Green-protecting preservative as well as preparation method and application thereof

Abstract

The invention provides a green-protecting preservative as well as a preparation method and application thereof, and relates to the technical field of fruit preservation. The green-protecting preservative disclosed by the invention is prepared from the following components in parts by weight: 20 to 40 parts of chitosan, 1 to 5 parts of 6-benayl aminopurine, 1 to 5 parts of gibberellic acid, 10 to 20 parts of citric acid and 3 to 10 parts of cortex cinnamomi extract. The green-protecting preservative disclosed by the invention is safe and simple to use, and can well maintain the color of the green lemons, delay the degradation of chlorophyll in the peel of the green lemons, maintain the fragrance of the green lemons and reduce the morbidity of diseases and insect pests such as black spots of the green lemons during storage, the color of the green lemon fruits changes slowly during storage, and the quality of the fruits is well maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of fruit preservation, and in particular relates to a green preservative and a preparation method and application thereof. Background Art

[0002] Lemon is a citrus fruit of the Rutaceae family, also known as motherwort. It is rich in citric acid, vitamin C and various mineral elements, which can improve the body's immunity and is one of the fruits with beauty and skin care effects. Green lemons are most suitable for juicing or making sour juice drinks. Due to their extremely sour taste, they are often used as seasoning in Thai or Southeast Asian cuisine. Therefore, green lemons are very popular in the market. However, green lemons are put on the market at a relatively concentrated time and have a high rot rate, which makes the economic benefits of fruit farmers low and the off-season green lemons are in short supply. The way to keep green lemons fresh and green has always been one of the biggest problems that plague fruit farmers.

[0003] At present, the preservation methods for lemons mainly include refrigeration preservation, controlled atmosphere preservation and preservative preservation. Although the above preservation methods have made some progress, there are still some shortcomings: refrigeration preservation has extremely high temperature requirements and huge investment costs; controlled atmosphere preservation is complex to operate, consumes high energy and has huge costs; although preservative preservation is low in cost, easy to operate and has obvious preservation effects, it has certain effects on human health. Therefore, it is extremely important to find a simple, fast, applicable and effective preservation method. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a green preservative, which is safe, easy to use, and can well maintain the color and quality of green lemons.

[0005] Another object of the present invention is to provide a method for preparing the greening and preservative agent.

[0006] Another object of the present invention is to provide an application of the greening and freshness-preserving agent.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The invention provides a green preservative, which comprises the following components in parts by weight: 20 to 40 parts of chitosan, 1 to 5 parts of 6-benzylaminopurine, 1 to 5 parts of gibberellic acid, 10 to 20 parts of citric acid and 3 to 10 parts of cinnamon extract.

[0009] Preferably, the deacetylation degree of the chitosan is 75% to 80%.

[0010] The present invention also provides a method for preparing the green preservative, comprising the following steps:

[0011] After mixing cinnamon with ethanol solvent, ultrasonic extraction method is used to obtain cinnamon extract;

[0012] Add chitosan to the acetic acid solution and stir to obtain a chitosan-acetic acid solution;

[0013] 6-benzylaminopurine, citric acid, gibberellic acid and chitosan-acetic acid solution are mixed to obtain a mixed solution; cinnamon extract is added to the mixed solution to obtain a green preservative.

[0014] Preferably, the conditions for ultrasonic extraction are: ultrasonic power is 150W to 350W, and extraction time is 0.5 to 2h.

[0015] Preferably, the concentration of the ethanol solvent is 60% to 90%.

[0016] Preferably, the weight ratio of the cinnamon to the ethanol solvent is 1:2-10.

[0017] Preferably, the weight ratio of chitosan to acetic acid solution is 1:40-60.

[0018] Preferably, the weight ratio of the cinnamon extract to the mixed solution is 0.025-0.75:1.

[0019] The present invention also provides a method for preserving greenness and freshness of green lemons, wherein the green preservative or the green preservative obtained by the preparation method is used to soak the green lemons for 0.5 to 10 minutes, and the lemons are dried after soaking until there is no water stain on the surface for preservation.

