A storage method for inhibiting cold injury of passion fruit

Abstract

The present application relates to the field of food preservation technology, and specifically discloses a storage and preservation method for inhibiting cold injury of passion fruit. The method comprises the following steps: (1) pretreatment: passion fruits with the same shape and maturity and without diseases and mechanical damage signs are soaked in a sterilizing agent solution, and then the moisture on the surface of the passion fruits is dried; (2) preservation treatment: the passion fruits in step (1) are fully soaked in a methyl jasmonate solution, then are subjected to room temperature fumigation treatment with the soaking solution, and then the moisture on the surface of the passion fruits is dried; (3) storage: the passion fruits obtained in step (2) are put into a preservation box, sealed with a preservation film, and stored in a low-temperature environment at 5±1℃. The method can effectively inhibit the occurrence of cold injury, delay the browning of the fruits, prolong the shelf life of the passion fruits in low-temperature storage, and has high treatment efficiency and is safe and harmless.

Description

Technical Field

[0001] This invention relates to the field of food preservation, and in particular to a method for storing and preserving passion fruit to inhibit chilling injury. Background Technology

[0002] Passion fruit, an egg-shaped fruit widely cultivated in tropical and subtropical regions, is highly valued by consumers for its unique aroma and flavor. However, passion fruit is extremely perishable after harvesting, quickly exhibiting signs of shriveling, rotting, and fermentation, severely impacting its commercial value and resulting in a very short shelf life. This is because passion fruit is a typical climacteric fruit, characterized by rapid respiration, significant water loss, and an acute ethylene response, leading to a rapid decline in its post-harvest physicochemical quality. To address this, various storage and preservation methods have been developed to maintain the post-harvest quality of passion fruit and maximize its shelf life. These methods include melatonin treatment, trisodium phosphate treatment, 1-MCP (1-methylcyclopropene) treatment, and calcium chloride treatment. These methods can significantly reduce weight loss and shriveling index during post-harvest storage, thereby substantially extending shelf life.

[0003] Passion fruit production areas in my country are concentrated in Guangxi, Yunnan, Guangdong, Hainan, and Fujian, with Guangxi having the largest planting area, accounting for 50-60% of the total production. Most passion fruit growing areas in Guangxi are mountainous with high altitudes and low nighttime temperatures. To ensure year-round supply, current passion fruit cultivation largely employs staggered planting techniques, which means that off-peak planting often encounters low nighttime temperatures and frequent late spring frosts. Furthermore, to facilitate nationwide sales, passion fruit is transported from the south to the north after harvest, where temperatures are even lower in autumn and winter. Post-harvest passion fruit is highly susceptible to chilling injury, which further deteriorates its quality. However, existing conventional passion fruit storage and preservation methods typically maintain temperatures at room temperature or 10-12°C, without specifically addressing low-temperature preservation. Therefore, when fruit merchants purchase passion fruit, in order to prevent chilling injury, they can only build a separate warehouse at room temperature or medium temperature, and cannot store and preserve passion fruit with other fruits in a traditional 4°C low-temperature cold storage.

[0004] In response to the aforementioned technologies, the inventors believe that it is necessary to develop a method for storing and preserving passion fruit that can inhibit chilling injury and extend the shelf life of low-temperature storage. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a storage and preservation method for suppressing chilling injury in passion fruit, which can suppress the occurrence of chilling injury in low-temperature storage of passion fruit, extend the shelf life of passion fruit in low-temperature storage, and is quick and convenient to handle without damaging the quality of passion fruit.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A method for storing and preserving passion fruit to inhibit chilling injury includes the following steps: (1) Soak passion fruits of the same shape and maturity and without signs of disease or mechanical damage in a fungicide solution, and then dry the surface of the passion fruits. (2) Soak the passion fruit in step (1) thoroughly in methyl jasmonate solution, then fumigate it at room temperature with the soaking solution in a bag, and then dry the surface of the passion fruit. (3) Put the passion fruit obtained in step (2) into a preservation box, seal it with plastic wrap, and store it in a low temperature environment of 5±1℃.

