Preparation method of primary-color high-anthocyanin eggplant

Abstract

The invention relates to the technical field of eggplant manufacturing, in particular to a method for manufacturing primary-color high-anthocyanin eggplants, which comprises the following steps: selecting purple eggplants, cleaning, cutting into long strips, soaking the long-strip-shaped eggplants in a honey solution, and adding citric acid into the honey solution; preparing a color protection solution, adding an enzymolysis blocking agent into the color protection solution, and pouring the eggplants into the color protection solution for later use; preparing a soaking solution, soaking the eggplants in the soaking solution for 10 minutes, taking out the eggplants, performing vacuum packaging on the eggplants to obtain the primary-color high-anthocyanin eggplants, and performing cold storage. According to the method, color protection and synergism of the eggplants are achieved through a dual-targeting mechanism, meanwhile, nutrition preservation of the eggplants is achieved, synergistic repair of cell membranes in the eggplants is achieved through combination of ficin protease and bromelain, and triple-effect removal of fungi, bacteria and biological membranes of the eggplants is achieved through combination of natamycin and subtilin.

Description

Technical Field

[0001] The invention relates to the technical field of eggplant production, in particular to a method for producing original-color, high-anthocyanin eggplant. Background Art

[0002] Natural, high-anthocyanin eggplants are varieties with higher levels of anthocyanins and darker skin. Anthocyanins are natural plant pigments that give eggplant its purple or purplish-black appearance and are associated with a variety of health benefits.

[0003] Currently, eggplants are susceptible to oxidation during production, and lemon juice is often used to preserve their color. However, this does not prevent discoloration, resulting in the eggplants being prone to discoloration during production, diminishing their aesthetic appeal. Furthermore, anthocyanins within the eggplants are easily released after cell wall damage, which can also cause discoloration during production. Based on this, the present invention provides a method for producing primary-color, high-anthocyanin eggplants. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing original color, high anthocyanin eggplant. The method for preparing original color, high anthocyanin eggplant prepared by the present invention not only has good original color protection performance, but also can ensure a high anthocyanin retention rate of the eggplant, and at the same time has good antibacterial and antiseptic properties.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for producing original color, high anthocyanin eggplant, the method comprising the following steps: Step 1: Select purple eggplant, clean it, cut it into long strips, soak the long strips of eggplant in honey solution, add citric acid to the honey solution, wherein the weight ratio of honey solution to citric acid is 1:0.08, soak for 10-15 minutes. After the soaking time is completed, remove the eggplant and centrifuge it for 5 seconds and set aside; Step 2: Prepare a color-protecting solution and add an enzymatic blocker to the solution. Place the eggplants in the solution and soak at 25°C for 3-5 minutes. Remove the eggplants and set aside. Step 3: prepare a soaking solution, immerse the eggplant in the soaking solution for 10 minutes, take out the eggplant and vacuum-pack it to obtain original color, high anthocyanin eggplant, and store it in a refrigerator.

[0006] Preferably, the preparation method of the honey solution is: ascorbic acid solution and honey water are added into a stainless steel container at a molar ratio of 0.2:1 and mixed and stirred for 1 minute. The honey water is cold water with a temperature of 2°C-4°C, which can achieve a color protection effect on eggplant.

[0007] Preferably, the color-protecting solution consists of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid, with the remainder being water.

[0008] Preferably, the method for preparing the color-protecting solution comprises the following steps: Step 1: Take 1L of water, the water temperature is ≤40℃; Step 2: Prepare a base material, which includes 0.2g-0.6g of N-acetyl-L-lysine, 0.003g-0.009g of 4-hexylresorcinol, 3g-9g of β-cyclodextrin, 0.48g-1.44g of perillaldehyde, and 6g-18g of γ-polyglutamic acid; Step 3: Stir 0.48g-1.44g of perillaldehyde and 3g-9g of β-cyclodextrin at 40°C for 2 hours to form an inclusion complex, and add 0.2g-0.6g of N-acetyl-L-lysine, 0.003g-0.009g of 4-hexylresorcinol and 6g-18g of γ-polyglutamic acid in sequence, adjust the pH to 4.0-5.0 with citric acid, and store in the dark to obtain a color protection solution. The acetyl group in N-acetyl-L-lysine can block the ε-amino group of lysine, thereby blocking the cross-linking target of 4-HR and forming amino-blocking protection. At the same time, acetylation increases fat solubility and carries color protection ingredients deep into the peel cells, enhancing the color protection permeability during eggplant production and achieving a secondary color protection effect on eggplant.

