Method for preserving strawberries

Abstract

The present application relates to postharvest preservation technical field, propose a kind of strawberry fresh-keeping method, comprising: first ozone treatment and 1-methylcyclopropene treatment are carried out to strawberry fruit, obtain the fruit after processing;The fruit after processing is stored and handled, and the fruit is handled with second ozone treatment in the storage process.The method creates aseptic storage environment for strawberry fruit, while synergistically improving the storage resistance of fruit.In the storage process of fruit, ozone treatment is carried out for different harvest period fruits, effectively prolongs the fresh-keeping time of different harvest period fruits, has the advantages of safety, no pollution, no residue, no pollution, easy operation, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to the field of postharvest preservation technology, specifically, to a method for preserving strawberries. Background Technology

[0002] Strawberries are an important economic fruit, but they are susceptible to rapid spoilage after harvest due to mechanical damage or microbial contamination, limiting their sales time and scope. Furthermore, bacteria, yeasts, and molds adhering to their surface can pose a threat to consumer health. It is also noteworthy that the post-harvest storage performance of strawberries is closely related to their harvest date. Different harvest months result in physiological differences in the fruit, leading to variations in post-harvest storage behavior and storability, and affecting their response to preservation treatments. This indicates that the harvest date is also a crucial factor in regulating the post-harvest preservation effect of strawberries, but this factor has not been adequately and effectively studied.

[0003] Therefore, further research is needed on methods for preserving strawberries and the preservation effects on strawberry fruits at different harvest times. Summary of the Invention

[0004] This invention aims to address, to a certain extent, the technical problems existing in the prior art. To this end, this invention proposes a strawberry preservation method. This method utilizes a combined treatment of ozone and 1-methylcyclopropene to create a sterile storage environment for the strawberry fruit while synergistically improving the fruit's storability. Furthermore, ozone treatment is applied to fruits harvested at different times during storage, effectively extending the shelf life of fruits from different harvest periods. This strawberry preservation method is safe, pollution-free, residue-free, harmless, and easy to operate, making it suitable for widespread application.

[0005] In a first aspect, the present invention provides a method for preserving strawberries. According to an embodiment of the present invention, the method includes: subjecting strawberry fruit to a first ozone treatment and a 1-methylcyclopropene treatment to obtain treated fruit; and storing the treated fruit, wherein the fruit is subjected to a second ozone treatment during the storage process.

[0006] Through research, the inventors discovered that combined treatment of harvested strawberry fruit with ozone and 1-methylcyclopropene fumigation achieves a synergistic preservation effect, constructing a synergistic preservation strategy both internally and externally. Ozone acts on the outside of the fruit, its strong oxidizing properties effectively killing pathogens on the fruit surface. 1-Methylcyclopropene, on the other hand, acts inside the fruit, acting as a highly effective ethylene inhibitor, specifically blocking the binding of ethylene to receptors, inhibiting ethylene-mediated ripening and senescence processes at the signaling source, enhancing the fruit's anti-aging ability, and achieving long-term preservation. Simultaneously, ozone acts as a signaling molecule, activating the fruit's antioxidant defense pathways, while 1-methylcyclopropene treatment effectively inhibits respiratory metabolism and reduces the excessive production of reactive oxygen species (ROS) during mitochondrial electron transport, maintaining the homeostasis of the antioxidant defense system. Therefore, ozone and 1-methylcyclopropene synergistically enhance the fruit's ROS scavenging ability and maintain the redox balance in the fruit's cells, thereby improving the fruit's antioxidant capacity and storage resistance.

[0007] According to embodiments of the present invention, the above-described strawberry preservation method may further include at least one of the following additional technical features: According to an embodiment of the present invention, the strawberry fruit includes early-harvest fruit and late-harvest fruit.

[0008] According to an embodiment of the present invention, the soluble solids content of the early-harvested fruit is 9.50% to 10.63%.

[0009] According to an embodiment of the present invention, the soluble solids content of the late-harvest fruit is 7.39% to 8.25%.

[0010] According to an embodiment of the present invention, the ozone concentration of the first ozone treatment and the second ozone treatment is each independently 20 mg / m³. 3 ~80 mg / m 3 .

[0011] According to an embodiment of the present invention, for the early-harvest fruit, the ozone concentration of the first ozone treatment and the second ozone treatment are each independently 20 mg / m³. 3 ~60 mg / m 3 .

[0012] According to an embodiment of the present invention, for the early-harvest fruit, the ozone concentration of the first ozone treatment and the second ozone treatment are each independently 35 mg / m³. 3 ~45 mg / m 3 .

[0013] According to an embodiment of the present invention, for the late-harvest fruit, the ozone concentration of the first ozone treatment and the second ozone treatment are each independently 40 mg / m³. 3 ~80 mg / m 3 .

[0014] According to an embodiment of the present invention, for the late-harvest fruit, the ozone concentration of the first ozone treatment and the second ozone treatment are each independently 55 mg / m³. 3 ~65 mg / m 3 .

[0015] According to an embodiment of the present invention, the duration of the first ozone treatment and the second ozone treatment is independently 20 min to 40 min.

[0016] According to an embodiment of the present invention, the temperatures of the first ozone treatment and the second ozone treatment are each independently 18°C ​​to 22°C.

[0017] According to an embodiment of the present invention, the concentration of 1-methylcyclopropene treated with 1-methylcyclopropene is 1 μL / L to 4 μL / L.

[0018] According to an embodiment of the present invention, the concentration of 1-methylcyclopropene treated with 1-methylcyclopropene is 2.5 μL / L to 3.5 μL / L.

[0019] According to an embodiment of the present invention, the 1-methylcyclopropene treatment time is 10 h to 14 h.

[0020] According to an embodiment of the present invention, the temperature for the 1-methylcyclopropene treatment is 18 °C to 22 °C.

[0021] According to an embodiment of the present invention, the storage treatment includes storage at room temperature or storage at low temperature.

[0022] According to an embodiment of the present invention, the ambient temperature for storage is 16 ℃ to 28 ℃.

[0023] According to an embodiment of the present invention, the temperature for low-temperature storage is 2 ℃ to 6 ℃.

[0024] According to an embodiment of the present invention, the relative humidity of the storage treatment is 75% to 85%.

[0025] According to an embodiment of the present invention, during the storage process, the fruit is subjected to a second ozone treatment at a preset time interval, the preset time interval being 1 d to 2 d.

[0026] According to an embodiment of the present invention, for the room temperature storage, the preset time interval is 1 day to 1.5 days.

[0027] According to an embodiment of the present invention, for the low-temperature storage, the preset time interval is 1.5 days to 2 days.

[0028] According to an embodiment of the present invention, the strawberry fruit is pre-cooled before the first ozone treatment.

[0029] According to an embodiment of the present invention, the temperature of the pre-cooling treatment is 2 ℃ to 6 ℃.

