Protein-based edible fruit preservative liquid

Abstract

Disclosed in the present invention is a protein-based edible fruit preservative liquid. The preservative liquid is a mixed solution of a protein compounded with a polysaccharide compound and a bio-based nanoparticle, and a film-forming agent. The preservative liquid can be modified on fruits by means of dipping or spraying to form a preservative coating. The protein-based edible fruit preservative liquid has a simple preparation method, can form a film on any fruit, and has good antibacterial properties and preservative effects. Moreover, the raw materials of the preservative liquid have the advantages of a low cost, good dispersion, complete non-toxicity, etc. The preservative liquid of the present invention has good preservative effects on both respiratory climacteric and non-respiratory climacteric fruits, can prolong the shelf life, and also has excellent preservative and antioxidant effects on fresh-cut fruits.

Description

Protein-based edible fruit preservative liquid TECHNICAL FIELD

[0001] The present application belongs to the field of natural polymer materials and food preservation, and particularly relates to a protein-based edible fruit preservative liquid formed by a protein / polysaccharide / biobased nanoparticle composite and a film-forming agent. BACKGROUND

[0002] Fresh fruits are nutritious, but the postharvest handling, storage and preservation of fruits are affected by various external factors such as the harvest period, geographical location and the characteristics of the product itself, which can accelerate the respiration and self-consumption of fruits, and make the fruits more prone to aging and rotting, thereby increasing the difficulty of fruit preservation. In particular, during the harvesting process, there may be violent picking and collision, improper storage methods, or bacterial invasion, and fruits that have been mechanically damaged are more difficult to store. As a result, fruits may rot on a large scale, resulting in serious economic losses, especially for high-value fruits. There are many methods for preserving fruits at present, such as irradiation preservation, modified atmosphere packaging, low-temperature storage, chemical preservatives, etc. However, these methods have certain shortcomings, such as energy consumption, safety issues, technical backwardness, complex operation, inability to industrialize production, insufficient preservation effect, etc. Therefore, the development of safe and efficient preservation technology has become an urgent demand of the industry, market and consumers. With the continuous development of modern preservation technology and people's concerns about the harmful residues of chemical preservatives, the development and utilization of safe natural preservatives have attracted widespread attention, and the food science community has launched a research and application boom of edible preservation films for fruit preservation.

[0003] Edible coating treatment has a good inhibitory effect on enzymatic browning of cut fruits, and can also reduce water transpiration, respiration and ethylene production. However, most of the edible preservation coatings studied so far cannot be used for all fruits, including fresh-cut and non-fresh-cut fruits, and have poor spreading properties on the fruit skin, which cannot adhere to the relatively hydrophobic fruit skin.

[0004] SUMMARY

[0005] The purpose of the present application is to provide a protein-based edible fruit preservative liquid with simple preparation method, safety and non-toxicity, which can adhere to the surface of any fruit and has good antibacterial performance and antioxidant properties, and to apply it to fresh-cut and non-fresh-cut fruits.

[0006] To achieve the above purpose, the protein-based edible fruit preservative solution adopted by the present application is a mixed solution of protein and film-forming agent compounded with polysaccharide compound and bio-based nanoparticles, and the preparation method is as follows: 1-500 mg / mL protein 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution and 1-500 mg / mL polysaccharide compound aqueous solution are mixed uniformly at a volume ratio of 1:1, 0.5%-5% bio-based nanoparticle dispersion liquid is added to the obtained mixed solution, and then 1-500 mg / mL film-forming agent 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution is added and mixed uniformly to obtain the preservative solution; wherein the volume ratio of the film-forming agent 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution to the protein 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution is 1:1, and the volume ratio of the bio-based nanoparticle dispersion liquid to the protein 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution is 0.5-1.5:1.

[0007] The polysaccharide compound is selected from any one of chitosan, chitooligosaccharide, chitin, cellulose, sodium alginate, brown algae glue, dextran, polysucrose, pectin, xanthan gum, carrageenan, carrageenan, locust bean gum, guar gum, gelatin, gum arabic, arabinogalactan, polylactic acid, chitin, hyaluronic acid, starch, spirulina polysaccharide, chitin, heparan sulfate, chondroitin sulfate, dermatan sulfate, bupleurum polysaccharide, ganoderma polysaccharide, kudzu fiber, sugar cane fiber, tobacco stem fiber, moringa fiber, polygalacturonide, microcrystalline cellulose, carboxymethyl cellulose, dextran gum, gellan gum.

