A method for inhibiting egg yolk cold gelation with low sugar and low salt

Abstract

The application discloses a low-sugar and low-salt egg yolk frozen gelation inhibition method and belongs to the technical field of food processing. The egg yolk frozen gelation inhibition method comprises the following steps: (1) egg yolk separation; (2) sugar alcohol and salt compounding; (3) low-temperature pre-freezing; (4) frozen storage; and (5) water bath heating thawing. The egg yolk is treated by using sugar alcohol and sodium chloride in cooperation, and the low-temperature pre-freezing and water bath heating thawing are used to jointly inhibit the egg yolk frozen gelation. Compared with the prior art, the application specifically reduces the addition amount of the sugar alcohol and the sodium chloride, retains the original sensory characteristics of the egg yolk, meets the demand of people on food health, and optimizes the pre-freezing and thawing process, so that the damage to the nutritional value and functional characteristics of the egg yolk is reduced to the maximum, and the application has a wide market application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to a low-sugar and low-salt egg yolk frozen gelation inhibition method, belonging to the technical field of food processing. BACKGROUND

[0002] China's egg production is the world's first, and per capita egg consumption is much higher than that of developed countries. Frozen technology is widely used in the storage and transportation of egg yolk. However, when the egg yolk is stored at-6℃ or below, it will gelate, which makes it difficult to mix with other food ingredients in the actual application process, limiting the application of frozen egg yolk liquid. Therefore, how to effectively inhibit the gelation of egg yolk during frozen storage has become a technical problem to be solved.

[0003] Commercial frozen egg yolk usually contains sodium chloride (salted egg yolk) and sucrose (sugared egg yolk) and other additives to inhibit gelation. The type of additive determines the use of egg yolk products in food production. For example, salted egg yolk is often used in the production of mayonnaise and salad dressing. While sugared egg yolk is more suitable for making cakes, donuts and ice cream and other products. However, in these foods, egg yolk is mainly used as a small amount of auxiliary material, and the application of sugar / salt egg yolk as the main raw material in food is limited by its high salt and high sugar properties. In addition, in recent years, as the number of obese patients, diabetic patients and "three high" people increases, people are increasingly rejecting high-sugar and high-salt foods, and the food industry is also paying more attention to the development of low-sugar and low-salt foods. A large number of products such as "sugar-free drinks" and "low-salt snacks" have appeared on the market. How to inhibit the gelation of egg yolk without changing the sensory characteristics of natural egg yolk has become an important bottleneck for further expanding the application market of frozen egg yolk liquid.

[0004] In addition, the existing methods for inhibiting the gelation of egg yolk during freezing also include the use of protease enzymatic treatment, which can destroy the protein structure in the egg yolk, decompose nutrients, produce more insoluble substances, and reduce the storage stability of the system. In addition, the actual effect of inhibiting the gelation of egg yolk during freezing is generally poor, the price is high, the comprehensive cost performance is low, and more bacterial contamination is likely to occur in actual industrial production, increasing the subsequent processing procedures. SUMMARY

[0005] In order to solve the above problems, the present application provides a low-sugar and low-salt egg yolk frozen gelation inhibition method, which uses sugar alcohol and sodium chloride to treat egg yolk, supplemented by low-temperature pre-freezing and water bath heating thawing process, to reduce the gelation of egg yolk during freezing.

[0006] The present application provides a low-sugar and low-salt egg yolk frozen gelation inhibition method, comprising the following steps:

[0007] (1) Egg yolk separation: fresh eggs are washed, the shell is broken, the egg white and egg yolk are separated, the egg yolk is collected, the yolk membrane is pierced, and the mixture is mixed to obtain fresh egg yolk liquid;

[0008] (2) Sugar alcohol and salt compounding: adding 0.5-4% sugar alcohol and 0-4% salt to the egg yolk liquid relative to the mass of the egg yolk, and mixing;

[0009] (3) Pre-freezing: placing the egg yolk liquid into -40℃ for pre-freezing for 0-6 days;

[0010] (4) Freezing: subsequently placing into -18℃ for freezing treatment;

[0011] (5) Thawing: thawing the egg yolk liquid after freezing treatment at 30-60℃.

[0012] In an embodiment of the present application, step (3) can be omitted.

[0013] In an embodiment of the present application, the sugar alcohol includes any one or more of erythritol, xylitol, mannitol, and maltitol. Preferably, the sugar alcohol is erythritol.

[0014] In an embodiment of the present application, the added amount of the sugar alcohol is 1-4% of the mass of the egg yolk. Specifically, 2% can be selected.

[0015] In an embodiment of the present application, the salt is sodium chloride.