[0030] According to an embodiment of the present invention, the precooling treatment time is 4 h to 6 h.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 The decay index, weight loss rate and firmness of strawberry fruits harvested in January under different concentration gradients of ozone or 1-MCP treatment. Figure 2 The decay index, weight loss rate and firmness of strawberry fruits harvested in February under different concentration gradient ozone or 1-MCP treatments were determined. Figure 3 The decay index, weight loss rate, and firmness of strawberry fruits harvested in March were determined under different concentration gradients of ozone or 1-MCP treatment. Figure 4 The decay index, weight loss rate, and firmness of strawberry fruits harvested in April under different concentration gradients of ozone or 1-MCP treatment were determined. Figure 5 The ascorbic acid content index of strawberries in different groups during low-temperature storage treatment; Figure 6 The total phenol content of strawberries in different groups during low-temperature storage treatment; Figure 7 The anthocyanin content index of strawberries in different groups during low-temperature storage treatment; Figure 8 The H2O2 content index of strawberries in different groups during low-temperature storage treatment; Figure 9 O2 levels in different groups of strawberries during low-temperature storage treatment - Content indicators; Figure 10 The MDA content of strawberries in different groups during low-temperature storage treatment; Figure 11The DPPH free radical scavenging rate of strawberries in different groups during low-temperature storage treatment; Figure 12 The SOD content of strawberries in different groups during low-temperature storage treatment; Figure 13 The CAT content index of strawberries in different groups during low-temperature storage treatment; Figure 14 APX content index of strawberries in different groups during low-temperature storage treatment; Figure 15 Images showing the preservation effects of different groups of strawberries under low-temperature storage treatment; Figure 16 The decay index, weight loss rate, and firmness of strawberries in different groups were compared when the strawberries were stored at room temperature. Figure 17 The brightness of strawberries in different groups during room temperature storage treatment L * Value, Red-green hue α *Value, SSC content, TA content indicators; Figure 18 Images showing the preservation effects of different groups of strawberries under normal temperature storage conditions. Detailed Implementation

[0033] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0034] In this embodiment of the invention, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this invention, but do not exclude other aspects.

[0035] In embodiments of the present invention, the terms “optionally,” “optionally,” or “optionally” generally refer to events or conditions described subsequently that may but may not occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0036] In this embodiment of the invention, the term "relative humidity" refers to the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure at the same temperature and pressure, expressed as a percentage, to characterize the degree of air humidity.

[0037] In this embodiment of the invention, the term "field heat" refers to the heat stored in the field environment (sunlight, temperature) and carried into the body of horticultural products such as fruits and vegetables during harvesting. It is sensible heat given by the external environment and is not generated by the product's own metabolism.

[0038] In this embodiment of the invention, the term "soluble solids content" refers to the total amount of all substances in fruit and vegetable juice that are soluble in water, mainly including sugars, organic acids, vitamins, soluble salts, etc., expressed as a percentage by mass.

[0039] In this embodiment of the invention, the term "titerable acidity" refers to the total amount of all organic acids in a fruit and vegetable sample that can be neutralized and titrated by a strong alkaline standard solution. It is expressed as the mass percentage of the main organic acids and reflects the total acid level of the fruit, which is closely related to flavor, maturity, and storage quality.

[0040] In this embodiment of the invention, the term "malondialdehyde (MDA)" refers to the main end product produced by lipid peroxidation of biological cell membranes. Its content can directly reflect the degree of cell membrane lipid damage and the level of aging and stress in the body. It is often used in postharvest storage of fruits and vegetables, plant stress resistance, and physiological and biochemical research as a physiological indicator for evaluating the degree of cellular oxidative damage and aging.

[0041] In this embodiment of the invention, the term "superoxide dismutase (SOD)" refers to a class of metal antioxidant enzymes that are widely present in living organisms and can specifically scavenge excess superoxide anion free radicals in the body, reduce membrane lipid peroxidation damage, and maintain cellular redox balance.

[0042] In this embodiment of the invention, the term "catalase (CAT)" refers to a class of antioxidant protective enzymes that are widely present in organisms. It can specifically catalyze the decomposition of hydrogen peroxide produced by cell metabolism, breaking it down into water and oxygen, thereby eliminating the toxicity of peroxides and reducing oxidative damage to cell membranes.

[0043] In this embodiment of the invention, the term "ascorbic acid peroxidase (APX)" refers to an important antioxidant enzyme in plants that uses ascorbic acid as an electron donor to specifically remove hydrogen peroxide from cells and participate in the balance of reactive oxygen species metabolism in chloroplasts and cytoplasm.

[0044] In one aspect of the invention, a method for preserving strawberries is provided. This method may include: S100: Strawberry fruits are subjected to a first ozone treatment and 1-methylcyclopropene fumigation (1-MCP) treatment to obtain the treated fruits.

[0045] According to an embodiment of the present invention, the strawberry fruit is pre-cooled before step S100. Pre-cooling treatment can achieve the following pretreatment effects: rapidly removing field heat from the fruit after harvest, reducing fruit respiration intensity and transpiration water loss, and maintaining fruit firmness and appearance quality. Simultaneously, it initially inhibits the growth of microorganisms on the fruit surface, enhances the bactericidal effect of subsequent ozone treatment, and shrinks the stomata on the fruit skin, reducing external environmental interference and facilitating the subsequent application and effectiveness of 1-MCP.

[0046] According to embodiments of the present invention, the pre-cooling temperature is 2℃~6℃. In some embodiments, the pre-cooling temperature is 2℃, 2.5℃, 3℃, 3.5℃, 4℃, 4.5℃, 5℃, 5.5℃, or 6℃. Pre-cooling at the above temperatures can effectively achieve the pre-treatment effect on the fruit, avoiding damage to the fruit due to excessively low temperatures or adverse effects from excessively high temperatures.

[0047] According to embodiments of the present invention, the pre-cooling treatment time is 4 h to 6 h. In some embodiments, the pre-cooling treatment time is 4 h, 4.5 h, 5 h, 5.5 h, or 6 h. Pre-cooling treatment that meets the above time can effectively achieve the pre-treatment effect on the fruit, avoiding damage to the fruit due to excessive time or affecting the treatment effect due to excessive time.

[0048] According to an embodiment of the present invention, in step S100, the strawberry fruit includes early-harvested fruit and late-harvested fruit.

[0049] According to embodiments of the present invention, the soluble solids (SSC) content of early-harvest fruits is 9.50%–10.63%. In some embodiments, the quality indicators of early-harvest fruits may further include titratable acidity (TA), color difference, ascorbic acid content, anthocyanin content, total phenolic content, etc. For example, for early-harvest red strawberry fruits, the titratable acidity (TA) is 0.32%–0.40%, and the lightness / darkness of the color difference (…) L *) ranged from 39.35 to 42.93, and the red-green saturation ( α The values ​​for * are 33.61 to 37.87.

[0050] According to embodiments of the present invention, the soluble solids (SSC) content of late-harvest fruit is 7.39%–8.25%. In some embodiments, the quality indicators of late-harvest fruit may further include titratable acidity (TA), color difference, ascorbic acid content, anthocyanin content, total phenolic content, etc. For example, for late-harvest red strawberry fruit, its titratable acidity (TA) is 0.34%–0.42%, and its color difference includes lightness / darkness (…). L *) ranged from 39.50 to 40.90, and the red-green saturation ( α *) ranges from 32.46 to 36.06.

[0051] According to an embodiment of the present invention, the ozone concentration in the first ozone treatment is 20 mg / m³. 3 ~80 mg / m 3 For early-harvested fruit, the ozone concentration for the first ozone treatment was 20 mg / m³. 3 ~60 mg / m 3 35 mg / m 3 ~45 mg / m3 In some embodiments, for early-harvested fruit, the ozone concentration for the first ozone treatment is 20 mg / m³. 3 22.5 mg / m 3 25 mg / m 3 27.5 mg / m 3 30 mg / m 3 32.5 mg / m 3 35 mg / m 3 37.5 mg / m 3 40 mg / m 3 42.5 mg / m 3 45 mg / m 3 47.5 mg / m 3 50 mg / m 3 52.5 mg / m 3 55 mg / m 3 57.5 mg / m 3 60 mg / m 3 For fruits harvested in the early stages, ozone treatment at the above concentrations can effectively sterilize the fruit surface and activate the fruit's antioxidant defense system.

