A mulberry compound fresh-keeping method and application

Abstract

The application discloses a mulberry compound fresh-keeping method and application, first, a chitosan acetic acid solution is sprayed on the surface of mulberries, after precooling, the mulberries are soaked in a tea polyphenol solution, then a natural compound bacteriostatic liquid is sprayed, and finally, light treatment is carried out. The steps are synergistic, the problem of poor effect of chemical preservative coating treatment or physical sterilization treatment in the prior art is overcome, enzyme browning and microbial reproduction can be effectively inhibited, and the shelf life of the mulberries is significantly improved; the shelf life of the mulberries stored at room temperature is 5-7 days, the shelf life of the mulberries stored in a refrigerator can be prolonged to 20-25 days, the raw materials of the application have a wide source and low cost, no chemical preservative is used, the application meets green food standards, the operation is simple and easy to realize, no special equipment is needed, and the application has a wide market application prospect.

Description

Technical Field

[0001] This invention relates to the field of agricultural product preservation technology, and in particular to a method and application of compound preservation of mulberries. Background Technology

[0002] Mulberries, also known as mulberry fruit, are the berries of the mulberry tree. They have thin skin, are very juicy, and have a water content as high as 80% to 85%. After being picked, they are extremely difficult to store. At room temperature, they will turn brown, soften, and rot within 2 to 3 days, which seriously restricts their fresh consumption and long-distance transportation.

[0003] Currently, most mulberries are stored using a single low-temperature refrigeration technique (0-4℃). While this can moderately extend the fruit's shelf life to 7-10 days, the low temperature environment cannot effectively inhibit the activity of endogenous enzymes such as polyphenol oxidase (PPO), and the fruit will still undergo enzymatic browning. Furthermore, some psychrophilic microorganisms can still slowly multiply under refrigeration conditions, making it difficult to fundamentally control fruit rot. To compensate for the shortcomings of low-temperature refrigeration, existing technologies attempt to use chemical preservative coatings and physical sterilization as auxiliary preservation methods. While chemical preservatives, such as XGZM coatings, have a certain preservation effect, these methods pose a risk of chemical residues, and the operation process is relatively cumbersome and costly, failing to meet the current market demand for natural, safe, and green preservation technologies. Physical sterilization involves treating mulberries with ozone or UV-C. While this can inhibit some pathogenic microorganisms, the extremely thin and delicate mulberry peel is easily damaged by such high-energy treatments. This damages the epidermal cell structure and accelerates the degradation of active ingredients such as anthocyanins, negatively impacting the fruit's appearance and nutritional value. Furthermore, existing technologies use freezing to preserve mulberries. Although this method allows for long-term storage, the juice loss rate after thawing is as high as 20%–30%, resulting in a soft, mushy texture, deteriorated quality, and essentially eliminating its fresh-eating value. Therefore, to address these problems and technical needs, it is necessary to develop a safe, efficient, easy-to-operate method for preserving mulberries that can inhibit browning. Summary of the Invention

[0004] The purpose of this invention is to provide a compound preservation method and application for mulberries, which overcomes the problem that the chemical preservative coating treatment or physical sterilization treatment in the prior art has poor effect. It can effectively inhibit enzymatic browning and microbial reproduction, and significantly improve the shelf life of mulberries.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for compound preservation of mulberries includes the following steps: (1) Spray mulberries with chitosan acetate solution; (2) Pre-cool the mulberries; (3) Soak mulberries in a tea polyphenol solution; (4) Spray the mulberries with a natural compound antibacterial solution; (5) Expose the mulberries to sunlight.

[0006] In this invention, before preserving the mulberries, the harvested mulberries are first screened to remove rotten, cracked, and unripe fruit, followed by routine impurity removal. This does not affect the understanding of this solution by those skilled in the art. As is common knowledge, after each liquid treatment step (including steps 1, 3, and 4), the mulberries need to be placed in a ventilated place to dry before proceeding to the next step.

[0007] In this invention, the concentration of the chitosan acetate solution is 0.3~0.8g / L, and the spray volume is 5~8mL / kg, which is used to inhibit the respiration and surface microbial growth of mulberries.

