Method for prolonging shelf life of agricultural product by using BOPE (biaxially-oriented polyethylene) film

Abstract

The invention relates to a method for prolonging shelf life of agricultural products by using a BOPE (biaxially oriented polyethylene) film, which is characterized in that PE (polyethylene) and BOPE film packaging are respectively applied to fresh tomato fruits (breathing climacteric change) and strawberry fruits (non-breathing climacteric change), the weight loss ratio, malondialdehyde and oxidation trend of the fruits are obviously reduced, and the activity of antioxidant enzyme POD (peroxidase) is obviously improved. The weight loss ratio of the strawberries packaged by the BOPE film is lower than that of a control group at the end of the storage period, the hardness and the soluble solid content of the fruits are higher than those of the control group, and the phenomena of aging, water loss, hardness and soluble solid (TSS) reduction of the harvested strawberries in the storage process are effectively delayed. The weight loss ratio of the tomato fruits packaged by the BOPE film is obviously reduced compared with that of a control group, and a good effect is achieved in the aspects of keeping the hardness and the soluble solid content of the fruits.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural product storage and preservation, and in particular to a method for extending the shelf life of agricultural products by using a BOPE film. Background Art

[0002] As perishable commodities, fruits and vegetables occupy an indispensable position in a healthy diet. They are rich in vitamins, minerals, and antioxidants, which are essential for improving metabolism and maintaining overall health. Among them, tomatoes, as an ornamental and edible fruit, are smaller in size and sweeter in taste than ordinary fruits. They are often used to embellish or decorate salads, pastas, and dishes. However, tomatoes are also perishable commodities with a relatively short shelf life, generally between 5 and 7 days. During the ripening process, tomatoes undergo complex physiological and chemical changes, which not only affect their flavor and aroma, but also change their texture and hardness. Although a variety of preservation methods have been adopted to extend the shelf life of fruits and vegetables, such as refrigeration, ethylene management, and controlled environment technology, the preservation of tomatoes remains a challenge. Its thin skin and juicy characteristics make it difficult for it to withstand the pressure during long-distance transportation and storage, and the post-harvest decay rate is as high as more than 30%, which poses a serious threat to its commercial value.

[0003] Among the many preservation technologies, packaging is a key link. Plastic films, especially biaxially oriented polyethylene films (BOPE), have been widely used in the field of fresh fruit and vegetable packaging due to their excellent performance and environmental advantages. BOPE film can still meet the use requirements when the thickness is reduced, which is of great significance in the packaging industry. BOPE film is widely used in various scenarios due to its excellent performance and wide application adaptability. Compared with other packaging materials, BOPE film shows a more balanced comprehensive performance and environmental advantages, which makes its market prospects in the packaging industry very broad. Summary of the invention

[0004] The object of the present invention is to provide a method for extending the shelf life of agricultural products by using BOPE film.

[0005] To achieve the above-mentioned purpose and other related purposes, the technical solution provided by the present invention is: a method for extending the shelf life of agricultural products by using BOPE film, and packaging agricultural products by using BOPE film.

[0006] The preferred technical solution is: using BOPE film to package agricultural products.

[0007] The preferred technical solution is: the agricultural product is strawberry or tomato.

[0008] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0009] 1. BOPE packaging significantly reduces the weight loss rate, malondialdehyde, and oxidation tendency of tomato fruits, and it is found that the activity of antioxidant enzyme POD is significantly increased.

[0010] 2. The effect of BOPE film packaging on the quality of post-harvest strawberry fruits. The weight loss rate of strawberries packaged with BOPE film at the end of the storage period was significantly lower than that of the control group, and the hardness and soluble solid content of the fruit were higher than those of the control group, indicating that BOPE film packaging effectively delayed the aging, water loss, hardness, and reduction of soluble solids (TSS) of post-harvest strawberries during storage. At the same time, the total phenol, flavonoid, anthocyanin, and total protein content of strawberry fruits packaged with BOPE film at the end of the storage period were significantly higher than those of the control group, indicating that BOPE film effectively extended the storage period of post-harvest strawberry fruits and maintained the high quality of strawberries.

[0011] 3. Effect of BOPE film packaging on the antioxidant activity of post-harvest strawberry fruit. During the entire storage period, the malondialdehyde (MDA) content in strawberries in all treatment groups increased. It is worth noting that compared with the control group, the BOPE treatment group can further inhibit the accumulation of MDA. In addition, the peroxidase (POD) activity in the BOPE-packaged fruit is higher than that in the control group, which indicates that BOPE treatment can significantly improve the antioxidant capacity of the fruit, reduce the oxidative damage of the fruit during post-harvest storage, maintain the excellent quality of the fruit, and thus delay the ripening process of the strawberry. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Effects of different treatments on the storage period of postharvest strawberries.

