Storage and fresh-keeping method for relieving low-temperature cold damage of picked peaches

Abstract

The invention relates to the technical field of agricultural product preservation, and particularly provides a storage and preservation method for relieving low-temperature cold damage after peaches are picked, which comprises the following steps: pre-cooling the picked peaches to 8-10 DEG C by using 100-1000ppm of acidic calcium sulfate composite ice water; performing cold domestication on the precooled peaches at 8-10 DEG C for 3-5 days, and then performing low-temperature storage at 0-5 DEG C. According to the storage and preservation method disclosed by the invention, 1-4 [mu] L / L of an ethylene inhibitor can be added during cold domestication and / or the low-temperature storage is in a low-voltage electrostatic field of 1-5 KV / cm. The storage and preservation method disclosed by the invention can effectively prolong the preservation period of the peaches, reduce the cold damage browning index of the pulp, maintain relatively low conductivity and MDA content, reduce the rotting rate, and maintain relatively high flavor and good commodity. The invention provides a new normal form for storage and preservation of peaches of different varieties, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural product preservation, and in particular relates to a storage and preservation method for reducing post-harvest low-temperature chilling damage of peaches. Background Art

[0002] Peach (Prunuspersica L.) is a typical respiratory climacteric fruit. It has vigorous metabolism after harvest and is easy to soften and rot at room temperature. The post-harvest loss rate is as high as 20-30%. Low temperature storage (0-4℃) is currently the main means to inhibit the respiration of peach fruits and delay maturity and aging, which can extend the shelf life to 20-30 days. However, peaches are sensitive to low temperatures. Low temperature storage of peaches after harvest will induce cell membrane damage, increase cell membrane permeability, increase conductivity, increase MDA content, cause metabolic disorders, and cause chilling injury symptoms such as flesh browning, flocculent and flavor loss, resulting in loss of commercial value. At the same time, low temperature will cause an imbalance in the activity of chilling injury-related enzymes (SOD, POD, PPO) and increase the accumulation of reactive oxygen species ROS.

[0003] Traditional low-temperature storage is to directly transfer peaches to a 0℃ cold storage after harvest. Although it can inhibit peach rot, the incidence of acute chilling damage is as high as over 60%, and the firmness of the flesh decreases. 1-Methylcyclopropene (1-MCP) inhibits fruit softening by competitively binding to ethylene receptors, but studies have found that 1-MCP treatment inhibits the expression of genes related to low-temperature acclimation, leading to increased chilling damage. Low-voltage electrostatic fields can extend the shelf life by inhibiting microbial growth and delaying the activity of cell wall degrading enzymes (such as polygalacturonase, PG), but lack a synergistic mechanism with temperature regulation, and the effect of alleviating chilling damage when used is limited. Based on the fact that the existing technology fails to balance the contradiction between "inhibiting ripening" and "alleviating chilling damage", there is an urgent need for a peach storage method that can break through the limitations of chilling damage. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a storage and preservation method for reducing post-harvest low-temperature chilling damage to peaches. The storage and preservation method can effectively extend the shelf life of peaches, reduce the chilling damage browning index of the pulp, maintain low conductivity and MDA content, reduce the rot rate, and maintain a high flavor.

[0005] The technical solution of the present invention is as follows:

[0006] The invention provides a storage and fresh-keeping method for reducing low-temperature chilling injury of post-harvest peaches, comprising the following steps: precooling the post-harvest peaches to 8-10 DEG C with 100ppm-1000ppm acid calcium sulfate (ACS) composite ice water; placing the precooled peaches in 8-10 DEG C cold acclimation (LTC) for 3-5 days, and then placing them in 0-5 DEG C low-temperature storage.

[0007] As an embodiment, 1-4 μL / L ethylene inhibitor is also added during the cold acclimation.

[0008] As an embodiment, the cryogenic storage is also in a low voltage electrostatic field (LVEF) of 1-5 KV / cm.

[0009] As an embodiment, 1-4 μL / L of ethylene inhibitor is also added during the cold acclimation, and the low-temperature storage is also in a low-voltage electrostatic field of 1-5 KV / cm.

[0010] As an embodiment, the peaches include juicy peaches, yellow peaches, nectarines, flat peaches, hairy peaches, and hawkbill peaches.

[0011] As an embodiment, the pH value of the acidic calcium sulfate composite ice water is 2-3.

[0012] As an embodiment, the cold acclimation is carried out in a sealed bag.

[0013] As an implementation mode, the precooling time is 15min-30min.

