Method for preserving cherry tomatoes through combination of low-voltage electrostatic field and modified atmosphere packaging and application of method

Abstract

The invention provides a method for preserving cherry tomatoes through combination of a low-voltage electrostatic field and modified atmosphere packaging and application of the method, and belongs to the technical field of preservation. The method comprises the following steps: pre-cooling cherry tomatoes, packaging the cherry tomatoes with a modified atmosphere packaging material, treating the cherry tomatoes in a low-voltage electrostatic field after packaging, and storing the cherry tomatoes. The low-voltage electrostatic field treatment is combined with the packaging treatment, so that the respiration rate can be reduced, and the gas environment in the package can be changed, thereby reducing the consumption of nutrient substances caused by respiration, improving the capability of cherry tomatoes for removing active oxygen, inhibiting membrane lipid peroxidation, reducing the accumulation of malondialdehyde, enhancing the antioxidant level and delaying the maturation and aging of the picked cherry tomatoes; the fresh quality of the cherry tomatoes is effectively maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of fresh-keeping, and in particular relates to a method for preserving cherry tomatoes by low-voltage electrostatic field combined with spontaneous atmosphere modification packaging and an application thereof. Background Art

[0002] Cherry tomato (Lycopersicon esculentum var.cerasiformeA.Gray) is a cultivated variety of annual or perennial vine herbaceous plant of the genus Lycopersicon in the Solanaceae family. Cherry tomatoes are rich in protein, potassium, calcium and other minerals, trace elements such as selenium and β-carotene, multiple vitamins, citric acid, malic acid, and their peel also contains rutin. Cherry tomatoes are eaten with their ripe and juicy berries and are deeply loved by people.

[0003] Cherry tomatoes, as a typical respiratory climacteric fruit and vegetable, have obvious after-ripening phenomenon. They will soon enter the respiratory climacteric period after picking. The existence of multiple physiological activities will continuously consume various organic substances stored in the body, resulting in a large loss of nutrients, making the tissue structure of cherry tomatoes soften rapidly, the appearance loses luster and plumpness, and the morphology wilts, so that the sensory quality and nutritional value will deteriorate sharply during transportation, storage, and sales. Although there are many preservation technologies for cherry tomatoes at present, the preservation effects are mostly unsatisfactory, and it is difficult to meet people's preservation needs for cherry tomatoes. Therefore, it is necessary to develop a preservation technology for cherry tomatoes to maintain the freshness of cherry tomatoes after harvest, delay subsequent maturation and aging, and avoid economic losses caused by quality degradation of cherry tomatoes during storage. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a method for preserving cherry tomatoes by low-voltage electrostatic field combined with spontaneous atmosphere modification packaging, which can increase the physical and chemical quality and antioxidant capacity of post-harvest cherry tomatoes, improve the storage quality of post-harvest cherry tomatoes, and extend the shelf life.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a method for preserving cherry tomatoes by combining low-voltage electrostatic field with spontaneous atmosphere packaging. The method comprises the following steps: precooling the cherry tomatoes, packaging them with spontaneous atmosphere packaging materials, and storing them in a low-voltage electrostatic field after packaging.

[0007] Preferably, the precooling temperature is 10-12° C. and the time is 30-40 minutes.

[0008] Preferably, the spontaneous modified atmosphere packaging material includes a PET fresh-keeping box, a perforated PE fresh-keeping bag or a microporous film fresh-keeping bag.

[0009] Preferably, the oxygen permeability of the microporous film fresh-keeping bag is 240000-250000 mL / (m 2 ·d).

[0010] Preferably, the permeability of the microporous film fresh-keeping bag to carbon dioxide is 250,000 to 260,000 mL / (m 2 ·d).

[0011] Preferably, the electric field strength of the low-voltage electrostatic field is 160-180V.

[0012] Preferably, the storage time is 20 to 26 days.

[0013] Preferably, the storage environment temperature is 8-12°C.

[0014] Preferably, the relative humidity of the storage environment is 80-90%.