[0013] Figure 2 Changes in postharvest weight loss rate of strawberries during storage under different treatments.

[0014] Figure 3 Changes in postharvest hardness of strawberries during storage under different treatments.

[0015] Figure 4 Changes in soluble solid matter content of postharvest strawberries during storage under different treatments.

[0016] Figure 5 Changes in total phenolic content of postharvest strawberries during storage under different treatments.

[0017] Figure 6 Changes in flavonoid content in postharvest strawberries during storage under different treatments.

[0018] Figure 7 Changes in anthocyanin content in postharvest strawberries during storage under different treatments.

[0019] Figure 8Changes in soluble protein content in postharvest strawberries during storage under different treatments.

[0020] Fig. 9 Changes in MDA content of postharvest strawberries during storage under different treatments.

[0021] Fig.10 Changes in POD activity of postharvest strawberries during storage under different treatments.

[0022] Fig.11 This is an apparent diagram showing the changes in the freshness-keeping effect of tomatoes at different storage times. Fig.12 The effect of different storage time on the weight loss rate of tomato fruit.

[0023] Fig.13 The effect of different storage times on the hardness of tomato fruit.

[0024] Fig.14 The effect of different storage times on the changes in soluble solids content in tomato fruits.

[0025] Fig.15 The effects of different storage times on the total phenolic content of tomato fruits.

[0026] Fig.16 The effect of different storage time on the content of flavonoids in tomato fruit.

[0027] Fig.17 The effect of different storage time on the soluble protein content of tomatoes.

[0028] Fig.18 The effect of different storage time on the changes of MDA content in tomatoes.

[0029] Fig.19 The effect of different storage time on the activity of tomato POD. DETAILED DESCRIPTION

[0030] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0031] See also Figure 1-19. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0032] Unless otherwise specified, the reagents or materials described in the following examples are commercially available.

[0033] Example 1: A method for extending the shelf life of agricultural products (strawberries)

[0034] When selecting samples of fresh strawberries, ensure that the selected fruits are consistent in size and color, specifically, about 60% of the surface area is bright red. At the same time, exclude those strawberries with mechanical damage, signs of pests and diseases, or microbial contamination. Divide the fresh strawberries into three equal parts and package them with BOPE film. Collect samples every 24 hours at 14°C, and then immediately transfer the samples to a frozen environment at -20°C for storage for subsequent use.

[0035] The detection method of this embodiment includes:

[0036] (1) Determination of weight loss rate of strawberry fruit

[0037] The weight loss rate calculation formula is as follows:

[0038] Weight loss rate (%) = (Q0-Qi) / Q0×100%;

[0039] Where Q0 is the mass of strawberry fruit before storage, g; Qi is the mass of strawberry fruit on the i-th day, g.

[0040] (2) Determination of strawberry fruit hardness

[0041] The hardness of strawberry fruit was measured using a GY-3 fruit hardness tester. A probe with a diameter of 8 mm was used to measure the equatorial part of each strawberry fruit and was pressed into the equator to a depth of 10 mm. Five strawberry fruits were taken at a time.

[0042] Two centrally symmetrical parts of the strawberry fruit were taken for measurement.

[0043] (3) Determination of soluble solids in strawberry fruit

[0044] The soluble solid content of strawberry fruit was determined using a handheld refractometer. The handheld refractometer was washed with clean water and zeroed before and after each use, and then a few drops of strawberry solution were dropped into the refractometer and the reading was read. The determination was repeated three times, and the average and standard deviation were calculated.

[0045] (4) Determination of total phenols, flavonoids and anthocyanins in strawberry fruit

[0046] Weigh 0.2g of ground pulp tissue powder, add 5mL of 1% HCl-methanol solution, and extract in a 4℃ refrigerator in the dark for 20min. Shake several times in the dark, and then centrifuge at 4℃ 12000rpm for 2min. Collect the supernatant for use. Use 1% hydrochloric acid-methanol solution to calibrate the baseline to zero, and then measure the absorbance of the filtrate at wavelengths of 280nm, 325nm, 600nm and 530nm. This process needs to be repeated three times to ensure the accuracy of the results.

[0047] The absorbance of the solution at a wavelength of 280 nm represents the total phenol content, the absorbance of the solution at a wavelength of 325 nm represents the flavonoid content, and the anthocyanin content U = (OD 530 -OD 600 ) / g.

[0049] (5) The soluble protein in strawberry fruit was determined by Coomassie Brilliant Blue G-250 staining.