[0008] In this invention, the pre-cooling involves placing the mulberries in a cold air pre-cooling warehouse with a temperature of 0~2℃ and a wind speed of 0.5~1.0m / s for 25~35 minutes to inhibit mulberry respiration and ethylene release, thereby extending shelf life.

[0009] In this invention, the concentration of the tea polyphenol solution is 1~5g / L, and the soaking time is 3~8min. It is used to inhibit the activity of polyphenol oxidase (PPO), slow down browning, and protect active ingredients such as anthocyanins from oxidation and destruction.

[0010] In this invention, the natural compound antibacterial liquid includes ginger juice, garlic water, rosemary extract solution, and water, with a spray volume of 5-8 mL / kg. It is a natural preservative without chemical components, used to inhibit and kill microorganisms and protect fruit cells from oxidative damage.

[0011] In this invention, the natural compound antibacterial liquid is prepared by mixing the following components in the following weight ratio: 0.8-1.2 parts ginger juice, 0.3-0.8 parts garlic water, and 0.1-0.5 parts rosemary extract solution, diluted with water to 100 parts. Further, the concentration of the ginger juice is 8-12 g / L; the concentration of the garlic water is 3-8 g / L; and the concentration of the rosemary extract solution is 1-5 g / L.

[0012] In this invention, the concentrations of the ginger juice, garlic water, and rosemary extract solutions mentioned above refer to the individual concentrations of each component, rather than the concentrations of each component in the prepared natural composite antibacterial solution.

[0013] In this invention, the illumination is blue light with a wavelength of 435-480nm and an intensity of 500-800 lux for 10-20 minutes, which is used to inhibit the activity of polyphenol oxidase (PPO), slow down browning, and protect active ingredients such as anthocyanins from oxidation and destruction.

[0014] This invention discloses preserved mulberries obtained according to the above-described mulberry compound preservation method.

[0015] This invention discloses the application of the above-mentioned mulberry compound preservation method in mulberry preservation.

[0016] Due to the application of the above-mentioned technical solutions, the beneficial effects of this invention compared to existing technologies are as follows: The mulberry compound preservation method provided by this invention can effectively improve the quality of preserved mulberries. It employs a technical route of spraying with chitosan acetate solution, pre-cooling, soaking in tea polyphenols, spraying with a natural compound antibacterial liquid, and light irradiation. The materials used are simple, convenient, environmentally friendly, and low-cost. It contains no chemical preservatives, meets green food standards, and compared to existing technologies, it can be operated without expensive specialized equipment and professional training, making it highly practical and possessing broad market application prospects. This invention uses chitosan acetate solution and a natural compound antibacterial liquid for spraying, using natural and non-toxic materials. The interspersed pre-cooling treatment can inhibit mulberry respiration and surface microbial growth. Soaking in tea polyphenol solution and blue light irradiation can effectively inhibit the activity of polyphenol oxidase, slow down browning, and protect anthocyanins and other active ingredients from oxidative damage. The synergistic effect of each step allows mulberries to have a shelf life of 5-7 days at room temperature and 20-25 days under cold storage. Attached Figure Description

[0017] Figure 1 This is a diagram showing the state of mulberries after 7 days of cold storage following preservation treatment using the method of this invention. Detailed Implementation

[0018] The raw materials used in the examples are: sodium chloride, chitosan, acetic acid solution, tea polyphenols, ginger, garlic, and rosemary extract, all of which are conventional products.

[0019] Before applying the preservation treatment of mulberries according to this invention, the mulberries need to undergo conventional impurity removal treatment. Specifically, select mulberries that are 8-9 ripe, undamaged, free from pests and diseases, and with intact stems. Soak them in a 0.5% (w / v) food-grade sodium chloride solution for 3 minutes, then remove them and let them drain naturally.

[0020] The mulberry compound preservation method disclosed in this invention includes the following steps: (1) spraying mulberries with chitosan acetate solution; (2) pre-cooling mulberries; (3) soaking mulberries in tea polyphenol solution; (4) spraying mulberries with natural compound antibacterial liquid; and (5) exposing mulberries to light.