[0052] According to an embodiment of the present invention, the ozone concentration in the first ozone treatment is 20 mg / m³. 3 ~80 mg / m 3 For late-harvested fruit, the ozone concentration for the first ozone treatment was 40 mg / m³. 3 ~80 mg / m 3 55 mg / m 3 ~65 mg / m 3 In some embodiments, for late-harvested fruit, the ozone concentration for the first ozone treatment is 40 mg / m³. 3 42.5 mg / m 3 45 mg / m 3 47.5 mg / m 3 50 mg / m 3 52.5 mg / m 3 55 mg / m 3 57.5 mg / m 3 60 mg / m 3 62.5 mg / m 3 65 mg / m 3 67.5 mg / m 3 70 mg / m 3 72.5 mg / m 375 mg / m 3 77.5 mg / m 3 80 mg / m 3 For late-harvest fruits, ozone treatment at the above concentrations can effectively sterilize the fruit surface and activate the fruit's antioxidant defense system.

[0053] According to embodiments of the present invention, the first ozone treatment time is 20 min to 40 min. In some embodiments, the first ozone treatment time is 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, or 40 min. Ozone treatment that meets the above treatment times can effectively achieve the bactericidal effect on the fruit surface and activate the fruit's antioxidant defense system, avoiding the risk of poor bactericidal effect due to too short a time or epidermal damage or quality deterioration due to too long a time.

[0054] According to embodiments of the present invention, the temperature of the first ozone treatment is 18 ℃ to 22 ℃. In some embodiments, the temperature of the first ozone treatment is 18 ℃, 18.5 ℃, 19 ℃, 19.5 ℃, 20 ℃, 20.5 ℃, 21 ℃, 21.5 ℃, or 22 ℃. Ozone treatment at the above temperatures can effectively achieve the bactericidal effect on the fruit surface and activate the fruit's antioxidant defense system, avoiding ozone degradation caused by excessively high temperatures or reduced ozone molecule diffusion activity caused by excessively low temperatures.

[0055] In some embodiments, the first ozone treatment involves placing strawberry fruit in an ozone fumigation bag for sealed gas fumigation. It should be noted that the first ozone treatment method may also include, but is not limited to, ozone water soaking or spraying, ozone atomization / gas phase spraying, and continuous low-concentration ozone slow release in cold chain / storage environments. Those skilled in the art should understand that the fumigation treatment methods in these embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention.

[0056] According to embodiments of the present invention, the concentration of 1-methylcyclopropene (1-MCP) used in the 1-methylcyclopropene treatment is 1 μL / L to 4 μL / L, preferably 2.5 μL / L to 3.5 μL / L. In some embodiments, the 1-MCP concentration is 1 μL / L, 1.25 μL / L, 1.5 μL / L, 1.75 μL / L, 2 μL / L, 2.25 μL / L, 2.5 μL / L, 2.75 μL / L, 3 μL / L, 3.25 μL / L, 3.5 μL / L, 3.75 μL / L, or 4 μL / L. Treatment with 1-MCP at the above concentrations can effectively maintain the antioxidant capacity of the fruit and increase its shelf life, avoiding excessive inhibition of normal physiological metabolism due to excessively high concentrations or poor preservation effect due to excessively low concentrations.

[0057] According to embodiments of the present invention, the treatment time for 1-methylcyclopropene is 10 h to 14 h. In some embodiments, the treatment time for 1-methylcyclopropene is 10 h, 10.5 h, 11 h, 11.5 h, 12 h, 12.5 h, 13 h, 13.5 h, and 14 h. 1-MCP treatment that meets the above time requirements can effectively maintain the antioxidant capacity of the fruit and improve its preservation time, avoiding excessive inhibition of the normal physiological metabolism of the fruit due to excessive time or poor preservation effect due to excessively short time.

[0058] According to embodiments of the present invention, the treatment temperature for 1-methylcyclopropene is 18 ℃ to 22 ℃. In some embodiments, the treatment temperature for 1-methylcyclopropene is 18 ℃, 18.5 ℃, 19 ℃, 19.5 ℃, 20 ℃, 20.5 ℃, 21 ℃, 21.5 ℃, and 22 ℃. 1-MCP treatment at the above temperatures can effectively maintain the antioxidant capacity of the fruit and improve its shelf life. It avoids excessively high temperatures that would increase fruit respiration and secrete more ethylene, thus weakening the effect of 1-MCP treatment, as well as 1-MCP escape caused by high temperatures, or excessively low temperatures that would cause the stomata on the fruit skin to shrink, making it difficult for the 1-MCP to effectively penetrate into the fruit and exert its effect.

[0059] In some embodiments, 1-MCP treatment involves placing a prepared 1-MCP aqueous solution in a sealed cardboard box for 1-MCP fumigation. Water is used as a dispersion medium or carrier to slowly release 1-MCP gas, maintaining a relatively constant gaseous concentration in the sealed space. It should be noted that 1-MCP treatment methods may also include, but are not limited to, gas-phase fumigation, liquid immersion, surface spraying / spraying, slow-release packaging, slow-release patches, and coatable film embedding. Those skilled in the art should understand that the fumigation treatment methods in these embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention.

[0060] S200: The treated fruit is stored, and during the storage process, the fruit is subjected to a second ozone treatment.

[0061] According to an embodiment of the present invention, in step S200, the storage treatment includes room temperature storage or low temperature storage. The room temperature storage temperature is 16 ℃ to 28 ℃, and the low temperature storage temperature is 2 ℃ to 6 ℃.

[0062] According to embodiments of the present invention, the relative humidity of the storage treatment is 75% to 85%. In some embodiments, the relative humidity of the storage treatment is 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, or 85%. The storage treatment that meets the above relative humidity can effectively extend the shelf life of strawberry fruits.

[0063] According to an embodiment of the present invention, the ozone concentration in the second ozone treatment is 20 mg / m³. 3 ~80 mg / m 3 For early-harvested fruit, the ozone concentration for the second ozone treatment was 20 mg / m³. 3 ~60 mg / m 3 35mg / m 3 ~45 mg / m 3 In some embodiments, for early-harvested fruit, the ozone concentration for the second ozone treatment is 20 mg / m³. 3 22.5 mg / m 3 25 mg / m 3 27.5 mg / m 3 30 mg / m 3 32.5 mg / m 3 35 mg / m 3 37.5 mg / m 3 40 mg / m 3 42.5 mg / m 3 45 mg / m 3 47.5 mg / m 3 50 mg / m 3 52.5 mg / m 3 55 mg / m 3 57.5 mg / m 3 60 mg / m 3 For fruits harvested in the early stages, a second ozone treatment at the above concentration can effectively sterilize the fruit surface and activate the fruit's antioxidant defense system.

[0064] According to an embodiment of the present invention, the ozone concentration for the second ozone treatment is 20 mg / m³.3 ~80 mg / m 3 For late-harvested fruit, the ozone concentration for the second ozone treatment was 40 mg / m³. 3 ~80 mg / m 3 55 mg / m 3 ~65 mg / m 3 In some embodiments, for late-harvested fruit, the ozone concentration for the second ozone treatment is 40 mg / m³. 3 42.5 mg / m 3 45 mg / m 3 47.5 mg / m 3 50 mg / m 3 52.5 mg / m 3 55 mg / m 3 57.5 mg / m 3 60 mg / m 3 62.5 mg / m 3 65 mg / m 3 67.5 mg / m 3 70 mg / m 3 72.5 mg / m 3 75 mg / m 3 77.5 mg / m 3 80 mg / m 3 For late-harvest fruits, a second ozone treatment at the above concentration can effectively sterilize the fruit surface and activate the fruit's antioxidant defense system.