[0015] The present invention also provides application of the method in transportation and management of cherry tomatoes.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0017] The present invention sequentially performs precooling, packaging and low-voltage electrostatic field treatment on the cherry tomatoes after harvest, and uses low-voltage electrostatic field technology to discharge in space to form a negative ion environment, which can effectively maintain the freshness of the cherry tomatoes, slow down the weight loss, the decrease of soluble solid content, the decrease of titratable acid content, the decrease of hardness, and maintain the color of the cherry tomatoes after harvest. The present invention combines low-voltage electrostatic field treatment with packaging treatment to reduce the respiration rate, change the gas environment in the package, thereby reducing the consumption of nutrients by respiration, improving the ability of cherry tomatoes to remove active oxygen, inhibiting membrane lipid peroxidation, reducing the accumulation of malondialdehyde, enhancing the antioxidant level, delaying the maturation and aging of cherry tomatoes after harvest, and effectively maintaining the fresh quality of cherry tomatoes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 : Photo record of cherry tomatoes;

[0019] Figure 2 : Soluble solids content of cherry tomatoes in different treatment groups;

[0020] Figure 3 : Relative conductivity of cherry tomatoes in different treatment groups;

[0021] Figure 4 : ABTS of cherry tomatoes in different treatment groups + Free radical scavenging rate. DETAILED DESCRIPTION

[0022] The invention provides a method for preserving cherry tomatoes by combining low-voltage electrostatic field with spontaneous atmosphere packaging. The method comprises the following steps: precooling the cherry tomatoes, packaging them with spontaneous atmosphere packaging materials, and storing them in a low-voltage electrostatic field after packaging.

[0023] The present invention precools cherry tomatoes, wherein the precooling temperature is 10-12°C and the time is 30-40 minutes; the temperature is preferably 11°C; and the time is preferably 32-35 minutes. The present invention quickly removes field heat from cherry tomatoes through precooling, thereby inhibiting postharvest respiratory consumption and microbial growth, delaying the aging of cherry tomatoes and reducing the occurrence of storage diseases.

[0024] The present invention packages the pre-cooled cherry tomatoes with a modified atmosphere packaging material, wherein the modified atmosphere packaging material includes a PET fresh-keeping box, a perforated PE fresh-keeping bag or a microporous film fresh-keeping bag. The perforated PE fresh-keeping bag of the present invention is preferably a perforated PE fresh-keeping bag with a thickness of 0.07 mm. The permeability of the microporous film fresh-keeping bag to oxygen is 240,000 to 250,000 mL / (m 2 ·d), the permeability to carbon dioxide is 250000~260000mL / (m 2 ·d).

[0025] The present invention places the encapsulated cherry tomatoes in a low-voltage electrostatic field for storage, that is, the low-voltage electrostatic treatment is continuously performed during the storage period. The electric field strength of the low-voltage electrostatic field is 160-180V, preferably 170V; the storage time of the low-voltage electrostatic field is 20-26d, preferably 22-25d, and more preferably 24d. The present invention uses low-voltage electrostatic field technology to discharge in space to form a negative ion environment, which can reduce the consumption of various organic substances stored in the body by respiration, reduce the loss of water, maintain the hardness of fruits and vegetables after harvest, slow down the increase in weight loss rate, delay the consumption of soluble solids, effectively inhibit the deterioration of cherry tomatoes, improve antioxidant capacity, reduce the degree of cell membrane lipid peroxidation and cell membrane electrolyte permeability, maintain the stability of cell membrane structure, reduce the accumulation of malondialdehyde, increase the content of antioxidant reduced glutathione, improve the storage quality of cherry tomatoes after harvest, and extend the shelf life.

[0026] The storage environment temperature of the present invention is 8-12° C., preferably 10° C.; the storage environment relative humidity is 80-90%, preferably 85%.

[0027] The present invention also provides the application of the above method in the transportation and management of cherry tomatoes. The present invention combines low-voltage electrostatic field treatment with packaging treatment to reduce the respiration rate, effectively delay the ripening and aging of cherry tomatoes after harvest, and effectively maintain the fresh quality of cherry tomatoes.

[0028] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the specific embodiments and comparative examples of the present invention, fresh cherry tomatoes that are uniform in size, free of mechanical damage, pests and diseases, and uniform in maturity after being picked for 2 hours are used. There are no strict requirements for PET fresh-keeping boxes and 0.07mm perforated PE fresh-keeping bags, which can be purchased conventionally; microporous membrane fresh-keeping bags were purchased from Tianjin Agricultural Products Processing and Storage and Fresh-keeping Center, and the oxygen permeability is 248000mL / (m 2 ·d), the permeability to carbon dioxide is 256000mL / (m 2 ·d).