[0009] Preferably, the mass ratio of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid is 1:0.015:15:2.5:30. N-acetyl-L-lysine chelates Cu²⁺ to weaken the activity of polyphenol oxidase, synergistically blocks the enzyme site of 4-HR, and further assists in enhancing the PPO inhibitory effect.

[0010] Preferably, the enzymatic blocker includes ficin and bromelain, and also includes a buffer and warm water. The preparation method of the enzymatic blocker is as follows: Step a: Prepare a buffer solution by taking 200 g of sodium dihydrogen phosphate and 800 g of disodium hydrogen phosphate, pouring them into 80 L of deionized water, stirring, and adjusting the pH value to 6.8 ± 0.1 to obtain a buffer solution; Step b: Pour 500 g of trehalose into the buffer solution and stir in a 40°C water bath until completely dissolved; Step c: Pour 50g of cysteine into 5L of warm water at 40°C and dissolve it. Mix it with the mixture prepared in step b. Pour 30g of ficin, 30g of bromelain and 100g of trehalose and premix them for 2 minutes. After premixing, slowly sprinkle the mixture onto the surface. Stir magnetically at a speed of 300rpm for 20 minutes. Step d: Filter through gauze to remove impurities and obtain an enzymatic blocker, which achieves color protection and enhancement of eggplant through a dual-targeting mechanism, while preserving the nutrition of eggplant and avoiding the amino acid damage problem caused by traditional eggplant production methods. Perillaldehyde can also delay the degradation of cyanidin-3-glucoside and increase the retention rate of anthocyanins.

[0011] Preferably, the mass ratio of the buffer solution to warm water is 1:400, and the mass ratio of ficin to bromelain is 1:1:2. Ficin activates superoxide dismutase to scavenge free radicals, thereby reducing the anthocyanin oxidation loss rate during eggplant production to below 5%, ensuring a high anthocyanin rate of the eggplant, and completely destroying PPO activity through dual-target enzymatic cleavage, while activating the cell defense system, further ensuring the freshness preservation effect of the eggplant.

[0012] Preferably, the soaking solution comprises nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin, and the mass ratio of nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin is 1:1.5:10:5:0.5:0.3.

[0013] Preferably, the preparation method of the soaking solution is as follows: Step 3.1: Encapsulation with perillaldehyde: 1.5 kg of perillaldehyde and 3 kg of β-cyclodextrin were stirred at 40° C. for 2 hours to obtain an inclusion complex; Step 3.2: Prepare the polysaccharide base solution by heating 800 L of deionized water to 45°C, adding 10 kg of γ-polyglutamic acid and 5 kg of pullulan, and stirring to dissolve; Step 3.3: 1 kg of nisin, 0.5 kg of natamycin and 0.3 kg of subtilisin are added in sequence, and then perillaldehyde inclusion complex, 5 kg of trehalose and 2 kg of citric acid are poured in, the pH is adjusted to 4.5, the volume is made up to 1000 L with deionized water, and high-pressure homogenization is performed at 20 MPa, which is repeated 3 times. The solution is filtered and sterilized to obtain a soaking solution. The combination of natamycin and subtilisin can achieve a triple-effect removal of fungi, bacteria and biofilms on eggplant. At the same time, the eggplant produced can be biodegraded to achieve no residue, so that the eggplant produced can achieve the three-in-one effect of antibacterial, antioxidant and moisturizing, thereby reducing the production cost.

