Passion fruit fresh-keeping composite coating material as well as preparation method and application thereof
Through the use of curcumin and chitosan quaternary ammonium composite coating materials, the problems of water loss and microbial reproduction of passion fruit during storage are solved, and the fruit preservation effect is achieved, which extends the storage period and maintains quality.
Patent Information
- Application Number
- CN202411647994.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-01-10
AI Technical Summary
Passion fruits are prone to water loss and fragile skin after harvesting, resulting in water loss and microbial reproduction during storage, resulting in decline in fruit quality and rot. The existing plastic wrap material is insufficient in breathability and cannot effectively antibacterial and antioxidant.
Using curcumin and chitosan quaternary ammonium salt as the main components, the film is formed by mixing curcumin solution and chitosan quaternary ammonium salt solution to provide antibacterial, antioxidant and appropriate barrier properties, satisfying passion fruit Ventilation and moisturizing needs.
Prolong the shelf life of passion fruit, maintain the appearance, taste and texture of the fruit, significantly reduce water loss and oxidation reaction, inhibit microbial growth, and delay fruit aging.
Smart Images
Figure CN119279019A_ABST
Abstract
Description
Technical Field
[0001] The invention specifically relates to a passion fruit fresh-keeping composite coating material and a preparation method thereof, and belongs to the technical field of fresh-keeping. Background Art
[0002] Passion fruit is a herbaceous vine of the genus Passiflora in the family Passifloraceae, widely planted in tropical and subtropical regions. There are two main types of passion fruit: purple fruit and yellow fruit. The fruit can be eaten raw or used as a vegetable or feed. The pulp is juicy and can be made into aromatic and delicious beverages, which have good economic value. However, the passion fruit peel is fragile and prone to cracks and damage before harvesting. During storage after harvesting, the peel is prone to wrinkling and drying due to water transfer. In addition, when the environmental humidity is high, the reproduction of microorganisms will be greatly active, which will lead to a decline in the quality of passion fruit and widespread rot. Therefore, the antibacterial preservation of passion fruit has become a key issue that needs to be solved urgently.
[0003] At present, in the field of fruit preservation, the use of plastic wrap materials to package fruits is a cheap, convenient and efficient method. Passion fruit, as a respiratory climacteric fruit, has significantly different requirements for plastic wrap materials compared to other fruits. Passion fruit is very easy to lose water after picking, which causes profound changes in appearance and texture, and rapidly decreases in aging and disease resistance. It needs to be stored in a relatively breathable and appropriately humid environment, which also puts special requirements on the air permeability and moisture retention of plastic wrap materials. Therefore, passion fruit fresh-keeping packaging usually needs to choose materials with good air permeability. Although the existing polyethylene (PE) plastic wrap has a certain air permeability, it has a single function and does not have antibacterial, antioxidant and other functional ingredients, and its preservation effect is poor.
[0004] Chitosan quaternary ammonium salt has been widely used in fruit and vegetable preservation due to its excellent film-forming, antibacterial and economical properties. It can form a protective film on the surface of the fruit, inhibit the growth of microorganisms and reduce water loss. Curcumin, as a natural polyphenol compound, has antioxidant and antibacterial properties and is a good antibacterial agent. Through the synergistic effect of the film-forming properties of chitosan quaternary ammonium salt and the antibacterial properties of curcumin, the synthesis of economical composite film materials is expected to be used in passion fruit preservation. However, the existing technology still lacks a preservative film material suitable for passion fruit preservation that can give full play to the efficacy of chitosan and curcumin. Summary of the invention
[0005] The technical problem to be solved by the present invention is to provide a fresh-keeping composite coating material suitable for passion fruit, and a preparation method and application thereof; the fresh-keeping composite coating material has the functional ingredients of curcumin and chitosan quaternary ammonium salt, and the fresh-keeping film formed by the coating on the surface of the fruit has good coating properties and appropriate barrier properties, and can simultaneously meet the special ventilation and air permeability, dry and cool storage conditions of passion fruit and the fresh-keeping requirements of anti-oxidation aging and anti-water evaporation of the fruit, and the stored passion fruit has good appearance, taste and texture and a long shelf life.
