is 0.1-0.5 wt % of the egg yolk solution after the thermal reaction.

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 preparation method according to claim 1, characterized in that: The phosphate in step (2) is a mixture of sodium pyrophosphate and sodium dihydrogen phosphate in a mass ratio of 1:1 to 2.

4. The preparation method according to claim 1, characterized in that: In step (3), the hydrolysis temperature is 50-60 degrees and the hydrolysis time is 2-4 hours.

5. The preparation method according to claim 1, characterized in that: In step (4), the hydrolysis pH is 5.0-7.0, the hydrolysis temperature is 50-55° C., and the hydrolysis time is 3-4 h.

6. The preparation method according to claim 1, characterized in that: The thermal reaction in step (5) is to keep the egg yolk solution after being hydrolyzed by the composite protease at a temperature of 50-60° C. for 20-28 hours.

7. The preparation method according to claim 1, characterized in that: In step (6), the oligosaccharide comprises konjac oligosaccharide or isomaltooligosaccharide.

8. The preparation method according to claim 1, characterized in that: In step (7), the sterilization temperature is 125-135 degrees and the sterilization time is 4-6 seconds.

9. An egg yolk liquid for spreading made by the preparation method according to any one of claims 1 to 8.

10. Use of the egg yolk liquid for spreading as claimed in claim 9 in the fields of food processing, cooking or baking.

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