A composite color-protecting agent for green vegetables in pre-prepared dishes

Abstract

The application discloses a composite color protection agent for protecting green vegetables in prefabricated dishes, which is prepared from the following raw materials in percentage by mass: green tea extract 50-60%, calcium ascorbate 6-12%, sodium citrate 16-28%, D-sodium isoascorbate 7-15%, and sodium chloride 0.5-3%, wherein the sum of the percentage by mass of the raw materials is 100%. The application selects the green tea extract, the calcium ascorbate, the sodium citrate, the D-sodium isoascorbate and the sodium chloride, and controls the adding amount of the raw materials, so that the synergistic effect can be fully exerted, and the green vegetables in the prefabricated dishes have obvious color protection effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of green vegetable color protection, and in particular, the present application relates to a composite color protection agent for green vegetable color protection in pre-prepared dishes. BACKGROUND

[0002] Pre-prepared dishes, also known as semi-finished dishes, are products or semi-finished products made by pre-processing of agricultural, livestock, poultry, and aquatic products with various auxiliary materials. For consumers, pre-prepared dishes can become a finished dish after simple cooking, which is simple and convenient, so more and more consumers start to choose pre-prepared dishes. The development of pre-prepared dishes has also evolved from the initial quick-frozen rice and noodles to pre-prepared dishes, and the product category development shows a trend of diversification. Among them, vegetables are an indispensable food material in the production of Chinese fast food and group meal catering products, and they are rich in minerals, vitamins and pigments, and are essential for a balanced diet. It has been proven that they can help alleviate cardiovascular disease, chronic disease, neurodegenerative disease, and certain types of cancer by reducing active oxygen and metal ion free radicals and changing the body's oxygen utilization. To some extent, the beneficial effects on diseases are due to the antioxidant substances in vegetables, including phenolic substances, flavonoids, beta-carotene, chlorophyll, and ascorbic acid.

[0003] However, due to the high-temperature blanching method used in the cooking and processing of vegetables, followed by heat storage or cold storage for preservation and transportation, the organization structure is damaged and the nutritional components are lost during the processing and preservation, resulting in yellowing of the color and seriously affecting the product quality and reducing the appetite of consumers.

[0004] Adding a color protection agent to pre-prepared dishes is a simple, efficient, and low-cost color protection method. Currently, during the heating and cooking process of vegetables, the cell structure and chlorophyll are damaged by heating and other factors, resulting in loss of the emerald green color of green vegetables and affecting the appearance. The reasons for these changes include enzymatic browning and non-enzymatic browning. Enzymatic browning not only causes color change and oxidative degradation, but also causes sensory and nutritional loss due to quinone condensation with other compounds; non-enzymatic browning is mainly catalyzed by the enzyme demetallized chlorophyll, which replaces magnesium ions in the porphyrin ring of chlorophyll a with hydrogen ions, forming demetallized chlorophyll (vegetables change from green to yellow). So far, blanching has been the most effective pretreatment method, which can reduce microbial load and destroy key enzymes that damage product quality. Most of the current domestic and foreign research on vegetable color protection is focused on fresh, cold, frozen, or canned vegetables, but there is little research on the color protection of pre-prepared dishes. With the rapid development of pre-prepared dish-related fields, it is particularly important to develop a color protection agent with safe ingredients and significant color protection effect. SUMMARY

[0005] The present application aims to provide a composite color protection agent for protecting the color of green vegetables in prepared dishes and having a significant color protection effect.

[0006] The present application aims to provide a composite color protection agent for protecting the color of green vegetables in prepared dishes and having a significant color protection effect.

[0007] The present application aims to provide a composite color protection agent for protecting the color of green vegetables in prepared dishes and having a significant color protection effect.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] In a first aspect,

[0010] The present application provides a composite color protection agent for protecting the color of green vegetables in prepared dishes, which is prepared from the following raw materials in the following mass percentages: green tea extract 50-60%, calcium ascorbate 6-12%, sodium citrate 16-28%, D-sodium isoascorbate 7-15%, and sodium chloride 0.5-3%, with the sum of the mass percentages of the raw materials being 100%.

[0011] As a preferred solution of the composite color protection agent, in the composite color protection agent, the mass percentages of the green tea extract, calcium ascorbate, sodium citrate, D-sodium isoascorbate, and sodium chloride are 55-60%, 8-10%, 18-22%, 8-14%, and 1-2%, respectively, and the sum of the mass percentages of the raw materials is 100%.