[0008] Compared to existing technologies, this invention provides a storage and preservation method for inhibiting chilling injury in passion fruit. First, a fungicide soaking treatment effectively removes pathogens adhering to the passion fruit surface, inhibiting disease growth during storage and reducing the risk of quality decline due to disease. Subsequent treatment combining methyl jasmonic acid soaking and fumigation significantly increases the content of antioxidants such as flavonoids and total phenols in the passion fruit, effectively enhancing its resistance to stress and protecting the integrity of cell membranes, thus inhibiting chilling injury under low-temperature conditions. Moreover, the soaking + bagging fumigation method is quick and convenient, requiring no strictly sealed environment for fumigation; treatment can begin immediately after harvesting. Furthermore, bagging fumigation only requires the extract from the passion fruit's surface, which can be reused, effectively reducing processing costs. Additionally, methyl jasmonic acid, as an endogenous plant substance, is relatively safe and environmentally friendly and will not affect the quality of the passion fruit. Based on experimental data, it can be seen that the storage and preservation method of this invention can extend the preservation time of passion fruit in a low temperature environment of 5±1℃ to more than 21 days, successfully solving the industry pain points of low temperature storage of passion fruit, off-peak marketing in winter, and short preservation period during the transportation of southern fruits to the north.

[0009] Further, step (2) involves soaking the fruit in a methyl jasmonate solution for 5 minutes, followed by fumigation at room temperature with the soaking solution in a bag for 3 hours. Soaking for 5 minutes ensures uniform contact of the agent with the fruit surface, preventing uneven protection against chilling injury due to inadequate local treatment; fumigation for 3 hours with the bag maintains a stable effective concentration of methyl jasmonate, preventing rapid volatilization and maximizing its chilling resistance. Simultaneously, the soaking and fumigation processes have a significant synergistic effect, achieving good storage and preservation results with only 3 hours of fumigation, a higher treatment efficiency than other existing methyl jasmonate-related preservation methods (conventional methods require 12–24 hours of treatment).

[0010] Furthermore, the concentration of the methyl jasmonate solution in step (2) is 10~100 μmol / L. A methyl jasmonate solution within this concentration range can enhance the stress resistance of passion fruit, inhibit cell membrane damage under low-temperature conditions, and reduce the occurrence of chilling injury symptoms, without causing physiological toxicity to the fruit due to excessively high concentrations, thus affecting the fruit's flavor and quality.

[0011] Furthermore, the concentration of methyl jasmonate solution in step (2) is 50 μmol / L. This concentration of methyl jasmonate has the best effect in inhibiting chilling injury in passion fruit. After being stored at a low temperature of 5±1℃ for 28 days, the chilling injury index is only 0.78, which can effectively delay the browning of passion fruit and maintain the good appearance quality of the fruit.

[0012] Furthermore, the same standard for shape and maturity in step (1) is that the passion fruit weighs 60-80g, is egg-shaped, and the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit. Passion fruit of this specification has moderate maturity, which not only has a certain degree of storage resistance, but also ensures the flavor and nutritional components of the fruit. After storage, it can still maintain good commercial quality and meet the market's quality requirements for the storage and preservation of passion fruit.

[0013] Furthermore, the bactericide solution in step (1) is a 0.1 wt% imidazole bactericide solution, and the soaking time is 10 minutes. This concentration range of imidazole bactericide solution can effectively kill pathogenic bacteria (such as molds and bacteria) on the surface of passion fruit. Soaking for 10 minutes can ensure the bactericidal effect, while not leaving too much residual agent, thus avoiding harm to human health.

[0014] Furthermore, the imidazole fungicide in step (1) is either prochloraz or imazalil. Both prochloraz and imazalil are conventional, highly effective, and low-toxic imidazole fungicides that have a significant inhibitory effect on common pathogens on the surface of passion fruit. Moreover, both are easily degraded and will not cause environmental pollution.