[0006] The technical solution of the present invention is as follows:
[0007] The invention provides a passion fruit fresh-keeping composite coating material. The coating material is prepared by mixing a curcumin solution and a chitosan quaternary ammonium salt solution; the curcumin solution is prepared by a curcumin raw material, dimethyl sulfoxide and acetic acid; the chitosan quaternary ammonium salt solution is prepared by a chitosan quaternary ammonium salt, ethanol and water; the coating material is a light yellow liquid and forms a film on the surface of the passion fruit after being naturally air-dried.
[0008] Furthermore, the concentration of the curcumin solution is 5-15 mg / mL, and the curcumin solution is prepared by dissolving the curcumin raw material in a mixed solution of dimethyl sulfoxide and acetic acid.
[0009] Furthermore, the preparation method of the chitosan quaternary ammonium salt solution comprises the following steps: dispersing the chitosan quaternary ammonium salt in ethanol, and then adding deionized water thereto to dissolve the chitosan quaternary ammonium salt, so as to obtain the chitosan quaternary ammonium salt solution.
[0010] Furthermore, the concentration of the chitosan quaternary ammonium salt solution is 500-800 mg / mL.
[0011] Preferably, the volume ratio of dimethyl sulfoxide, acetic acid, ethanol and water in the coating material is 1:1:66:32.
[0012] The present invention also provides a method for preparing the passion fruit preservative composite coating material, comprising the following steps:
[0013] S1. Preparation of curcumin solution: dissolving the curcumin raw material in a mixed solution consisting of dimethyl sulfoxide and acetic acid to obtain a curcumin solution with a concentration of 5 to 15 mg / mL;
[0014] S2. Preparation of chitosan quaternary ammonium salt solution: dispersing chitosan quaternary ammonium salt in ethanol and adding deionized water thereto for ultrasonic dissolution to obtain a chitosan quaternary ammonium salt solution with a concentration of 500 to 800 mg / mL;
[0015] S3, preparation of coating material: uniformly mixing the curcumin solution described in step S1 and the chitosan quaternary ammonium salt solution described in step S2 to form a film-forming liquid, thereby obtaining the coating material;
[0016] Wherein, the volume ratio between the added amount of the curcumin solution and the added amount of the chitosan solution in the film-forming solution is 1:49.
[0017] Furthermore, in step S1, the volume ratio of dimethyl sulfoxide to acetic acid in the mixed solution is 1:1.
[0018] Furthermore, the ultrasonic dissolution conditions in step S2 are: ultrasonic power 150-250 W, temperature 25-40° C., time 10-15 min.
[0019] The present invention applies the passion fruit fresh-keeping composite coating material to passion fruit fresh-keeping.
[0020] The present invention also provides a method for preserving passion fruit by applying the above-mentioned preservative composite coating material, comprising the following steps:
[0021] The passion fruit is immersed in the passion fruit preservative composite coating material, taken out after soaking, and naturally air-dried to form a film; then the passion fruit after film formation is placed in a breathable fresh-keeping box and stored at room temperature.
[0022] Furthermore, the passion fruit is immersed in the fresh-keeping composite coating material for 10 to 30 seconds.
[0023] Different from the prior art, the present invention has the following beneficial effects:
[0024] 1. The passion fruit preservative composite coating material of the present invention has the functional ingredients of curcumin and chitosan quaternary ammonium salt, wherein chitosan quaternary ammonium salt has excellent film-forming property, and the dense protective film formed on the surface of the fruit can effectively block the invasion of external oxygen and water, reduce the water loss and oxidation reaction of the fruit, thereby delaying the aging process of the fruit; curcumin has powerful antibacterial properties, and its active ingredients can destroy the cell membrane of microorganisms, inhibit their growth and reproduction, and reduce the corruption risk caused by microorganisms on the surface of the fruit; in addition, curcumin can scavenge free radicals, inhibit the oxidation reaction inside the fruit, and prevent quality deterioration and nutrient loss; the composite coating material provided by the present invention combines the excellent film-forming property of chitosan quaternary ammonium salt with the strong antioxidant and antibacterial properties of curcumin, and can effectively prolong the storage period of the fruit and inhibit the growth of microorganisms.