[0020] The present invention also provides the green-keeping and fresh-keeping agent, or the use of the green-keeping and fresh-keeping agent obtained by the preparation method in preparing fruit green-keeping and fresh-keeping products.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The active ingredients of the green preservative of the present invention include chitosan, 6-benzylaminopurine, gibberellic acid, citric acid and cinnamon extract. In the present invention, chitosan is a natural preservative, which is easy to form a film, and the film has a certain selective permeability to O2, CO2 and C2H4, and has a moisturizing function, which can effectively make fruits dormant, thereby extending the shelf life of fruits; 6-benzylaminopurine is a plant growth regulator, which belongs to the cytokinin class, can promote the synthesis of nucleic acids and proteins, inhibit their decomposition, and has the effect of promoting plant cell division and delaying tissue aging; gibberellic acid mainly promotes plant growth and development; citric acid has a certain antibacterial effect, which can inhibit the growth of bacteria and microorganisms; cinnamon extract has certain antibacterial and antiseptic properties. The present invention uses the raw materials to prepare a green preservative, which has the characteristics of safety and simple use, can well maintain the color of green lemons, delay the degradation of chlorophyll in green lemon peels, maintain the fragrance of green lemons, reduce the incidence of diseases and insect pests during storage such as green lemon black spot disease, and the color of green lemon fruits changes slowly during storage, so that the fruit quality is well maintained. DETAILED DESCRIPTION

[0023] The present invention provides a green preservative, which preferably comprises the following components by weight: 20 to 40 parts of chitosan, 1 to 5 parts of 6-benzylaminopurine, 1 to 5 parts of gibberellic acid, 10 to 20 parts of citric acid, and 3 to 10 parts of cinnamon extract; more preferably, it comprises the following components by weight: 25 to 30 parts of chitosan, 2 to 4 parts of 6-benzylaminopurine, 2 to 4 parts of gibberellic acid, 15 to 18 parts of citric acid, and 5 to 8 parts of cinnamon extract. In the present invention, the deacetylation degree of the chitosan is preferably 75% to 80%. The present invention does not specifically limit the source of the raw materials, and all of them can be purchased through conventional channels.

[0024] The present invention also provides a method for preparing the green preservative, which preferably comprises the following steps:

[0025] After mixing cinnamon with ethanol solvent, ultrasonic extraction method is used to obtain cinnamon extract;

[0026] Add chitosan to the acetic acid solution and stir to obtain a chitosan-acetic acid solution;

[0027] 6-benzylaminopurine, citric acid, gibberellic acid and chitosan-acetic acid solution are mixed to obtain a mixed solution; cinnamon extract is added to the mixed solution to obtain a green preservative.

[0028] In the present invention, cinnamon and ethanol solvent are preferably mixed in a weight ratio of 1:2 to 10 and placed in an ultrasonic extraction container for ultrasonic extraction to obtain cinnamon extract for standby use. In the present invention, the conditions of the ultrasonic extraction are preferably: ultrasonic power of 150W to 350W, extraction time of 0.5 to 2h; more preferably, ultrasonic power of 200W to 250W, extraction time of 1h. In the present invention, the concentration of the ethanol solvent is preferably 60% to 90%; more preferably, 70% to 80%. In the present invention, the ethanol solvent can be prepared by mixing anhydrous ethanol and water in proportion to prepare an ethanol solvent of the required concentration, or a conventional commercially available ethanol solvent of the corresponding concentration can be used. In the present invention, the cinnamon is preferably fresh, impurity-free cinnamon stems and leaves or cinnamon bark. In the present invention, the cinnamon is preferably washed, dried, and crushed before ultrasonic extraction. The present invention uses ultrasonic extraction to obtain cinnamon extract, which can improve the extraction efficiency of the effective components of cinnamon. The invention mainly extracts cinnamaldehyde and polyphenols from cinnamon, and plays an antibacterial and antiseptic effect in the greening and preservative agent.

[0029] In the present invention, the chitosan and the acetic acid solution are preferably mixed at a weight ratio of 1:40 to 60 to prepare a chitosan-acetic acid solution; more preferably, they are mixed at a weight ratio of 1:50. During the mixing process, the chitosan is fully stirred to completely dissolve in the acetic acid solution. In the present invention, the concentration of the acetic acid solution is preferably 0.5% to 2%; more preferably 1%.