[0014] As an embodiment, the low-temperature refrigeration temperature is 1-3°C.

[0015] As an embodiment, the low temperature storage time is 20-40 days.

[0016] As an implementation mode, the low-voltage electrostatic field is 2-3 KV / cm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. Since peach is a cold-sensitive fruit, it is very easy to suffer from chilling damage at 2-5°C. The present invention first uses acidic calcium sulfate composite ice water with strong antibacterial properties for precooling, and adopts programmed cooling to improve the adaptability of peach fruit to long-term low temperature (0-5°C). While reducing field heat, acidic calcium sulfate composite ice water can kill pathogens carried on the surface of peach fruit before harvesting, and calcium ions can effectively activate the cold resistance mechanism of peach fruit and reduce the stress of peach fruit to cold water. Precooling with acidic calcium sulfate composite ice water can effectively reduce the chilling damage of peach fruit, reduce the chilling damage browning index, and maintain good aroma quality.

[0019] 2. Cold acclimation was also carried out during the programmed cooling period, which can improve the peach fruit's ability to adapt to long-term low temperatures and reduce the occurrence of subsequent chilling damage.

[0020] 3. The combination of the two processes of acidic calcium sulfate composite ice water precooling and cold acclimation in the storage and preservation method of the present invention has a synergistic effect, which can effectively extend the shelf life of peaches, reduce the chilling browning index of the pulp, maintain a low conductivity and MDA content, reduce the rot rate, and maintain a high flavor and good commercial quality.

[0021] 4. The peaches treated by the storage and preservation method of the present invention can be kept fresh for 3-5 days at low temperature storage (0-5°C), and can be kept fresh for 20-40 days at room temperature (20-30°C) after low temperature storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a cross-sectional view of the browning of 'Jinxiu' yellow peach after being stored in different storage and preservation methods;

[0023] Figure 2 is the browning index of 'Jinxiu' yellow peach after being stored by different storage and preservation methods;

[0024] Figure 3 The electrical conductivity of 'Jinxiu' yellow peach after being stored by different storage and preservation methods;

[0025] Figure 4 The hardness of 'Jinxiu' yellow peach after being stored by different storage and preservation methods;

[0026] Figure 5 This is a cross-sectional view of the browning of 'Da Tuan Mi Lu' peaches after being stored in different storage and preservation methods;

[0027] Figure 6 is the browning index of 'Da Tuan Mi Lu' peaches after being stored by different storage and preservation methods;

[0028] Figure 7 The electrical conductivity of 'Da Tuan Mi Lu' peaches after being stored by different storage and preservation methods;

[0029] Figure 8 The hardness of 'Da Tuan Mi Lu' peaches after being stored by different storage and preservation methods. DETAILED DESCRIPTION

[0030] The invention provides a storage and fresh-keeping method for reducing low-temperature chilling damage of post-harvest peaches, comprising the following steps: selecting peaches that are 70% to 80% mature, uniform in size, free of pests and diseases, and free of mechanical damage; precooling the harvested peaches to 8-10 DEG C with 100ppm-1000ppm of acidic calcium sulfate composite ice water; first placing the precooled peaches at 8-10 DEG C for cold acclimation for 3-5 days, and then placing them in low-temperature storage at 0-5 DEG C.

[0031] In the present invention, the peach includes juicy peach, yellow peach, nectarine, flat peach, hairy peach, and hawk-billed peach. As an embodiment, the peach is yellow peach or juicy peach.

[0032] In the present invention, 100ppm-1000ppm acidic calcium sulfate composite ice water is used for precooling, so that peaches are cooled from field heat to 8-10℃, and programmed cooling is used to improve the adaptability of peaches to long-term low temperature (0-5℃). ACS (Acidic calcium sulfate) is an acidic solution of a slightly soluble ⅡA complex (AGⅡS), with a special element arrangement structure, similar to Ca(OH)2, and contains some SO4 2- With Ca 2+ . In the present invention, the acidic calcium sulfate composite ice water is a buffer solution with a pH of 2-3. The lower pH value has the characteristics of strong antibacterial property and low corrosiveness, and can kill pathogens carried on the surface of peach fruit. At the same time, free calcium ions can induce cold resistance of peach fruit, reduce the stress response of fruit to low temperature stress, effectively reduce the chilling damage of peach fruit, reduce the chilling damage browning index, and maintain good aroma quality. Too high a concentration of acidic calcium sulfate may damage the peel, enter the inside of the fruit through the pores or wounds of the fruit epidermis, cause the fruit to be disturbed by the external environment, and shorten the shelf life; too low a concentration may not achieve the expected fresh-keeping effect. As an embodiment, the concentration of the acidic calcium sulfate composite ice water is 200ppm-500ppm; as an embodiment, the precooling time is 15min-30min.