[0016] In an embodiment of the present application, the added amount of the salt is 0.5-4% of the mass of the egg yolk. Specifically, 2% can be selected.

[0017] In an embodiment of the present application, the pre-freezing condition is pre-freezing at -40℃ for 1-6 days. Specifically, 3 days can be selected.

[0018] In an embodiment of the present application, the freezing condition is freezing at -18℃ for 7-90 days.

[0019] In an embodiment of the present application, the thawing condition is thawing by heating to 30-60℃ for 20-40 minutes. Specifically, heating at 50℃ for 30 minutes can be selected.

[0020] The present application also provides a low-sugar and low-salt frozen egg yolk liquid product resistant to frozen storage, and a preparation method thereof, which comprises:

[0021] (1) Egg yolk separation: washing fresh eggs, breaking the shells, separating the egg white and egg yolk, collecting the egg yolk, puncturing the vitelline membrane, mixing, and obtaining fresh egg yolk liquid;

[0022] (2) Sugar alcohol and salt compounding: adding 0.5-4% sugar alcohol and 0-4% salt to the egg yolk liquid relative to the mass of the egg yolk, and mixing;

[0023] (3) Pre-freezing: placing the egg yolk liquid into -40℃ for pre-freezing for 0-6 days;

[0024] (4) Freezing: Subsequently, freezing treatment is performed at -18°C.

[0025] (5) Thawing: The egg yolk liquid after freezing treatment is thawed at 30-60°C.

[0026] The application also provides the use of the above method in inhibiting the freezing gelation of egg yolk.

[0027] The application also provides the use of the above frozen egg yolk liquid product in preparing egg yolk products, health foods or functional foods.

[0028] The application has the following beneficial effects:

[0029] (1) The application provides a method for inhibiting the freezing gelation of egg yolk with low sugar and low salt, which comprises the following steps: treating egg yolk by using a combination of sugar alcohol and sodium chloride, and then performing low-temperature pre-freezing and water bath heating thawing, so as to reduce the freezing gelation of egg yolk, and the consistency coefficient of the treated egg yolk is reduced by 94.5%.

[0030] (2) The addition of sugar alcohol in the application has the following advantages: 1) lower sweetness and heat than sucrose; 2) does not cause blood sugar to rise, which is beneficial to patients with diabetes and obesity; 3) not affected by microorganisms, does not produce acid, and does not cause tooth decay; 4) does not participate in browning reactions and does not undergo caramelization when heated.

[0031] (3) The application helps to solve the problem of freezing gelation of egg yolk, prolongs the storage time of liquid egg yolk, prevents it from spoiling, and at the same time reduces its gel strength and improves its flowability, so that it is easy to mix with other food raw materials in the processing process; the application minimizes the addition of sugar alcohol and sodium chloride, retains the original sensory characteristics of egg yolk, and also meets the demand of people for healthy food; the optimization of the pre-freezing and thawing process also minimizes the damage to the nutritional value and functional characteristics of egg yolk. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a comparison chart of the influence of different sugar alcohols on the flowability of egg yolk frozen gel.

[0033] Figure 2 It is a comparison chart of the influence of different pre-freezing and thawing combinations on the microstructure of egg yolk frozen gel.

[0034] Figure 3 It is a comparison chart of the macro influence of different combinations of sugar alcohol and salt on egg yolk frozen gel. DETAILED DESCRIPTION

[0035] The preferred embodiments of the application are described below, and it should be understood that the embodiments are used to better explain the application and are not used to limit the application.

[0036] 1. Measurement of flow properties

[0037] 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.

[0038] The flowability of the samples was determined using the steady shear mode of the rheometer. The shear rate was set to 0.1 s -1 ~ 100 s -1 The resulting curve of apparent viscosity versus shear rate was fitted by the power law equation (1):

[0039] η = K x ε n-1

[0040] wherein 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.

[0041] 2. Determination of gel strength

[0042] The gel strength of the frozen egg yolk liquid samples was determined using a TPA texture analyzer for a penetration test. A flat bottom probe (P / 5) was used to test a 5 g sample stored in a 10 mL beaker. The test parameters were as follows: pre-test speed, test speed, and post-test speed were all 2.0 mm / s, the penetration distance was 5 mm, and the trigger force was 5 g.