[0065] According to embodiments of the present invention, the second ozone treatment time is 20 min to 40 min. In some embodiments, the second ozone treatment time is 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, or 40 min. The second ozone treatment that meets the above treatment time can effectively achieve the bactericidal effect on the fruit surface and activate the fruit's antioxidant defense system, avoiding the risk of poor bactericidal effect due to too short a time or epidermal damage or quality deterioration due to too long a time.

[0066] According to embodiments of the present invention, the temperature of the second ozone treatment is 18 ℃ to 22 ℃. In some embodiments, the temperature of the second ozone treatment is 18 ℃, 18.5 ℃, 19 ℃, 19.5 ℃, 20 ℃, 20.5 ℃, 21 ℃, 21.5 ℃, or 22 ℃. The second ozone treatment meeting the above temperatures can effectively achieve the bactericidal effect on the fruit surface and activate the fruit's antioxidant defense system, avoiding ozone degradation caused by excessively high temperatures or reduced ozone molecule diffusion activity caused by excessively low temperatures.

[0067] According to an embodiment of the present invention, during the storage process, the fruit is subjected to a second ozone treatment at a preset time interval, which is 1 to 2 days. The second ozone treatment that meets the aforementioned preset time interval can inhibit surface microorganisms and induce a defensive response in the fruit, while also taking into account preservation effect and convenience, reducing operating costs and mechanical disturbance risks, and avoiding excessive oxidation stimulation caused by overly frequent treatment, which increases the risk of epidermal damage, water loss and quality deterioration.

[0068] According to an embodiment of the present invention, for storage at room temperature, the preset time interval is 1 day to 1.5 days, preferably 1 day.

[0069] According to an embodiment of the present invention, for low-temperature storage, the preset time interval is 1.5 days to 2 days, preferably 2 days.

[0070] In some embodiments, the second ozone treatment involves placing the fruit in an ozone fumigation bag for sealed gas fumigation. It should be noted that the second ozone treatment method may also include, but is not limited to, ozone water soaking or spraying, ozone atomization / gas phase spraying, and continuous low-concentration ozone slow release in cold chain / storage environments. Those skilled in the art should understand that the fumigation treatment methods in the embodiments of this invention are for illustrative purposes only and should not be considered as limiting the scope of the invention.

[0071] Example 1: Suitable conditions for ozone and 1-MCP treatment (1) Experimental materials and pretreatment Red strawberries with a surface redness of 70% to 80% were collected in January, February, March, and April. Strawberries harvested in January and February had a soluble solids content of 9.50%–10.63%, indicating early-harvest fruit, while those harvested in March and April had a soluble solids content of 7.39%–8.25%, indicating late-harvest fruit. Healthy, undamaged fruits of uniform size and shape, free from pests or mechanical damage, were selected as experimental subjects. After harvesting, the fruits were pre-cooled at 4 ℃ for 6 h to remove field heat, yielding the fruits to be treated.

[0072] (2) Evaluation indicators The decay index, weight loss rate, and hardness were used as evaluation indicators, with three replicates per group. The calculation or testing methods for each indicator are as follows: Rot Index: The degree of strawberry rot is divided into 5 levels. Based on the statistical results of the rot degree of the samples taken, the rot status of strawberries in each group is statistically analyzed, and the rot index is calculated according to the following formula: .

[0073] Weight loss rate: The percentage (%) of weight reduction is determined by measuring the weight of strawberries stored for different times and calculating the ratio of the difference between the measured weight and the initial weight to the initial weight.

[0074] Hardness: The hardness of the strawberry was evaluated using a GY-4-J digital tester equipped with a probe (5 mm in diameter) at two symmetrical locations with an insertion depth of 5.0 mm, expressed in Newtons (N).

[0075] (3) Experimental setup 1. Single-factor experiment on ozone treatment or 1-MCP treatment Four ozone concentration gradients were set: 20 mg / m³ 3 (0.8 mg / kg), 40 mg / m 3 (1.6 mg / kg), 60 mg / m 3 (2.4 mg / kg), 80 mg / m 3 (3.2 mk / kg) The fruit to be treated was subjected to sealed fumigation in ozone fumigation bags. The sealed fumigation group without ozone gas was used as the control group (CK). The first ozone fumigation treatment and the second ozone fumigation treatment were carried out. The treatment temperature of the first ozone fumigation treatment and the second ozone fumigation treatment were both 20 ℃ and the treatment time was 30 min.

[0076] Three 1-MCP concentration gradients were set up: 2 μL / L, 3 μL / L, and 4 μL / L. The prepared 1-MCP solutions and the fruits to be treated were placed in sealed cardboard boxes and subjected to sealed fumigation treatment at 20 ℃ for 12 h. The group that was subjected to sealed fumigation treatment at 20 ℃ for 12 h with an aqueous solution without 1-MCP was used as the control group.

[0077] Single-factor experiments were conducted on strawberry fruits from different harvest periods to investigate ozone or 1-MCP treatments. The same treatment procedures were applied to strawberry fruits from different harvest periods, including: 1) Ozone fumigation treatment The fruits were first subjected to a 30-minute ozone fumigation treatment. After the treatment, they were stored for 12 days at a temperature of 4 ℃ and a relative humidity of 80%. The second ozone fumigation treatment was carried out at the storage time points of the 3rd, 6th and 9th days according to the preset time interval of 2 days. The various indicators were statistically analyzed on the storage treatment of the 0th, 3rd, 6th, 9th and 12th days, with 3 replicates for each group.

[0078] 2) 1-MCP fumigation treatment The fruits to be treated were subjected to 1-MCP fumigation for 12 h. After the treatment, they were stored for 12 days at a temperature of 4 ℃ and a relative humidity of 80%. The various indicators were statistically analyzed on the storage days of 0, 3, 6, 9 and 12, with 3 replicates for each group.

[0079] refer to Figure 1 , 2 As shown in Figures 3 and 4, among which, Figure 1 A, 1C, and 1E represent the decay index, weight loss rate, and firmness of January-harvested strawberries under different ozone concentration gradient treatments and storage days, respectively. Figure 1 B, 1D, and 1F represent the decay index, weight loss, and firmness of January-harvested strawberries under different concentration gradients of 1-MCP treatment for different storage days. Figure 2 A, 2C, and 2E represent the decay index, weight loss rate, and firmness of strawberry fruits harvested in February under different storage days under ozone treatment with different concentration gradients. Figure 2 B, 2D, and 2F represent the decay index, weight loss rate, and firmness of strawberry fruits harvested in February after different storage days under different concentration gradients of 1-MCP treatment. Figure 3 A, 3C, and 3E represent the decay index, weight loss rate, and firmness of strawberry fruits harvested in March under different concentration gradient ozone treatments and storage days, respectively. Figure 3 B, 3D, and 3F represent the decay index, weight loss, and firmness of strawberry fruits harvested in March after different storage days under different concentration gradients of 1-MCP treatment. Figure 4 A, 4C, and 4E represent the decay index, weight loss rate, and firmness of strawberry fruits harvested in April after different storage days under ozone treatment at different concentration gradients. Figure 4 B, 4D, and 4F represent the decay index, weight loss rate, and firmness of January-harvested strawberries under different concentration gradients of 1-MCP treatment for different storage days, respectively. The above figures show that, for strawberries harvested in January, February, March, and April, the decay index and weight loss rate increase with increasing post-harvest storage days, while firmness decreases. However, different concentrations of ozone or 1-MCP treatment do not inhibit each other in evaluating the evaluation indicators of strawberries harvested at different times during storage.