[0030] In the following embodiments, unless otherwise specified, all of them are conventional methods.

[0031] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0032] Example 1

[0033] A method for preserving cherry tomatoes by low-voltage electrostatic field combined with spontaneous atmosphere packaging:

[0034] (1) Precool fresh cherry tomatoes at 10°C for 30 min and then lay them flat in a PET fresh-keeping box;

[0035] (2) Store in an environment with a temperature of 10°C, a relative humidity of 85%, and a low-voltage electrostatic field of 170V.

[0036] Example 2

[0037] A method for preserving cherry tomatoes by low-voltage electrostatic field combined with spontaneous atmosphere packaging:

[0038] (1) Precool fresh cherry tomatoes at 10°C for 30 min, then lay them flat in a 0.07 mm holed PE bag, and seal them with a hand-operated sealer;

[0039] (2) Store in an environment with a temperature of 10°C, a relative humidity of 85%, and a low-voltage electrostatic field of 170V.

[0040] Example 3

[0041] A method for preserving cherry tomatoes by low-voltage electrostatic field combined with spontaneous atmosphere packaging:

[0042] (1) Precooling fresh cherry tomatoes at 10° C. for 30 min, laying them flat into a microporous film fresh-keeping bag, and sealing them with a hand-operated sealing machine;

[0043] (2) Stored in a 170V low-voltage electrostatic field environment at a temperature of 10°C, a relative humidity of 85% (low-voltage electrostatic treatment is continued during the storage period), recorded as LVEF-3.

[0044] Comparative Example 1

[0045] The difference from Example 3 is that in step (2), the storage is carried out in a low-voltage electrostatic field environment at 10°C and a relative humidity of 85%, and low-voltage electrostatic field treatment (170V) is carried out on days 0, 4, 8, 12, 16, 20, and 24, with a treatment time of 12 hours, recorded as LVEF-1.

[0046] Comparative Example 2

[0047] The difference from Example 3 is that in step (2), the cells are stored in a low-voltage electrostatic field environment at 10° C. and a relative humidity of 85%, and are treated on days 0, 8, 16, and 24, with each treatment lasting 12 hours, which is recorded as LVEF-2.

[0048] Comparative Example 3

[0049] A method for preserving cherry tomatoes:

[0050] (1) Precool fresh cherry tomatoes at 10°C for 30 min and then lay them flat in a PET fresh-keeping box;

[0051] (2) Stored at a temperature of 10°C and a relative humidity of 85%, referred to as MAP-1.

[0052] Comparative Example 4

[0053] A method for preserving cherry tomatoes:

[0054] (1) Precool fresh cherry tomatoes at 10°C for 30 min, then lay them flat in a 0.07 mm perforated PE bag and seal them with a hand sealer.

[0055] (2) Stored at a temperature of 10°C and a relative humidity of 85%, referred to as MAP-2.

[0056] Comparative Example 5

[0057] A method for preserving cherry tomatoes:

[0058] (1) Precool fresh cherry tomatoes at 10°C for 30 minutes, then lay them flat in a microporous film fresh-keeping bag, and seal them with a hand-operated sealing machine.

[0059] (2) Stored at a temperature of 10°C and a relative humidity of 85%, referred to as MAP-3.

[0060] Comparative Example 6

[0061] A method for preserving cherry tomatoes:

[0062] Fresh cherry tomatoes were directly stored at 10°C and recorded as MAP-0.

[0063] Comparative Example 7

[0064] A method for preserving cherry tomatoes:

[0065] Fresh cherry tomatoes were precooled at 10°C for 30 minutes, and then stored in a 170V low-voltage electrostatic field environment at 10°C, 85% relative humidity (low-voltage electrostatic treatment was continued during the storage period), which was recorded as LVEF-01.

[0066] Test Example 1

[0067] The cherry tomatoes of Example 3 and Comparative Examples 1 to 6 were measured (Note: MAP-0, MAP-1, MAP-2, and MAP-3 are samples from the same batch; LVEF-01, LVEF-1, LVEF-2, and LVEF-3 are samples from the same batch. There are differences between the two batches of samples, but fresh cherry tomatoes that are uniform in size, free of mechanical damage, pests and diseases, and have the same maturity after being picked for 2 hours were used):

[0068] 1. Take photos and record

[0069] Cherry tomatoes were photographed and recorded on the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, and 24th days of storage. Figure 1 shown.