[0021] Specifically, this invention first sprays mulberries with a chitosan acetate solution, forming a semi-permeable protective film on the mulberry surface to inhibit respiration and aid in antioxidant activity. Then, the mulberries are pre-cooled to lower the core temperature, further inhibiting respiration and ethylene release, thus delaying aging. Next, the mulberries are soaked in a tea polyphenol solution, whose strong antioxidant capacity inhibits polyphenol oxidase activity, slowing the enzymatic browning process and protecting anthocyanins and other active ingredients from oxidative degradation. Following this, a natural compound antibacterial liquid is sprayed, utilizing the synergistic antibacterial effects of ginger, garlic, and rosemary extracts to inhibit or kill putrefactive microorganisms on the mulberry surface. Finally, blue light treatment is applied, inducing an increase in the activity of endogenous antioxidant enzymes in the mulberries through specific wavelengths of blue light and promoting the accumulation of secondary metabolites, thereby effectively delaying the post-harvest aging process of mulberries and significantly extending their shelf life.

[0022] Performance testing is a standard technique, briefly described below: Rot rate: The rot rate is determined by counting the number of rotten mulberries before and after storage. Rot rate = (number of rotten mulberries / total number of mulberries) × 100%. The rot determination of mulberries is a conventional technique. As long as there is damage, it is judged as rotten fruit. Weight loss rate: The weight loss rate is determined by weighing the amount of weight reduction of mulberries before and after storage. Weight loss rate = (original weight - weight after storage) / original weight × 100%; Anthocyanin retention rate was determined using an existing anthocyanin content detection kit (Shanghai Shangbao Biotechnology Co., Ltd., BA1610) and the instructions. The determination was repeated 5 times, and the average value was taken. Anthocyanin retention rate = (anthocyanin content after storage / original anthocyanin content) × 100%. Hardness was determined using an existing texture analyzer (Shanghai Baosheng Industrial Development Co., Ltd., TAXTC-18) and the method described in the instruction manual. Example 1

[0023] A method for compound preservation of mulberries includes the following steps: (1) Take 0.5g of chitosan and add it to an aqueous solution of acetic acid with a volume concentration of 1%. Stir and dissolve at room temperature and then make up to 1L to obtain a chitosan acetic acid solution with a concentration of 0.5g / L. (2) Take the mulberries after the impurity removal treatment and spray the chitosan acetate solution from step (1) on their surface. Spray 7 mL of chitosan acetate solution per kg of mulberries. After spraying, let them air dry naturally and then place them in a cold air pre-cooling room with a temperature of 2℃ and a wind speed of 0.5 m / s for 30 min to pre-cool. (3) Take 2g of tea polyphenols and add them to pure water. Stir and dissolve at room temperature until the volume is 1L to obtain a tea polyphenol solution with a concentration of 2g / L. (4) Take the pre-cooled mulberries, soak them in the tea polyphenol solution of step (3) for 5 minutes, then take them out and let them drain naturally. (5) Take 10 mL of ginger juice with a concentration of 10 g / L, 5 mL of garlic water with a concentration of 5 g / L, and 3 mL of rosemary extract solution with a concentration of 3 g / L and add them to purified water. Stir and mix at room temperature until dissolved in 1 L to obtain a natural compound antibacterial solution. (6) Take the mulberries treated with tea polyphenol solution and spray the surface of them with the natural compound antibacterial liquid from step (5). Spray 7 mL of natural compound antibacterial liquid per kg of mulberries and let them air dry naturally after spraying. (7) Take the mulberries treated with natural compound antibacterial liquid and irradiate them with blue light with a wavelength of 435nm and a light intensity of 650lux for 15 minutes to complete the compound preservation of the mulberries.

[0024] In this embodiment, a 10 g / L ginger juice is obtained by adding 10 g of ginger to purified water, homogenizing, and then diluting to 1 liter; a 5 g / L garlic water is obtained by adding 5 g of garlic to purified water, homogenizing, and then diluting to 1 liter; and a 3 g / L rosemary extract solution is obtained by adding 3 g of rosemary extract to purified water, stirring and dissolving at room temperature, and then diluting to 1 liter. Application Example 1

[0025] 10 kg of mulberries after the preservation treatment in Example 1 were stored at a normal temperature of 22°C. On the third day of storage, the rot rate was 4.2%. Application Example 2

