Chlorella-tea polyphenol composite coating preservation technology

Abstract

The invention discloses a chlorella and tea residue extract mixed fruit protection film, which takes chlorella and tea polyphenol as main active ingredients, and realizes preservation of various fruits through a composite coating technology. The preparation method comprises the following steps: dissolving food-grade chlorella powder and tea polyphenol powder in distilled water according to a mass ratio of (0.5-2): 1; uniformly smearing the smearing liquid on the surfaces of fruits and vegetables, and naturally air-drying to form the protective film. The protective film can effectively inhibit water evaporation, delay browning, maintain the activity of antioxidant enzyme and remarkably prolong the shelf life, particularly, when the mass ratio of the chlorella powder to the tea polyphenol powder is 1: 1, the preservation effect is optimal, and the product has the advantages of greenness, degradability, low cost, simplicity and convenience in operation and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fruit and vegetable preservation, and specifically relates to a compound coating technology taking Chlorella and tea polyphenol as materials. The technology can be widely used in the fields of food and fruit and vegetable preservation. BACKGROUND

[0002] Fruits are rich in vitamins, sugars, minerals and other essential nutrients for the human body, and play a crucial role in maintaining human health. However, fruits are prone to rotting, browning, damage and water loss after ripening, which not only leads to huge economic losses, but also may pose a potential threat to human health. Therefore, finding effective, green and convenient preservation measures has become a pressing problem. Traditionally, plastic preservative film wrapping or chemical preservative treatment is often used, but plastic film is difficult to degrade and can cause "white pollution", and chemical additives have potential safety risks, which do not meet the requirements of green and sustainable development.

[0003] In recent years, developing degradable and environmentally friendly alternative preservation materials has become a top priority. In this context, edible coating technology has become a research hotspot due to its green, safe and biodegradable advantages. This type of coating forms a functional film on the surface of fruits, which can inhibit water evaporation, block the invasion of oxygen and microorganisms, and delay oxidation, thereby maintaining fruit quality.

[0004] Currently, commonly used edible film-forming materials include polysaccharides (such as chitosan, sodium alginate), proteins (such as gelatin) and the like. Among them, Chlorella has potential in the preservation field due to its rich active ingredients such as polysaccharides and proteins, as well as good film-forming properties and biological activity. Studies have shown that Chlorella polysaccharides have a free radical scavenging rate of more than 50%, and an inhibition rate of common pathogenic bacteria of up to 58.29%. Tea polyphenol, as a tea extract, has strong free radical scavenging ability and antibacterial properties, and can effectively inhibit polyphenol oxidase activity and delay browning.

[0005] However, single coating materials have limitations in mechanical strength, stability and functional synergy. Chlorella coating has limited mechanical strength and functional stability; tea polyphenol is prone to oxidation and inactivation during storage. Existing research shows that the combination of polysaccharides and polyphenols can improve coating performance, but there is still a lack of research on the combination of Chlorella and tea polyphenol, and the synergistic mechanism and optimal ratio of the two still need to be further explored.

[0006] Therefore, developing a compound coating based on Chlorella and tea polyphenol can make full use of the complementary advantages of natural ingredients, which not only conforms to the trend of green development, but also has important significance for reducing plastic pollution and reducing postharvest losses of fruits and vegetables. This study aims to optimize the ratio and build an efficient and environmentally friendly fruit preservation solution, providing technical support for implementing the "double carbon" goal and promoting the green transformation of food packaging.

[0007] In view of this, the present application is proposed. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application provides a green, safe and degradable Chlorella vulgaris and tea polyphenol composite coating preservation technology. The technology utilizes the synergistic effect of natural active ingredients to form a multifunctional protective film on the surface of fruits, which can effectively reduce water loss, maintain nutritional components, inhibit browning and delay the spoilage process, thereby significantly extending the storage time and shelf life of fruits and vegetables and improving the storage quality. The present application aims to provide an environmentally friendly, simple and cost-effective green preservation solution for fruits and vegetables.

[0009] A Chlorella vulgaris and tea polyphenol composite coating preservation technology for fruit and vegetable preservation, the preparation method comprises the following specific steps: (1) Raw material preparation: food-grade Chlorella vulgaris powder and tea polyphenol extracted from tea residue are selected as the main active ingredients. This step makes full use of agricultural by-products and realizes resource utilization.