[0015] Furthermore, the food storage box in step (3) is made of polypropylene, and the food storage film is made of transparent polypropylene. Polypropylene is non-toxic, heat-resistant, cold-resistant, and has moderate air permeability. It can provide a stable storage environment for passion fruit, prevent the food storage box from breaking under low temperature conditions, maintain suitable humidity and gas concentration inside the box, reduce fruit moisture loss and respiration intensity, and delay fruit aging. The transparent food storage film makes it easy to observe the state of the fruit during storage, detect abnormalities in time, and has good sealing properties, which can effectively prevent the invasion of external pathogens and further extend the shelf life of the fruit.

[0016] Furthermore, this invention also applies for protection of the application of the storage and preservation method for inhibiting chilling injury in passion fruit storage and preservation.

[0017] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram showing the changes in flavonoid content in passion fruit treated by the storage and preservation methods of Example 2 and Comparative Example 1. Figure 2 This is a schematic diagram showing the changes in total phenolic content of passion fruit treated by the storage and preservation methods of Example 2 and Comparative Example 1. Figure 3 This is a schematic diagram showing the changes in MDA content of passion fruit treated by the storage and preservation methods of Example 2 and Comparative Example 1. Figure 4 This is a schematic diagram showing the change in relative conductivity of passion fruit treated by the storage and preservation methods of Example 2 and Comparative Example 1. Figure 5 These are comparative photographs showing the external changes of passion fruit treated by the storage and preservation methods of Example 2, Comparative Example 1, and Comparative Example 2. Figure 6 This is a schematic diagram showing the changes in L* values ​​of passion fruit treated by the storage and preservation methods of Example 2, Comparative Example 1, and Comparative Example 2. Figure 7 This is a schematic diagram showing the changes in the a* value of passion fruit treated by the storage and preservation methods of Example 2, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0019] The present application will be further described in detail below with reference to the embodiments. It should be emphasized that the embodiments described in the present invention are illustrative and not limiting. Therefore, the present invention is not limited to the embodiments described in the specific embodiments. Other embodiments derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

[0020] Unless otherwise specified, the reagents and instruments used in this specific embodiment are all commercially available products.

[0021] The passion fruit variety used in the following examples and comparative examples is Golden Passion Fruit, which was produced in an orchard in Pinggui District, Hezhou, Guangxi.

[0022] Example 1 A method for storing and preserving passion fruit to inhibit chilling injury, the specific steps of which are as follows: (1) Soak passion fruits of the same shape and maturity and without signs of disease or mechanical damage in a 0.1wt% fungicide solution for 10 minutes, and then dry the surface of the passion fruits. In step (1) of this embodiment, the same standard for shape and maturity is that the passion fruit weighs 60-80g, is egg-shaped, the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit, and the fungicide is imazalil. (2) Soak the passion fruit treated in step (1) in a 10 μmol / L methyl jasmonate aqueous solution for 5 min, then cover it with the soaking solution and fumigate at room temperature for 3 h, and then dry the surface of the passion fruit. The aqueous solution of methyl jasmonate in step (2) of this embodiment is prepared by the following method: first, dissolve methyl jasmonate in 1 ml of anhydrous ethanol, and then add it together to 1 L of distilled water; (3) Pack the passion fruit obtained in step (2) into a polypropylene preservation box, seal it with transparent polypropylene preservation film, and store it in a low temperature environment of 5±1℃.