[0025] 2. Different from the prior art, the curcumin solution used in the present invention introduces dimethyl sulfoxide as a cosolvent for curcumin, and utilizes the property that dimethyl sulfoxide can be mutually dissolved with water and curcumin to improve the problem that curcumin is difficult to dissolve and disperse in water, thereby maximizing the efficacy of curcumin; in addition, the present invention also makes the solution system present an acidic condition by adding acetic acid, thereby improving the stability and biological activity of curcumin in the solution system and the membrane system, and solving the problem of antibacterial preservation of passion fruit after harvest.
[0026] 3. The present invention provides a complete and scientific formula of a fresh-keeping composite coating material. The coating material uses curcumin, chitosan quaternary ammonium salt and a small amount of acetic acid and dimethyl sulfoxide as main raw materials, and the raw materials are simple, clean, efficient and safe. Different from the existing fresh-keeping materials containing functional ingredients such as turmeric and chitosan, the coating material prepared by the present invention has good antibacterial and antioxidant functions and appropriate barrier properties, which can meet the special ventilation, air permeability, dry and cool storage conditions of passion fruit, and can meet the discharge requirements of carbon dioxide and other gases generated by respiration of passion fruit during storage, as well as the fresh-keeping requirements of blocking the infiltration of external moisture and impurities, which can effectively reduce the water loss and oxidation reaction of the fruit and delay the aging process of the fruit. The passion fruit preserved by the fresh-keeping coating material of the present invention has good appearance, taste and texture, and a long shelf life. It is an excellent choice for passion fruit preservation, and is also expected to be applied to the preservation of other fruits and vegetables, and has good practical application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 The effect of purple passion fruit (top) and yellow passion fruit (bottom) coated before harvest.
[0028] Figure 2 The preservation effect diagram of purple passion fruit treated with film after harvest, where D0-CK is the untreated group on the 0th day after harvest, D5-CK is the untreated group on the 5th day after harvest, and D5-film is the film-treated group on the 5th day after harvest.
[0029] Figure 3 The preservation effect diagram of yellow passion fruit treated with film after harvest, where D0-CK is the untreated group on the 0th day after harvest, D5-CK is the untreated group on the 5th day after harvest, D5-film is the film-treated group on the 5th day after harvest, D10-CK is the untreated group on the 10th day after harvest, and D10-film is the film-treated group on the 10th day after harvest.
[0030] Figure 4 Effect of coating treatment on color change of purple passion fruit after harvest, where D5-CK is the untreated group on the 5th day after harvest, and D5-film is the film-treated group on the 5th day after harvest, * represents significant difference P<0.05, ** represents significant difference P<0.01 (Tukey's test).
[0031] Figure 5 Effect of coating treatment on color change of yellow passion fruit after harvest, where D5-CK is the untreated group on the 5th day after harvest, D5-film is the film-treated group on the 5th day after harvest, D10-CK is the untreated group on the 10th day after harvest, and D10-film is the film-treated group on the 10th day after harvest, * represents significant difference P<0.05, ** represents significant difference P<0.01 (Tukey's test).
[0032] Figure 6Effects of coating treatments on respiration of postharvest passion fruit.
[0033] Figure 7 Effect of coating treatment on water loss rate of purple passion fruit after harvest, where D5-CK is the untreated group on the 5th day after harvest, and D5-film is the film-treated group on the 5th day after harvest, * represents significant difference P<0.05, ** represents significant difference P<0.01 (Tukey's test).
[0034] Figure 8 Effect of coating treatment on water loss rate of yellow passion fruit after harvest, where D5-CK is the untreated group on the 5th day after harvest, D5-film is the film-treated group on the 5th day after harvest, D10-CK is the untreated group on the 10th day after harvest, and D10-film is the film-treated group on the 10th day after harvest, * represents significant difference P<0.05, ** represents significant difference P<0.01 (Tukey's test).