[0008] The bio-based nanoparticles are selected from any one of cellulose nanocrystals, microfibrillated cellulose, bacterial nanocellulose, chitosan nanocrystals, chitin nanocrystals, chitin nanocrystals, xylan nanocrystals, or any one of the aforementioned biomass nanomaterials modified by molecules.

[0009] The protein is selected from any one of lactoferrin, fibrinogen, collagen, keratin, casein, lysozyme, whey protein, soy protein, albumin, pepsin, beta-lactoglobulin, chymotrypsin, hemoglobin, myosin, myoglobin, lactalbumin, silk fibroin, alpha-amylase, albumin, histone, protamine, skim milk, albumin, gelatin, legumin, corn protein, walnut protein, hovenia dulcis protein, wheat gluten, barley protein, kidney bean protein, serum protein, lactadherin, immunoglobulin, ovalbumin, ovalbumin, glutenin, glutelin, phosphoprotein, flavoprotein, lipoprotein, glycoprotein, egg yolk globulin, scleroprotein.

[0010] The film-forming agent is selected from any one of glutathione, cysteine, mercaptoethanol, dithiothreitol, hydrogen peroxide, peracetic acid, tris (2-carboxyethyl) phosphonium hydrochloride, ammonium persulfate, sodium hypochlorite, sodium percarbonate, ascorbic acid, oxygen, chlorine, fluorine, ozone, sodium ferrite, sodium dichromate, chromic acid, nitric acid, potassium permanganate, ammonium persulfate, sodium hypochlorite, sodium percarbonate, sodium perborate, trivalent cobalt salt, periodic acid, lead dioxide.

[0011] In the preparation method, 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution of 5-100 mg / mL protein and 5-100 mg / mL polysaccharide compound aqueous solution are mixed uniformly at a volume ratio of 1:1, a biobased nanoparticle dispersion liquid with a mass concentration of 0.5%-2% is added to the obtained mixed solution, 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution of 5-100 mg / mL film-forming agent is added after uniform mixing, and uniform mixing is continued to obtain the preservative solution.

[0012] In the preparation method, the 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution of the film-forming agent is adjusted to a pH of 6-10 with NaOH before use.

[0013] The preservative solution of the present application needs to be stored at low temperature (preferably 2-8°C), and when used, the preservative solution is modified on the fruit in the form of a preservative coating by immersion coating or spraying; in the immersion coating method, the fruit is soaked in the preservative solution for 2-30 minutes.

[0014] The protein-based edible fruit preservative solution of the present application can preserve any one of all fresh-cut fruits and non-fresh-cut fruits, and the non-fresh-cut fruits include any one of all respiratory climacteric fruits and non-respiratory climacteric fruits. The fruits specifically include any one of berry fruits, citrus fruits, stone fruits, pome fruits, melon fruits, etc.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] The present application effectively breaks the disulfide bond of the protein by using the film-forming agent to induce rapid self-assembly of the protein, forming a preservative coating, and the obtained preservative coating can adhere to the surface of all fruits and has good spreading property and antibacterial performance. The addition of the film-forming agent provides excellent antioxidant property to the preservative solution, forming an edible preservative coating with good antibacterial performance and antioxidant property. The preservative coating has excellent spreading property, the preparation method is simple and green, and the obtained coating is non-toxic and harmless, which can solve the problem of a large amount of fruits with short shelf life in life, causing waste. Specifically as follows:

[0017] (1) The preservative solution is safe, non-cytotoxic and edible;

[0018] (2) The fresh-keeping coating formed by the fresh-keeping liquid has washability and can be washed off by water flushing only;

[0019] (3) The fresh-keeping coating formed by the fresh-keeping liquid has a lower water vapor transmission rate compared with other polysaccharide and protein-based fresh-keeping coatings, so as to reduce water evaporation and improve the fresh-keeping effect;

[0020] (4) The fresh-keeping liquid can be used for fresh-cut fruit fresh-keeping and antioxidant, including fresh-cut apples, pears, peaches, bananas, Hami melons, dragon fruits, citrus fruits, etc., which is conducive to prolonging the shelf life of fruits and avoiding waste;

[0021] (5) The fresh-keeping liquid has universality and can be used for fresh-keeping of any fruits, including respiratory climacteric fruits (mango, banana, cherry tomato, peach, apricot, apple, pear, kiwi, persimmon, etc.) and non-respiratory climacteric fruits (loquat, citrus, strawberry, winter jujube, blackberry, carambola, cherry, grape, lemon, lychee, pineapple, etc.), so as to prolong the shelf life of fruits. BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a field emission scanning electron microscope image of the protein-based fresh-keeping coating in Example 1.