[0023] Example 2 A method for storing and preserving passion fruit to inhibit chilling injury, the specific steps of which are as follows: (1) Soak passion fruits of the same shape and maturity and without signs of disease or mechanical damage in a 0.1wt% fungicide solution for 10 minutes, and then dry the surface of the passion fruits. In step (1) of this embodiment, the same standard for shape and maturity is that the passion fruit weighs 60-80g, is egg-shaped, the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit, and the fungicide is imazalil. (2) Soak the passion fruit treated in step (1) in a 50 μmol / L methyl jasmonate aqueous solution for 5 min, then cover it with the soaking solution and fumigate at room temperature for 3 h, and then dry the surface of the passion fruit. The aqueous solution of methyl jasmonate in step (2) of this embodiment is prepared by the following method: first, dissolve methyl jasmonate in 1 ml of anhydrous ethanol, and then add it together to 1 L of distilled water; (3) Pack the fresh passion fruit obtained in step (2) into a polypropylene preservation box, seal it with transparent polypropylene preservation film, and store it in a low temperature environment of 5±1℃.

[0024] Example 3 A method for storing and preserving passion fruit to inhibit chilling injury, the specific steps of which are as follows: (1) Soak passion fruits of the same shape and maturity and without signs of disease or mechanical damage in a 0.1wt% fungicide solution for 10 minutes, and then dry the surface of the passion fruits. In step (1) of this embodiment, the same standard for shape and maturity is that the passion fruit weighs 60-80g, is egg-shaped, the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit, and the fungicide is imazalil. (2) Soak the passion fruit treated in step (1) in a 100 μmol / L methyl jasmonate aqueous solution for 5 min, then cover it with the soaking solution and fumigate at room temperature for 3 h, and then dry the surface of the passion fruit. The aqueous solution of methyl jasmonate in step (2) of this embodiment is prepared by the following method: first, dissolve methyl jasmonate in 1 ml of anhydrous ethanol, and then add it together to 1 L of distilled water; (3) Pack the fresh passion fruit obtained in step (2) into a polypropylene preservation box, seal it with transparent polypropylene preservation film, and store it in a low temperature environment of 5±1℃.

[0025] Comparative Example 1 A method for storing and preserving passion fruit to inhibit chilling injury, the specific steps of which are as follows: (1) Soak passion fruits of the same shape and color and without signs of disease or mechanical damage in a 0.1wt% fungicide solution for 10 minutes, and then dry the surface of the passion fruits. In step (1) of this embodiment, the same standard for shape and maturity is that the passion fruit weighs 60-80g, is egg-shaped, the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit, and the fungicide is imazalil. (2) Soak the passion fruit treated in step (1) in distilled water (containing 0.1% volume fraction of anhydrous ethanol) for 5 minutes, then cover it with the soaking solution and fumigate at room temperature for 3 hours, and then dry the surface of the passion fruit. (3) Pack the fresh passion fruit obtained in step (2) into a polypropylene preservation box, seal it with transparent polypropylene preservation film, and store it in a low temperature environment of 5±1℃.

[0026] Comparative Example 2 A method for storing and preserving passion fruit to inhibit chilling injury, the specific steps of which are as follows: (1) Soak passion fruits of the same shape and color and without signs of disease or mechanical damage in a 0.1wt% fungicide solution for 10 minutes, and then dry the surface of the passion fruits. In step (1) of this embodiment, the same standard for shape and maturity is that the passion fruit weighs 60-80g, is egg-shaped, the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit, and the fungicide is imazalil. (2) The passion fruit treated in step (1) was fumigated with 1-MCP at room temperature for 3 hours and then placed in a ventilated place to air dry naturally; wherein the fumigation concentration of 1-MCP was 0.8 μL / L and the fumigation environment was a closed space. (3) Pack the fresh passion fruit obtained in step (2) into a polypropylene preservation box, seal it with transparent polypropylene preservation film, and store it in a low temperature environment of 5±1℃.