[0033] In the present invention, after the surface moisture of the pre-cooled peaches is dried, they are placed in a sealed bag and placed at 8-10°C for cold acclimation for 3-5 days. Placing the peaches in a sealed bag for cold acclimation during the programmed cooling process can enhance the adaptability of the fruit to low temperatures and reduce the chilling damage of the fruit caused by long-term low-temperature storage. As an embodiment, 5-10 kg is loaded into the single sealed bag. In one embodiment, the sealed bag includes a sealed fresh-keeping bag, a sealed moisture-proof bag, and a sealed vacuum bag.

[0034] In the present invention, the cold-acclimated peaches are placed in low-temperature storage at 0-5° C. As an embodiment, the low-temperature storage temperature is 1-3° C. As an embodiment, the low-temperature storage time is 20-40 days.

[0035] The present invention also provides a storage and preservation method, which comprises adding 1-4 μL / L ethylene inhibitor during the cold acclimation of the above storage and preservation method. The composite ethylene inhibitor in the programmed cooling and cold acclimation process of the present invention can effectively slow down the softening of peach fruits and maintain good commercial properties. As an embodiment, the ethylene inhibitor includes a 1-MCP preservative and a Pt catalyst for ethylene decomposition. As an embodiment, the 1-MCP preservative is added to a sealed bag in the form of gas or embedded powder. In one embodiment, the embedded powder volatilizes in a moist sealed bag, thereby preventing the binding of ethylene to its receptor and inhibiting the physiological effects of ethylene.

[0036] The present invention also provides a storage and preservation method in which the low-temperature storage of the above storage and preservation method is placed in a low-voltage electrostatic field of 1-5 KV / cm. The present invention places the cold-acclimated peaches in a low-temperature storage environment containing a low-voltage electrostatic field of 1-5 KV / cm, which can effectively reduce the chilling damage of long-term refrigeration to the fruit and maintain good commercial quality.

[0037] The present invention also provides a storage and preservation method in which 1-4 μL / L ethylene inhibitor is added during the cold acclimation of the above storage and preservation method and the low-temperature storage is in a low-voltage electrostatic field of 1-5 KV / cm. The present invention can make appropriate adjustments at various stages of fruit aging after harvesting, and after rapid precooling after harvesting, it can achieve both antibacterial (low pH and ACS strong antibacterial) and induction resistance effects, and then cold acclimation is carried out at the precooling terminal temperature (8-10°C) for 3-5 days, so that it can adapt to long-term low temperatures, while using ethylene control technology to reduce the softening of the fruit texture and maintain the commercial quality after long-term storage. Long-term low-temperature storage is combined with a low-voltage electrostatic field, which uses its influence on the activity of water molecules to further reduce long-term low-temperature cold stress, so that peaches can maintain good commercial quality after long-term low-temperature storage.

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0039] The materials, reagents, etc. used in the following embodiments, unless otherwise specified, are all commercially available reagents, consumables, etc., and if specific conditions of use are not specified, they are usually carried out under conventional conditions or under conditions recommended by the company.

[0040] Example 1

[0041] Harvest 7-8 mature 'Jinxiu' yellow peaches, and select 'Jinxiu' yellow peaches with uniform size, no pests and diseases, and no mechanical damage. Precool the harvested peaches in a 200ppm, pH 2-3 acidic calcium sulfate (ACS) ice water solution for 30 minutes to 8-10℃. After drying the surface moisture of the precooled peaches, put them in sealed fresh-keeping bags, put 5-10kg in each bag, store them in a cold storage at 8-10℃ for 5 days, and then transfer them to a cold storage at 2℃ for low temperature storage for 30 days.

[0042] Example 2

[0043] Harvest 7-8 mature 'Jinxiu' yellow peaches, and select 'Jinxiu' yellow peaches with uniform size, no pests, and no mechanical damage. Precool the harvested peaches in a 500ppm, pH 2-3 acidic calcium sulfate (ACS) ice water solution for 20 minutes to 8-10℃. After drying the surface moisture of the precooled peaches, put them in sealed fresh-keeping bags, put 5-10kg in each bag, store them in a cold storage at 8-10℃ for 3 days, and then transfer them to a cold storage at 2℃ for low temperature storage for 20 days.