[0012] As a preferred solution of the composite color protection agent, in the composite color protection agent, the mass percentages of the green tea extract, calcium ascorbate, sodium citrate, D-sodium isoascorbate, and sodium chloride are 55-60%, 8-10%, 18-22%, 8-14%, and 1-2%, respectively, and the sum of the mass percentages of the raw materials is 100%.

[0013] The present application also provides a preparation method of the composite color protection agent, which comprises uniformly mixing the green tea extract, the calcium ascorbate, the sodium citrate, the D-sodium isoascorbate, and the sodium chloride.

[0014] In a second aspect,

[0015] The present application also provides a color protection liquid for protecting the color of green vegetables in prepared dishes, which is prepared by adding the composite color protection agent to water in an amount of 0.2-0.3 wt%.

[0016] In a third aspect,

[0017] The present application also provides an application of the composite color protection agent in protecting the color of green vegetables in prepared dishes, which comprises:

[0018] The composite color protection agent is added into water to prepare a color protection solution in an amount of 0.2-0.3 wt%;

[0019] After the green vegetables are pretreated, the green vegetables are soaked in the color protection solution.

[0020] In some embodiments, the pretreatment is blanching.

[0021] In a specific embodiment, the green vegetables are green peppers, the blanching temperature is 90℃, and the blanching time is 15s.

[0022] In some embodiments, the soaking temperature is 4℃, and the soaking time is 15min.

[0023] In some embodiments, the ratio of the green vegetables to the color protection solution is 1:5.

[0024] In some embodiments, the green vegetables include, but are not limited to, green peppers, beans, garlic sprouts, rape, spinach, cabbage, soybeans, asparagus lettuce, cucumbers, and the like.

[0025] In a fourth aspect, the embodiments of the present application also provide a method for protecting the color of green vegetables in a pre-prepared dish, which comprises the following steps:

[0026] S1: washing and cutting the green vegetables;

[0027] S2: blanching the green vegetables obtained in step S1, wherein when the green vegetables are green peppers, the blanching temperature is 90℃, and the blanching time is 15s;

[0028] S3: taking out the blanched vegetables in step S2, soaking the blanched vegetables in a 4℃ color protection solution for 15min, and then taking out and draining the blanched vegetables for standby.

[0029] The present application has the following advantages:

[0030] (1) The present application optimizes the components and the ratio of the color protection agent, selects green tea extract, calcium ascorbate, sodium citrate, D-sodium erythorbate, and sodium chloride, combines them, and controls the amount of addition, so that the synergistic effect can be fully played, and the green vegetables in the field of pre-prepared dishes have obvious color protection effect.

[0031] (2) The green tea extract, calcium ascorbate, sodium citrate, D-sodium erythorbate, and sodium chloride used in the present application do not contain chemical and irritating odor, and do not mask the unique aroma of the vegetables themselves; in addition, they also have certain preservation function, and after the color protection treatment, the vegetables themselves have almost no loss of aroma after being stored for a period of time through hot storage, cold storage, and freezing storage.

[0032] (3) The green tea extract, calcium ascorbate, sodium citrate, sodium D-isoascorbate and sodium chloride used in the present application are all food-grade additives, safe and non-toxic, and can ensure the safety of the prepared food products. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Color change of green pepper during storage at 4℃ for 21d for Example 2 and blank group (Comparative Example 12);

[0034] Figure 2 Color change of green pepper after sterilization at 121℃ for 20min for Example 1, Example 2 and Comparative Example 12;

[0035] Figure 3 Color change of green pepper after hot storage at 60℃ for 4h for Example 1, 2, 3 and Comparative Examples 7, 8, 9, 10, 11 and 12;

[0036] Figure 4 Color change of green pepper after thawing for 5min for Example 2 and Comparative Examples 5, 6 and 12 after frozen at -18℃ for 60d. DETAILED DESCRIPTION