[0043] Example 1

[0044] (1) Egg yolk separation: fresh eggs were washed, the shells were broken, and the egg white and egg yolk were separated, the egg white was discarded, the egg yolk was placed on a water-absorbing paper and rolled back and forth to remove excess egg white, the yolk membrane was pierced, and the egg yolk was collected and stirred until uniform for use;

[0045] (2) 2% erythritol was added to the egg yolk liquid collected in step (1) and stirred until uniform;

[0046] (3) 2% sodium chloride was added to the egg yolk liquid obtained in step (2) and stirred until uniform;

[0047] (4) The egg yolk liquid obtained in step (3) was placed in a -40 °C refrigerator for pre-freezing for 3 days;

[0048] (5) The frozen egg yolk liquid obtained in step (4) was stored in a -18 °C refrigerator for 7 days;

[0049] (6) The frozen egg yolk liquid obtained in step (5) was quickly taken out and placed in a water bath at 50 °C for thawing for 30 minutes.

[0050] Example 2

[0051] Step (3) in Example 1 was omitted, and other conditions or parameters were consistent with Example 1:

[0052] (1) Egg yolk separation: Fresh eggs were washed, the shells were broken, and the egg white and egg yolk were separated, the egg white was discarded, the egg yolk was placed on the water-absorbing paper and rolled back and forth to remove the excess egg white, the yolk membrane was pierced, and the egg yolk was collected and stirred until uniform for use;

[0053] (2) 2% erythritol was added to the egg yolk liquid collected in step (1) and stirred uniformly;

[0054] (3) The egg yolk liquid treated in step (2) was placed in a -40°C refrigerator for pre-freezing for 3 days;

[0055] (4) The frozen egg yolk liquid obtained in step (3) was stored in a -18°C refrigerator for 7 days;

[0056] (5) The frozen egg yolk liquid obtained in step (4) was quickly taken out and placed in a water bath at 50°C for thawing for 30 minutes.

[0057] Example 3

[0058] Step (4) in Example 1 was omitted, and other conditions or parameters were consistent with Example 1:

[0059] (1) Egg yolk separation: Fresh eggs were washed, the shells were broken, and the egg white and egg yolk were separated, the egg white was discarded, the egg yolk was placed on the water-absorbing paper and rolled back and forth to remove the excess egg white, the yolk membrane was pierced, and the egg yolk was collected and stirred until uniform for use;

[0060] (2) 2% erythritol was added to the egg yolk liquid collected in step (1) and stirred uniformly;

[0061] (3) 2% sodium chloride was added to the egg yolk liquid treated in step (2) and stirred uniformly;

[0062] (4) The frozen egg yolk liquid obtained in step (3) was stored in a -18°C refrigerator for 7 days;

[0063] (5) The frozen egg yolk liquid obtained in step (4) was quickly taken out and placed in a water bath at 50°C for thawing for 30 minutes.

[0064] Example 4

[0065] Steps (3) and (4) in Example 1 were omitted, and other conditions or parameters were consistent with Example 1:

[0066] (1) Egg yolk separation: Fresh eggs were washed, the shells were broken, and the egg white and egg yolk were separated, the egg white was discarded, the egg yolk was placed on the water-absorbing paper and rolled back and forth to remove the excess egg white, the yolk membrane was pierced, and the egg yolk was collected and stirred until uniform for use;

[0067] (2) Add 2% erythritol to the egg yolk liquid collected in step (1) and stir evenly;

[0068] (3) Place the frozen egg yolk liquid obtained in step (2) in a -18°C refrigerator for storage for 7 days;

[0069] (4) Quickly take out the frozen egg yolk liquid obtained in step (3) and place it in a water bath at 50°C for thawing for 30 minutes.

[0070] Example 5

[0071] Step (3) in Example 1 is omitted, and the step of placing in a water bath at 50°C for thawing for 30 minutes in step (6) is replaced by placing in air at room temperature 25°C for thawing for 120 minutes. Other conditions or parameters are consistent with Example 1:

[0072] (1) Egg yolk separation: Take fresh eggs, wash them, break the shells, separate the egg white and egg yolk, discard the egg white, roll the egg yolk on the water-absorbing paper back and forth to remove excess egg white, prick the yolk membrane, collect the egg yolk and stir until uniform for use;

[0073] (2) Add 2% erythritol to the egg yolk liquid collected in step (1) and stir evenly;

[0074] (3) Place the egg yolk liquid obtained by processing in step (2) in a -40°C refrigerator for pre-freezing for 3 days;

[0075] (4) Place the frozen egg yolk liquid obtained in step (3) in a -18°C refrigerator for storage for 7 days;

[0076] (5) Quickly take out the frozen egg yolk liquid obtained in step (4) and place it in air at room temperature 25°C for thawing for 120 minutes.