[0014] Preferably, the vacuum packaging is to evacuate the eggplants soaked in the soaking solution to -0.09 MPa and refrigerate at 4°C. The combination of natamycin and nisin can improve the antibacterial rate of the eggplant during storage. Nisin forms holes by perforating the bacterial membrane, and natamycin enters through the holes and combines with fungal ergosterol to completely kill the bacteria, achieving dual killing of fungi and bacteria, so that the eggplant can be stored for 50 days.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, by setting a color protection solution, when N-acetyl-L-lysine and 4-hexylresorcinol act synergistically on eggplant, the acetyl group in N-acetyl-L-lysine can block the ε-amino group of lysine, thereby blocking the cross-linking target of 4-HR and forming amino blocking protection. At the same time, acetylation increases fat solubility and carries color protection ingredients deep into the peel cells, thereby enhancing the color protection penetration during eggplant production. N-acetyl-L-lysine chelates Cu²⁺ to weaken the activity of polyphenol oxidase, cooperates with the enzyme site blockade of 4-HR, and further It can help enhance the PPO inhibition effect, realize the color protection and enhancement of eggplant through a dual-target mechanism, and realize the nutritional preservation of eggplant at the same time, avoiding the amino acid damage problem caused by the traditional method of making eggplant. Perillaldehyde can delay the degradation of cyanidin-3-glucoside, improve the retention rate of anthocyanins, further block the effectiveness of enzymatic browning, and realize the delayed browning of eggplant. The combination of perillaldehyde and γ-polyglutamic acid can achieve the synergistic effect of antibacterial, moisturizing and disease resistance on eggplant, delay the shelf life of eggplant, and improve the ability to resist cold damage.

[0016] 2. In the present invention, by adding an enzymatic blocker to the color protection solution, the phenylalanine-glycine bond in ficin can destroy the hydrophobic pocket structure of the PPO active center and seal the microcracks in the eggplant cells. Bromelain is used to activate phospholipase A2, thereby accelerating membrane phospholipid reconstruction and achieving coordinated repair of the cell membrane in the eggplant. Bromelain promotes glutathione synthesis and can reduce the generated quinone substances. Ficin activates superoxide dismutase to scavenge free radicals, thereby reducing the anthocyanin oxidation loss rate during eggplant production to below 5%, ensuring a high anthocyanin rate of the eggplant. The dual-target enzymatic cleavage completely destroys the PPO activity and simultaneously activates the cell defense system, further ensuring the fresh-keeping effect of the eggplant.

[0017] 3. In the present invention, by setting up an immersion solution, natamycin and subtilisin are combined to achieve a triple-effect removal of fungi, bacteria, and biofilm on eggplant. At the same time, the eggplant produced can be biodegraded to achieve no residue, so that the eggplant produced can achieve the triple effects of antibacterial, antioxidant, and moisturizing, reducing production costs and further extending the shelf life of eggplant. The combination of natamycin and nisin can improve the antibacterial rate of eggplant during storage. Nisin forms holes by perforating the bacterial membrane, and natamycin enters through the holes and combines with fungal ergosterol to completely kill the bacteria, achieving dual killing of fungi and bacteria, improving the biofilm removal rate on the eggplant surface, and further enhancing the anti-corrosion strength of eggplant during storage. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] It should be noted that the raw materials used in the following examples are all commercially available raw materials.

[0020] Example 1, a method for producing original color, high anthocyanin eggplant, comprising the following steps: Step 1: Select purple eggplant, clean it, cut it into long strips, soak the long strips of eggplant in honey solution, add citric acid to the honey solution, wherein the weight ratio of honey solution to citric acid is 1:0.08, soak for 10 minutes. After the soaking time is completed, remove the eggplant and centrifuge it for 5 seconds and set aside; Step 2: Prepare a color-protecting solution and add an enzymatic blocker to the solution. Place the eggplants in the solution and soak at 25°C for 3 minutes. Remove the eggplants and set aside. Step 3: prepare a soaking solution, immerse the eggplant in the soaking solution for 10 minutes, take out the eggplant and vacuum-pack it to obtain original color, high anthocyanin eggplant, and store it in a refrigerator.

[0021] The preparation method of the honey solution is as follows: ascorbic acid solution and honey water are added into a stainless steel container at a molar ratio of 0.2:1 and mixed and stirred for 1 minute. The honey water is cold water with a temperature of 2°C.

[0022] The color protection solution consists of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid, and the rest is water.