[0037] Some color protection agents are also reported in the related art. For example, Yu YJ et al. explored the effects of sodium bicarbonate concentration, calcium ascorbate concentration and blanching time on the color of green leafy vegetables through single-factor experiments, and solved the problem of yellowing and softening of green leafy vegetables in catering foods under high temperature (≥60℃) through optimization of process and raw materials. Zhou X et al. optimized the color protection pretreatment conditions of quick-frozen sweet beans through response surface experiments. The optimized pretreatment conditions were: calcium chloride concentration of 0.636g / L, sodium bicarbonate concentration of 0.534g / L and blanching for 45s, and the sensory score of sweet beans could reach 8.59. Within 60d of frozen storage, the color and appearance of sweet beans were maintained in a relatively optimal range. In addition, the fruit and vegetable color protection agent (copper lactate and zinc lactate) studied by Shen WR et al. and the bamboo leaf color protection liquid (sodium copper chlorophyll and zinc chloride) studied by Chen YQ et al. could achieve good color protection effect. Liu SX et al. pointed out after studying the green protection of green pepper soft cans that: using Cu 2+ solution to soak green peppers for 22h at pH 7.0, or using Zn 2+ solution to soak green peppers for 22h at pH 8.0, the green color of the products was well maintained.

[0038] The embodiment of the present application provides a composite color protection agent for protecting green vegetables in pre-prepared dishes, which is prepared from the following raw materials in mass percentage: green tea extract 50-60%, calcium ascorbate 6-12%, sodium citrate 16-28%, D-sodium isoascorbate 7-15%, and sodium chloride 0.5-3%, and the sum of the mass percentages of the raw materials is 100%.

[0039] In the formula of the composite color protection agent, the mass percentage of the green tea extract can be 50%, 52%, 54%, 55%, 58%, 60%, etc., the mass percentage of the calcium ascorbate can be 6%, 8%, 9%, 10%, 11%, 12%, etc., the mass percentage of the sodium citrate can be 16%, 18%, 19%, 22%, 24%, 28%, etc., the mass percentage of the D-sodium isoascorbate can be 7%, 8%, 9%, 10%, 12%, 15%, etc., and the mass percentage of the sodium chloride can be 0.5%, 1%, 1.5%, 2%, 3%, etc.

[0040] The embodiment of the present application creatively selects the components and the ratio of the color protection agent, and the components work in coordination, the color protection effect is stronger, and the original color of the vegetables can be maintained for a longer time.

[0041] The green tea extract in the present application is a natural nutrient substance with wide application value. The green tea extract is an active ingredient extracted from tea leaves, mainly including tea polyphenols, vitamins and theanine, etc. These components are widely considered to have strong antioxidant effect, can scavenge free radicals, inhibit the occurrence of oxidation reaction, and slow down the cell aging process. As an excellent antioxidant, tea polyphenols can scavenge free radicals, and can complex with proteins to make the protein structure relatively stable and not easy to degrade, so that the combination of chlorophyll and protein is more stable, and the green color of the vegetables is maintained. Meanwhile, the green tea extract can also inhibit the reproduction of bacteria, and prevent the natural pigment from fading due to photo-oxidation, so as to inhibit the enzymatic browning of the vegetables.

[0042] The calcium ascorbate can effectively inhibit the increase of the weight loss rate of the vegetables during storage, delay the degradation of chlorophyll, vitamin C (V C ), soluble solids (TSS) and total phenols (TP), maintain the hardness value and color value, reduce the activity of polyphenol oxidase (PPO) and peroxidase (POD), and inhibit the growth of microorganisms, effectively maintain the sensory quality of the vegetables, and also inhibit the enzymatic browning of the vegetables.

[0043] Sodium citrate is the most important citrate at present, which is mainly produced by neutralizing the citric acid generated by fermentation of starch materials with alkali materials, and has many excellent properties: (1) biodegradability. After being diluted by a large amount of water in nature, part of the sodium citrate becomes citric acid, and both of them coexist in the same system. Citric acid is easily biodegraded in water by oxygen, heat, light, bacteria and microorganisms. (2) metal ion complexing ability. Sodium citrate has good complexing ability to Ca 2+ , Mg 2+ and other metal ions, and also has good complexing ability to other metal ions such as Fe 2+ . Thus, the occurrence of chlorophyll (green) porphyrin reaction of removing one Mg 2+ to generate demagnesium chlorophyll and pyro-demagnesium chlorophyll (brown) can be delayed, thereby achieving the effect of inhibiting non-enzymatic browning of vegetables. In addition, its safety, non-toxicity and biodegradability also indicate the safety and reliability of the color protection agent composition.