[0070] Depend on Figure 1 It can be seen that the cherry tomatoes in the MAP-0 group first showed sepal wilt, and the cherry tomato fruits had severely withered on the 24th day of storage, losing their commercial value. The cherry tomatoes in the MAP-3 group showed mold spots on the 24th day of storage, while the LVEF-3 group did not show dryness of the fruit stalks and sepals and rot and mildew during storage. The microporous membrane fresh-keeping bag packaging treatment plus continuous low-voltage electrostatic field treatment preservation method of the present invention better maintains the appearance quality of cherry tomatoes.

[0071] 2. Calculation of weight loss rate (%)

[0072] Using a laboratory electronic analytical balance with an accuracy of 0.01 g, the cherry tomatoes on the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, and 24th days of storage were weighed separately, recorded as W1, and the initial weight was recorded as W0, and the weight loss rate was calculated: The results are shown in Table 1.

[0073] Table 1 Weight loss rate of cherry tomatoes under different treatments (%)

[0074]

[0075] 21 <![CDATA[16.49 a ]]> <![CDATA[10.02 b ]]> <![CDATA[2.85 d ]]> <![CDATA[3.47 c ]]> <![CDATA[1.79 e ]]> <![CDATA[1.87 e ]]> <![CDATA[1.44 f ]]> 24 <![CDATA[19.79 a ]]> <![CDATA[11.36 b ]]> <![CDATA[3.56 d ]]> <![CDATA[5.31 c ]]> <![CDATA[2.07 ef ]]> <![CDATA[2.39 e ]]> <![CDATA[1.77 f ]]>

[0076] The results showed that after 24 days of storage, the weight loss rate of cherry tomatoes under different treatments gradually increased, but the weight loss rate of cherry tomatoes in the LVEF-3 group was the lowest at 1.77%. Figure 1 The degree of decay of cherry tomatoes, the preservation method of the microporous film fresh-keeping bag packaging treatment plus continuous low-voltage electrostatic field treatment can appropriately reduce the loss of water in cherry tomatoes and slow down the weight loss of cherry tomatoes.

[0077] 3. Hardness (N) calculation

[0078] On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st and 24th days of storage, cherry tomato samples of the same size were taken for full texture analysis. The test conditions were 60 mm / min, the deformation percentage was 50%, and the trigger force was 1.5N.

[0079] Table 2 Hardness of cherry tomatoes under different treatments (N)

[0080] Storage time (d) MAP-0 MAP-1 MAP-2 MAP-3 LVEF-1 LVEF-2 LVEF-3 0 <![CDATA[28.47 b ]]> <![CDATA[28.47 b ]]> <![CDATA[28.47 b ]]> <![CDATA[28.47 b ]]> <![CDATA[32.57 a ]]> <![CDATA[32.57 a ]]> <![CDATA[32.57 a ]]> 3 <![CDATA[25.97 c ]]> <![CDATA[26.83 bc ]]> <![CDATA[27.53 bc ]]> <![CDATA[27.90 bc ]]> <![CDATA[28.97 ab ]]> <![CDATA[28.87 ab ]]> <![CDATA[30.53 a ]]> 6 <![CDATA[23.63 c ]]> <![CDATA[24.10 bc ]]> <![CDATA[25.33 c ]]> <![CDATA[27.27 b ]]> <![CDATA[28.27 ab ]]> <![CDATA[27.80 b ]]> <![CDATA[29.50 a ]]> 9 <![CDATA[19.20 e ]]> <![CDATA[21.53 d ]]> <![CDATA[24.20 c ]]> <![CDATA[27.03 ab ]]> <![CDATA[27.50 ab ]]> <![CDATA[26.77 b ]]> <![CDATA[28.43 a ]]> 12 <![CDATA[18.53 c ]]> <![CDATA[20.27 c ]]> <![CDATA[22.67 b ]]> <![CDATA[26.40 a ]]> <![CDATA[27.03 a ]]> <![CDATA[26.63 a ]]> <![CDATA[28.40 a ]]> 15 <![CDATA[16.77 c ]]> <![CDATA[17.57 c ]]> <![CDATA[22.00 b ]]> <![CDATA[25.87 a ]]> <![CDATA[25.97 a ]]> <![CDATA[25.77 a ]]> <![CDATA[27.90 a ]]> 18 <![CDATA[16.30 d ]]> <![CDATA[17.03 d ]]> <![CDATA[21.10 c ]]> <![CDATA[24.23 b ]]> <![CDATA[25.60 ab ]]> <![CDATA[25.50 ab ]]> <![CDATA[26.87 a ]]> 21 <![CDATA[15.30 d ]]> <![CDATA[15.97 d ]]> <![CDATA[19.07 c ]]> <![CDATA[22.63 b ]]> <![CDATA[25.73 a ]]> <![CDATA[24.53 ab ]]> <![CDATA[26.67 a ]]> 24 <![CDATA[13.63 e ]]> <![CDATA[15.67 de ]]> <![CDATA[17.77 cd ]]> <![CDATA[19.60 c ]]> <![CDATA[23.33 b ]]> <![CDATA[22.90 b ]]> <![CDATA[26.30 a ]]>