[0030] In the present invention, cinnamon extract is added to the above mixed solution to obtain a green preservative. In the present invention, the weight ratio of the cinnamon extract to the mixed solution is preferably 0.025-0.75:1, more preferably 0.03-0.55. In the present invention, as an operative method, 0.025-0.75 parts of cinnamon extract are added per liter of the mixed solution.

[0031] The present invention also provides a method for protecting green and preserving green lemons, wherein the green preservative or the green preservative obtained by the preparation method is used to soak the green lemons for 0.5 to 10 minutes, and the fruit is dried until there is no water stain on the surface after soaking, and then stored; more preferably, soaking for 2 to 8 minutes. In the present invention, as an practicable method, the green lemons that have reached the edible standard and are more than 80% mature and free of pests and diseases are harvested by the "one fruit two cuts" method, and the fruits without mechanical damage are selected for sterilization and cleaning, and then soaked in the above-mentioned green preservative solution for 0.5 to 10 minutes, and the fruit is dried until there is no water stain on the surface after soaking, and then stored in a cold storage. In the present invention, as another practicable method, after soaking and drying, the fruit is packaged with a single fruit with holes using a preservative film and placed in an indoor storage or a cold storage. In the present invention, the preservative film can use conventional commercial products. In the present invention, the preservative film is preferably one or more of a polyvinyl chloride film, a POF packaging film, and an OPP heat-sealing film.

[0032] The present invention also provides a green preservative, or a use of the green preservative obtained by the preparation method in preparing a fruit green preservative product. In the present invention, the fruit includes but is not limited to citrus fruit; the citrus fruit is preferably lemon. The green preservative of the present invention is safe and easy to use. It can be used to soak the fruit. It can well maintain the color of the lemon, delay the degradation of chlorophyll in the lemon peel, maintain the fragrance of the lemon, reduce the incidence of diseases and insect pests during storage such as lemon black spot, and the color of the lemon fruit changes slowly during storage, and the fruit quality is well maintained.

[0033] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0034] In the experimental methods in the following examples, the deacetylation degree of chitosan is 75% to 80%, which is from MacLean Biochemical Technology Co., Ltd.; acetic acid and ethanol are from Sinopharm Chemical Reagent Co., Ltd.; 6-benzylaminopurine is from Sangon Biotechnology Co., Ltd.; gibberellic acid, emulsion, active ingredient content 3wt%, is from Shanghai Tongrui Biotechnology Co., Ltd.; citric acid is from Weifang Yingxuan Industrial Co., Ltd.

[0035] Example 1

[0036] A green preservative, wherein the active ingredients of the green preservative are composed of the following raw materials in parts by weight: 40 parts of chitosan, 1 part of 6-benzylaminopurine, 1 part of gibberellic acid, 20 parts of citric acid, and 10 parts of cinnamon extract;

[0037] The preparation method of the green preservative comprises the following steps: mixing cinnamon leaves with 70% ethanol solvent at a weight ratio of 1:5, and extracting cinnamon extract by ultrasonic extraction for standby use; the ultrasonic extraction conditions are ultrasonic power of 300W and extraction for 2h;

[0038] Chitosan was added to a 1% acetic acid solution, and the chitosan and acetic acid solution were mixed at a weight ratio of 1:50, and the mixture was stirred until the chitosan was dissolved to obtain a chitosan-acetic acid solution;

[0039] 6-benzylaminopurine, citric acid, gibberellic acid and chitosan-acetic acid solution are mixed to obtain a mixed solution; 0.75 parts of cinnamon extract are added to each liter of the mixed solution to obtain a green preservative.

[0040] Example 2

[0041] A green preservative, wherein the active ingredients of the green preservative are composed of the following raw materials in parts by weight: 20 parts of chitosan, 2 parts of 6-benzylaminopurine, 1 part of gibberellic acid, 10 parts of citric acid, and 3 parts of cinnamon extract;

[0042] The preparation method of the green preservative comprises the following steps: mixing cinnamon leaves with 70% ethanol solvent in a weight ratio of 1:2, and extracting cinnamon extract by ultrasonic extraction for standby use; the ultrasonic extraction conditions are ultrasonic power of 2500W and extraction for 1h;

[0043] Chitosan powder was added to 1% acetic acid solution, and the chitosan powder and acetic acid solution were mixed at a weight ratio of 1:50, and the mixture was stirred until the chitosan was dissolved to obtain a chitosan-acetic acid solution;

[0044] 6-benzylaminopurine, citric acid, gibberellic acid and chitosan-acetic acid solution are mixed to obtain a mixed solution; 0.55 parts of cinnamon extract are added to each liter of the mixed solution to obtain a green preservative.