[0023] The preparation method of the color protection solution comprises the following steps: Step 1: Take 1L of water at 20℃; Step 2: Prepare a base material, which includes 0.2 g of N-acetyl-L-lysine, 0.003 g of 4-hexylresorcinol, 3 g of β-cyclodextrin, 0.48 g of perillaldehyde, and 6 g of γ-polyglutamic acid; Step 3: Stir 0.48 g of perillaldehyde and 3 g of β-cyclodextrin at 40°C for 2 hours to form an inclusion complex, then add 0.2 g of N-acetyl-L-lysine, 0.003 g of 4-hexylresorcinol and 6 g of γ-polyglutamic acid in sequence, adjust the pH to 4.0 with citric acid, and store in the dark to obtain a color-protecting solution.

[0024] The mass ratio of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid is 1:0.015:15:2.5:30.

[0025] The enzymatic blocker includes ficin and bromelain, as well as a buffer and warm water. The preparation method of the enzymatic blocker is as follows: Step a: Prepare a buffer solution by taking 200 g of sodium dihydrogen phosphate and 800 g of disodium hydrogen phosphate, pouring them into 80 L of deionized water, stirring, and adjusting the pH value to 6.8 ± 0.1 to obtain a buffer solution; Step b: Pour 500 g of trehalose into the buffer solution and stir in a 40°C water bath until completely dissolved; Step c: Pour 50g of cysteine into 5L of warm water at 40°C and dissolve it. Mix it with the mixture prepared in step b. Pour 30g of ficin, 30g of bromelain and 100g of trehalose and premix them for 2 minutes. After premixing, slowly sprinkle the mixture onto the surface. Stir magnetically at a speed of 300rpm for 20 minutes. Step d: Filter through gauze to remove impurities and obtain an enzymatic blocker.

[0026] The mass ratio of buffer solution to warm water is 1:400, and the mass ratio of ficin to bromelain is 1:1:2.

[0027] The soaking solution includes nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin, and the mass ratio of nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin is 1:1.5:10:5:0.5:0.3.

[0028] The soaking solution is prepared as follows: Step 3.1: Encapsulation with perillaldehyde: 1.5 kg of perillaldehyde and 3 kg of β-cyclodextrin were stirred at 40° C. for 2 hours to obtain an inclusion complex; Step 3.2: Prepare the polysaccharide base solution by heating 800 L of deionized water to 45°C, adding 10 kg of γ-polyglutamic acid and 5 kg of pullulan, and stirring to dissolve; Step 3.3: Add 1 kg of nisin, 0.5 kg of natamycin, and 0.3 kg of subtilisin in sequence, then pour in perillaldehyde inclusion complex, 5 kg of trehalose, and 2 kg of citric acid, adjust the pH to 4.5, make up to 1000 L with deionized water, and homogenize under high pressure at 20 MPa, repeat 3 times, filter and sterilize to obtain the soaking solution.

[0029] Vacuum packaging is to evacuate the eggplants after soaking in the soaking solution to -0.09MPa and refrigerate them at 4℃.

[0030] Example 2, a method for producing original color, high anthocyanin eggplant, comprising the following steps: Step 1: Select purple eggplant, clean it, cut it into long strips, soak the long strips of eggplant in honey solution, add citric acid to the honey solution, wherein the weight ratio of honey solution to citric acid is 1:0.08, soak for 12 minutes. After the soaking time is completed, remove the eggplant and centrifuge it for 5 seconds and set aside; Step 2: Prepare a color-protecting solution and add an enzymatic blocker to the solution. Place the eggplants in the solution and soak at 25°C for 4 minutes. Remove the eggplants and set aside. Step 3: prepare a soaking solution, immerse the eggplant in the soaking solution for 10 minutes, take out the eggplant and vacuum-pack it to obtain original color, high anthocyanin eggplant, and store it in a refrigerator.

[0031] The preparation method of the honey solution is as follows: ascorbic acid solution and honey water are added into a stainless steel container at a molar ratio of 0.2:1, and mixed and stirred for 1 minute. The honey water is cold water with a temperature of 3°C.

[0032] The color protection solution consists of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid, and the rest is water.