[0081] The results showed that after 24 days of storage, the hardness of cherry tomatoes after storage showed an overall downward trend, but the hardness of cherry tomatoes after LVEF-3 treatment was higher than that of other treatments. The microporous film fresh-keeping bag packaging treatment plus continuous low-voltage electrostatic field treatment preservation method of the present invention can maintain the texture characteristics of cherry tomatoes and delay the decline of hardness.

[0082] 4. Determination of soluble solids content

[0083] On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, and 24th day of storage, three cherry tomatoes were taken from each group, homogenized, and filtered. The soluble solids content of cherry tomatoes at different storage times was determined using a portable digital refractometer. The results are as follows: Figure 2 shown.

[0084] according to Figure 2It can be seen that the soluble solid content of each treatment group increased briefly during storage and then began to decline. The soluble solid content of cherry tomatoes in the MAP-0 and MAP-1 groups was always higher than that of other treatment groups after reaching the peak value. This may be due to the large amount of water loss in the later period, which caused the soluble solid content to remain at a high level. Compared with other treatment groups, the soluble solid content of the LVEF-3 group decreased more slowly, indicating that the microporous membrane fresh-keeping bag packaging treatment plus continuous low-voltage electrostatic field treatment preservation method of the present invention can delay the consumption of soluble solids in cherry tomatoes.

[0085] 5. Determination of L* value and a* value

[0086] The chromaticity value was measured by a colorimeter. On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, and 24th day of storage, 20 cherry tomatoes were fixed in each group as the chromaticity value measurement objects, and the L* value and a* value were measured at three different positions each time. The results are shown in Tables 3 and 4.