[0044] D-sodium isoascorbate can inhibit the activity of polyphenol oxidase, and can be used for storage of vegetables. It has a synergistic effect when used with citric acid and citrate, and can increase the antioxidant effect and inhibit the enzymatic browning of fruits and vegetables caused by polyphenol oxidase.

[0045] Sodium chloride is a common salt, which can not only be used for seasoning, but also can be used for protecting the color of food. In the process of food processing, sodium chloride can play a role in color protection, making the color of food more bright and beautiful. The color protection principle of sodium chloride is as follows: the sodium ions in sodium chloride can combine with the negative charge part of the pigment molecules in food to form a stable complex. This complex can prevent the pigment molecules from being further affected by factors such as oxidation and light, thereby protecting the color of food. The presence of sodium chloride can also inhibit non-enzymatic browning of vegetables and prevent fading of color.

[0046] The color protection agent prepared in the present application has stronger color protection effect than other existing color protection materials on the market, and the original color of the vegetables can be maintained for a longer time, which has important value for the color protection of vegetables in the field of pre-prepared dishes. In addition, the components in the color protection agent composition that inhibit enzymatic browning, such as green tea extract, calcium ascorbate and D-sodium isoascorbate, and the components that inhibit non-enzymatic browning, such as sodium citrate and sodium chloride, can have a synergistic effect, and the color protection effect of the vegetables can be optimized.

[0047] The embodiments of the present application will be described in detail below, and the embodiments described below are exemplary and are intended to explain the present application, but cannot be understood as a limitation of the present application.

[0048] The raw materials and reagents used in the following examples are commercially available or can be prepared by known methods unless otherwise stated.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art.

[0050] In this text, the term "comprising", "including" is an open expression, that is, including the content indicated by the present application, but not excluding other aspects.

[0051] In this text, in the case of describing the value as a range, it should be understood that this disclosure includes the disclosure of all possible sub-ranges within the range, and the specific numerical values falling within the range, regardless of whether the specific numerical values or specific sub-ranges are explicitly indicated.

[0052] The following are specific examples and comparative examples of the present application, it is further pointed out that the following comparative examples are not prior art, only for comparison with the scheme of the example, not as a limitation of the present application.

[0053] In the examples and comparative examples of the present application, green tea extract is purchased from Shandong Guishuo Biological Technology Co., Ltd.; calcium ascorbate is purchased from Shandong Qilu Biological Technology Co., Ltd.; sodium citrate is purchased from Shandong Qilu Biological Technology Co., Ltd.; D-sodium erythorbate is purchased from Shandong Qilu Biological Technology Co., Ltd.; sodium chloride is purchased from Guangdong Hongyuan Food Ingredients Co., Ltd.; experimental vegetables are purchased from Tianjin Dongli Huarun Wanjia Supermarket.

[0054] Example 1

[0055] A preparation method of a composite color protection agent, comprising the following steps:

[0056] Green tea extract 580g, calcium ascorbate 100g, sodium citrate 220g, D-sodium erythorbate 90g, sodium chloride 10g, are mixed uniformly to prepare a composite color protection agent.

[0057] Example 2

[0058] A preparation method of a composite color protection agent, comprising the following steps:

[0059] Green tea extract 600g, calcium ascorbate 80g, sodium citrate 200g, D-sodium erythorbate 100g, sodium chloride 20g, are mixed uniformly to prepare a composite color protection agent.

[0060] Example 3

[0061] A preparation method of a composite color protection agent, comprising the following steps:

[0062] Green tea extract 570g, calcium ascorbate 90g, sodium citrate 190g, sodium D-isoascorbate 135g, sodium chloride 15g are mixed uniformly to prepare a composite color protection agent.

[0063] Comparative Example 1

[0064] A method for preparing a composite color protection agent, comprising the following steps:

[0065] Green tea extract 480g, calcium ascorbate 100g, sodium citrate 400g, sodium chloride 20g are mixed uniformly to prepare a composite color protection agent.

[0066] Comparative Example 2

[0067] A method for preparing a composite color protection agent, comprising the following steps:

[0068] Green tea extract 510g, calcium ascorbate 110g, sodium D-isoascorbate 355g, sodium chloride 25g are mixed uniformly to prepare a composite color protection agent.

[0069] Comparative Example 3

[0070] A method for preparing a composite color protection agent, comprising the following steps:

[0071] Green tea extract 540g, calcium ascorbate 120g, sodium citrate 340g are mixed uniformly to prepare a composite color protection agent.