[0033] The preparation method of the color protection solution comprises the following steps: Step 1: Take 1L of water at 30℃; Step 2: Prepare a base material, which includes 0.5 g of N-acetyl-L-lysine, 0.006 g of 4-hexylresorcinol, 6 g of β-cyclodextrin, 0.96 g of perillaldehyde, and 12 g of γ-polyglutamic acid; Step 3: Stir 0.96 g of perillaldehyde and 6 g of β-cyclodextrin at 40°C for 2 hours to form an inclusion complex, then add 0.4 g of N-acetyl-L-lysine, 0.006 g of 4-hexylresorcinol and 12 g of γ-polyglutamic acid in sequence, adjust the pH to 4.5 with citric acid, and store in the dark to obtain a color-protecting solution.

[0034] The mass ratio of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid is 1:0.015:15:2.5:30.

[0035] The enzymatic blocker includes ficin and bromelain, as well as a buffer and warm water. The preparation method of the enzymatic blocker is as follows: Step a: Prepare a buffer solution by taking 200 g of sodium dihydrogen phosphate and 800 g of disodium hydrogen phosphate, pouring them into 80 L of deionized water, stirring, and adjusting the pH value to 6.8 ± 0.1 to obtain a buffer solution; Step b: Pour 500 g of trehalose into the buffer solution and stir in a 40°C water bath until completely dissolved; Step c: Pour 50g of cysteine into 5L of warm water at 40°C and dissolve it. Mix it with the mixture prepared in step b. Pour 30g of ficin, 30g of bromelain and 100g of trehalose and premix them for 2 minutes. After premixing, slowly sprinkle the mixture onto the surface. Stir magnetically at a speed of 300rpm for 20 minutes. Step d: Filter through gauze to remove impurities and obtain an enzymatic blocker.

[0036] The mass ratio of buffer solution to warm water is 1:400, and the mass ratio of ficin to bromelain is 1:1:2.

[0037] The soaking solution includes nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin, and the mass ratio of nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin is 1:1.5:10:5:0.5:0.3.

[0038] The soaking solution is prepared as follows: Step 3.1: Encapsulation with perillaldehyde: 1.5 kg of perillaldehyde and 3 kg of β-cyclodextrin were stirred at 40° C. for 2 hours to obtain an inclusion complex; Step 3.2: Prepare the polysaccharide base solution by heating 800 L of deionized water to 45°C, adding 10 kg of γ-polyglutamic acid and 5 kg of pullulan, and stirring to dissolve; Step 3.3: Add 1 kg of nisin, 0.5 kg of natamycin, and 0.3 kg of subtilisin in sequence, then pour in perillaldehyde inclusion complex, 5 kg of trehalose, and 2 kg of citric acid, adjust the pH to 4.5, make up to 1000 L with deionized water, and homogenize under high pressure at 20 MPa, repeat 3 times, filter and sterilize to obtain the soaking solution.

[0039] Vacuum packaging is to evacuate the eggplants after soaking in the soaking solution to -0.09MPa and refrigerate them at 4℃.

[0040] Example 3, a method for producing original color, high anthocyanin eggplant, comprising the following steps: Step 1: Select purple eggplant, clean it, cut it into long strips, soak the long strips of eggplant in honey solution, add citric acid to the honey solution, wherein the weight ratio of honey solution to citric acid is 1:0.08, soak for 15 minutes. After the soaking time is completed, remove the eggplant and centrifuge it for 5 seconds and set aside; Step 2: Prepare a color-protecting solution and add an enzymatic blocker to the solution. Place the eggplants in the solution and soak at 25°C for 5 minutes. Remove the eggplants and set aside. Step 3: prepare a soaking solution, immerse the eggplant in the soaking solution for 10 minutes, take out the eggplant and vacuum-pack it to obtain original color, high anthocyanin eggplant, and store it in a refrigerator.

[0041] The preparation method of the honey solution is as follows: ascorbic acid solution and honey water are added into a stainless steel container at a molar ratio of 0.2:1, and mixed and stirred for 1 minute. The honey water is cold water with a temperature of 2°C-4°C.

[0042] The color protection solution consists of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid, and the rest is water.