[0080] refer to Figure 1 and Figure 2 As shown, for strawberry fruits harvested in January and February, at 40 mg / m³... 3 Under ozone treatment (1.6 mk / kg) or 1-MCP treatment (3 μL / L), the spoilage index and weight loss during storage were at their lowest levels, while the hardness was at its highest. (Reference) Figure 3 and Figure 4 As shown, for strawberry fruits harvested in March and April, at 60 mg / m³ 3 Ozone treatment at 2.4 mg / kg or 1-MCP treatment at 3 μL / L resulted in the lowest rot index and weight loss during storage, while the highest firmness. These results indicate that the optimal ozone treatment concentration for early-harvest strawberries in January and February is 40 mg / kg. 3 (1.6 mk / kg), the preferred concentration of 1-MCP for treatment is 3 μL / L; the preferred concentration of ozone treatment for late-harvest strawberries in March and April is 60 mg / m³. 3 (2.4 mk / kg), the preferred concentration of 1-MCP treatment is 3 μL / L.

[0081] 2. Orthogonal experiment on strawberry preservation conditions Based on the single-factor experiments, a two-factor, three-level orthogonal experiment was conducted. The decay index, weight loss rate, and firmness were used as evaluation indicators. The specific treatments included: first, the fruit underwent a 30-minute ozone fumigation treatment, followed by a 12-hour 1-MCP fumigation treatment. After the initial treatment, the fruit was stored at 4 ℃ and 80% relative humidity for 12 days. Second ozone fumigation treatments were conducted at preset time intervals of 2 days on days 3, 6, and 9. All indicators were statistically analyzed on day 12 of storage. Each group had three replicates. The formal experimental designs for strawberry harvesting in January, February, March, and April are shown in Tables 1, 2, 3, and 4, respectively.

[0082]

[0083] The results of the orthogonal experiments for harvesting strawberries in January, February, March, and April are shown in Tables 5, 6, 7, and 8, respectively. K The value is the sum of the comprehensive scores of all experiments at the same level for a certain experimental factor; k The value corresponds to a certain factor K The average effect value of the experimental index at that level is obtained by dividing the value by the number of times that level appears in the orthogonal array. R The value is the average effect value of a certain factor. kThe difference between the maximum and minimum values ​​represents the degree of influence of the factor level change on the test index. The comprehensive score is obtained by weighted summation of multiple evaluation indicators according to their weights. Specifically, the decay index (negative indicator), weight loss rate (negative indicator), and hardness (positive indicator) are standardized by range processing to obtain standardized index values. The negative index is calculated as (Xmax-X) / (Xmax-Xmin), and the positive index is calculated as (X-Xmin) / (Xmax-Xmin). Xmax is the maximum value of each indicator among a certain negative or positive indicator, Xmin is the minimum value of each indicator among a certain negative or positive indicator, and X is the negative or positive index value corresponding to a certain test number. Then, the standardized values ​​of each indicator are averaged using the equal weight method to obtain the comprehensive score. The calculation formula is: Comprehensive score = (standardized value of decay index + standardized value of weight loss rate + standardized value of hardness) ÷ 3.

[0084] From the R values ​​in Tables 5, 6, 7, and 8, it can be seen that for strawberries harvested in January, February, March, and April, the influence of factor A (ozone) is greater than that of factor B (1-MCP). Furthermore, in the orthogonal experimental results, for strawberries harvested in January (Table 5), the combination with the highest comprehensive score is A2B2; for strawberries harvested in February (Table 6), the combination with the highest comprehensive score is A5B5; for strawberries harvested in March (Table 7), the combination with the highest comprehensive score is A8B8; and for strawberries harvested in April (Table 8), the combination with the highest comprehensive score is A11B11. Corresponding to the experimental design parameters in Tables 1, 2, 3, and 4, the results show that the optimal combined treatment for early-stage strawberry harvesting in January and February is an ozone treatment concentration of 40 mg / m³. 3 (1.6 mk / kg), 1-MCP treatment concentration 3 μL / L; the optimal combined treatment for late-harvest strawberries in March and April is ozone treatment concentration of 60 mg / m³. 3 (2.4 mk / kg), 1-MCP treatment concentration 3 μL / L.

[0085]

[0086]

[0087]

[0088]

[0089] Example 2: Low-temperature storage and preservation effect of combined ozone and 1-MCP treatment (1) Detection indicators 1) Quality Indicators 1. Soluble solids content (SSC): The strawberry sample was manually squeezed and the juice was placed on a PAL-1 handheld digital refractometer to measure the SSC (%).

[0090] 2. Titratable acidity (TA): Measured using a PAL-Easy ACID F5 pH meter, in units of %.

[0091] 3. Color difference: Surface color was measured using a Minolta CR-400 colorimeter. Measurements were taken at three symmetrical locations along the equatorial axis of each strawberry to analyze lightness and darkness. L *Value and red-green hue α *value.

[0092] 4. Ascorbic acid content: Weigh 2 g of the frozen sample powder, add 5 mL of oxalic acid-EDTA solution and grind in an ice bath. Centrifuge at 8000 rpm for 15 min at 4 ℃. Take 1 mL of the supernatant and add 4 mL of oxalic acid-EDTA. Then add 0.5 mL of 3% metaphosphoric acid-acetic acid solution, 1.0 mL of 5% sulfuric acid solution, and 2.0 mL of 5% ammonium molybdate solution. Dilute to 25 mL with distilled water. React at 80 ℃ for 60 min. Cool. Using a blank reference tube without sample, measure the absorbance at 760 nm. The unit is mg / 100g. -1 The ascorbic acid content.

[0093] 5. Anthocyanin content: determined by pH differential method. 1 g of the sample powder was added to 5 mL of 80% acetone solution (containing 0.2% formic acid) and centrifuged at 10,000 rpm for 20 min at 4 ℃. 1 mL of the supernatant was mixed thoroughly with 4 mL of sodium acetate buffer (pH 4.5) and 4 mL of potassium chloride buffer (pH 1.0), and reacted at 40 ℃ for 20 min. The absorbance values ​​of both solutions were measured at 510 nm and 700 nm, respectively. The difference in absorbance values ​​represented the relative anthocyanin content.

[0094] 6. Total phenol content: Take 2 g of the frozen sample powder, add 30 mL of 60% ethanol solution, grind thoroughly in an ice bath, extract thoroughly for 2 h in a dark and low-temperature environment, centrifuge at 4 ℃ and 10000 rpm for 20 min, collect 0.1 mL of supernatant, add 3 mL of deionized water, 0.5 mL of Folin-Ciocalteu reagent, and 2 mL of Na2CO3 solution, shake well, let stand for 60 min, and finally dilute to the mark with deionized water. Measure the absorbance at 760 nm. The unit is mg / g. -1 Total phenol content.

[0095] 2) Antioxidant indicators 7. Hydrogen peroxide (H2O2) content: Take 1 g of the frozen sample powder to be tested, add 5 mL of 0.25% trichloroacetic acid, centrifuge at 4 ℃ and 10000 rpm for 20 min, take 1 mL of the supernatant, add 2 mL of 100 mmol / L potassium phosphate buffer (pH 7.0) and 2 mL of 0.75 mol / L potassium iodide, and measure the absorbance value at 390 nm to obtain the H2O2 content.