[0050] (6) Determination of malondialdehyde in strawberry fruit

[0051] First, take 0.2g of ground pulp tissue powder and add 1mL of 10% trichloroacetic acid (TCA) solution. Subsequently, centrifuge at 12000rpm for 2min in a low-temperature centrifuge at 4°C to separate the supernatant and store it in a low-temperature environment. Next, take 0.6mL of the supernatant and put it into a test tube, and then add 0.6mL of 0.67% thiobarbituric acid (TBA) solution to it. Heat the test tube in a boiling water bath for 20min, and then cool it quickly. Take the cooled supernatant and perform colorimetric analysis at wavelengths of 450nm, 532nm and 600nm. Based on the colorimetric results, calculate the malondialdehyde (MDA) concentration in the sample extract. Finally, based on the fresh weight of the strawberry sample, calculate the MDA content in the sample.

[0052] (7) Determination of POD activity in strawberry fruit

[0053] First, accurately weigh 0.2g of fruit and vegetable tissue sample and add 1mL of extraction buffer. Centrifuge the mixture at 4℃ and 12000rpm for 2min to collect the supernatant as the enzyme extract and store it at low temperature for subsequent use. Next, take a test tube, add 3.0mL of 25mol / L guaiacol solution and 0.2mL of enzyme extract, and then quickly add 0.2mL of 0.5mol / L hydrogen peroxide solution to start the chemical reaction and start timing immediately. Subsequently, pour the reaction mixture into a cuvette and place it in the sample chamber of the spectrophotometer. Using distilled water as a reference, record the absorbance value of the reaction system at a wavelength of 470nm 15 seconds after the start of the reaction, and record this value as the initial absorbance. After that, record the absorbance value every 1min, measure continuously, and collect data at least 6 time points. This process needs to be repeated three times to ensure the accuracy and repeatability of the results.

[0054] Calculate the absorbance change per minute ΔOD 470 :

[0055] Among them, ΔOD 470 —Reaction absorbance change per minute;

[0056] OD 470F —The absorbance end value of the reaction mixture;

[0057] OD 470I —Initial absorbance value of the reaction mixture;

[0058] t p —Reaction termination time, min;

[0059] t l —Reaction initial time, min.

[0060] One unit of peroxidase activity is defined as the increase of 1 absorbance change per gram of fruit and vegetable sample (fresh weight) per minute. The unit is ΔOD 470 / min*g, the calculation formula is:

[0061] Where, V is the total volume of sample extract, mL;

[0062] VS—volume of sample extract taken during determination, mL;

[0063] m—sample mass, g.

[0064] 1. The influence of BOPE film on the storage period of strawberry fruit

[0065] Decay is one of the most direct and obvious indicators for evaluating the preservation effect of fruits. Figure 1 It can be seen that the decay of strawberries showed an increasing trend throughout the storage process. The control group showed decay on the third day of treatment. As the number of treatment days increased, the fruit quality of the BOPE group was significantly better than that of other groups, with the least decay. Therefore, BOPE film treatment can reduce the post-harvest decay of strawberry fruits. Therefore, we further studied other physiological and biochemical indicators.

[0066] 2. Effect of BOPE film on weight loss rate during strawberry storage

[0067] Weight loss can directly reflect the freshness of the fruit after harvest. Figure 2 It can be seen that during the entire treatment process, the weight loss rates of the treatment group and the control group increased, and the weight loss rate of the control group was the highest. Compared with the control group, the weight loss rate of the fruit in the BOPE treatment group was the lowest, indicating that the use of BOPE film greatly reduced the water loss of strawberry fruit during storage.

[0068] 3. Effect of BOPE film on the hardness of strawberries during storage

[0069] Fruit hardness is one of the important indicators to measure fruit maturity and storage quality, and it gradually decreases as the fruit matures. Figure 3 As shown in the figure, the firmness of strawberry fruit in all strawberry treatment groups decreased during storage. However, compared with the CK group, the fruit firmness of the BOPE group was still at a higher level.

[0070] 4. Effect of BOPE film on soluble solids during strawberry storage

[0071] The total soluble solids (TSS) content of strawberries is an important indicator for measuring the sugar content of strawberry fruits. Figure 4 As shown in the figure, the total soluble solids content of all treatment groups and the control group showed the same downward trend throughout the storage process. However, there were significant differences in the total soluble solids content between the treatment groups and the control group, among which the soluble solids content of the CK group decreased most significantly. On the 5th day of treatment, the soluble solids content of the CK group was 3.5%, while the soluble solids content of the PE group and the BOPE group were 4% and 4.9%, respectively.