[0077] Example 6

[0078] Step (3) and (4) in Example 1 are omitted, and the step of placing in a water bath at 50°C for thawing for 30 minutes in step (6) is replaced by placing in air at room temperature 25°C for thawing for 120 minutes. Other conditions or parameters are consistent with Example 5:

[0079] (1) Egg yolk separation: Take fresh eggs, wash them, break the shells, separate the egg white and egg yolk, discard the egg white, roll the egg yolk on the water-absorbing paper back and forth to remove excess egg white, prick the yolk membrane, collect the egg yolk and stir until uniform for use;

[0080] (2) Add 2% erythritol to the egg yolk liquid collected in step (1) and stir evenly;

[0081] (3) Place the frozen egg yolk liquid obtained in step (2) in a -18°C refrigerator for storage for 7 days;

[0082] (4) The frozen yolk liquid obtained in step (3) is quickly taken out and placed in air at room temperature of 25°C for thawing for 120 minutes.

[0083] The flow and gel strength of the yolk liquid obtained in Examples 1-6 were tested, and the results are shown in Table 1.

[0084] Table 1 Flow and gel strength of the yolk liquid obtained after thawing in Examples 1-6

[0085]

[0086] As shown in Table 1, comparative analysis of Examples 2, 4, 5, and 6 shows that pre-freezing at -40°C for 3 days and heating thawing in a water bath at 50°C both help to reduce the frozen gelation of yolk, with the consistency coefficient reduced by 22.9% and 65.4%, respectively. In relative terms, the inhibitory effect of heating thawing in a water bath at 50°C is better. Both can act together in the freezing and thawing system of yolk to reduce the frozen gelation of yolk, with the consistency coefficient reduced by 76.3% and the gel strength reduced by 65.5%.

[0087] Comparing Example 1 with Examples 2 and 3 shows that erythritol can still play a role in inhibiting the frozen gel of yolk after pre-freezing at -40°C, but adding sodium chloride is not conducive to the inhibition of gel when pre-freezing at -40°C. When yolk is not pre-frozen at -40°C but directly frozen at -18°C, adding sodium chloride can significantly inhibit the frozen gelation of yolk liquid. In summary, Example 3 has the best inhibitory effect on the frozen gel of yolk, with the consistency coefficient reduced by 94.5% compared with the conventional yolk freezing process.

[0088] Comparative Example 1:

[0089] Preparation of fresh yolk: Fresh eggs were washed, the shells were broken, and the egg white and yolk were separated, with the egg white discarded. The yolk was rolled on absorbent paper to remove excess egg white, the yolk membrane was punctured, and the yolk was collected and stirred until uniform for use. The relevant performance indicators of the yolk liquid were determined, and the results are shown below.

[0090]

[0091]

[0092] Comparative Example 2:

[0093] Referring to Example 6, step (2) was omitted:

[0094] (1) Yolk separation: Fresh eggs were washed, the shells were broken, and the egg white and yolk were separated, with the egg white discarded. The yolk was rolled on absorbent paper to remove excess egg white, the yolk membrane was punctured, and the yolk was collected and stirred until uniform for use;

[0095] (2) The frozen yolk liquid obtained in step (1) was stored in a refrigerator at -18°C for 7 days;

[0096] (3) The frozen yolk liquid obtained in step (2) was taken out and thawed in air at room temperature for 120 minutes. The relevant performance indicators of the yolk liquid were determined, and the results are shown below:

[0097]

[0098] Comparative Example 3:

[0099] Referring to Example 6, 2% erythritol in step (2) was replaced by 2% xylitol, 2% mannitol and 2% maltitol, respectively. Other conditions or parameters were consistent with Example 6.

[0100] The flow conditions and gel strength of the obtained frozen yolk liquid are shown in Table 2:

[0101] Table 2 Effect of adding different sugar alcohols on the flow conditions and gel strength of the frozen yolk liquid

[0102]

[0103] As shown in Table 2, the smaller the molecular weight of the added sugar alcohol, the smaller the consistency coefficient of the frozen yolk liquid, the larger the flow index, and the smaller the gel strength. Compared with the sample without added sugar alcohol, the sample with added erythritol has a K value reduced by 53%, an n value increased by 123%, and a gel strength reduced by 44.5%. Among the four samples with added sugar alcohol, it has the lowest consistency, gel strength and the highest flowability. The experiment proves that small molecule sugar alcohol can more effectively inhibit ice crystal formation, reduce the degree of protein denaturation, and weaken the crosslinking between protein molecules.

[0104] Comparative Example 4:

[0105] Referring to Comparative Example 2, the yolk liquid was pre-frozen in a refrigerator at -40°C for 1-6 days before step (2). Other conditions or parameters were consistent with Comparative Example 2.