[0087] Table 3 L* values ​​of cherry tomatoes under different treatments

[0088] Storage time (d) MAP-0 MAP-1 MAP-2 MAP-3 LVEF-1 LVEF-2 LVEF-3 0 <![CDATA[32.41 a ]]> <![CDATA[32.41 a ]]> <![CDATA[32.41 a ]]> <![CDATA[32.41 a ]]> <![CDATA[31.69 a ]]> <![CDATA[31.69 a ]]> <![CDATA[31.69 a ]]> 3 <![CDATA[33.22 ab ]]> <![CDATA[33.10 ab ]]> <![CDATA[33.31 ab ]]> <![CDATA[33.71 a ]]> <![CDATA[32.28 b ]]> <![CDATA[32.22 b ]]> <![CDATA[32.21 b ]]> 6 <![CDATA[33.28 ab ]]> <![CDATA[33.68 a ]]> <![CDATA[33.77 a ]]> <![CDATA[34.08 a ]]> <![CDATA[32.48 b ]]> <![CDATA[32.56 b ]]> <![CDATA[32.69 b ]]> 9 <![CDATA[33.18 abc ]]> <![CDATA[33.14 abc ]]> <![CDATA[33.43 ab ]]> <![CDATA[33.96 a ]]> <![CDATA[32.67 bc ]]> <![CDATA[32.46 c ]]> <![CDATA[32.59 bc ]]> 12 <![CDATA[32.86 ab ]]> <![CDATA[33.79 a ]]> <![CDATA[33.11 ab ]]> <![CDATA[33.20 ab ]]> <![CDATA[32.47 b ]]> <![CDATA[32.33 b ]]> <![CDATA[32.33 b ]]> 15 <![CDATA[32.42 ab ]]> <![CDATA[33.24 a ]]> <![CDATA[32.60 ab ]]> <![CDATA[32.85 ab ]]> <![CDATA[32.21 b ]]> <![CDATA[32.20 b ]]> <![CDATA[32.23 b ]]> 18 <![CDATA[32.35 a ]]> <![CDATA[32.69 a ]]> <![CDATA[32.53 a ]]> <![CDATA[32.79 a ]]> <![CDATA[32.09 a ]]> <![CDATA[32.16 a ]]> <![CDATA[32.19 a ]]> 21 <![CDATA[32.12 bc ]]> <![CDATA[32.73 ab ]]> <![CDATA[32.76 ab ]]> <![CDATA[32.92 a ]]> <![CDATA[32.01 c ]]> <![CDATA[31.99 c ]]> <![CDATA[32.09 bc ]]> 24 <![CDATA[32.26 abc ]]> <![CDATA[32.42 c ]]> <![CDATA[32.08 bc ]]> <![CDATA[32.67 ab ]]> <![CDATA[31.88 c ]]> <![CDATA[31.67 c ]]> <![CDATA[31.96 c ]]>

[0089] Table 4 a* values ​​of cherry tomatoes under different treatments

[0090] Storage time (d) MAP-0 MAP-1 MAP-2 MAP-3 LVEF-1 LVEF-2 LVEF-3 0 <![CDATA[12.19 a ]]> <![CDATA[12.19 a ]]> <![CDATA[12.19 a ]]> <![CDATA[12.19 a ]]> <![CDATA[12.49 a ]]> <![CDATA[12.49 a ]]> <![CDATA[12.49 a ]]> 3 <![CDATA[15.12 a ]]> <![CDATA[17.25 ab ]]> <![CDATA[14.07 b ]]> <![CDATA[13.95 b ]]> <![CDATA[13.10 b ]]> <![CDATA[13.57 b ]]> <![CDATA[13.28 b ]]> 6 <![CDATA[16.15 ab ]]> <![CDATA[16.93 a ]]> <![CDATA[17.14 a ]]> <![CDATA[15.58 ab ]]> <![CDATA[14.55 b ]]> <![CDATA[14.44 b ]]> <![CDATA[14.30 b ]]> 9 <![CDATA[14.88 b ]]> <![CDATA[16.28 ab ]]> <![CDATA[15.77 ab ]]> <![CDATA[17.02 a ]]> <![CDATA[16.04 ab ]]> <![CDATA[15.92 ab ]]> <![CDATA[15.69 ab ]]> 12 <![CDATA[16.97 a ]]> <![CDATA[15.92 ab ]]> <![CDATA[16.83 a ]]> <![CDATA[16.35 ab ]]> <![CDATA[15.45 ab ]]> <![CDATA[15.01 b ]]> <![CDATA[14.95 b ]]> 15 <![CDATA[15.43 abc ]]> <![CDATA[15.75 abc ]]> <![CDATA[16.68 ab ]]> <![CDATA[16.78 a ]]> <![CDATA[14.27 c ]]> <![CDATA[14.47 bc ]]> <![CDATA[14.33 c ]]> 18 <![CDATA[16.46 a ]]> <![CDATA[15.47 abc ]]> <![CDATA[16.22 ab ]]> <![CDATA[16.50 a ]]> <![CDATA[14.83 bc ]]> <![CDATA[14.39 c ]]> <![CDATA[14.34 c ]]> 21 <![CDATA[15.96 a ]]> <![CDATA[15.91 ab ]]> <![CDATA[15.85 ab ]]> <![CDATA[16.33 a ]]> <![CDATA[14.33 bc ]]> <![CDATA[14.10 c ]]> <![CDATA[13.79 c ]]> 24 <![CDATA[16.93 a ]]> <![CDATA[15.31 abc ]]> <![CDATA[14.84 abc ]]> <![CDATA[15.81 ab ]]> <![CDATA[13.29 c ]]> <![CDATA[13.30 c ]]> <![CDATA[13.79 bc ]]>

[0091] According to Tables 3 and 4, there is no significant difference between the L* values ​​of cherry tomatoes after storage under different treatments and the L* values ​​before storage, and the a* values ​​of cherry tomatoes in the LVEF-3 group have no significant change during the entire storage period compared with the a* values ​​under other treatments. This shows that the microporous film fresh-keeping bag packaging treatment plus continuous low-voltage electrostatic field treatment preservation method of the present invention can maintain the original color of cherry tomatoes to a great extent and delay the deterioration of the color of cherry tomatoes.