[0035] Fig. 9 Effects of coating treatment on the textural characteristics of purple passion fruit after harvest, where D0-CK is the untreated group on day 0 after harvest, D5-CK is the untreated group on day 5 after harvest, and D5-film is the film-treated group on day 5 after harvest; different letters in the figure indicate significant differences, and the significance level is 0.05 (Tukey's test).
[0036] Fig.10 Effects of coating treatment on the textural properties of yellow passion fruit after harvest, where D0-CK is the untreated group on day 0 after harvest, D5-CK is the untreated group on day 5 after harvest, D5-film is the film-treated group on day 5 after harvest, D10-CK is the untreated group on day 10 after harvest, and D10-film is the film-treated group on day 10 after harvest; different letters in the figure indicate significant differences, and the significance level is 0.05 (Tukey's test). DETAILED DESCRIPTION
[0037] The present invention will be further described below in conjunction with the accompanying drawings and preferred embodiments. The given embodiments are only for illustrating the present invention, rather than for limiting the scope of the present invention.
[0038] Unless otherwise specified, the materials, reagents, etc. used in the following examples can be obtained from commercial sources; the methods in the following examples are conventional methods unless otherwise specified.
[0039] Example 1
[0040] The present embodiment provides a passion fruit preservation composite coating material, which is formed by mixing a curcumin solution and a chitosan quaternary ammonium salt solution; the curcumin solution is prepared from a curcumin raw material, dimethyl sulfoxide and acetic acid; the chitosan quaternary ammonium salt solution is prepared from a chitosan quaternary ammonium salt, ethanol and water; the coating material is a light yellow liquid, which forms a film on the surface of the passion fruit after natural air drying.
[0041] The concentration of the curcumin solution is 5-10 mg / mL, and the curcumin solution is prepared by dissolving the curcumin raw material in a mixed solution of dimethyl sulfoxide and acetic acid;
[0042] The method for preparing the chitosan quaternary ammonium salt solution comprises the following steps: dispersing the chitosan quaternary ammonium salt in ethanol, and then adding deionized water thereto to dissolve the chitosan quaternary ammonium salt, thereby obtaining the chitosan quaternary ammonium salt solution;
[0043] Wherein, the concentration of the chitosan quaternary ammonium salt solution is 500-1000 mg / mL.
[0044] The volume ratio of dimethyl sulfoxide, acetic acid, ethanol and water in the coating material is 1:1:66:32.
[0045] The preparation method of the passion fruit preservative composite coating material comprises the following steps:
[0046] S1, weighing 10-20 mg of curcumin raw material and dissolving it in a mixed solution of dimethyl sulfoxide and acetic acid to prepare a curcumin solution, wherein the volume ratio of dimethyl sulfoxide to acetic acid in the mixed solution is 1:1, and the curcumin concentration of the prepared curcumin solution is 5-10 mg / mL;
[0047] S2, dispersing 0.5-1.0 g of chitosan quaternary ammonium salt in ethanol and adding deionized water thereto for ultrasonic dissolution to obtain a chitosan quaternary ammonium salt solution with a concentration of 500-1000 mg / mL;
[0048] S3, mixing and stirring the solutions obtained in step 1 and step 2 to obtain a chitosan quaternary ammonium salt-curcumin film-forming solution;
[0049] Wherein, the volume ratio between the added amount of the curcumin solution and the added amount of the chitosan solution in the film-forming solution is 1:49.
[0050] In this embodiment, the passion fruit coating material prepared by the above method is applied to the preservation of purple passion fruit before harvest, comprising the following steps:
[0051] Seven days before harvesting, immerse the fruit in a container containing the above-mentioned composite coating solution for 5 seconds, and then air-dry naturally to ensure that the coating evenly covers the entire surface of the fruit.
[0052] The coating results of the passion fruit coating material are as follows Figure 1 As shown in the figure, the glossiness of the passion fruit skin was significantly improved after coating treatment, the hardness was well maintained, and no obvious spots or corruption appeared before picking.