[0106] The flow conditions and gel strength of the obtained frozen yolk liquid are shown in Table 3:

[0107] Table 3 Effect of different pre-freezing times on the flow conditions and gel strength of the frozen yolk liquid

[0108]

[0109]

[0110] As shown in Table 3, initially, as the pre-freezing time is prolonged, the consistency coefficient of the frozen yolk liquid sample continuously decreases, and the flow index continuously increases, to some extent, reducing the formation of gel. However, the frozen yolk liquid samples pre-frozen for 3 days, 4 days, 5 days and 6 days have similar fluidity. The test of gel strength also reflects the similar law. The experiment proves that the pre-freezing process can indeed improve the fluidity of the frozen yolk liquid. Low temperature is conducive to the rapid formation of small ice crystals, reduces the formation of large ice crystals, is conducive to the protection of the structure of proteins, reduces the protein aggregation phenomenon, and pre-freezing for 3 days has a higher cost performance, reduces energy consumption, and has a better effect of inhibiting the freezing gelation of yolk.

[0111] Comparative Example 5:

[0112] Referring to Comparative Example 2, the air normal temperature thawing in step (3) is replaced by water bath heating thawing, and the thawing temperature is 20-60°C, and the water bath thawing time is 30 minutes. Other conditions or parameters are consistent with Example 1.

[0113] The flow condition and gel strength of the obtained frozen yolk liquid are shown in Table 3:

[0114] Table 4 Effect of different water bath heating thawing temperatures on the flow condition and gel strength of the frozen yolk liquid

[0115]

[0116] As shown in Table 4, the frozen yolk liquid thawed in a water bath at 20°C has better fluidity than that thawed in air at normal temperature, which may be due to the higher heat conduction efficiency of water bath thawing and the faster thawing rate, reducing the damage of the secondary crystallization of ice crystals to the protein structure during the melting process. With the increase of the thawing temperature, the fluidity of the frozen yolk liquid shows a trend of first increasing and then decreasing. It is speculated that at a higher temperature, the yolk protein denatures, the protein aggregates, and a gel network is formed, thereby enhancing the gel strength, and thus reducing the fluidity. The experimental results prove that when the thawing temperature increases from 40°C to 50°C, the consistency coefficient and the gel strength of the frozen yolk continuously decrease, and when the thawing temperature increases from 50°C to 60°C, the viscosity of the frozen yolk liquid begins to increase. Therefore, it is considered that the comprehensive effect of heating thawing at 50°C is the best. Compared with the sample without heating thawing, the consistency coefficient of the frozen yolk liquid thawed at 50°C decreases by 42.9%, the flow index increases by 133%, and the fluidity is the best.

[0117] The above provided examples are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order. Those skilled in the art make obvious improvements to the present application in combination with the existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. A method for inhibiting the freezing gelation of low-sugar and low-salt egg yolk, comprising the following steps: (1) Egg yolk separation: Fresh eggs are washed, the shells are broken, the egg white and egg yolk are separated, the egg white is discarded, the egg yolk is placed on the water absorption paper and rolled back and forth to remove excess egg white, the yolk membrane is pierced, and the egg yolk is collected and stirred until uniform for standby; (2) Adding 2% erythritol to the egg yolk liquid collected in step (1) and stirring uniformly; (3) Adding 2% sodium chloride to the egg yolk liquid obtained in step (2) and stirring uniformly; (4) Placing the frozen egg yolk liquid obtained in step (3) in a -18℃ refrigerator for storage for 7 days; (5) Quickly taking out the frozen egg yolk liquid obtained in step (4) and placing it in a water bath at 50℃ for heating and thawing for 30 minutes.

2. A low-sugar, low-salt and freeze-tolerant frozen yolk liquid product, characterized in that, The preparation method comprises the following steps: (1) Egg yolk separation: Fresh eggs are washed, the shells are broken, the egg white and egg yolk are separated, the egg white is discarded, the egg yolk is placed on the water absorption paper and rolled back and forth to remove excess egg white, the yolk membrane is pierced, and the egg yolk is collected and stirred until uniform for standby; (2) Adding 2% erythritol to the egg yolk liquid collected in step (1) and stirring uniformly; (3) Adding 2% sodium chloride to the egg yolk liquid obtained in step (2) and stirring uniformly; (4) Placing the frozen egg yolk liquid obtained in step (3) in a -18℃ refrigerator for storage for 7 days; (5) Quickly taking out the frozen egg yolk liquid obtained in step (4) and placing it in a water bath at 50℃ for heating and thawing for 30 minutes.

3. Use of the low-sugar and low-salt frozen egg yolk liquid product of claim 2 in the preparation of egg yolk food and health food.

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