[0023] FIG. 2 is a contact angle diagram of the protein-based fresh-keeping coating in Example 1.

[0024] FIG. 3 is an infrared spectrum diagram of the protein-based fresh-keeping coating in Example 1.

[0025] FIG. 4 is a tensile property diagram of the protein-based fresh-keeping coating in Example 2.

[0026] FIG. 5 is an effect diagram of the fresh-keeping liquid prepared in Example 7 on inhibiting Escherichia coli.

[0027] FIG. 6 is an effect diagram of the fresh-keeping liquid prepared in Example 7 on inhibiting Staphylococcus aureus.

[0028] FIG. 7 is a contact angle change diagram of the fresh-keeping liquid prepared in Example 8 on the winter jujube skin.

[0029] FIG. 8 is a contact angle change diagram of the fresh-keeping liquid prepared in Example 8 on the apple skin.

[0030] FIG. 9 is a contact angle change diagram of the fresh-keeping liquid prepared in Example 8 on the orange skin.

[0031] FIG. 10 is a cytotoxicity diagram of the fresh-keeping liquid prepared in Example 8.

[0032] FIG. 11 is an effect diagram of the fresh-keeping liquid prepared in Example 8 on spreading on different fruit skins.

[0033] FIG. 12 is a contact angle diagram of the protein-based fresh-keeping coating before and after washing in Example 8.

[0034] Fig. 13 is a graph showing the preservation effect of fresh-cut apples treated with the preservation solution of Example 9 during storage.

[0035] Fig. 14 is a graph showing the change in Vc content of fresh-cut apples treated with the preservation solution of Example 9 during storage.

[0036] Fig. 15 is a graph showing the change in titratable acid content of fresh-cut pears treated with the preservation solution of Example 10 during storage.

[0037] Fig. 16 is a graph showing the preservation effect of strawberries treated with the preservation solution of Example 11 during storage.

[0038] Fig. 17 is a graph showing the change in weight loss rate of loquats treated with the preservation solution of Example 12 during storage.

[0039] Fig. 18 is a graph showing the preservation effect of loquats treated with the preservation solution of Example 12 during storage.

[0040] Fig. 19 is a graph showing the preservation effect of kumquats treated with the preservation solution of Example 13 during storage.

[0041] Fig. 20 is a graph showing the change in Vc content of winter jujubes treated with the preservation solution of Example 14 during storage.

[0042] Fig. 21 is a graph showing the preservation effect of nectarines treated with the preservation solution of Example 14 during storage.

[0043] Fig. 22 is a graph showing the preservation effect of cherry tomatoes treated with the preservation solution of Example 18 during storage. DETAILED DESCRIPTION

[0044] The present application will be further described in detail by reference to the following drawings and examples, but the scope of the present application is not limited to these examples.

[0045] Example 1

[0046] At room temperature, 100 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 15 mL 2 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 100 mg L-cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was cast in a polytetrafluoroethylene mold to obtain a protein-based preservative coating. As shown in FIG. 1, the preservative coating is relatively dense and uniform. As shown in FIG. 2, the preservative coating has a larger water contact angle, indicating that it has good water vapor barrier performance. FIG. 3 shows the successful preparation of the preservative coating.

[0047] Example 2

[0048] At room temperature, 200 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 10 mL 2 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 200 mg L-cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was cast in a polytetrafluoroethylene mold to obtain a protein-based preservative coating. The protein-based preservative coating was placed on the grips of a tensile machine and stretched under the action of external force, and the elongation at break could reach 39% (see FIG. 4).

[0049] Example 3

[0050] At room temperature, 200 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 10 mL 2 wt% bacterial nanocellulose dispersion (dispersed with ultrapure water) was added and mixed uniformly; 200 mg L-cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution.

[0051] Example 4

[0052] At room temperature, 200 mg of bovine serum albumin was added to 10 mL of 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 60 mg of sodium alginate was added to 10 mL of ultrapure water, and then the two solutions were mixed, and 10 mL of 2wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 100 mg of mercaptoethanol was added to 10 mL of 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and the pH was adjusted to 6 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain the preservative solution.

[0053] Example 5

[0054] At room temperature, 200 mg of lysozyme was added to 10 mL of 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg of sodium alginate was added to 10 mL of ultrapure water, and then the two solutions were mixed, and 10 mL of 1wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 200 mg of glutathione was added to 10 mL of 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and the pH was adjusted to 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain the preservative solution.