[0072] Comparative Example 4

[0073] A method for preparing a composite color protection agent, comprising the following steps:

[0074] Green tea extract 520g, calcium ascorbate 100g, sodium D-isoascorbate 380g are mixed uniformly to prepare a composite color protection agent.

[0075] Comparative Example 5

[0076] A method for preparing a composite color protection agent, comprising the following steps:

[0077] Green tea extract 150g, calcium ascorbate 300g, sodium citrate 400g, sodium D-isoascorbate 100g, sodium chloride 50g are mixed uniformly to prepare a composite color protection agent.

[0078] Comparative Example 6

[0079] A method for preparing a composite color protection agent, comprising the following steps:

[0080] Green tea extract 200g, calcium ascorbate 200g, sodium citrate 450g, sodium D-isoascorbate 50g, sodium chloride 100g are mixed uniformly to prepare a composite color protection agent.

[0081] Comparative Example 7: Green tea extract.

[0082] Comparative Example 8: Calcium ascorbate.

[0083] Comparative Example 9: Sodium citrate.

[0084] Comparative Example 10: Sodium D-erythorbate.

[0085] Comparative Example 11: Sodium chloride.

[0086] Comparative Example 12: Blank group.

[0087] Comparative Example 13: Fried dishes.

[0088] Application

[0089] The green pepper with high use frequency and obvious color change in the pre-prepared dish cooking package is selected as the experimental vegetable raw material in the embodiment of the application.

[0090] The color protection agent is added into water in an amount of 0.2% to prepare a color protection liquid;

[0091] The green pepper is prepared into a pre-prepared dish cooking package according to the process of cleaning and cutting → blanching → color protection agent soaking → taking out and draining water → frying dishes according to the process → packaging and storage. The blanching is used as a main means for processing vegetables, and the blanching can play a role in enzyme inactivation and sterilization, so as to prevent discoloration, taste change and nutrient loss in the subsequent processing process. The blanching temperature and time are also key factors affecting the color of vegetables. If the blanching temperature is too high, the chlorophyll in the tissue cells will be converted into de-magnesium chlorophyll, and the discoloration of vegetables will be aggravated. If the blanching time is too long, the vegetable cell tissue will be damaged and become soft, and the release of organic acid in the cells will accelerate the de-magnesium reaction of chlorophyll and reduce the content of chlorophyll. Therefore, the blanching temperature of the green pepper should not be too high, and the blanching time should not be too long.

[0092] The specific application steps of the embodiment of the application are as follows:

[0093] S1: Clean the green pepper, remove the green pepper stem, and cut the green pepper into small pieces for standby; at the same time, prepare the pork tenderloin, cut it into pieces for standby;

[0094] S2: Prepare water in a pot, and when the water temperature in the pot is 90℃, add the green pepper pieces for blanching, and take out the green pepper pieces after blanching for 15s;

[0095] S3: Immediately pour the taken-out green pepper pieces into the 4℃ color protection liquid prepared in advance for color protection; the soaking time is 15min, and the solid-liquid ratio (vegetable: water = 1:5);

[0096] S4: Take out and drain water for standby;

[0097] S5: Add appropriate amount of oil (about 10 ml) in the pot, add 5g of green onion, 5g of garlic and stir-fry for 10s, add pork tenderloin (about 100g) and stir-fry for 4min, add 3g of cooking wine, 3g of cooking oil, then add green pepper pieces (about 150g), stir-fry for 1min, then take out the dishes;

[0098] S6: The taken-out dishes are stored under different conditions respectively.

[0099] Newly fried dishes: the specific steps are:

[0100] S1: Wash the green pepper clean, remove the stem and cut it into small pieces for standby; At the same time, prepare pork tenderloin and cut it into pieces for standby;

[0101] S2: Prepare water in the pot, and when the water temperature in the pot reaches 90℃, add green pepper pieces and blanch for 15s, then take out;

[0102] S3: Drain and reserve;

[0103] S4: Add appropriate amount of oil (about 10 ml) in the pot, add 5g of green onion, 5g of garlic and stir-fry for 10s, add pork tenderloin (about 100g) and stir-fry for 4min, add 3g of cooking wine, 3g of cooking oil, then add green pepper pieces (about 150g), stir-fry for 1min, then take out the dishes;

[0104] S5: Put the taken-out dishes on the plate.