[0010] (2) Formula weighing: accurately weigh the Chlorella vulgaris powder and tea polyphenol powder according to the specified mass ratio. After systematic optimization, the optimal ratio of Chlorella vulgaris to tea polyphenol is 1:1, and in this experiment, the solvent is 20 g of distilled water, i.e. 0.1 g of Chlorella vulgaris powder and 0.1 g of tea polyphenol powder are weighed, and the concentration of each component is 1%.

[0011] (3) Solution preparation: add the weighed mixed powder into an appropriate amount of distilled water, mix uniformly at room temperature to form a uniform and stable composite coating solution. The entire preparation process does not require heating or the use of organic solvents, which is safe and environmentally friendly.

[0012] (4) Coating application: after washing and drying the fresh fruits and vegetables, the composite coating solution is uniformly applied to the surface of the fruits and vegetables by immersion, brushing or spraying. The coated fruits and vegetables are placed in a well-ventilated environment for natural air drying, and a transparent and dense protective film is formed on the surface.

[0013] Effects of the embodiments of the present application: By comparing the preservation effects of the blank group, the pure water group, the single component coating group and the composite coating group of the present application, it is proved that the present application has significant advantages. In the fresh-cut apple model, after 24 hours of storage, the mass loss rate of the composite coating treatment group of the present application is only 27%, which is significantly lower than that of the Chlorella vulgaris coating group (32%) and the tea polyphenol coating group (30%), showing excellent water retention performance.

[0014] In terms of antioxidant indexes, the total phenol content of the fruit and vegetable treated by the composite coating film reaches 1.79 times of the Chlorella coating film alone and 1.06 times of the tea polyphenol coating film alone, indicating that it can better maintain the antioxidant substance content of the fruit and vegetable. In particular, the catalase (CAT) activity of the composite coating film group is as high as 5.98 U / g, which is 5.03 times and 1.60 times of the Chlorella coating film alone (1.19 U / g) and the tea polyphenol coating film alone (3.74 U / g), respectively, revealing the strong antioxidant synergistic effect of the two, which can effectively enhance the ability of the fruit and vegetable to remove harmful substances such as hydrogen peroxide, delay cell membrane lipid peroxidation, and maintain cell integrity.

[0015] In terms of sensory quality, the composite coating film can effectively delay the browning of the skin of bananas and other fruits, and maintain good appearance color.

[0016] In summary, the Chlorella and tea polyphenol composite coating film preservation technology provided by the application not only has simple preparation process, natural and degradable raw materials, and low cost, but also realizes efficient maintenance of the postharvest quality of fruits and vegetables through the synergistic effect of the components, and has important application and popularization value and good environmental benefits. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 The figure is a schematic diagram of the preparation process of Chlorella powder; Figure 2 The figure is a schematic diagram of the preparation process of tea polyphenol powder; Figure 3 The figure is a schematic diagram of the preparation process of the preservation liquid; Figure 4 The figure is a schematic diagram of the preservation liquid being applied to banana and apple slices, respectively; DETAILED DESCRIPTION Some embodiments of the application will be described in detail below with reference to the drawings. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

[0019] Example 1: Short-term preservation effect of composite coating film on fresh-cut apples 0.1 g of food-grade Chlorella powder and 0.1 g of tea polyphenol powder were weighed and dissolved in distilled water, and stirred until completely dissolved, to prepare 20 g of Chlorella-tea polyphenol composite coating liquid.

[0020] Fresh apples with uniform size and maturity were selected and cut into uniform thickness slices. Apple slices were randomly selected and coated with the above-mentioned composite coating solution on one side. The same amount of pure water was coated as a control group, and the blank group was not treated. All treated apple slices were placed in a cool and dry place and stored at room temperature for 24 h.

[0021] After storage, various indicators were measured. The mass loss rate of fresh-cut apples in the composite coating treatment group was 27%, which was 17.6% lower than that in the single Chlorella group, proving that the composite coating has excellent moisturizing performance and can effectively reduce water transpiration, making the mass loss rate of fresh-cut apples lower.

[0022] The total phenol content of the apple in the composite coating treatment group was 31.83 mg / g, which was 1.79 times and 1.06 times that of the Chlorella coating group and the tea polyphenol coating group, respectively. This shows that the composite coating can more effectively slow down the oxidation loss of phenolic substances and maintain the antioxidant capacity of fruits and vegetables.