[0044] Example 3

[0045] Harvest 7-8 mature 'Jinxiu' yellow peaches, and select 'Jinxiu' yellow peaches with uniform size, no pests, and no mechanical damage. Precool the harvested peaches in a 1000ppm, pH 2-3 acidic calcium sulfate (ACS) ice water solution for 15 minutes to precool the peaches to 8-10℃. After drying the surface moisture of the precooled peaches, put them in sealed fresh-keeping bags, put 5-10kg in each bag, store them in a cold storage at 8-10℃ for 4 days, and then transfer them to a cold storage at 2℃ for low temperature storage for 40 days.

[0046] Example 4

[0047] The same as Example 1, except that 1 g of 1-MCP embedding powder is added into the sealed fresh-keeping bag so that the 1-MCP concentration in the bag is 1-3 μL / L.

[0048] Example 5

[0049] The same as Example 1, except that the cold storage at 2°C is placed in a low voltage electrostatic field (LVEF) of 2KV / cm.

[0050] Example 6

[0051] The same as Example 1, except that 1 g of 1-MCP embedding powder is added to the sealed fresh-keeping bag so that the 1-MCP concentration in the bag is 1-3 μL / L, and the cold storage at 2°C is in a low voltage electrostatic field (LVEF) of 2 KV / cm.

[0052] Comparative Example 1

[0053] Harvest 7-8 mature 'Jinxiu' yellow peaches, and select 'Jinxiu' yellow peaches of uniform size, free of pests and diseases, and without mechanical damage. Precool the harvested peaches in ice water for 30 minutes, precooling the peaches to 8-10℃. After drying the surface moisture of the cooled fruits, directly put them in a cold storage at 2℃ for 30 days.

[0054] Comparative Example 2

[0055] Harvest 7-8 mature 'Jinxiu' yellow peaches, and select 'Jinxiu' yellow peaches with uniform size, no pests, and no mechanical damage. Precool the harvested peaches in a 200ppm, pH 2-3 acidic calcium sulfate (ACS) ice water solution for 30 minutes to 8-10℃. After drying the surface moisture of the fruit after cooling, directly put it in a cold storage at 2℃ for 30 days.

[0056] Example 7

[0057] The 7-8 mature "Da Tuan Mi Lu" peaches were harvested, and the "Da Tuan Mi Lu" peaches with uniform size, no pests and diseases, and no mechanical damage were selected. The harvested peaches were precooled in a 400ppm, pH 2-3 acidic calcium sulfate (ACS) ice water solution for 25 minutes to precool the peaches to 8-10°C. After the precooled peaches were dried on the surface, they were placed in sealed fresh-keeping bags, with 5-10 kg in each bag, placed in a cold storage at 8-10°C for 5 days, and then transferred to a cold storage at 3°C ​​for low-temperature storage for 25 days.

[0058] Example 8

[0059] The same as Example 7, except that 2 g of 1-MCP embedding powder was added to the sealed fresh-keeping bag so that the 1-MCP concentration in the bag was 2-4 μL / L.

[0060] Example 9

[0061] The same as Example 7, except that the cold storage at 3°C ​​is placed in a low voltage electrostatic field (LVEF) of 3KV / cm.

[0062] Example 10

[0063] The same as Example 7, except that 2 g of 1-MCP embedding powder was added to the sealed fresh-keeping bag so that the 1-MCP concentration in the bag was 2-4 μL / L, and the cold storage at 3°C ​​was placed in a low voltage electrostatic field (LVEF) of 3 KV / cm.

[0064] Comparative Example 3

[0065] Harvest 7-8 mature 'Da Tuan Mi Lu' peaches, and select 'Da Tuan Mi Lu' peaches of uniform size, free of pests and diseases, and without mechanical damage. Precool the harvested peaches in ice water for 25 minutes, precooling the peaches to 8-10℃. After drying the surface moisture of the cooled fruits, directly put them in a cold storage at 3℃ for low temperature storage for 25 days.

[0066] Comparative Example 4

[0067] The 7-8 mature "Da Tuan Mi Lu" peaches were harvested, and the "Da Tuan Mi Lu" peaches with uniform size, no pests, and no mechanical damage were selected. The harvested peaches were placed in a 400ppm, pH 2-3 acidic calcium sulfate (ACS) ice water solution for precooling for 25 minutes to 8-10℃. After the surface moisture of the fruit was removed by air drying, the fruit was directly placed in a cold storage at 3℃ for low temperature storage for 25 days.