[0027] Comparative Example 3 A method for storing and preserving passion fruit to inhibit chilling injury, the specific steps of which are as follows: (1) Soak passion fruits of the same shape and color and without signs of disease or mechanical damage in a 0.1wt% fungicide solution for 10 minutes, and then dry the surface of the passion fruits. In step (1) of this embodiment, the same standard for shape and maturity is that the passion fruit weighs 60-80g, is egg-shaped, the mature color area of ​​the fruit accounts for 70% of the outer surface of the fruit, and the fungicide is imazalil. (2) The passion fruit treated in step (1) was fumigated with 1-MCP at room temperature for 3 hours and then placed in a ventilated place to air dry naturally; wherein the fumigation concentration of 1-MCP was 0.1 μL / L and the fumigation environment was a closed space. (3) Pack the fresh passion fruit obtained in step (2) into a polypropylene preservation box, seal it with transparent polypropylene preservation film, and store it in a low temperature environment of 5±1℃.

[0028] Experimental Example 1 1. Test Subjects: Fresh passion fruit harvested from the same batch (harvested less than 24 hours ago), selecting 60-80g egg-shaped fruits with a yellow area covering 70% of the fruit. Passion fruit meeting the requirements was treated with the storage and preservation methods of Examples 1-3 and Comparative Examples 1-3. Each storage and preservation method was tested in 3 parallel groups, with each parallel group containing 6 passion fruit fruits.

[0029] 2. Testing Method: On days 0, 7, 14, 21, and 28, the chilling injury index of passion fruit in each parallel group was recorded, and the final result was the average. The chilling injury index was graded according to the size of the chilling injury symptom area on the fruit surface, as follows: Level 0: No symptoms of chilling injury were observed; Level 1: Area affected by cold damage ≤ 25%; Level 2: 25% < area of ​​chilling injury symptoms < 50%; Level 3: 50% < cold damage symptom area < 75%; Level 4: Cold damage symptoms cover an area ≥75%.

[0030] Chilling injury index = (∑(chilling injury level × number of fruits at that level) / total number of fruits) × 100%.

[0031] 3. Test results: as shown in Table 1 below.

[0032] Table 1. Results of Cold Damage Index for Examples 1-3 and Comparative Examples 1-3

[0033] As shown in Table 1, when the storage and preservation method of Example 2 was used, passion fruit showed the best effect in inhibiting chilling injury. No chilling injury symptoms appeared until the 14th day, and the chilling injury index on the 28th day was only 0.78, which was much lower than the chilling injury index of Examples 1, 3, Comparative Example 1, and Comparative Example 3 at the same time. Comparative Example 2, which showed a relatively good effect in inhibiting chilling injury, had a chilling injury index of 1.33 on the 28th day, which was nearly twice that of Example 2. This further proves that the present invention can effectively inhibit chilling injury in passion fruit at low temperature (5±1℃) and extend the preservation time of passion fruit during low-temperature storage.

[0034] Furthermore, the chilling injury indices of Examples 1 and 3 on days 14, 21, and 28 were all lower than those of Comparative Example 1 during the same period. This indicates that the storage and preservation method of the present invention, after treatment with 10 μmol / L and 100 μmol / L methyl jasmonate aqueous solutions, also has a certain inhibitory effect on chilling injury in passion fruit under low-temperature (5±1℃) conditions. However, due to the relatively short fumigation time of 1-MCP, the inhibitory effect on chilling injury in Comparative Example 3 was not significant, with a chilling injury index only slightly lower than that of Comparative Example 1 during the same period. This indicates that when the fumigation time of low-concentration 1-MCP is shortened to 3 hours, the effect on inhibiting chilling injury in passion fruit is minimal.

[0035] Experiment Example 2 1. Test subjects: passion fruit from Example 2 and Comparative Example 1 in Experiment 1.

[0036] 2. Test method: Detect the flavonoid content, total phenol content, MDA (malondialdehyde) content, and relative conductivity of passion fruit in the corresponding groups.

[0037] 3. Test results: as attached. Figure 1-4 As shown.

[0038] Depend on Figure 1 and Figure 2 It can be seen that the passion fruit treated by the storage and preservation method of Example 2 of this scheme had higher flavonoid and total phenolic content than the passion fruit of the comparative group 1 at the same time after the start of low-temperature storage. Furthermore, on days 7, 14, and 21, the flavonoid and total phenolic content of the passion fruit of Example 2 was higher than that on day 0. As flavonoids and total phenols are antioxidants, the higher their content, the better the fruit's resistance to stress. This not only extends the storage time but also ensures the quality of the passion fruit. This fully demonstrates that the reason why the storage and preservation method of this invention can extend the storage time is that it can effectively increase the antioxidant content of the passion fruit.