[0045] Example 3

[0046] A green preservative, wherein the active ingredients of the green preservative are composed of the following raw materials in parts by weight: 30 parts of chitosan, 5 parts of 6-benzylaminopurine, 5 parts of gibberellic acid, 15 parts of citric acid, and 8 parts of cinnamon extract;

[0047] The preparation method of the green preservative comprises the following steps: mixing cinnamon leaves with 70% ethanol solvent at a weight ratio of 1:10, and extracting cinnamon extract by ultrasonic extraction for standby use; the ultrasonic extraction conditions are ultrasonic power of 150W and extraction for 0.5h;

[0048] Chitosan powder was added to 1% acetic acid solution, and the chitosan powder and acetic acid solution were mixed at a weight ratio of 1:60, and the mixture was stirred until the chitosan was dissolved to obtain a chitosan-acetic acid solution;

[0049] 6-benzylaminopurine, citric acid, gibberellic acid and chitosan-acetic acid solution are mixed to obtain a mixed solution; 0.025 parts of cinnamon extract are added to each liter of the mixed solution to obtain a green preservative.

[0050] Example 4

[0051] A method for protecting green lemons and preserving freshness comprises: harvesting green lemons that have reached edible standards, are more than 80% mature, and are free of pests and diseases by a "one fruit, two cuts" method; selecting green lemons without mechanical damage, sterilizing and cleaning them, and then soaking them in a green protecting and fresh-keeping agent solution of Example 1 for 2 minutes; drying the fruits after soaking until there is no water stain on the surface, and storing them in a cold storage.

[0052] Example 5

[0053] A method for preserving green lemons, comprising: harvesting green lemons that have reached edible standards, are more than 80% mature, and are free of pests and diseases by a "one fruit, two cuts" method; selecting green lemons without mechanical damage, sterilizing and cleaning them, and then soaking them in a green preservative solution of Example 2 for 0.5 minutes; drying the fruits after soaking until there is no water stain on the surface, and storing them in a cold storage.

[0054] Example 6

[0055] A method for preserving green lemons, comprising: harvesting green lemons that have reached edible standards, are more than 80% mature, and are free of pests and diseases by a "one fruit, two cuts" method; selecting green lemons without mechanical damage, sterilizing and cleaning them, and then soaking them in a green preservative solution of Example 3 for 10 minutes; drying the fruits after soaking until there is no water stain on the surface, and storing them in a cold storage.

[0056] Comparative Example 1

[0057] A greening and fresh-keeping agent, wherein the effective components of the greening and fresh-keeping agent are composed of the following raw materials in parts by weight: 10 parts of chitosan, 2 parts of 6-benzylaminopurine, 15 parts of citric acid, and 5 parts of cinnamon extract.

[0058] The preparation method is the same as Example 1 except that gibberellic acid is not added.

[0059] Test Example 1

[0060] After harvesting green lemons that have reached the edible standard and have a maturity of more than 80% and are free of pests and diseases using the "one fruit, two cuts" method, 40 green lemons without mechanical damage are selected for sterilization and cleaning, and then soaked in the green preservative solutions of Examples 1 to 2 and Comparative Example 1 for 2 minutes. After soaking, the fruits are dried until there is no water stain on the surface, and stored in a cold storage. The color difference of the green lemons stored for 1 day, 4 days, 11 days, 18 days and 25 days is measured respectively. At the same time, a control group is set up, and the harvested green lemons are washed and soaked in clean water for 2 minutes. The green lemons of each treatment group of Example 1, Example 2, Comparative Example 1 and the control group are measured with a colorimeter, and 3 different points are selected at the equator of the green lemon. The L* value, a* value, and b* value of each point are recorded, and each group is repeated 3 times. The effects of different treatment methods on the color difference of green lemons are shown in Table 1. Among them, L*, a*, and b* represent the brightness, red-green color, and yellow-blue color, respectively. "L*" represents the brightness of the object, and 0-100 represents from black to white; "a*" represents the red-green color of the object: positive values ​​represent red, and negative values ​​represent green; "b*" represents the yellow-blue color of the object: positive values ​​represent yellow, and negative values ​​represent blue.