[0068] Test Example 1

[0069] With Comparative Example 1 as CK group, Comparative Example 2 as T1 group, Example 1 as T2 group, Example 4 as T3 group, Example 5 as T4 group, and Example 6 as T5 group, the 'Jinxiu' yellow peaches preserved by each group of storage and preservation methods were transferred to room temperature (25°C) and stored for 3 days to simulate the shelf life of the product, and the browning degree of the cross section of each group of 'Jinxiu' yellow peaches and the product quality were evaluated.

[0070] The degree of browning is divided into 5 levels according to the browning area: Level 0, no chilling damage; Level 1, 0% < browning area < 25%; Level 2, 26% < browning area < 50%; Level 3, 51% < browning area < 75%; Level 4, browning area > 75%. Figure 1 It can be seen that more than 60% of the yellow peaches in the CK group showed browning after 30 days of low-temperature storage, resulting in loss of commercial value; the T1 group was able to keep the yellow peaches fresh after 30 days of low-temperature storage, but more than 70% of the area would still appear browning after 3 days of storage at room temperature, which could not effectively prevent chilling injury and still lead to loss of commercial value; the T2, T3, T4 and T5 groups were all able to keep the yellow peaches fresh after 30 days of low-temperature storage, and could significantly reduce the browning area after 3 days of storage at room temperature, among which the effects of the T3, T4 and T5 groups were better.

[0071] Malondialdehyde (MDA) was used to evaluate the degree of membrane lipid oxidation damage in fruits. Its content was determined by thiobarbituric acid (TBA) method. The results were calculated based on fresh weight. The experimental results of each group are shown in Table 1.

[0072] Table 1 Effects of different storage methods on MDA of 'Jinxiu' yellow peach

[0073]

[0074]

[0075] (Different letters indicate significant differences between the two groups, p<0.05)

[0076] It can be seen from Table 1 that each group of storage and preservation methods can effectively prevent the yellow peaches from oxidative rancidity and keep the yellow peaches in a relatively fresh state.

[0077] The browning index evaluates the chilling injury index of the fruit. It is measured based on the percentage of the browning area of ​​the cut surface to the total area of ​​the fruit cut surface. The calculation formula of the browning index is as follows:

[0078]

[0079] The experimental results of the browning index of each group are shown in Table 2 and Figure 2 .

[0080] Table 2 Effects of different storage and preservation methods on the browning index of 'Jinxiu' yellow peach

[0081] IB CK T1 T2 T3 T4 T5 0d 0 0 0 0 0 0 30d 41.69±4.2a 12.32±1.2b 10.23±0.98b 9.56±1b 4.23±1c 2.32±1c 30S3d 85.36±2.3a 45.29±3.7b 26.32±3.15c 15.36±3d 12.61±2d 8.69±1.5e

[0082] (Different letters indicate significant differences between the two groups, p<0.05)

[0083] From Table 2 and Figure 2 It can be seen that compared with the CK group, the browning index of yellow peaches in the T1 group after 30 days of low-temperature refrigeration and 3 days of room temperature shelf storage can be significantly reduced, but the browning index of yellow peaches in the room temperature shelf storage for 3 days is still above 45%, affecting the commercial quality of peaches. Compared with the CK group and the T1 group, the browning index of yellow peaches in the T2 group, the T3 group, the T4 group and the T5 group after 30 days of low-temperature refrigeration and 3 days of room temperature shelf storage has dropped significantly, indicating that the various process steps in the T2 group, the T3 group, the T4 group and the T5 group play a synergistic role, which can further reduce the long-term low-temperature cold stress, so that peaches can still maintain good commercial quality after long-term low-temperature storage. Among them, the T4 group and the T5 group have the best effect.

[0084] Conductivity is used to evaluate the cell membrane permeability and maturity of the fruit. The conductivity is measured by using a 3mm puncher to punch holes in similar positions of 6 peach fruits for 3 times, cutting the samples with a surgical blade to obtain a pulp tissue disc with a diameter of 3mm and a thickness of 1mm. The disc is immersed in 20mL of distilled water, and the sample conductivity is measured with a conductivity meter (DDS-11A, China) and recorded as L0. After 0.5 hours, the sample conductivity is tested again and recorded as L1. Then the solution is boiled for 0.5 hours, and the sample conductivity is measured and recorded as L2. The conductivity is calculated by the following formula: Conductivity = (L1-L0) / (L2-L0). The experimental results of the conductivity of each group are shown in Tables 3 and Figure 3 .