[0096] 8. Weigh 2.0 g of the frozen sample powder to be tested, add 5.0 mL of extraction buffer, grind into a homogenate under ice bath conditions, centrifuge at 12000 g, 4 ℃ for 20 min, and collect the supernatant for determination. Take 1.0 mL of the supernatant, add 1.0 mL of 50 mmol / L, pH 7.8 phosphate buffer and 1.0 mL of 1 mmol / L hydroxylamine hydrochloride solution, shake well, and incubate at 25 ℃ for 1 h. After removal, add 1.0 mL of 17 mmol / L p-aminobenzenesulfonic acid solution and 1.0 mL of 7 mmol / L α-naphthylamine solution, mix well, and incubate at 25 ℃ for 20 min for colorimetric reaction, and immediately measure the absorbance value at 530 nm. O2· - Hydroxylamine hydrochloride is oxidized to nitrite. The nitrite then undergoes diazotization with p-aminobenzenesulfonic acid and α-naphthylamine, resulting in a colorimetric reaction. The absorbance at 530 nm is directly proportional to the nitrite concentration; therefore, the nitrite content can be determined from the standard curve, and the O2 concentration can be calculated based on the colorimetric and oxidation reactions. - The generation rate.

[0097] 9. Malondialdehyde (MDA) content: Take 1 g of the frozen sample powder and centrifuge it with 5 mL of 0.1% trichloroacetic acid solution at 4℃ and 10000 rpm for 20 min. Take 2 mL of the supernatant and mix it with 4 mL of 0.6% thiobarbituric acid. Incubate the mixture in boiling water for 20 min. After cooling, measure the absorbance values ​​at wavelengths of 450 nm, 532 nm, and 600 nm. The MDA content is calculated according to the following formula: MDA (μmol / g) = 6.45 × (A 532 -A 600 -0.56×A 450 Among them, A 450 A represents the absorbance value of the sample at a wavelength of 450 nm. 532 A represents the absorbance value of the sample at a wavelength of 532 nm. 600 This indicates the absorbance value of the sample at a wavelength of 600 nm.

[0098] 10. DPPH free radical scavenging ability: Take 1 g of the frozen sample powder, add 5 mL of 70% ethanol, and centrifuge at 4 ℃ and 10000 rpm for 20 min. Take 0.2 mL of the supernatant and mix it with 3.8 mL of 0.12 mmol / L DPPH solution. Incubate the mixture in the dark at 25 ℃ for 30 min, and measure its absorbance at 517 nm. Use the DPPH working solution without the sample as the control group. Calculate the DPPH free radical scavenging ability according to the formula: .

[0099] 11. Superoxide dismutase (SOD): The assay was performed using the WST-8 assay kit (purchased from Suzhou Grace Biotechnology, catalog number G0101W). Refer to the instruction manual for detailed operating procedures.

[0100] 12. Catalase (CAT): Weigh 5.0 g of the frozen sample powder to be tested, add 5.0 mL of 0.1 mol / L sodium phosphate buffer (pH 7.5, containing 5 mmol / L DTT and 5% PVPP), grind into a homogenate under ice bath conditions, centrifuge at 4 ℃ and 12000×g for 30 min, and collect the supernatant as the enzyme extraction solution. For the assay, take 2.9 mL of 20 mmol / L H2O2 solution in a cuvette, then add 100 μL of the enzyme extraction solution to start the reaction, and mix immediately. Using distilled water as a blank control, record the initial absorbance value at 240 nm 15 s after the start of the reaction, and then measure the absorbance change every 30 s, continuously measuring and recording at least 6 data points.

[0101] 13. Ascorbic acid peroxidase (APX): Weigh 5.0 g of the frozen sample powder to be tested, add 5.0 mL of 0.1 mmol / L sodium phosphate buffer (pH 7.5, containing 0.1 mmol / L EDTA, 1 mmol / L ascorbic acid and 2% PVPP), grind and homogenize under ice bath conditions, centrifuge at 4 ℃ and 12000×g for 30 min, and collect the supernatant as the enzyme extraction solution. For the assay, add 2.6 mL of reaction buffer and 0.1 mL of enzyme extraction solution to the reaction system sequentially, and finally add 0.3 mL of 2 mmol / L H2O2 solution to start the reaction. Mix immediately and start timing. Using distilled water as a blank control, record the initial absorbance value at 290 nm 15 s after the start of the reaction, and then measure the absorbance change every 30 s, continuously measuring and recording at least 6 data points.

[0102] (2) Group settings The experimental strawberries, after pre-cooling treatment (with treatment parameters as described in Example 1), were divided into early-harvest fruits and late-harvest fruits for the experiment. The groups were set as follows: Experimental Group 1: Combined Ozone and 1-MCP Treatment Group (O3 + 1-MCP). Specifically, the fruits were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored at 4 ℃ and 80% relative humidity for 12 days. Second ozone fumigation was performed at preset intervals of 2 days on days 3, 6, and 9. Various indicators were measured on days 0, 3, 6, 9, and 12 of the storage period. For fruits harvested early in the season, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 40 mg / m³. 3 (1.6 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 60 mg / m³. 3 (2.4 mk / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 ℃, and the concentration of 1-MCP was 3 μL / L.

[0103] Control Group 1: Control Group (CK). Specifically, the fruits to be treated were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored for 12 days at a temperature of 4 ℃ and a relative humidity of 80%. Second ozone fumigation was then performed at preset intervals of 2 days, on days 3, 6, and 9 of the storage period. Various indicators were measured on days 0, 3, 6, 9, and 12 of the storage period. For fruits harvested early in the season, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mk / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 ℃, and the concentration of 1-MCP was 0 μL / L.

[0104] Control Group 2: Ozone Treatment Group (O3). Specifically, the fruits to be treated were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored for 12 days at a temperature of 4 ℃ and a relative humidity of 80%. Second ozone fumigation was then performed at preset intervals of 2 days, on days 3, 6, and 9 of the storage period. Various indicators were measured on days 0, 3, 6, 9, and 12 of the storage period. For fruits harvested early in the season, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 40 mg / m³. 3 (1.6 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 60 mg / m³. 3 (2.4 mg / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 °C, and the concentration of 1-MCP was 0 μL / L.

[0105] Control group 3: 1-MCP treatment group (1-MCP). Specifically, the fruit to be treated was first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruit was stored at 4 ℃ and 80% relative humidity for 12 days. Second ozone fumigation was performed at preset time intervals of 2 days on days 3, 6, and 9 of the storage period. Various indicators were measured on days 0, 3, 6, 9, and 12 of the storage period. For early-harvest fruit, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mk / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 ℃, and the concentration of 1-MCP was 3 μL / L.

[0106] (3) Test results 1) Quality indicator test results The SSC detection results of experimental group 1 and control groups 1-3 are shown in Table 9; the TA detection results are shown in Table 10; brightness and darkness L *The detection results of the red-green color are shown in Table 11; α The results of the *value detection are shown in Table 12. Among them, the contents of SSC and TA both showed a trend of first increasing and then decreasing with the extension of storage time. In experimental group 1 of O3+1-MCP, the contents of SSC and TA in early-harvest and late-harvest fruits were higher than those in control groups 1-3 during storage. L *value andα The * values ​​showed a decreasing trend with the extension of storage time. In experimental group 1 of O3+1-MCP, the values ​​of early-harvested fruit and late-harvested fruit were... L *value and α The decrease in * values ​​during storage was 1-3 less than that in the control group. This indicates that the combined treatment of O3+1-MCP can effectively maintain soluble solids, titratable acid, and brightness of fruits during storage in both early and late harvest periods. L * Value and Red-Green Intensity Value α The *value index is stable, preserving the fruit's internal nutrients and appearance color quality.