[0092] 6. Calculation of relative conductivity (%)

[0093] On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, and 24th day of storage, take 2.0g of the corresponding cherry tomatoes, treat them with deionized water three times, absorb the water with filter paper, add 25mL of deionized water, let it stand at room temperature for 30min, measure the conductivity C1, then boil it in a water bath for 15min, and measure the conductivity C2 after cooling. Calculate the relative conductivity:

[0094] according to Figure 3It can be seen that with the extension of time, the relative conductivity of each treatment group showed an upward trend, and the relative conductivity of the LVEF-3 group increased the slowest, indicating that the microporous membrane fresh-keeping bag packaging treatment plus the continuous low-voltage electrostatic field treatment can effectively inhibit the increase of cell membrane permeability and electrolyte leakage of cherry tomatoes during storage to a certain extent, and has a significant effect on improving the preservation quality of cherry tomatoes.

[0095] Test Example 2

[0096] The antioxidant index of cherry tomatoes in Example 3, Comparative Example 5 and Comparative Example 7 was measured:

[0097] 1. Calculation of malondialdehyde content (nmol / g)

[0098] On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st and 24th days of storage, 0.1 g of the corresponding cherry tomatoes were taken respectively, and the malondialdehyde content of the cherry tomatoes was detected using a malondialdehyde content detection kit.

[0099] Table 5 Malondialdehyde content of cherry tomatoes under different treatments (nmol / g)

[0100] Storage time (d) LVEF-01 MAP-3 LVEF-3 0 <![CDATA[6.03 a ]]> <![CDATA[6.03 a ]]> <![CDATA[6.03 a ]]> 3 <![CDATA[9.62 a ]]> <![CDATA[8.66 a ]]> <![CDATA[7.57 a ]]> 6 <![CDATA[10.59 a ]]> <![CDATA[9.84 ab ]]> <![CDATA[8.05 b ]]> 9 <![CDATA[10.88 a ]]> <![CDATA[10.68 a ]]> <![CDATA[9.16 a ]]> 12 <![CDATA[10.92 ab ]]> <![CDATA[10.01 a ]]> <![CDATA[9.43 b ]]> 15 <![CDATA[12.06 a ]]> <![CDATA[11.02 a ]]> <![CDATA[10.10 a ]]> 18 <![CDATA[12.26 a ]]> <![CDATA[11.19 b ]]> <![CDATA[11.09 b ]]> 21 <![CDATA[12.52 a ]]> <![CDATA[11.35 a ]]> <![CDATA[11.20 a ]]> 24 <![CDATA[12.74 a ]]> <![CDATA[12.22 ab ]]> <![CDATA[11.37 b ]]>

[0101] It can be seen that after 24 days of storage, the malondialdehyde content of cherry tomatoes treated with LVEF-3 group was lower than that of LVEF-01 group and MAP-3 group. The microporous membrane modified atmosphere packaging treatment plus low-voltage electrostatic field treatment preservation method of the present invention can reduce the accumulation of malondialdehyde and reduce the degree of membrane lipid peroxidation.

[0102] 2. Calculation of reduced glutathione content (μg / g)

[0103] On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st and 24th days of storage, 0.1 g of the corresponding cherry tomatoes were taken respectively, and the reduced glutathione content of the cherry tomatoes was detected using a reduced glutathione content detection kit.