[0043] The preparation method of the color protection solution comprises the following steps: Step 1: Take 1L of water, the water temperature is ≤40℃; Step 2: Prepare a base material, which includes 0.6 g of N-acetyl-L-lysine, 0.009 g of 4-hexylresorcinol, 9 g of β-cyclodextrin, 1.44 g of perillaldehyde, and 18 g of γ-polyglutamic acid; Step 3: Stir 1.44 g of perillaldehyde and 9 g of β-cyclodextrin at 40°C for 2 hours to form an inclusion complex, then add 0.6 g of N-acetyl-L-lysine, 0.009 g of 4-hexylresorcinol and 18 g of γ-polyglutamic acid in sequence, adjust the pH to 5.0 with citric acid, and store in the dark to obtain a color-protecting solution.

[0044] The mass ratio of N-acetyl-L-lysine, 4-hexylresorcinol, β-cyclodextrin, perillaldehyde and γ-polyglutamic acid is 1:0.015:15:2.5:30.

[0045] The enzymatic blocker includes ficin and bromelain, as well as a buffer and warm water. The preparation method of the enzymatic blocker is as follows: Step a: Prepare a buffer solution by taking 200 g of sodium dihydrogen phosphate and 800 g of disodium hydrogen phosphate, pouring them into 80 L of deionized water, stirring, and adjusting the pH value to 6.8 ± 0.1 to obtain a buffer solution; Step b: Pour 500 g of trehalose into the buffer solution and stir in a 40°C water bath until completely dissolved; Step c: Pour 50g of cysteine into 5L of warm water at 40°C and dissolve it. Mix it with the mixture prepared in step b. Pour 30g of ficin, 30g of bromelain and 100g of trehalose and premix them for 2 minutes. After premixing, slowly sprinkle the mixture onto the surface. Stir magnetically at a speed of 300rpm for 20 minutes. Step d: Filter through gauze to remove impurities and obtain an enzymatic blocker.

[0046] The mass ratio of buffer solution to warm water is 1:400, and the mass ratio of ficin to bromelain is 1:1:2.

[0047] The soaking solution includes nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin, and the mass ratio of nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin is 1:1.5:10:5:0.5:0.3.

[0048] The soaking solution is prepared as follows: Step 3.1: Encapsulation with perillaldehyde: 1.5 kg of perillaldehyde and 3 kg of β-cyclodextrin were stirred at 40° C. for 2 hours to obtain an inclusion complex; Step 3.2: Prepare the polysaccharide base solution by heating 800 L of deionized water to 45°C, adding 10 kg of γ-polyglutamic acid and 5 kg of pullulan, and stirring to dissolve; Step 3.3: Add 1 kg of nisin, 0.5 kg of natamycin, and 0.3 kg of subtilisin in sequence, then pour in perillaldehyde inclusion complex, 5 kg of trehalose, and 2 kg of citric acid, adjust the pH to 4.5, make up to 1000 L with deionized water, and homogenize under high pressure at 20 MPa, repeat 3 times, filter and sterilize to obtain the soaking solution.

[0049] Vacuum packaging is to evacuate the eggplants after soaking in the soaking solution to -0.09MPa and refrigerate them at 4℃.

[0050] Comparative Example 1: This comparative example differs from Example 1 in that the color protecting solution is not contained in this comparative example.

[0051] Comparative Example 2: This comparative example differs from Example 1 in that: this comparative example does not contain an enzymatic blocker.

[0052] Comparative Example 3: This comparative example differs from Example 1 in that the present comparative example does not contain an immersion solution.

[0053] Performance test: The performance test of the preparation method of the original color and high anthocyanin eggplant prepared in Examples 1-3 and Comparative Examples 1-3 was carried out. The test method is as follows: Color retention rate: Use CIELAB colorimeter (GB / T21865-2020) to calculate the ΔE value before and after treatment. Color retention rate = (1-ΔE / ΔE0) × 100% (ΔE0 is the initial color difference). Anthocyanin retention rate: High performance liquid chromatography (HPLC, GB5009.157-2016) was used to determine the ratio of anthocyanin content after drying to that of fresh eggplant.