[0107]

[0108]

[0109] The ascorbic acid content in experimental group 1 and control groups 1-3 was as follows: Figure 5 As shown, the total phenol content is as follows: Figure 6 As shown, the anthocyanin content is as follows: Figure 7 As shown, where, Figure 5 A, 6A, and 7A represent the test results of fruits harvested early in the season. Figure 5 B, 6B, and 7B represent the test results for fruits harvested late in the season. (Reference) Figure 5 As shown, the ascorbic acid content of fruits harvested early and late both exhibited a decreasing trend during storage treatment. The decrease in ascorbic acid content in O3+1-MCP experimental group 1 was significantly lower than that in control groups 1-3. (Reference) Figure 6 As shown, the total phenolic content of fruits harvested early and late both exhibited a trend of first increasing and then decreasing during storage. The total phenolic content of O3+1-MCP experimental group 1 was higher than that of control groups 1-3 during storage. (Reference) Figure 7 As shown, the anthocyanin content of both early-harvest and late-harvest fruits exhibited a trend of first increasing and then decreasing during storage treatment. In the early-harvest fruits of O3+1-MCP experimental group 1, the anthocyanin content was higher than that of control groups 1-3 during storage, while the anthocyanin content in the late-harvest fruits of experimental group 1 showed good retention during storage. These results indicate that the combined treatment with O3+1-MCP can effectively maintain the stability of ascorbic acid, total phenolic, and anthocyanin content in fruits from both early and late harvests during storage, thus preserving the fruit's intrinsic nutrients.

[0110] 2) Results of antioxidant index testing The H2O2 content of experimental group 1 and control groups 1-3 is as follows: Figure 8 As shown, O2 - Content such as Figure 9 As shown, the MDA content is as follows Figure 10As shown, where, Figure 8 A, 9A, and 10A represent the test results of fruits harvested at an early stage. Figure 8 B, 9B, and 10B represent the test results for fruits harvested late in the season. (Reference) Figure 8 As shown, the H2O2 content of fruits harvested early and late both showed an increasing trend during storage treatment. The increase in H2O2 content in O3+1-MCP experimental group 1 was significantly lower than that in control groups 1-3. On day 6, the H2O2 content in the early and late harvest CK groups was 29.32% and 23.70% higher than that in the O3+1-MCP compound treatment group, respectively, and the accumulation of H2O2 was significantly inhibited in the later storage period (days 6-12). (Reference) Figure 9 As shown, O2 levels during storage of early-harvest and late-harvest fruits. - The content of all O3+1-MCP experimental groups showed an increasing trend, with O2 content showing an increasing trend. - The increase in content was significantly lower than that in the control group (1-3). (Reference) Figure 10 As shown, as strawberry fruits mature and age, MDA content gradually accumulates, exacerbating lipid peroxidation and showing an upward trend. In the control group (CK), both early-harvest and late-harvest fruits showed an increasing MDA content during storage treatment. Specifically, in the O3+1-MCP experimental group 1, the increase in MDA content in early-harvest fruits was significantly lower than that in the control groups 1-3, while in late-harvest fruits, the MDA content showed an effective inhibitory effect compared to the CK group.

[0111] The DPPH free radical scavenging rate results of experimental group 1 and control groups 1-3 are as follows: Figure 11 As shown, the SOD content is as follows Figure 12 As shown, the CAT content is as follows Figure 13 As shown, the APX content is as follows: Figure 14 As shown, where, Figure 11 A, 12A, 13A, and 14A represent the test results of fruits harvested early in the season. Figure 11 B, 12B, 13B, and 14B represent the test results for fruits harvested late in the season. (Reference) Figure 11 As shown, the DPPH free radical scavenging capacity of fruits harvested early and late both exhibited a trend of first increasing and then decreasing during storage treatment. The variation range of DPPH free radical scavenging capacity in O3+1-MCP experimental group 1 was significantly lower than that in control groups 1-3, and its DPPH free radical scavenging capacity was higher than that in control groups 1-3. (Reference) Figure 12 As shown, the SOD content of both early-harvest and late-harvest fruits exhibited a trend of first increasing and then decreasing during storage. In the early-harvest fruits of the O3+1-MCP experimental group 1, the SOD content was effectively maintained and was higher than that of the control group 1-3 in the later stages of storage. In the late-harvest fruits, the SOD content was consistently higher than that of the control group 1-3. (Reference) Figure 13 As shown, the CAT content of fruits harvested early and late both exhibited a trend of first increasing and then decreasing during storage treatment. The CAT content of O3+1-MCP experimental group 1 was higher than that of control groups 1-3. (Reference) Figure 14 As shown, the APX content of fruits harvested early and late showed a trend of first increasing and then decreasing during storage treatment. The APX content of O3+1-MCP experimental group 1 was higher than that of control group 1-3.

[0112] The above results indicate that the antioxidant capacity of late-harvest fruits is relatively weaker than that of early-harvest fruits. However, the combined treatment with O3+1-MCP can effectively enhance the antioxidant capacity of strawberries in both early and late harvests, remove reactive oxygen species-related components during storage, and preserve the nutritional quality of stored strawberries. (Reference) Figure 15 As shown, the combined treatment of O3+1-MCP can maintain the external color quality of low-temperature storage and has a distinct preservation effect.

[0113] Example 3: Room temperature storage and preservation effect of combined treatment with ozone and 1-MCP (1) Detection indicators Including decay index, weight loss rate, hardness, SSC content, TA content, and lightness / darkness. L * Value and Red-Green Intensity Value α *Value. The calculation of each detection index refers to the corresponding index calculation method in Example 1 or Example 2.

[0114] (2) Group settings Experimental Group 2: Combined Ozone and 1-MCP Treatment Group (O3 + 1-MCP). Specifically, the fruits were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored for 6 days at 22 ℃ and 80% relative humidity. Second ozone fumigation was performed on days 2 and 4 at predetermined intervals. Quality indicators were statistically analyzed on days 0, 1, 2, 4, and 6 of the storage period. For fruits harvested early in the season, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 40 mg / m³. 3 (1.6 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 60 mg / m³. 3 (2.4 mk / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20℃, and the concentration of 1-MCP was 3 μL / L.

[0115] Control Group 4: Control Group (CK). Specifically, the fruits to be treated were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored for 6 days at 22 ℃ and 80% relative humidity. Second ozone fumigation was then performed on days 2 and 4 at predetermined intervals. Quality indicators were statistically analyzed on days 0, 1, 2, 4, and 6 of the storage period. For fruits harvested early in the season, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mk / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 ℃, and the concentration of 1-MCP was 0 μL / L.

[0116] Control Group 5: Ozone Treatment Group (O3). Specifically, the fruits to be treated were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored for 6 days at 22 ℃ and 80% relative humidity. Second ozone fumigation was performed on days 2 and 4 at preset time intervals of 1 day. Quality indicators were statistically analyzed on days 0, 1, 2, 4, and 6 of the storage period. For fruits harvested early in the season, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 40 mg / m³. 3 (1.6 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 60 mg / m³. 3 (2.4 mk / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 ℃, and the concentration of 1-MCP was 0 μL / L.

[0117] Control group 6: 1-MCP treatment group (1-MCP). Specifically, the fruits to be treated were first subjected to 30 min of ozone fumigation, followed by 12 h of 1-MCP fumigation. After the initial treatment, the fruits were stored for 6 days at 22 ℃ and 80% relative humidity. Second ozone fumigation was performed on days 2 and 4 at preset time intervals of 1 day. Quality indicators were statistically analyzed on days 0, 1, 2, 4, and 6 of the storage period. For fruits harvested early, the temperature for both the first and second ozone treatments was 20 ℃, and the ozone concentration was 0 mg / m³. 3(0 mk / kg); the temperature for both the first and second ozone treatments of late-harvest fruit was 20 ℃, and the ozone concentration was 0 mg / m³. 3 (0 mg / kg); the temperature for 1-MCP treatment of early-harvest and late-harvest fruits was 20 °C, and the concentration of 1-MCP was 3 μL / L.