[0055] Example 6

[0056] At room temperature, 100 mg of whey protein was added to 10 mL of 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg of sodium alginate was added to 10 mL of ultrapure water, and then the two solutions were mixed, and 10 mL of 1wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 100 mg of glutathione was added to 10 mL of 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and the pH was adjusted to 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain the preservative solution.

[0057] Example 7

[0058] At room temperature, 100 mg lysozyme was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 10 mL 1 wt% cellulose nanofiber dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 100 mg cysteine was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain the preservative solution. As shown in FIG. 5, the preservative solution has good antibacterial effect on Escherichia coli. As shown in FIG. 6, the preservative solution has good antibacterial effect on Staphylococcus aureus.

[0059] Example 8

[0060] At room temperature, 80 mg lysozyme was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 10 mL 0.5 wt% bacterial nanocellulose dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 80 mg cysteine was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain the preservative solution. The preservative solution was sprayed on the fruit to form a protein-based preservative coating on the fruit.

[0061] As shown in FIG. 7, the contact angle of the preservative solution on the winter jujube skin decreased from 74° to 44° at 5 min, indicating that the preservative solution has good spreadability on the winter jujube skin. As shown in FIG. 8, the contact angle of the preservative solution on the apple skin decreased from 41° to 19° at 5 min, indicating that the preservative solution has good spreadability on the apple skin. As shown in FIG. 9, the contact angle of the preservative solution on the orange skin decreased from 65° to 44° at 5 min, indicating that the preservative solution has good spreadability on the orange skin. As shown in FIG. 10, the preservative solution has no cytotoxicity. As shown in FIG. 11, water on different fruit skins is in the form of water droplets and cannot spread, while the preservative solution spreads uniformly on different fruit skins. As shown in FIG. 12, the water contact angle of the fruit with preservative coating after washing is consistent with that of the original fruit skin, indicating that the preservative coating has washability.

[0062] Example 9

[0063] At room temperature, 80 mg lysozyme was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 10 mL 0.5 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 80 mg cysteine was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was sprayed on fresh-cut apples to form a protein-based preservative coating on the apples. As shown in FIG. 13, the fresh-cut apples sprayed with the preservative solution were still fresh without browning phenomenon on the 6th day of low-temperature storage, while the apples without preservative treatment had already rotted, indicating that the preservative solution had good fresh-keeping effect on fresh-cut apples. As shown in FIG. 14, the loss of Vc in the fresh-cut apples sprayed with the preservative solution was very slow during low-temperature storage, while the loss of Vc in the apples without preservative treatment was very fast, indicating that the preservative solution could slow down the loss of nutrients in fresh-cut apples.

[0064] Example 10

[0065] At room temperature, 80 mg lysozyme was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 10 mL 0.5 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 80 mg cysteine was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was sprayed on fresh-cut apples to form a protein-based preservative coating on the apples. As shown in FIG. 13, the fresh-cut apples sprayed with the preservative solution were still fresh without browning phenomenon on the 6th day of low-temperature storage, while the apples without preservative treatment had already rotted, indicating that the preservative solution had good fresh-keeping effect on fresh-cut apples. As shown in FIG. 14, the loss of Vc in the fresh-cut apples sprayed with the preservative solution was very slow during low-temperature storage, while the loss of Vc in the apples without preservative treatment was very fast, indicating that the preservative solution could slow down the loss of nutrients in fresh-cut apples.

[0066] Example 11

[0067] At room temperature, 100 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 100 mg cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The strawberries were soaked in the preservative solution for 2 min to form a protein-based preservative coating on the surface of the strawberries. As shown in FIG. 16, the strawberries without preservative treatment began to rot on the 4th day of storage, while the strawberries soaked in the preservative solution began to rot on the 10th day of storage, indicating that the preservative solution extended the shelf life of the strawberries by at least 6 days.

[0068] Example 12

[0069] At room temperature, 200 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was added and mixed uniformly; 200 mg cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was sprayed on the loquats, or the loquats were soaked in the preservative solution for 6 min to form a protein-based preservative coating on the loquats. As shown in FIG. 17, the loquats sprayed with the preservative solution lost water slowly during storage, while the loquats without preservative treatment lost water quickly. As shown in FIG. 18, the loquats without preservative treatment began to rot on the 8th day of storage, while the loquats soaked in the preservative solution began to rot on the 20th day of storage, indicating that the preservative solution extended the shelf life of the loquats by at least 12 days.