[0104] Table 6 Reduced glutathione content of cherry tomatoes under different treatments (μg / g)

[0105] Storage time (d) LVEF-01 MAP-3 LVEF-3 0 <![CDATA[91.93 a ]]> <![CDATA[91.93 a ]]> <![CDATA[91.93 a ]]> 3 <![CDATA[106.56 a ]]> <![CDATA[108.51 a ]]> <![CDATA[114.4 a ]]> 6 <![CDATA[107.75 b ]]> <![CDATA[120.07 a ]]> <![CDATA[125.09 a ]]> 9 <![CDATA[109.79 b ]]> <![CDATA[121.27 b ]]> <![CDATA[146.47 a ]]> 12 <![CDATA[116.22 c ]]> <![CDATA[136.00 b ]]> <![CDATA[149.81 a ]]> 15 <![CDATA[112.49 b ]]> <![CDATA[127.23 a ]]> <![CDATA[139.42 a ]]> 18 <![CDATA[107.76 b ]]> <![CDATA[125.44 a ]]> <![CDATA[137.03 a ]]> 21 <![CDATA[104.20 b ]]> <![CDATA[123.05 a ]]> <![CDATA[126.53 a ]]> 24 <![CDATA[94.02 b ]]> <![CDATA[119.57 a ]]> <![CDATA[124.44 a ]]>

[0106] According to Table 6, the reduced glutathione (GSH) content of cherry tomatoes gradually increased with the extension of storage time. After 24 days of storage, the reduced glutathione content of cherry tomatoes treated with LVEF-3 group was significantly higher than that of LVEF-01 group and MAP-3 group. Reduced glutathione is an important antioxidant, indicating that the microporous membrane fresh-keeping bag modified atmosphere packaging treatment plus low-voltage electrostatic field treatment can enhance the antioxidant capacity of cherry tomatoes.

[0107] 3. Detection of ABTS + Free radical scavenging rate

[0108] On the 0th, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, and 24th days of storage, 0.5 g of the corresponding cherry tomatoes were taken and 7 mmol / LABTS + Working solution, use UV spectrophotometer to measure the OD value of working solution and anhydrous ethanol at 734nm, record it as A0; measure the OD value of working solution and sample extract, record it as A1. Within a certain range, the change of its absorbance is proportional to the degree of free radical removal.

[0109] according to Figure 4 It can be seen that after 24 days of storage, the ABTS of cherry tomatoes treated with microporous film fresh-keeping bag modified atmosphere packaging and low-voltage electrostatic field treatment + The improvement in free radical scavenging rate indicates that its antioxidant capacity is enhanced.

[0110] In summary, the post-harvest preservation technology of the present invention can reduce the respiration rate of cherry tomatoes and adjust the gas environment in the package, thereby reducing the consumption of nutrients by respiration, reducing water loss, maintaining the hardness of cherry tomatoes, slowing down the increase in weight loss rate, and improving antioxidant capacity, thereby maintaining the original color of cherry tomatoes to a great extent, delaying the consumption of soluble solids, reducing the degree of cell membrane lipid peroxidation and cell membrane electrolyte permeability, maintaining the stability of cell membrane structure, reducing the accumulation of malondialdehyde, and increasing the content of antioxidant reduced glutathione.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preserving cherry tomatoes by low-voltage electrostatic field combined with spontaneous atmosphere packaging, characterized in that: The method comprises the following steps: precooling the cherry tomatoes, packaging them with a spontaneous atmosphere packaging material, and storing them in a low-voltage electrostatic field after packaging.

2. The method according to claim 1, characterized in that The precooling temperature is 10-12° C. and the precooling time is 30-40 minutes.

3. The method according to claim 1, characterized in that The spontaneous atmosphere modified packaging material includes a PET fresh-keeping box, a perforated PE fresh-keeping bag or a microporous film fresh-keeping bag.

4. The method according to claim 3, characterized in that The permeability of the microporous film fresh-keeping bag to oxygen is 240000~250000mL / (m 2 ·d).

5. The method according to claim 3, characterized in that: The permeability of the microporous film fresh-keeping bag to carbon dioxide is 250,000 to 260,000 mL / (m 2 ·d).

6. The method according to claim 1, characterized in that The electric field strength of the low-voltage electrostatic field is 160-180V.

7. The method according to claim 1, characterized in that The storage time is 20 to 26 days.

8. The method according to claim 1, characterized in that: The storage environment temperature is 8-12°C.

9. The method according to claim 1, characterized in that: The relative humidity of the storage environment is 80-90%.

10. Use of the method according to any one of claims 1 to 9 in the transportation and management of cherry tomatoes.

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