[0053] Example 2
[0054] The present embodiment provides a passion fruit preservation composite coating material, which is formed by mixing a curcumin solution and a chitosan quaternary ammonium salt solution; the curcumin solution is prepared from a curcumin raw material, dimethyl sulfoxide and acetic acid; the chitosan quaternary ammonium salt solution is prepared from a chitosan quaternary ammonium salt and water; the coating material is a light yellow liquid, and forms a film on the surface of the passion fruit after natural air drying.
[0055] The concentration of the curcumin solution is 5 mg / mL, and the curcumin solution is prepared by dissolving the curcumin raw material in a mixed solution of dimethyl sulfoxide and acetic acid;
[0056] The method for preparing the chitosan quaternary ammonium salt solution comprises the following steps: dissolving the chitosan quaternary ammonium salt in deionized water to obtain the chitosan quaternary ammonium salt solution;
[0057] Wherein, the concentration of the chitosan quaternary ammonium salt solution is 500 mg / mL.
[0058] The volume ratio of dimethyl sulfoxide, acetic acid and water in the coating material is 1:1:98.
[0059] The preparation method of the passion fruit preservative composite coating material comprises the following steps:
[0060] S1, weighing 10-20 mg of curcumin raw material and dissolving it in a mixed solution of dimethyl sulfoxide and acetic acid to prepare a curcumin solution, wherein the volume ratio of dimethyl sulfoxide to acetic acid in the mixed solution is 1:1, and the curcumin concentration of the prepared curcumin solution is 5 mg / mL;
[0061] S2, dissolving 0.5-1.5 g of chitosan quaternary ammonium salt in deionized water and mixing by ultrasonic to obtain a chitosan quaternary ammonium salt solution with a concentration of 500 mg / mL;
[0062] S3, mixing and stirring the solutions obtained in step 1 and step 2 to obtain a chitosan quaternary ammonium salt-curcumin film-forming solution;
[0063] Wherein, the volume ratio between the added amount of the curcumin solution and the added amount of the chitosan solution in the film-forming solution is 1:49.
[0064] In this embodiment, the passion fruit coating material prepared by the above method is applied to the preservation of yellow passion fruit before harvest, comprising the following steps:
[0065] Seven days before harvesting, immerse the fruit in a container containing the above-mentioned composite coating solution for 5 seconds, and then air-dry naturally to ensure that the coating evenly covers the entire surface of the fruit.
[0066] The coating results of the passion fruit coating material are as follows Figure 1 As shown in the figure, the glossiness of the passion fruit skin was significantly improved after coating treatment, the hardness was well maintained, and no obvious spots or corruption appeared before picking.
[0067] Example 3
[0068] The present embodiment provides a passion fruit preservation composite coating material, which is formed by mixing a curcumin solution and a chitosan quaternary ammonium salt solution; the curcumin solution is prepared from a curcumin raw material, dimethyl sulfoxide and acetic acid; the chitosan quaternary ammonium salt solution is prepared from a chitosan quaternary ammonium salt, ethanol and water; the coating material is a light yellow liquid, which forms a film on the surface of the passion fruit after natural air drying.
[0069] The concentration of the curcumin solution is 12.5-20 mg / mL; the curcumin solution is prepared by dissolving the curcumin raw material in a mixed solution of dimethyl sulfoxide and acetic acid;
[0070] The method for preparing the chitosan quaternary ammonium salt solution comprises the following steps: dispersing the chitosan quaternary ammonium salt in ethanol, and then adding deionized water thereto to dissolve the chitosan quaternary ammonium salt, thereby obtaining the chitosan quaternary ammonium salt solution;
[0071] Wherein, the concentration of the chitosan quaternary ammonium salt solution is 500-1000 mg / mL.
[0072] The volume ratio of dimethyl sulfoxide, acetic acid and water in the coating material is 1:1:66:32.