[0085] Table 3 Effects of different storage and preservation methods on the electrical conductivity of 'Jinxiu' yellow peach

[0086] Conductivity CK T1 T2 T3 T4 T5 0d 0.26±0.1 0.26±0.1 0.26±0.05 0.26±0 0.26±0 0.26±0.1 30d 0.45±0a 0.39±0b 0.3±0.02b 0.32±0b 0.25±0c 0.21±0c 30S3d 0.58±0a 0.46±0b 0.38±0.01c 0.35±0c 0.30±0c 0.28±0d

[0087] (Different letters indicate significant differences between the two groups, p<0.05)

[0088] From Table 3 and Figure 3It can be seen that compared with the CK group, the T1 group, T2 group, and T3 group can reduce the conductivity of yellow peaches after low-temperature storage and reduce the cell membrane permeability. The T4 group and T5 group have better effects in reducing conductivity under low-temperature storage. After being stored at room temperature, the conductivity increased significantly. Compared with the CK group, the T1 group can effectively reduce the conductivity. The conductivity of the T2 group, T3 group, and T4 group is significantly lower than that of the CK group and T1 group, indicating that the synergistic treatment of each group can effectively reduce chilling damage and membrane permeability. In addition, the T5 group showed the lowest conductivity during the shelf life, indicating that the T5 group has the best effect on maintaining the integrity of the cell membrane, which is also consistent with its best preservation effect. It shows that the T5 group can more effectively maintain the integrity of the cell membrane and reduce the degree of chilling damage during long-term low-temperature storage, thereby improving the commercial quality of peaches.

[0089] The hardness of peaches was used to evaluate their freshness and taste. The hardness was measured using a texture analyzer with a probe diameter of 5 mm, a downward pressure speed of 1 mm / s, a test depth of 10 mm, and the skin was tested. The hardness of each fruit was the average of two measurements in Newton (N). The experimental results of each group of hardness are shown in Tables 4 and Figure 4 .

[0090] Table 4 Effects of different storage and preservation methods on the firmness of 'Jinxiu' yellow peach

[0091] hardness CK T1 T2 T3 T4 T5 0d 23.2±1.52 23.2±1.52 23.2±1.52 23.2±1.52 23.2±1.52 23.2±1.52 30d 18.78±2.56a 20.58±2.35a 11.69±2.32b 16.85±1.96a 13.25±2.36b 17.68±2.61a 30S3d 14.89±1.23a 12.37±1.28a 7.56±1.14b 8.25±1.65b 5.46±0.98c 5.98±1.21c

[0092] (Different letters indicate significant differences between the two groups, p<0.05)

[0093] From Table 4 and Figure 4 It can be seen that compared with the CK group, there was no significant difference in the hardness of yellow peaches in the T1 group after 30 days of low-temperature refrigeration and 3 days of room temperature storage; the hardness of yellow peaches in the T2 and T4 groups decreased after 30 days of low-temperature refrigeration, indicating that the ethylene inhibitor: 1-MCP / Pt catalyst for ethylene decomposition can effectively maintain the hardness of the fruit and maintain good commodity properties. After all peaches were stored at room temperature for 3 days, the CK and T1 groups could not be well ripened and softened, resulting in a hardness of more than 10N, indicating that they had chilling damage and cell wall leatheriness. The T2 and T3 groups were able to soften normally, indicating that their chilling damage level was not high. Among them, the T4 and T5 groups maintained a lower hardness after 3 days of room temperature shelf storage, indicating that the T4 and T5 groups had better room temperature ripening effects, which could further reduce the hardness of yellow peaches and make them soft, glutinous and juicy.

[0094] Test Example 2

[0095] Comparative Example 3 was used as the CK group, Comparative Example 4 was used as the T1 group, Example 7 was used as the T2 group, Example 8 was used as the T3 group, Example 9 was used as the T4 group, and Example 10 was used as the T5 group. The 'Da Tuan Mi Lu' peaches preserved by the storage and preservation methods of each group were transferred to room temperature (25°C) and stored for 3 days to simulate the shelf life of the commodity. The browning degree of the cross section of the 'Da Tuan Mi Lu' peaches in each group was evaluated. Figure 5 .Depend on Figure 5 It can be seen that more than 50% of the peaches in the CK group showed browning after 25 days of low-temperature storage, resulting in loss of commercial value; the peaches in the T1 group were able to keep fresh after 25 days of low-temperature storage, but more than 40% of the area would still appear browning after 3 days of storage at room temperature, which could not effectively prevent chilling injury and still lead to loss of commercial value; the peaches in the T2, T3, T4 and T5 groups were able to keep fresh after 25 days of low-temperature storage, and could significantly reduce the browning area after 3 days of storage at room temperature, among which the effects of the T3, T4 and T5 groups were better.