[0039] Depend on Figure 3 and Figure 4It can be seen that the passion fruit treated by the storage and preservation method in Example 2 of this scheme had lower MDA content and relative conductivity than the passion fruit in Comparative Example 1 after the start of low-temperature storage. MDA and relative conductivity are both parameters related to cell membrane integrity. The lower the value of both, the more intact the cell membrane of the fruit, the less chilling injury, and the better the preservation effect. This also proves that the storage and preservation method of this invention can delay the damage of fruit cell membranes at the cellular level, thereby extending the preservation time.

[0040] Experimental Example 3 1. Test subjects: passion fruit from Example 2, Comparative Example 1, and Comparative Example 2 in Experiment 1.

[0041] 2. Test method: The L* value (brightness value) and a* (red-green value) of passion fruit were measured using a 3nh NR110 colorimeter. The smaller the L* value, the higher the degree of browning of the fruit. The higher the a* value, the redder the fruit, which also indicates the higher the degree of spoilage.

[0042] 3. Test results: such as Figure 5-7 .

[0043] like Figure 5 As shown, the passion fruit in Comparative Example 1 began to show obvious browning on day 21, and by day 28 it was almost completely browned, resulting in the complete loss of commercial value. The passion fruit in Comparative Example 2 and Example 2 showed better browning, and even by day 28, no severe browning was observed.

[0044] like Figure 6 As shown, the L* value of passion fruit in Comparative Example 1 decreased significantly, exhibiting a linear downward trend overall, with a relatively small decrease only on day 7, after which the L* value decreased significantly. The decrease in L* value of passion fruit in Comparative Example 2 and Example 2 was significantly less than that in Comparative Example 1, and the decreases were similar for both before day 21. However, by day 28, the L* value of passion fruit in Comparative Example 2 showed a significant decrease. Figure 7 As shown, the a* value of passion fruit in Comparative Example 1 increased significantly, especially from day 7 to day 14. The increase in a* value of passion fruit in Comparative Example 2 (Example 2) was also significantly lower than that in Comparative Example 1. Both groups showed similar increases before day 21, but by day 28, the a* value of passion fruit in Comparative Example 2 showed a significant increase.

[0045] according to Figure 6 and Figure 7Analysis shows that while the storage and preservation method (1-MCP fumigation) in Comparative Example 2 can extend the storage time of passion fruit at low temperatures and inhibit chilling injury, it can only extend the low-temperature storage time to 21 days. In contrast, the storage and preservation method in Example 2 of this invention can extend the low-temperature storage time to 28 days. Furthermore, in Comparative Example 2, the 1-MCP fumigation treatment increased the fumigation concentration to 0.8 μL / L to shorten the fumigation time to 3 hours. This indicates that, even with a higher 1-MCP concentration and the same 3-hour fumigation time, the preservation method in Comparative Example 2 is less effective at inhibiting chilling injury than the storage and preservation method in Example 2 of this invention. Therefore, the storage and preservation method in Example 2 of this invention not only inhibits chilling injury in passion fruit and extends its shelf life but also effectively improves the effect of inhibiting chilling injury.

[0046] Experiment Example 4 1. Test Subjects: Fresh passion fruit harvested from the same batch (harvested less than 24 hours ago). Egg-shaped fruits weighing 60-80g with a yellow area comprising 70% of the fruit were selected. Passion fruit meeting the requirements were treated according to the storage and preservation methods of Examples 1-3 and Comparative Examples 1-3. Ten passion fruits were treated in each group. After storage at 5±1℃ for 14 days, three passion fruits from each group with a chilling injury level of 0 were selected. Additionally, three passion fruits harvested on the same day with a maturity of 70% were used as a control group.