[0073] The preparation method of the passion fruit preservative composite coating material comprises the following steps:
[0074] S1, weighing 25-40 mg of curcumin raw material and dissolving it in a mixed solution of dimethyl sulfoxide and acetic acid to prepare a curcumin solution, wherein the volume ratio of dimethyl sulfoxide to acetic acid in the mixed solution is 1:1, and the curcumin concentration of the prepared curcumin solution is 12.5-20 mg / mL;
[0075] S2, dispersing 0.5-1.0 g of chitosan quaternary ammonium salt in ethanol and adding deionized water thereto for ultrasonic dissolution to obtain a chitosan quaternary ammonium salt solution with a concentration of 500-1000 mg / mL;
[0076] S3, mixing and stirring the solutions obtained in step 1 and step 2 to obtain a chitosan quaternary ammonium salt-curcumin film-forming solution;
[0077] Wherein, the volume ratio between the added amount of the curcumin solution and the added amount of the chitosan solution in the film-forming solution is 1:49.
[0078] In this embodiment, the passion fruit coating material prepared by the above method is applied to the preservation of harvested purple passion fruit, comprising the following steps:
[0079] Immerse the harvested fruits in the composite coating solution to ensure that the fruits are completely immersed. The immersion time is 30 seconds, then take out the fruits and place them in a clean and ventilated environment to dry until a uniform and transparent coating is formed on the surface of the fruits.
[0080] The coated passion fruit was stored under natural conditions (temperature 22±2°C, relative humidity 60%). Figure 2 , 4 As shown in Figures 7 and 9, compared with the untreated group, the skin of the coating treatment group changed color evenly and without wrinkles, and the water loss rate was reduced by 40%. After coating treatment, the fruit hardness, brittleness, elasticity, cohesion, adhesiveness and chewiness were not significantly different from the texture characteristics of the fruit on day 0 after picking. Coating treatment can significantly delay the aging process of the fruit, and the storage period of the fruit can be extended by 5 days.
[0081] Example 4
[0082] The present embodiment provides a passion fruit preservation composite coating material, which is formed by mixing a curcumin solution and a chitosan quaternary ammonium salt solution; the curcumin solution is prepared from a curcumin raw material, dimethyl sulfoxide and acetic acid; the chitosan quaternary ammonium salt solution is prepared from a chitosan quaternary ammonium salt, ethanol and water; the coating material is a light yellow liquid, which forms a film on the surface of the passion fruit after natural air drying.
[0083] The concentration of the curcumin solution is 7.5-12.5 mg / mL, and the curcumin solution is prepared by dissolving the curcumin raw material in a mixed solution of dimethyl sulfoxide and acetic acid;
[0084] The method for preparing the chitosan quaternary ammonium salt solution comprises the following steps: dispersing the chitosan quaternary ammonium salt in ethanol, and then adding deionized water thereto to dissolve the chitosan quaternary ammonium salt, thereby obtaining the chitosan quaternary ammonium salt solution;
[0085] Wherein, the concentration of the chitosan quaternary ammonium salt solution is 800 mg / mL.
[0086] The volume ratio of dimethyl sulfoxide, acetic acid and water in the coating material is 1:1:40:58.
[0087] The preparation method of the passion fruit preservative composite coating material comprises the following steps:
[0088] S1, weighing 15-25 mg of curcumin raw material and dissolving it in a mixed solution of dimethyl sulfoxide and acetic acid to prepare a curcumin solution, wherein the volume ratio of dimethyl sulfoxide to acetic acid in the mixed solution is 1:1, and the curcumin concentration of the prepared curcumin solution is 7.5-12.5 mg / mL;
[0089] S2, dispersing 0.8 g of chitosan quaternary ammonium salt in ethanol and adding deionized water thereto for ultrasonic dissolution to obtain a chitosan quaternary ammonium salt solution with a concentration of 800 mg / mL;
[0090] S3, mixing and stirring the solutions obtained in step 1 and step 2 to obtain a chitosan quaternary ammonium salt-curcumin film-forming solution;
[0091] Wherein, the volume ratio between the added amount of the curcumin solution and the added amount of the chitosan solution in the film-forming solution is 1:49.