[0061] Table 1 Effects of different treatment methods on the color difference of green lemon

[0062]

[0063] Note: The data in the table are average values.

[0064] According to Table 1, a* represents the change process of lemon skin from green to red. The smaller the value, the deeper the green. As time goes by, the skin of the four-season green lime gradually becomes lighter during storage. When the control group is stored for 25 days, the green color decreases significantly. The green change rate of a* value is from low to high in Example 2, Example 1, Comparative Example 1, and Control Group, indicating that Example 2 has the best green preservation effect. As time goes by, the b* value becomes larger and larger. The four-season green lime in Example 2 has a small area of ​​the fruit that turns yellow, while other examples turn yellow significantly. The yellowing rate is also from low to high in Example 2, Example 1, Comparative Example 1, and Control Group.

[0065] 10 fruits of each treatment group of Example 2, Example 1, Comparative Example 1 and Control Group were selected and weighed, and weighed once every 7 days to calculate the weight loss rate. The weight loss rate calculation formula is: weight loss rate (%) = (initial mass - mass at the time of measurement) / initial mass × 100%. The effects of different treatment methods on the weight loss rate of green lemons are shown in Table 2.

[0066] Table 2 Effect of different treatment methods on weight loss rate of green lemon

[0067]

[0068] Note: The data in the table are average values.

[0069] The respiration and transpiration of fruits and vegetables will cause the loss of quality, which will reduce the fullness of the fruit, make it lose its luster, cause wrinkles, lose nutrients, and even lose its commercial value. The smaller the weight loss rate of fruits and vegetables during storage, the better the preservation. Therefore, the weight loss rate is one of the important indicators for measuring the quality of fruits and vegetables. According to Table 2, after the green lemons were soaked in the green preservative of the present invention for 25 days of storage, the weight loss rate was less than that of the control group, indicating that the green preservative of the present invention can improve the preservation effect of green lemons.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A green preservative, characterized in that: The greening and fresh-keeping agent comprises the following components in parts by weight: 20 to 40 parts of chitosan, 1 to 5 parts of 6-benzylaminopurine, 1 to 5 parts of gibberellic acid, 10 to 20 parts of citric acid and 3 to 10 parts of cinnamon extract.

2. The green preservative according to claim 1, characterized in that: The deacetylation degree of the chitosan is 75% to 80%.

3. The method for preparing the green preservative according to claim 1 or 2, characterized in that: The steps include: After mixing cinnamon with ethanol solvent, ultrasonic extraction method is used to obtain cinnamon extract; Add chitosan to the acetic acid solution and stir to obtain a chitosan-acetic acid solution; 6-benzylaminopurine, citric acid, gibberellic acid and chitosan-acetic acid solution are mixed to obtain a mixed solution; cinnamon extract is added to the mixed solution to obtain a green preservative.

4. The preparation method according to claim 3, characterized in that: The conditions of the ultrasonic extraction are: ultrasonic power is 150W to 350W, and extraction time is 0.5 to 2h.

5. The preparation method according to claim 3, characterized in that: The concentration of the ethanol solvent is 60% to 90%.

6. The preparation method according to claim 3, characterized in that: The weight ratio of the cinnamon bark to the ethanol solvent is 1:2-10.

7. The preparation method according to claim 3, characterized in that: The weight ratio of the chitosan to the acetic acid solution is 1:40-60.

8. The preparation method according to claim 3, characterized in that: The weight ratio of the cinnamon extract to the mixed solution is 0.025-0.75:

1.

9. A method for preserving green lemons, characterized in that: The green preservative according to claim 1 or 2, or the green preservative obtained by the preparation method according to any one of claims 2 to 8, is used to soak the lemon for 0.5 to 10 minutes, and the lemon is dried after soaking until there is no water stain on the surface for storage.

10. Use of the green-keeping and fresh-keeping agent according to claim 1 or 2, or the green-keeping and fresh-keeping agent obtained by the preparation method according to any one of claims 2 to 8 in the green-keeping and fresh-keeping of fruits.

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