[0070] Example 13

[0071] At room temperature, 200 mg lysozyme was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, 5 mL 1 wt% bacterial nanocellulose dispersion (dispersed with ultrapure water) was added and mixed uniformly; 200 mg cysteine was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, then it was further mixed uniformly with the mixed solution to obtain the preservative solution. The kumquat was soaked in the preservative solution for 10 min to form a protein-based preservative coating on the kumquat. As shown in FIG. 19, the kumquat without preservative treatment began to rot on the 20th day of storage, while the kumquat soaked in the preservative solution began to rot on the 32nd day of storage, indicating that the preservative solution extended the shelf life of the kumquat by at least 12 days.

[0072] Example 14

[0073] At room temperature, 200 mg lysozyme was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, 5 mL 1 wt% bacterial nanocellulose dispersion (dispersed with ultrapure water) was added and mixed uniformly; 200 mg cysteine was added into 10 mL 4-hydroxyethyl piperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, then it was further mixed uniformly with the mixed solution to obtain the preservative solution. The kumquat was soaked in the preservative solution for 10 min to form a protein-based preservative coating on the kumquat. As shown in FIG. 19, the kumquat without preservative treatment began to rot on the 20th day of storage, while the kumquat soaked in the preservative solution began to rot on the 32nd day of storage, indicating that the preservative solution extended the shelf life of the kumquat by at least 12 days.

[0074] Example 15

[0075] At room temperature, 100 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1 wt% bacterial nanocellulose dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 100 mg glutathione was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then the mixture was further mixed uniformly to obtain a preservative solution. The preservative solution was sprayed on bananas to form a protein-based preservative coating on the bananas.

[0076] Example 16

[0077] At room temperature, 300 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1.2 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 300 mg cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, and then the mixture was further mixed uniformly to obtain a preservative solution. The preservative solution was sprayed on figs to form a protein-based preservative coating on the figs.

[0078] Example 17

[0079] At room temperature, 200 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 50 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1.5 wt% cellulose nanocrystal dispersion (dispersed with ultrapure water) was further added and mixed uniformly; 200 mg cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 10 with 5 mol / L sodium hydroxide aqueous solution, and then the mixture was further mixed uniformly to obtain a preservative solution. The mango was soaked in the preservative solution for 5 min to form a protein-based preservative coating on the mango.

[0080] Example 18

[0081] At room temperature, 100 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1.2 wt% cellulose nanofiber dispersion (dispersed with ultrapure water) was added and mixed uniformly; 100 mg cysteine was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 8 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was sprayed on the cherry tomatoes to form a protein-based preservative coating on the cherry tomatoes. As shown in FIG. 22, the cherry tomatoes without preservative treatment began to rot on the 8th day of storage, while the cherry tomatoes soaked in the preservative solution began to rot on the 16th day of storage, indicating that the preservative solution extended the shelf life of the cherry tomatoes by at least 8 days.

[0082] Example 19

[0083] At room temperature, 100 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 1.2 wt% cellulose nanofiber dispersion (dispersed with ultrapure water) was added and mixed uniformly; 143 mg tris(2-carboxyethyl) phosphonium hydrochloride was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 7 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The preservative solution was sprayed on the papayas to form a protein-based preservative coating on the papayas.

[0084] Example 20

[0085] At room temperature, 50 mg lysozyme was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4, 100 mg sodium alginate was added into 10 mL ultrapure water, then the two solutions were mixed, and 5 mL 0.5 wt% cellulose nanofiber dispersion (dispersed with ultrapure water) was added and mixed uniformly; 143 mg tris(2-carboxyethyl) phosphonium hydrochloride was added into 10 mL 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution with pH of 7.4 and adjusted to pH of 6 with 5 mol / L sodium hydroxide aqueous solution, and then it was further mixed uniformly with the mixed solution to obtain a preservative solution. The grapes were soaked in the preservative solution for 10 min to form a protein-based preservative coating on the grapes.