[0096] According to the determination method of browning index, the experimental results of browning index of each group are shown in Table 5 and Figure 6 .

[0097] Table 5 Effects of different storage and preservation methods on the browning index of 'Da Tuan Mi Lu' peaches

[0098] IB CK T1 T2 T3 T4 T5 0 0 0 0 0 0 0 25d 50.36±2.36a 35±2.22b 30±1.23c 20.65±1.21d 5.21±0.32e 4.25±0.65e 25S3 90.25±3.21a 70.36±2.94b 40.69±2.64c 29.98±1.65d 15.35±2.21e 6.28±1.62f

[0099] (Different letters indicate significant differences between the two groups, p<0.05)

[0100] From the experimental results in Table 5, it can be seen that compared with the CK group, the browning index of peaches in the T1 group after 30 days of low-temperature refrigeration and 3 days of room temperature shelf storage can be significantly reduced, but the browning index after 3 days of room temperature storage is still above 70%, affecting the commercial quality of peaches. Compared with the CK group and the T1 group, the browning index of peaches in the T2 group, the T3 group, the T4 group and the T5 group after 30 days of low-temperature refrigeration and 3 days of room temperature shelf storage has dropped significantly, indicating that the various process steps in the T2 group, the T3 group, the T4 group and the T5 group play a synergistic role, which can further reduce the long-term low-temperature cold stress, so that peaches can still maintain good commercial quality after long-term low-temperature storage. Among them, the T4 group and the T5 group have the best effect.

[0101] According to the conductivity determination method, the experimental results of each group of conductivity are shown in Table 6 and Figure 7 .

[0102] Table 6 Effects of different storage and preservation methods on the electrical conductivity of 'Da Tuan Mi Lu' peaches

[0103] Conductivity CK T1 T2 T3 T4 T5 0 0.31±0.06 0.31±0.06 0.31±0.06 0.31±0.06 0.31±0.06 0.31±0.06 25d 0.46±0.02a 0.41±0.03a 0.35±0.01b 0.31±0.02b 0.23±0.02c 0.25±0.01c 25S3 0.62±0.04a 0.51±0.01b 0.53±0.03b 0.4±0.02c 0.3±0.01d 0.28±0.02d

[0104] (Different letters indicate significant differences between the two groups, p<0.05)

[0105] From the experimental results in Table 6, it can be seen that compared with the CK group, the T1 group, the T2 group, and the T3 group can reduce the conductivity of peaches after low-temperature storage and reduce the cell membrane permeability. The T4 group and the T5 group have better effects in reducing conductivity under low-temperature storage. After being stored at room temperature, the conductivity increased significantly. Compared with the CK group, the T1 group can effectively reduce the conductivity. The conductivity of the T3 group and the T4 group is significantly lower than that of the CK group and the T1 group, indicating that the synergistic treatment of each group can effectively reduce chilling damage and membrane permeability. In addition, the T5 group showed the lowest conductivity during the shelf life, indicating that the T5 group has the best effect on maintaining the integrity of the cell membrane, which is also consistent with its best preservation effect. It shows that the T5 group can more effectively maintain the integrity of the cell membrane and reduce the degree of chilling damage during long-term low-temperature storage, thereby improving the commercial quality of peaches.

[0106] According to the hardness determination method, the experimental results of each group of hardness are shown in Table 7 and Figure 8 .

[0107] Table 7 Effects of different storage methods on the firmness of 'Da Tuan Mi Lu' peaches

[0108] hardness CK T1 T2 T3 T4 T5 0d 28.72±2.12 28.72±2.12 28.72±2.12 28.72±2.12 28.72±2.12 28.72±2.12 25d 24.36±1.68a 23.95±1.69a 15.69±1.78b 20.95±1.54a 16.54±1.36b 21.68±1.56a 25S3 18.32±2.61a 13.62±1.87b 8.36±1.25c 7.26±1.23c 4.36±0.85d 5.12±1.14d

[0109] (Different letters indicate significant differences between the two groups, p<0.05)

[0110] From the experimental results in Table 7, it can be seen that compared with the CK group, there is no significant difference in the hardness of peaches in the T1 group after 25 days of low-temperature refrigeration and 3 days of room temperature shelf; the hardness of peaches in the T2 and T4 groups after 25 days of low-temperature refrigeration decreased, indicating that the ethylene inhibitor: 1-MCP / Pt catalyst for ethylene decomposition can effectively maintain the hardness of the fruit and maintain good commodity properties. After 3 days of room temperature shelf, all peaches in the CK and T1 groups could not be well ripened and softened, resulting in a hardness of more than 10N, indicating that they suffered chilling damage and cell wall leatheriness. The T2 and T3 groups were able to soften normally, indicating that their chilling damage level was not high. Among them, the T4 and T5 groups maintained a lower hardness after 3 days of room temperature shelf, indicating that the T4 and T5 groups had better room temperature ripening effects, which could further reduce the hardness of peaches and make them soft and juicy.