[0023] Among them, the catalase (CAT) activity of the apple in the composite coating treatment group was as high as 5.98 U / g, which was 5.03 times and 1.60 times that of the Chlorella coating group and the tea polyphenol coating group, respectively. The results reveal that there is a significant antioxidant synergistic effect between Chlorella and tea polyphenol, which can greatly enhance the ability of fruits and vegetables to remove active oxygen and delay cell aging.

[0024] The experimental results show that the composite coating of the present application can effectively maintain the postharvest quality of fresh-cut apples in short-term storage of 24 h through excellent moisturizing performance and strong antioxidant synergistic effect.

[0025] Example 2: Fresh-keeping effect of composite coating on bananas 0.2 g of Chlorella powder and 0.2 g of tea polyphenol powder were weighed and dissolved in distilled water, respectively, and stirred until completely dissolved to prepare 20 g of Chlorella coating solution and tea polyphenol coating solution.

[0026] Fresh bananas with uniform maturity and undamaged skin were selected and randomly divided into four groups: composite coating group, Chlorella coating group, tea polyphenol coating group, and blank control group (without any treatment). Except for the blank control group, the rest of the groups were evenly coated with the corresponding coating solution on the entire surface of the bananas. All bananas were stored under the same environmental conditions for 6 d.

[0027] The color change of the banana skin was observed regularly during storage, and the CAT enzyme activity was measured at the end of storage. The results showed that: After 6 d of storage, the banana skin of the blank control group had large areas of black spots and severe browning; the browning degree of the Chlorella coating group and the tea polyphenol coating group was lighter, indicating that coating treatment helped to delay the browning process of bananas.

[0028] It is found by testing CAT enzyme activity that CAT enzyme activity of the Chlorella alone coating group and the tea polyphenol alone coating group is significantly higher than that of the blank control and the distilled water group, indicating that the coating treatment can well maintain the antioxidant enzyme system activity of bananas, enhance the ability of removing active oxygen, thereby delaying cell aging.

[0029] The example proves that the Chlorella coating solution and the tea polyphenol coating solution of the application have a preservation effect on bananas, can effectively delay browning and maintain physiological activity, and provides an implementation basis for subsequent compound coating solution coating preservation.

[0030] In summary, the Chlorella-tea polyphenol compound coating preservation technology provided by the application is verified by experiments to have a significant preservation effect on different fruits and vegetables in short-term and long-term storage, and shows a good application prospect and economic and environmental benefits.

[0031] The above is only a preferred embodiment of the application and is not used to limit the application, and the application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A Chlorella tea polyphenol complex coating solution for fruit preservation, characterized by, Chlorella powder and tea polyphenol powder are used as the main antioxidant components for preservation. Preferably, considering the preservation effect and cost, 0.1 g of Chlorella powder and 0.1 g of tea polyphenol powder are added to 20 g of coating solution, and the mass ratio of Chlorella powder to tea polyphenol powder is 1:1, so that the composite coating solution has the best preservation effect. Preferably, the preparation method of the Chlorella tea polyphenol composite coating solution is that Chlorella powder and tea polyphenol powder are mixed in a mass ratio of 1:1 and completely dissolved in distilled water.

2. A fruit preservation method using the Chlorella tea polyphenol complex spread of claim 1, characterized by, The method comprises the following steps: Step 1: uniformly applying the coating solution to the surface of the fruit; Step 2: placing the coated fruit in a cool and dry place for storage under normal temperature conditions, and the coating solution can form an edible protective film on the surface.

3. The fruit preservation method according to claim 2, characterized by, The application of the coating technology can effectively reduce the quality loss rate of the fruit during storage.

4. The fruit preservation method according to claim 2 or 3, characterized by, The application of the coating technology can significantly delay the browning process of the fruit.

5. The fruit preservation method according to any one of claims 2 to 4, characterized in that, The application of the coating technology can effectively maintain the antioxidant enzyme activity of the fruit during storage, and the catalase (CAT enzyme) in the coated fruit can still maintain high activity after placement.

6. The fruit preservation method according to any one of claims 2 to 5, characterized in that, The use of the coating solution can effectively maintain the total phenol content of the fruit during storage, and the total phenol content of the coated fruit is increased.

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