[0026] 10 kg of mulberries treated according to Example 1 were stored in a conventional refrigerated environment at 2°C. After 7 days of storage, the rot rate was 1.8%. (See [reference needed]). Figure 1 On the 21st day of storage, the rot rate was 4.6%, the weight loss rate was 4.5%, the anthocyanin retention rate was 84.7%, the hardness remained ≥2.0N, and the taste was acceptable. Comparison Example

[0027] 10 kg of mulberries, after only impurity removal, were stored in a conventional refrigerated environment at 2℃. After 7 days of storage, the rot rate was 10.6% and the anthocyanin retention rate was 52.1%. Comparative Example 1

[0028] Take 10 kg of mulberries after impurity removal treatment, treat them with a commercially available fruit and vegetable bactericide and preservative that claims to have a long shelf life, be easy to operate, leave no residue, and be non-toxic, and then store them in a refrigerated environment at 2℃. After 7 days of storage, the rot rate is 2.8%. Comparative Example 2

[0029] Take 10 kg of mulberries after impurity removal treatment, and follow the preservation method in Example 1, omitting the chitosan acetate solution spraying step, while keeping the rest the same, to obtain preserved mulberries. After 7 days of conventional storage in a 2℃ refrigerated environment, the spoilage rate was 3.5%. Comparative Example 3

[0030] Take 10 kg of mulberries after impurity removal treatment, and follow the preservation method in Example 1, omitting the tea polyphenol solution treatment step, while keeping the rest the same, to obtain preserved mulberries. Store them in a conventional refrigerated environment at 2℃. After 7 days of storage, the spoilage rate is 3.3%. Comparative Example 4

[0031] Take 10 kg of mulberries after impurity removal treatment, and follow the preservation method in Example 1, omitting the natural compound antibacterial liquid treatment step, while keeping the rest the same, to obtain preserved mulberries. Store them in a conventional refrigerated environment at 2℃. After 7 days of storage, the spoilage rate is 3.0%.

[0032] It can be seen that the mulberry compound preservation method of the present invention has synergistic effects in each step, which can effectively improve the quality of preserved mulberries and significantly extend their shelf life.

[0033] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the principle of the present invention, and these should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for compound preservation of mulberries, characterized in that: Includes the following steps: (1) Spray mulberries with chitosan acetate solution; (2) Pre-cool the mulberries; (3) Soak mulberries in a tea polyphenol solution; (4) Spray the mulberries with a natural compound antibacterial solution; (5) Expose the mulberries to sunlight.

2. The mulberry compound preservation method according to claim 1, characterized in that: The concentration of the chitosan acetate solution is 0.3~0.8 g / L, and the spray volume is 5~8 mL / kg.

3. The mulberry compound preservation method according to claim 1, characterized in that: The pre-cooling process involves placing the mulberries in a cold air pre-cooling chamber with a temperature of 0~2℃ and a wind speed of 0.5~1.0m / s for 25~35 minutes.

4. The mulberry compound preservation method according to claim 1, characterized in that: The concentration of the tea polyphenol solution is 1~5g / L, and the soaking time is 3~8min.

5. The mulberry compound preservation method according to claim 1, characterized in that: The natural compound antibacterial liquid includes ginger juice, garlic water, rosemary extract solution, and water, with a spray volume of 5~8 mL / kg.

6. The mulberry compound preservation method according to claim 5, characterized in that: The natural compound antibacterial liquid is prepared by mixing the following components in the following weight ratio: 0.8-1.2 parts ginger juice, 0.3-0.8 parts garlic water, 0.1-0.5 parts rosemary extract solution, and water is added to make up to 100 parts.

7. The mulberry compound preservation method according to claim 6, characterized in that: The concentration of the ginger juice is 8-12 g / L; the concentration of the garlic water is 3-8 g / L; and the concentration of the rosemary extract solution is 1-5 g / L.

8. The mulberry compound preservation method according to claim 1, characterized in that: The illumination is blue light with a wavelength of 435~480nm and an intensity of 500~800 lux, irradiated for 10~20 minutes.

9. Preserved mulberries obtained by the mulberry compound preservation method according to any one of claims 1 to 8.

10. The application of the mulberry compound preservation method according to any one of claims 1 to 8 in the preservation of mulberries.

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