[0047] 2. Test method: Record the maturity (the proportion of yellow area on the outer surface of the fruit) of each group of passion fruit at 0h, 12h, 24h, 36h and 48h, and take the average value of the results.

[0048] 3. Test results: as shown in Table 2.

[0049] Table 2. Results of self-ripening changes in passion fruit after storage in Examples 1-3 and Comparative Examples 1-3.

[0050] As shown in Table 2, the storage and preservation methods of Examples 1-3 of this invention do not affect the natural ripening of passion fruit after storage. After 14 days of low-temperature storage, the passion fruit can still complete the process from 70% maturity to near full maturity within 48 hours, and its self-ripening progress is basically the same as that of freshly picked passion fruit. However, the passion fruit treated by the storage and preservation method of Comparative Example 1, because it was treated with only distilled water, although it did not appear to have chilling injury on the surface, actually had accumulated a large amount of cell damage. Therefore, after rewarming, obvious browning occurred, which seriously affected the quality. The passion fruit in Comparative Examples 2 and 3 was affected by the use of 1-MCP, which affected the passion fruit's own ethylene self-ripening system. Its self-ripening efficiency was slower than that of the freshly picked control group of passion fruit. In particular, the passion fruit in Comparative Example 2 had a very slow self-ripening efficiency, and even after 48 hours, its maturity only increased by 10%.

[0051] Further analysis of the treatment method of applying 1-MCP to the low-temperature storage and preservation of passion fruit (Comparative Example 2 and Comparative Example 3) revealed that this method has some unsolvable problems in the actual application of passion fruit storage and preservation.

[0052] First, 1-MCP fumigation is a gas-phase fumigation process, which requires a strictly controlled, enclosed environment. If air leaks occur during fumigation, the effectiveness of 1-MCP in suppressing chilling injury will be significantly reduced. Furthermore, 1-MCP works by competitively binding to ethylene receptors on the plant epidermis, even inhibiting the expression of endogenous ethylene, thus slowing fruit ripening. For 1-MCP fumigation to be optimal, it needs to fully bind to the ethylene receptors on the fruit surface, requiring sufficient fumigation time. Therefore, 1-MCP fumigation generally requires 6-12 hours, and in special cases, even 12-24 hours. However, the post-harvest treatment window for passion fruit is only 24 hours. Therefore, any unexpected events or emergencies can cause the treatment window to be missed, resulting in additional losses and impacting the profits of growers and buyers.

[0053] While ensuring the inhibition of chilling injury, shortening the fumigation time of 1-MCP can be achieved by increasing its concentration during fumigation (as demonstrated by the results of Comparative Example 2 in Experiment 1). However, this approach has adverse consequences. Firstly, it significantly increases processing costs because 1-MCP is a gas at room temperature and has low solubility and instability in water, requiring gas-phase fumigation. This means that 1-MCP can only be used once per fumigation session, and the amount of 1-MCP used is not dependent on the quantity of passion fruit to be treated but rather on the volume of the enclosed space during fumigation. In other words, the amount of 1-MCP used will not decrease with a reduction in the quantity of passion fruit and cannot be adjusted according to actual conditions. Secondly, high concentrations of 1-MCP not only block ethylene receptors but also inhibit the endogenous ethylene secretion of passion fruit, slowing down the later ripening process and even preventing self-ripening, severely impacting the quality of the passion fruit (as demonstrated by the results of Comparative Examples 2 and 3 in Experiment 4).

[0054] Compared to existing technologies, this invention effectively increases the flavonoid and total phenolic content of the fruit, reduces MDA content and relative conductivity, delays fruit browning, maintains fruit quality, and extends the shelf life of passion fruit during low-temperature storage by combining fungicide soaking, methyl jasmonate soaking + bagging fumigation, and low-temperature sealed storage. Treatment with 50 μmol / L methyl jasmonate can even extend the shelf life of passion fruit during low-temperature storage to 28 days, and the chilling injury index on the 28th day is only 0.78, still retaining most of the commercial value of the passion fruit.