[0092] In this embodiment, the passion fruit coating material prepared by the above method is applied to the preservation of harvested purple passion fruit, comprising the following steps:
[0093] Immerse the harvested fruits in the composite coating solution to ensure that the fruits are completely immersed. The immersion time is 30 seconds, then take out the fruits and place them in a clean and ventilated environment to dry until a uniform and transparent coating is formed on the surface of the fruits.
[0094] The coated passion fruit was stored under natural conditions (temperature 22±2°C, relative humidity 60%). Figure 3 , 5 As shown in Figures 8 and 10, compared with the untreated group, the skin of the coating-treated group changed color evenly and without wrinkles, and the water loss rate was reduced by 57-67%. After coating treatment, the fruit hardness, crispness, and cohesiveness were not significantly different from the texture characteristics of the fruit on the 0th day after picking, and the trend of decreasing cohesiveness and chewiness could be effectively delayed. Coating treatment can reduce respiration and significantly delay the aging process of the fruit, and the storage period of the fruit can be extended by 15 days ( Figure 6 ).
[0095] The above embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.
Claims
1. A passion fruit preserving composite coating material, characterized in that: The coating material is prepared by mixing a curcumin solution and a chitosan quaternary ammonium salt solution; the curcumin solution is prepared by curcumin raw material, dimethyl sulfoxide and acetic acid; the chitosan quaternary ammonium salt solution is prepared by chitosan quaternary ammonium salt, ethanol and water; the coating material is a light yellow liquid, and forms a film on the surface of the passion fruit after being naturally air-dried.
2. A passion fruit preservative composite coating material according to claim 1, characterized in that: The concentration of the curcumin solution is 5-15 mg / mL, and the curcumin solution is prepared by dissolving curcumin raw material in a mixed solution of dimethyl sulfoxide and acetic acid.
3. A passion fruit preserving composite coating material according to claim 1, characterized in that: The preparation method of the chitosan quaternary ammonium salt solution comprises the following steps: Dispersing chitosan quaternary ammonium salt in ethanol, and then adding deionized water thereto to dissolve the chitosan quaternary ammonium salt, to prepare the chitosan quaternary ammonium salt solution; The concentration of the chitosan quaternary ammonium salt solution is 500-800 mg / mL.
4. A passion fruit preserving composite coating material according to claim 1, characterized in that: The volume ratio of dimethyl sulfoxide, acetic acid, ethanol and water in the coating material is 1:1:66:
32.
5. A method for preparing a passion fruit preservative composite coating material, characterized in that: The steps include: S1. Preparation of curcumin solution: dissolving the curcumin raw material in a mixed solution consisting of dimethyl sulfoxide and acetic acid to obtain a curcumin solution with a concentration of 5 to 15 mg / mL; S2. Preparation of chitosan quaternary ammonium salt solution: dispersing chitosan quaternary ammonium salt in ethanol and adding deionized water thereto for ultrasonic dissolution to obtain a chitosan quaternary ammonium salt solution with a concentration of 500 to 800 mg / mL; S3, preparation of coating material: uniformly mixing the curcumin solution described in step S1 and the chitosan quaternary ammonium salt solution described in step S2 to form a film-forming liquid, thereby obtaining the coating material; Wherein, the volume ratio between the added amount of the curcumin solution and the added amount of the chitosan solution in the film-forming solution is 1:
49.
6. The method for preparing a passion fruit preservative composite coating material according to claim 5, characterized in that: The volume ratio of dimethyl sulfoxide to acetic acid in the mixed solution in step S1 is 1:
1.
7. The method for preparing a passion fruit preservative composite coating material according to claim 5, characterized in that: The conditions for ultrasonic dissolution in step S2 are: ultrasonic power 150-250 W, temperature 25-40° C., and reaction time 10-15 min.
8. A passion fruit preservation method, characterized in that: The steps include: The passion fruit is immersed in the passion fruit preservative composite coating material as described in any one of claims 1 to 4 or the passion fruit preservative composite coating material prepared by the preparation method as described in any one of claims 5 to 7, taken out after soaking, and naturally air-dried to form a film; and then the passion fruit after film formation is placed in a breathable fresh-keeping box and stored at room temperature.