[0118] (3) Test results The test results of decay index, weight loss rate, and hardness of experimental group 2 and control group 4-6 are as follows: Figure 16 As shown, where, Figure 16 A, 16C, and 16E represent the test results for the decay index, weight loss rate, and firmness of fruits in the early stages of harvest, respectively. Figure 16 B, 16D, and 16F represent the test results for the decay index, weight loss rate, and firmness of late-harvest fruits, respectively. The results indicate that, based on... Figure 16 As shown in A and 16B, the decay index of strawberries gradually increased with prolonged storage at room temperature, with a significant increase in the later stages of storage. However, the decay index of experimental group 2, treated with the O3+1-MCP combination, was 4-6 times lower than that of the control group during room temperature storage. At 6 days, the decay index of strawberries in experimental group 2 was 22.78% lower than that of the control group in the early harvest stage and 29.45% lower in the late harvest stage. (Reference) Figure 16 As shown in C and 16D, the weight loss rate of strawberries increased with increasing storage time at room temperature. The overall weight loss rate of strawberries in the late harvest was higher than that in the early harvest. Meanwhile, the weight loss rate of experimental group 2, treated with the O3+1-MCP combination, was 4-6 times lower than that of the control group during storage at room temperature. (Reference) Figure 16 As shown in E and 16F, the firmness of strawberries decreased with increasing storage time at room temperature. The initial firmness of strawberries in the late harvest was lower than that of strawberries in the early harvest, and the decrease was more obvious in the later storage period. However, the firmness of experimental group 2, which was treated with O3+1-MCP, was 4-6 times higher than that of the control group during the storage process at room temperature. At 6 days, the firmness of strawberries in experimental group 2 in the early harvest was 39.29% higher than that of the CK group, and the firmness of strawberries in the late harvest was 27.27% higher than that of the CK group.

[0119] SSC content, TA content, and brightness in experimental group 2 and control group 4-6 L * Value, Red-green hue α *Value detection results are as follows Figure 17 As shown, where, Figure 17 A, 17C, 17E, and 17G represent the lightness and darkness of fruits harvested in the early stages. L * Value, Red-green hue α The test results for * value, SSC content, and TA content, Figure 17 B, 17D, 17F, and 17H represent the lightness or darkness of fruits harvested late in the season. L * Value, Red-green hueα The results showed that the reference values, SSC content, and TA content were obtained. Figure 17 As shown in A and 17B, strawberries L The * value continuously decreased with prolonged storage at room temperature, and the O3+1-MCP co-treatment in experimental group 2... L The decrease in *value during room temperature storage was significantly lower than that in the control group (4-6). (Reference) Figure 17 As shown in C and 17D, strawberries α The color deterioration value initially increases and then decreases with prolonged storage at room temperature. However, the rate of color deterioration varies among strawberries harvested at different times, with earlier harvested fruits showing better color. α *The value reaches its peak on the 2nd day after storage at room temperature; late-stage fruits should be harvested. α The value reached its highest point on day 4 of storage at room temperature, while the value in experimental group 2, treated with the combined O3+1-MCP treatment, was higher. α The values ​​were all 4-6 higher than the control group during storage at room temperature. (See also...) Figure 18 As shown, experimental group 2, treated with the combined O3+1-MCP, maintained the red appearance of strawberries during room temperature storage, effectively mitigating the overall color deterioration process of strawberry fruits. (Reference) Figure 17 As shown in Figures E and 17F, the SSC content of strawberries initially increased and then decreased with prolonged storage at room temperature. The SSC content of experimental group 2, treated with the O3+1-MCP co-treatment, was consistently 4-6 times higher than that of the control group during room temperature storage. (Reference) Figure 17 As shown in G and 17H, the TA content of strawberries showed a trend of first increasing and then decreasing with the extension of storage time at room temperature. However, the rate of change of TA content of strawberries at different harvest periods was not consistent. The TA content of early-harvest fruits reached its highest value on the 4th day of storage at room temperature, while the TA content of late-harvest fruits reached its highest value on the 2nd day of storage at room temperature. The TA content of experimental group 2, which was treated with O3+1-MCP, was 4-6 times higher than that of the control group during the storage process at room temperature.

[0120] The above results indicate that there are differences in the physiological state of fruits in the early and late stages of harvest. Appropriate component concentrations need to be applied to the two types of fruits separately. Furthermore, ozone treatment during storage also requires appropriate methods depending on the storage conditions. The O3+1-MCP combined treatment method proposed in this invention can synergistically improve the storage resistance and antioxidant capacity of strawberry fruits, effectively extending their shelf life.

[0121] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0122] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preserving strawberries, characterized in that, include: Strawberry fruits were subjected to a first ozone treatment and a 1-methylcyclopropene treatment to obtain the treated fruits; The treated fruit is then stored, and during the storage process, the fruit undergoes a second ozone treatment.

2. The method according to claim 1, characterized in that, The strawberry fruit includes early-harvest fruit and late-harvest fruit; Optionally, the soluble solids content of the early-harvested fruit is 9.50% to 10.63%; Optionally, the soluble solids content of the late-harvest fruit is 7.39% to 8.25%.

3. The method according to claim 1, characterized in that, The ozone concentration in the first and second ozone treatments is independently 20 mg / m³. 3 ~80 mg / m 3 .

4. The method according to claim 2, characterized in that, For the early-harvest fruit, the ozone concentration for both the first and second ozone treatments was independently 20 mg / m³. 3 ~60 mg / m 3 ; Preferably, for the early-harvest fruit, the ozone concentration of the first ozone treatment and the second ozone treatment are each independently 35 mg / m³. 3 ~45 mg / m 3 .

5. The method according to claim 2, characterized in that, For the late-harvest fruit, the ozone concentration for the first and second ozone treatments was independently 40 mg / m³. 3 ~80 mg / m 3 ; Preferably, for the late-harvest fruit, the ozone concentration of the first ozone treatment and the second ozone treatment are each independently 55 mg / m³. 3 ~65 mg / m 3 .

6. The method according to claim 1, characterized in that, The duration of the first ozone treatment and the second ozone treatment is independently 20 min to 40 min; Optionally, the temperatures of the first ozone treatment and the second ozone treatment are each independently between 18 °C and 22 °C.

7. The method according to claim 1, characterized in that, The concentration of 1-methylcyclopropene treated with 1-methylcyclopropene is 1 μL / L to 4 μL / L; Preferably, the concentration of 1-methylcyclopropene treated with 1-methylcyclopropene is 2.5 μL / L to 3.5 μL / L; Optionally, the 1-methylcyclopropene treatment time is 10 h to 14 h; Optionally, the 1-methylcyclopropene treatment is performed at a temperature of 18 °C to 22 °C.

8. The method according to claim 1, characterized in that, The storage treatment includes storage at room temperature or storage at low temperature; Optionally, the ambient temperature storage temperature is 16 ℃ to 28 ℃; Optionally, the temperature for the low-temperature storage is 2 ℃ to 6 ℃; Optionally, the relative humidity of the storage treatment is 75% to 85%.

9. The method according to claim 1, characterized in that, During the storage process, the fruit is subjected to a second ozone treatment at a preset time interval, which is 1 to 2 days. Optionally, for the room temperature storage, the preset time interval is 1 day to 1.5 days; Optionally, for the low-temperature storage, the preset time interval is 1.5 days to 2 days.

10. The method according to claim 1, characterized in that, The strawberry fruit is pre-cooled before the first ozone treatment; Optionally, the temperature of the pre-cooling treatment is 2 ℃ to 6 ℃; Optionally, the precooling treatment time is 4 h to 6 h.

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