[0054] Decay rate: According to national food safety standards (such as GB 29921) and industry classification (such as NY / T 944), the core limit is the total colony count ≤ 10 5 CFU / g, sensory decay area ≤3%, control the decay rate to <1% (premium grade) or <3% (standard grade). Enzymatic hydrolysis time: record the time when the enzymatic hydrolysis treatment reaches the optimal substrate dispersion state. Anthocyanin loss rate during storage: After refrigeration at 4°C for 10 days, the anthocyanin content loss ratio was measured. Shelf life: Pass the total colony count test (GB4789.2-2016), with the total colony count ≤ 10 4 CFU / g is the end point of shelf life, and the test data obtained are recorded in Table 1 below:

[0055] In the test method, by analyzing and comparing the data in Table 1, it can be seen that the performance of the original color and high anthocyanin eggplant prepared in Examples 1-3 meets the technical indicators and has good overall performance, while the original color and high anthocyanin eggplant prepared in Comparative Examples 1-3 are weaker than the original color and high anthocyanin eggplant prepared in Examples 1-3 in terms of color retention rate, anthocyanin retention rate, rot rate and shelf life; This shows that the acetyl group in N-acetyl-L-lysine can block the ε-amino group of lysine, thereby blocking the cross-linking target of 4-HR and forming amino-blocking protection. At the same time, it carries the color-protecting ingredients deep into the peel cells, enhancing the color-protecting penetration during eggplant production, further assisting in enhancing the PPO inhibition effect, and achieving nutritional preservation of eggplant. It circumvents the amino acid damage problem caused by traditional eggplant production methods and delays the browning of eggplant production. The combination of perillaldehyde and γ-polyglutamic acid achieves a synergistic effect of antibacterial, moisturizing, and disease resistance on eggplant, delaying the shelf life of eggplant and solving the problem of unstable primary color protection and weak antibacterial and antimicrobial inhibition of eggplant. The phenylalanine-glycine bond within the ficin in the enzymatic blocker can destroy the hydrophobic pocket structure of the PPO active center, sealing the microcracks in the eggplant cells. Bromelain is used to activate phospholipase A2, thereby accelerating membrane phospholipid reconstruction and achieving coordinated repair of the cell membrane within the eggplant. Bromelain also promotes glutathione synthesis, reducing the oxidative loss rate of anthocyanins during eggplant production to below 5%. The dual-target enzymatic cleavage completely destroys PPO activity while activating the cell defense system, further ensuring the freshness of the eggplant and solving the problem of severe anthocyanin loss during eggplant storage. The soaking solution contains nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin. The combination of natamycin and subtilisin can achieve a triple removal of fungi, bacteria and biofilms on eggplant, so that the eggplant produced can achieve the three-in-one effect of antibacterial, antioxidant and moisturizing. At the same time, the combination of natamycin and nisin can improve the antibacterial rate of eggplant during storage, achieve dual killing of fungi and bacteria, improve the removal rate of biofilm on the surface of eggplant, further enhance the anti-corrosion strength of eggplant during storage, and solve the problem of easy rot during storage.

[0056] Comparing and analyzing the relevant data in the table shows that the method for producing the original color, high anthocyanin eggplant of the present invention not only has good thermal stability but also has good anti-aging properties. This shows that the method for producing the original color, high anthocyanin eggplant provided by the present invention has a broader market prospect and is more suitable for promotion.

[0057] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0058] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing primary color, high anthocyanin eggplant, characterized by: The production method comprises the following steps: Step 1: Select purple eggplant, clean it, cut it into long strips, soak the long strips of eggplant in honey solution, add citric acid to the honey solution, wherein the weight ratio of honey solution to citric acid is 1:0.08, soak for 10-15 minutes. After the soaking time is completed, remove the eggplant and centrifuge it for 5 seconds and set aside; Step 2: Prepare a color-protecting solution and add an enzymatic blocker to the solution. Place the eggplants in the solution and soak at 25°C for 3-5 minutes. Remove the eggplants and set aside. Step 3: prepare a soaking solution, immerse the eggplant in the soaking solution for 10 minutes, take out the eggplant and vacuum-pack it to obtain original color, high anthocyanin eggplant, and store it in a refrigerator.

2. The method for producing primary color, high anthocyanin eggplant according to claim 1, characterized in that: The preparation method of the honey solution is as follows: ascorbic acid solution and honey water are added into a stainless steel container at a molar ratio of 0.2:1, and mixed and stirred for 1 minute. The honey water is cold water with a temperature of 2°C-4°C.