[0105] The storage methods of green pepper stir-fried pork products at 60℃ hot storage for 4h, -18℃ frozen for 60d, 4℃ cold storage for 21d, and 121℃ sterilization for 20min were used to detect the color protection effect of green pepper in the cooking bags of the examples and the comparative examples, respectively. The examples and the comparative examples were taken out at the specified time, and the newly fried dishes at the detection node were subjected to sensory evaluation. The results are shown in Tables 3-1, 3-2, 3-3, 3-4, etc. At the same time, the color of green pepper was tested. The color change degree was evaluated by comparing the Lab values measured by color difference meter to judge the color protection effect of the color protection agent. The results are shown in Tables 4-1, 4-2, 4-4, 4-4. The color change graphs of green pepper of some examples and comparative examples are shown in Figures 1-4

[0106] Table 1 Formulation ingredients and contents of the compound color protection agent in the examples and the comparative examples

[0107]

[0108] Table 2 Sensory evaluation standard of color protection effect

[0109]

[0110] ​

[0111] Table 3 - Color protection effect of each example and comparative example after 4h hot storage at 160C

[0112]

[0113]

[0114] Table 3 - Color protection effect of each example and comparative example after 21d cold storage at 24C

[0115]

[0116] Table 3 - Color protection effect of each example and comparative example after 60d frozen at -18C

[0117]

[0118]

[0119] Table 3 - Color protection effect of each example and comparative example after 20min sterilization at 121C

[0120]

[0121]

[0122] From Table 3-1, Table 3-2, Table 3-3 and Table 3-4, it can be seen that the green peppers treated with the composite color protection agent prepared in Example 1-3 showed good color protection effect after hot storage, cold storage, freezing and high temperature sterilization for a period of time, respectively, and the color score in sensory evaluation was above 80; under the four different storage conditions, the green color sensory score of Comparative Example 3 was higher than that of Comparative Example 4, followed by Comparative Example 2 and Comparative Example 1, and the green color sensory scores of Comparative Example 5 and Comparative Example 6 were significantly lower than those of Comparative Example 1, 2, 3 and 4. In addition, Comparative Example 12 (blank group) showed very low sensory score under the four storage conditions, indicating that if no color protection agent is added, the sensory quality of the vegetables will decrease significantly after high temperature sterilization, hot storage, cold storage and freezing. Comparative Example 13 is a dish made by simulating the family present, which is used as a standard sample for comparison with each example, and the result shows that the sensory score of Example 2 is closer to that of Comparative Example 13 (standard sample). This result shows that the composite color protection agent has good color protection effect, and the effective components have good synergistic effect, and only mixing several of them cannot achieve the best effect, and the addition ratio also has a significant effect on the color protection effect.

[0123] Table 4 - Color difference value data of each example and comparative example after 4h hot storage at 160C

[0124] L* value a* value b* value Example 1 32.54 -7.21 11.23 Example 2 32.72 -7.96 10.28 Example 3 32.15 -6.41 11.55 Comparative Example 1 30.12 -0.14 17.11 Comparative Example 2 30.32 -0.61 16.17 Comparative Example 3 30.16 -1.52 14.65 Comparative Example 4 30.25 -1.15 15.12 Comparative Example 5 28.73 0.12 18.13 Comparative Example 6 28.56 0.05 17.92 Comparative Example 7 25.24 2.03 25.45 Comparative Example 8 25.44 2.05 25.42 Comparative Example 9 25.31 2.03 25.47 Comparative Example 10 25.39 2.02 25.54 Comparative Example 11 25.47 2.06 25.36 Comparative Example 12 21.66 5.51 27.51 Comparative Example 13 35.21 -8.72 9.42

[0125] Table 4-2 Color difference data of each example and comparative example after 21 d of refrigeration at 24°C

[0126]

[0127]

[0128] Table 4-3 Color difference data of each example and comparative example after 60 d of refrigeration at 18°C

[0129]

[0130]

[0131] Table 4-4 Color difference data of each example and comparative example after 20 min of sterilization at 121°C