Claims

1. A protein-based edible fruit preservative solution, characterized by: The preservative solution is a mixed solution of a protein and a film forming agent compounded with a polysaccharide compound and a bio-based nanoparticle; The bio-based nanoparticle is selected from any one of cellulose nanocrystal, microfibrillated cellulose, bacterial nanocellulose, chitosan nanocrystal, chitin nanocrystal, chitin nanocrystal, xylan nanocrystal, or any one of the aforementioned biomass nanoparticles modified by molecules; The film forming agent is selected from any one of glutathione, cysteine, mercaptoethanol, dithiothreitol, hydrogen peroxide, peroxyacetic acid, tris(2-carboxyethyl)phosphonium hydrochloride, ammonium persulfate, sodium hypochlorite, sodium percarbonate, ascorbic acid, oxygen, chlorine, fluorine, ozone, sodium ferrite, sodium dichromate, chromic acid, nitric acid, potassium permanganate, ammonium persulfate, sodium hypochlorite, sodium percarbonate, sodium perborate, trivalent cobalt salt, periodic acid, lead dioxide; The preparation method of the preservative solution is as follows: 1-500 mg / mL protein 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution and 1-500 mg / mL polysaccharide compound aqueous solution are mixed uniformly at a volume ratio of 1:1, 0.5%-5% bio-based nanoparticle dispersion liquid is added to the obtained mixed solution, and then 1-500 mg / mL film forming agent 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution is added and mixed uniformly to obtain the preservative solution; wherein the volume ratio of the film forming agent 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution to the protein 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution is 1:1, and the volume ratio of the bio-based nanoparticle dispersion liquid to the protein 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution is 0.5-1.5:

1.

2. The protein-based edible fruit preservative solution according to claim 1, characterized in that: The protein is selected from any one of lactoferrin, fibrinogen, collagen, keratin, casein, lysozyme, whey protein, soy protein, albumin, pepsin, beta-lactoglobulin, chymotrypsin, hemoglobin, myosin, myoglobin, lactalbumin, silk fibroin, alpha-amylase, albumin, histone, protamine, skim milk, albumin, gelatin, legumin, corn protein, walnut protein, jujube kernel protein, wheat gluten, barley protein, oat protein, rice protein, soybean protein, mung bean protein, pea protein, kidney bean protein, serum rice protein, lactadherin, immunoglobulin, ovalbumin, ovalbumin, glutenin, glutelin, phosphoprotein, flavoprotein, lipoprotein, glycoprotein, egg yolk globulin, scleroprotein; 3. The protein-based edible fruit preservative solution according to claim 1, characterized in that: The polysaccharide compound is selected from any one of chitosan, chitooligosaccharide, chitin, cellulose, sodium alginate, brown algae gum, dextran, polysucrose, pectin, xanthan gum, carrageenan, carrageenan, locust bean gum, guar gum, gelatin, gum arabic, arabinogalactan, polylactic acid, chitin, hyaluronic acid, starch, spirulina polysaccharide, chitin, heparan sulfate, chondroitin sulfate, dermatan sulfate, bupleurum polysaccharide, ganoderma polysaccharide, kudzu fiber, sugar cane fiber, tobacco stem fiber, moringa fiber, polygalacturonic acid, microcrystalline cellulose, carboxymethyl cellulose, dextran gum, gellan gum; 4. The protein-based edible fruit preservative solution according to claim 1, characterized in that The preparation method of the preservative solution is as follows: 4- hydroxyethylpiperazine ethanesulfonic acid buffer solution containing 5-100 mg / mL of protein and 5-100 mg / mL of polysaccharide compound aqueous solution are mixed uniformly at a volume ratio of 1:1, a biobased nanoparticle dispersion liquid with a mass concentration of 0.5%-5% is added to the obtained mixed solution, 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution containing 5-100 mg / mL of a film-forming agent is added after uniform mixing, and uniform mixing is continued to obtain the preservative solution.

5. The protein-based edible fruit preservative solution according to claim 1 or 4, characterized in that: The 4-hydroxyethylpiperazine ethanesulfonic acid buffer solution of the film-forming agent is adjusted to a pH of 6-10 with NaOH before use.

6. The protein-based edible fruit preservative solution according to claim 1, characterized in that: The biobased nanoparticle dispersion liquid is prepared by dispersing biobased nanoparticles in ultrapure water.

7. The protein-based edible fruit preservative solution according to claim 1, characterized in that: The fruit is any one of fresh-cut fruit and non-fresh-cut fruit, and the non-fresh-cut fruit includes any one of respiratory climacteric fruit and non-respiratory climacteric fruit.

8. The protein-based edible fruit preservative solution according to claim 1 or 7, characterized in that: The fresh-cut fruit includes any one of berry fruit, citrus fruit, stone fruit, pome fruit, and melon fruit.

9. The protein-based edible fruit preservative solution of claim 1, wherein: In use, the preservative solution is modified on the fruit in the form of a preservative coating by dip coating or spray coating, and in the dip coating, the fruit is soaked in the preservative solution for 2-30 minutes.

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