3. The method for producing primary color, high anthocyanin eggplant according to claim 1, characterized in that: The color protection solution consists of N-acetyl-L-lysine, 4-hexylresorcinol, beta-cyclodextrin, perillaldehyde and gamma-polyglutamic acid, and the rest is water.

4. The method for producing primary color, high anthocyanin eggplant according to claim 1, characterized in that: The preparation method of the color protection solution comprises the following steps: Step 1: Take 1L of water, the water temperature is ≤40℃; Step 2: Prepare a base material, which includes 0.2g-0.6g of N-acetyl-L-lysine, 0.003g-0.009g of 4-hexylresorcinol, 3g-9g of β-cyclodextrin, 0.48g-1.44g of perillaldehyde, and 6g-18g of γ-polyglutamic acid; Step 3: Stir 0.48g-1.44g of perillaldehyde and 3g-9g of β-cyclodextrin at 40°C for 2 hours to form an inclusion complex, then add 0.2g-0.6g of N-acetyl-L-lysine, 0.003g-0.009g of 4-hexylresorcinol and 6g-18g of γ-polyglutamic acid in sequence, adjust the pH to 4.0-5.0 with citric acid, and store in the dark to obtain a color-protecting solution.

5. The method for producing primary color, high anthocyanin eggplant according to claim 4, characterized in that: The mass ratio of the N-acetyl-L-lysine, 4-hexylresorcinol, beta-cyclodextrin, perillaldehyde and gamma-polyglutamic acid is 1:0.015:15:2.5:

30.

6. The method for producing primary color, high anthocyanin eggplant according to claim 1, characterized in that: The enzymatic blocker includes ficin and bromelain, and also includes a buffer and warm water. The preparation method of the enzymatic blocker is as follows: Step a: Prepare a buffer solution by taking 200 g of sodium dihydrogen phosphate and 800 g of disodium hydrogen phosphate, pouring them into 80 L of deionized water, stirring, and adjusting the pH value to 6.8 ± 0.1 to obtain a buffer solution; Step b: Pour 500 g of trehalose into the buffer solution and stir in a 40°C water bath until completely dissolved; Step c: Pour 50g of cysteine into 5L of warm water at 40°C and dissolve it. Mix it with the mixture prepared in step b. Pour 30g of ficin, 30g of bromelain and 100g of trehalose and premix them for 2 minutes. After premixing, slowly sprinkle the mixture onto the surface. Stir magnetically at a speed of 300rpm for 20 minutes. Step d: Filter through gauze to remove impurities and obtain an enzymatic blocker.

7. The method for producing primary color, high anthocyanin eggplant according to claim 6, characterized in that: The mass ratio of the buffer solution to warm water is 1:400, and the mass ratio of the ficin to bromelain is 1:1:

2.

8. The method for producing primary color, high anthocyanin eggplant according to claim 1, characterized in that: The soaking solution comprises nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin, and the mass ratio of nisin, perillaldehyde, γ-polyglutamic acid, pullulan, natamycin and subtilisin is 1:1.5:10:5:0.5:0.

3.

9. The method for producing primary color, high anthocyanin eggplant according to claim 8, characterized in that: The preparation method of the soaking solution is as follows: Step 3.1: Encapsulation with perillaldehyde: 1.5 kg of perillaldehyde and 3 kg of β-cyclodextrin were stirred at 40° C. for 2 hours to obtain an inclusion complex; Step 3.2: Prepare the polysaccharide base solution by heating 800 L of deionized water to 45°C, adding 10 kg of γ-polyglutamic acid and 5 kg of pullulan, and stirring to dissolve; Step 3.3: Add 1 kg of nisin, 0.5 kg of natamycin, and 0.3 kg of subtilisin in sequence, then pour in perillaldehyde inclusion complex, 5 kg of trehalose, and 2 kg of citric acid, adjust the pH to 4.5, make up to 1000 L with deionized water, and homogenize under high pressure at 20 MPa, repeat 3 times, filter and sterilize to obtain the soaking solution.

10. The method for producing original color, high anthocyanin eggplant according to claim 9, characterized in that: The vacuum packaging is to evacuate the eggplants soaked in the soaking solution to -0.09 MPa and keep them at a refrigerated temperature of 4°C.

Images