[0132] L* value a* value b* value Example 1 30.54 -6.42 11.22 Example 2 30.74 -6.97 10.17 Example 3 30.15 -6.22 11.45 Comparative Example 1 28.11 -0.21 17.22 Comparative Example 2 28.34 -0.55 16.11 Comparative Example 3 28.66 -1.03 14.41 Comparative Example 4 28.45 -0.85 15.03 Comparative Example 5 28.35 0.97 18.43 Comparative Example 6 28.57 0.25 17.82 Comparative Example 7 22.14 2.93 25.85 Comparative Example 8 22.25 2.96 25.82 Comparative Example 9 22.35 2.91 25.87 Comparative Example 10 22.38 2.82 25.84 Comparative Example 11 22.41 2.88 25.86 Comparative Example 12 19.35 6.43 31.57 Comparative Example 13 35.88 -8.77 9.51

[0133] As can be seen from Tables 4-1, 4-2, 4-3 and 4-4, the composite color protection agent prepared in Example 1-3 showed good color protection effect after the green peppers were treated and then stored under heat, refrigerated, frozen and high-temperature sterilized for a period of time. The color difference instrument measurement results are shown in the above tables. The L* value represents brightness, and the greater the L* value, the higher the brightness. The a* value represents the red-green color difference, and the smaller the a* value (a* < 0), the greener the color; the greater the a* value (a* > 0), the redder the color. The b* value represents the yellow-blue color difference, and the greater the b* value (b* > 0), the yellower the color; the smaller the b* value (b* < 0), the bluer the color. Under the four different storage conditions, the a* value of Comparative Example 3 was higher than that of Comparative Example 4, followed by Comparative Example 2 and Comparative Example 1, and the a* values of Comparative Examples 5 and 6 were significantly lower than those of Comparative Examples 1, 2, 3 and 4. In addition, Comparative Example 12 (blank group) showed very low a* values under the four storage conditions, indicating that if no color protection agent is added, the green color of the vegetables will decrease significantly after high-temperature sterilization, heat storage, refrigeration and freezing. Comparative Example 13 is a dish made by simulating home cooking, which is used as a standard sample for comparison with each example. The results show that the a* value of Example 2 is closer to that of Comparative Example 13 (standard sample). This result shows that the composite color protection agent has good color protection effect, and the effective components have good synergistic effect. Mixing only a few of them cannot achieve the optimal effect, and the addition ratio also has a significant impact on the color protection effect.

[0134] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the terminology "comprising" is used in the disclosure as comprising but not limited to, that is, it is open-ended and does not exclude the presence of additional features, structures, materials, or characteristics.

[0135] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above-described embodiments are exemplary, and are not to be interpreted as limiting the present disclosure, and the ordinary skilled in the art can make changes, modifications, replacements, and variations to the above-described embodiments within the scope of the present disclosure.

Claims

1. A color protection solution for use in the color protection of green vegetables in pre-prepared dishes, characterized in that, The color protection liquid is prepared by adding the composite color protection agent into water at an adding amount of 0.2-0.3wt%. The composite color protection agent is made of raw materials in the following mass percentages: green tea extract 55%-60%, calcium ascorbate 8%-10%, sodium citrate 18%-22%, sodium D-erythorbate 8%-14%, and sodium chloride 1%-2%, and the sum of the mass percentages of the raw materials is 100%.

2. The color protection solution for green vegetables in pre-prepared dishes according to claim 1, characterized in that, The composite color protection agent is made of raw materials in the following mass percentages: green tea extract 60%, calcium ascorbate 8%, sodium citrate 20%, sodium D-erythorbate 10%, and sodium chloride 2%. 3.The color protection solution for green vegetables in pre-prepared dishes according to claim 1 or 2, characterized in that, The composite color protection agent is prepared by uniformly mixing the green tea extract, the calcium ascorbate, the sodium citrate, the sodium D-erythorbate, and the sodium chloride.

4. Use of the color protection solution according to any one of claims 1 to 3 for the color protection of green vegetables in pre-prepared dishes, characterized in that, The method comprises the steps of: The green vegetables are pretreated and then soaked in the color protection liquid.

5. Use according to claim 4, characterized in that, The pretreatment is blanching treatment.

6. Use according to claim 4, characterized in that, The soaking treatment is performed at a temperature of 4°C for 15 minutes.

7. Use according to claim 4, characterized in that, The ratio of the green vegetables to the color protection liquid is 1:

5.

8. Use according to claim 4, characterized in that, The green vegetables are green peppers, beans, garlic sprouts, rape, spinach, cabbage, soybeans, asparagus lettuce, or cucumbers.

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