[0111] The experimental results show that the storage and preservation method of the present invention can reduce the browning area of ​​different varieties of peaches, reduce the chilling browning index of the flesh, maintain low conductivity and MDA content, and is suitable for a variety of peach varieties such as juicy peaches, yellow peaches, and nectarines, reduce the degree of chilling damage to peach flesh during long-term low-temperature storage, reduce the long-term low-temperature cold stress of different varieties of peach fruits, and maintain good commercial properties. Moreover, the storage and preservation method of the present invention for reducing low-temperature chilling damage to peaches after harvest is also beneficial to the ripening effect during the shelf life, making the peaches soft, glutinous and juicy.

[0112] The present invention constructs a multi-dimensional preservation system of cold resistance, sterilization, delayed ripening and membrane protection through the multi-step coordination of acidic calcium sulfate composite ice water precooling → cold acclimation → ethylene inhibition → low-voltage electrostatic field. The multifunctional application of acidic calcium sulfate: breaking through the traditional precooling method, achieving the coordination of sterilization, calcium strengthening and pH regulation. The collaborative innovation of cold acclimation and ethylene inhibition: activating the cold resistance mechanism of peach fruit itself through temperature gradient regulation and ethylene signal blocking. The cross-border application of low-voltage electrostatic field: using physical field to enhance cell membrane stability and create a new path for fruit and vegetable preservation. Combining food chemistry (acidic calcium sulfate), plant physiology (cold acclimation), molecular biology (ethylene inhibition) and biophysics (electrostatic field), an interdisciplinary collaborative preservation system is constructed, breaking through the limitations of a single technology, and significantly improving the preservation effect and economic benefits. The low-temperature storage period of the method of the present invention is extended to 20-40 days (traditional methods are only 10-15 days), the cold injury browning index is reduced by 60%, the conductivity and MDA content are significantly reduced, and the fruit hardness and flavor are maintained. Acidic calcium sulfate and ethylene inhibitor (1-MCP) are both food-grade additives that meet national standards. The low-voltage electrostatic field is a physical treatment with no risk of chemical residues. The cost of acidic calcium sulfate is only 1 / 3 of that of traditional fungicides. The electrostatic field equipment is reusable and has low maintenance costs. The present invention provides a new paradigm for the storage and preservation of different varieties of peaches and has broad application prospects.

[0113] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A storage and preservation method for reducing post-harvest low temperature and chilling damage of peaches, characterized in that: The following steps are involved: After harvest, the peaches are precooled to 8-10°C with 100ppm-1000ppm acidic calcium sulfate composite ice water; the precooled peaches are first placed at 8-10°C for cold acclimation for 3-5 days, and then placed in 0-5°C low temperature storage.

2. The storage and preservation method according to claim 1, characterized in that: 1-4 μL / L of ethylene inhibitor was also added during the cold acclimation.

3. The storage and preservation method according to claim 1 or 2, characterized in that: The low temperature storage is also in a low voltage electrostatic field of 1-5 KV / cm.

4. The storage and preservation method according to any one of claims 1 to 3, characterized in that: The peaches include juicy peaches, yellow peaches, nectarines, flat peaches, hairy peaches, and hawk-billed peaches.

5. The storage and preservation method according to any one of claims 1 to 3, characterized in that: The pH value of the acidic calcium sulfate composite ice water is 2-3.

6. The storage and preservation method according to any one of claims 1 to 3, characterized in that: The cold acclimation was performed in sealed bags.

7. The storage and preservation method according to any one of claims 1 to 3, characterized in that: The precooling time is 15min-30min.

8. The storage and preservation method according to any one of claims 1 to 3, characterized in that: The low temperature refrigeration temperature is 1-3°C.

9. The storage and preservation method according to any one of claims 1 to 3, characterized in that: The low temperature storage time is 20-40 days.

10. The storage and preservation method according to claim 3, characterized in that: The low-voltage electrostatic field is 2-3 KV / cm.

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