[0055] Furthermore, compared to existing 1-MCP storage and preservation methods, the storage and preservation method of this invention is quick and convenient to operate. The entire process requires no complex equipment or the construction of a special sealed space for fumigation. It only requires soaking in the extract (methyl jasmonate aqueous solution) for 5 minutes before bagging and fumigation. Moreover, the extract can be reused, and only a small amount of extract carried out from the surface of the passion fruit after soaking is needed for bagging and fumigation. Based on this treatment method, harvesting and preservation can even be carried out simultaneously, greatly improving processing efficiency. In contrast, the 1-MCP storage and preservation method, limited by the need for a dedicated sealed fumigation space, requires a certain number of passion fruits to be harvested before fumigation can begin. Furthermore, the 1-MCP storage and preservation method cannot perform bagging and fumigation as in this application. On the one hand, the sealing of bagged fumigation is not as good, and the gaseous 1-MCP can easily escape; on the other hand, individual 1-MCP fumigation of each passion fruit requires a large amount of 1-MCP, which is too costly and impractical.

[0056] In addition, the methyl jasmonate used in the preservation method of this invention is an endogenous plant substance. Specifically, it enhances the stress resistance of passion fruit by increasing its own antioxidants, thereby inhibiting chilling injury, and does not affect the quality of passion fruit. 1-MCP, on the other hand, is a chemically synthesized substance. Its mechanism of action is to competitively bind to ethylene receptors and simultaneously inhibit the endogenous secretion of ethylene, which will affect the quality of passion fruit to some extent.

[0057] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for storing and preserving passion fruit to inhibit chilling injury, characterized in that, Includes the following steps: (1) Pretreatment: Soak passion fruits of the same shape and maturity and without signs of disease or mechanical damage in a fungicide solution, and then dry the surface of the passion fruits. (2) Preservation treatment: Soak the passion fruit in step (1) in methyl jasmonate solution, then cover it with the soaking solution and fumigate at room temperature, and then dry the surface of the passion fruit. (3) Storage: Put the passion fruit obtained in step (2) into a preservation box, seal it with plastic wrap, and store it in a low temperature environment of 5±1℃.

2. The method for storing and preserving passion fruit to inhibit chilling injury according to claim 1, characterized in that: Step (2) involves soaking the product in methyl jasmonate solution for 5 minutes, followed by fumigation at room temperature for 3 hours with the soaking solution in a bag.

3. The method for storing and preserving passion fruit to inhibit chilling injury according to claim 1, characterized in that: The concentration of the methyl jasmonate solution in step (2) is 10~100 μmol / L.

4. The method for storing and preserving passion fruit to inhibit chilling injury according to claim 1, characterized in that: The concentration of the methyl jasmonate solution in step (2) is 50 μmol / L.

5. The method for storing and preserving passion fruit to inhibit chilling injury according to claim 1, characterized in that: The same standard for shape and maturity in step (1) is that the passion fruit weighs 60-80g, is egg-shaped, and the mature color area of ​​the fruit occupies 70% of the outer surface of the fruit.

6. The method for storing and preserving passion fruit to inhibit chilling injury according to claim 1, characterized in that: The bactericide solution in step (1) is a 0.1 wt% imidazole bactericide solution, and the soaking time is 10 min.

7. A method for storing and preserving passion fruit to inhibit chilling injury according to claim 6, characterized in that: The imidazole fungicide in step (1) is either imazalil or thiamethoxam.

8. The method for storing and preserving passion fruit to inhibit chilling injury according to claim 1, characterized in that: The food storage box in step (3) is made of polypropylene, and the food storage film is made of transparent polypropylene.

9. The application of the storage and preservation method for inhibiting chilling injury of passion fruit as described in any one of claims 1 to 8 in the storage and preservation of passion fruit.

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