[0072] 5. Effect of BOPE film on the content of total phenols, flavonoids and anthocyanins during strawberry storage

[0073] The total phenolic and flavonoid contents of strawberry fruits showed an increasing trend during postharvest storage. Figure 5 , Figure 6The data in the study showed that the growth rate of total phenolic and flavonoid content in the BOPE film-treated group exceeded that of the control group and other treatment groups throughout the treatment period. This finding suggests that BOPE film can effectively inhibit the formation of free radicals in strawberries, thereby maintaining the quality of strawberries during storage and processing.

[0074] Anthocyanin is a water-soluble natural pigment widely found in plants, which can give fruits a variety of colors, such as red, yellow and purple. During the ripening process of strawberries, the anthocyanin content slowly increases, and the anthocyanin content of strawberries at the ripening stage is the highest. Figure 7 As shown in the figure, on the 5th day of treatment, the anthocyanin content in the PE or BOPE treatment group increased significantly and was higher than that in the control group, which indicates that BOPE film treatment can delay the ripening process of strawberry fruit and play a certain role in preservation.

[0075] 6. Effect of BOPE film on soluble protein content during strawberry storage

[0076] Soluble protein is an important osmotic regulator and nutrient. The increase and accumulation of soluble protein can improve the water holding capacity of cells and protect important substances and biofilms in cells. Figure 8 As shown in the data, with the extension of postharvest storage time, the soluble protein content of strawberry generally showed a downward trend, while the soluble protein content of the PE group and BOPE group showed an upward trend 3-5 days after storage (DAS), indicating that BOPE treatment can alleviate the degradation of protein in strawberry fruit during storage.

[0077] 7. Effect of BOPE film on the content of MDA during strawberry storage

[0078] like Fig. 9 As shown in the figure, the malondialdehyde (MDA) content in strawberries of all treatment groups increased during the entire storage period. It is worth noting that compared with the CK treatment group, the BOPE treatment group could further inhibit the accumulation of MDA, thereby delaying the ripening process of strawberries.

[0079] 8. Effect of BOPE film on POD activity during strawberry storage

[0080] The changes of POD activity during storage are as follows: Fig.10 As shown in the figure. Throughout the treatment process, the POD activity of strawberry fruits treated with PE / BOPE was higher than that of the control group. In addition, BOPE treatment can significantly improve the antioxidant capacity of the fruit, reduce the oxidative damage of the fruit during postharvest storage, and maintain the excellent quality of the fruit.

[0081] This example compares the effects of a control group, a PE film packaging group, and a BOPE film packaging group on the quality of post-harvest strawberries.

[0082] The results show that BOPE film packaging has the best preservation effect on post-harvest strawberries. The research results are as follows:

[0083] (1) BOPE film packaging extends the storage period of post-harvest strawberries and the hardness of the strawberry fruit;

[0084] (2) BOPE film packaging delayed the increase of weight loss rate of post-harvest strawberries and the loss of soluble protein and soluble solids;

[0085] (3) BOPE film can effectively inhibit the formation of free radicals in strawberries, thereby maintaining the quality of strawberries during storage and processing, delaying the ripening process of strawberry fruits, and playing a certain role in preserving freshness;

[0086] (4) BOPE film delayed the increase of MDA content in postharvest strawberries and maintained high POD activity during storage.

[0087] Example 2: A method for extending the shelf life of agricultural products (tomatoes)

[0088] Tomatoes without damage, green ripe, uniform maturity and size were selected as test materials, 5 in each group, and then the tomatoes were packaged in PE and BOPE, and the unpackaged CK group was placed in the same storage environment as a control. The storage temperature was room temperature, and samples were randomly selected every day during the storage period to test the maturity-related indicators.

[0089] The detection method of this embodiment includes:

[0090] (1) Method for measuring fruit firmness

[0091] In order to measure the hardness of the fruit, we can use the GY-1 fruit hardness tester. The following are the specific measurement steps:

[0092] 1. Select 5 tomatoes as samples. 2. Select three locations at equal distances from the equator of each tomato. 3. Use a GY-1 fruit hardness tester to measure the hardness of the flesh at these three locations. In this way, we can obtain the hardness data of each tomato at different locations, and then analyze the hardness changes of the entire sample to evaluate the maturity and storage quality of the fruit. These data are of great reference value for guiding the storage and transportation of fruits and vegetables.

[0093] (2) Determination of fruit weight loss rate

[0094] Select 5 tomatoes of similar size and without damage. Use an electronic balance to accurately weigh the initial weight (W0) of each tomato and record it.

[0095] Storage process: Put the weighed tomatoes into the pre-prepared storage conditions. Store them in a sealed container under controlled environmental conditions with constant temperature and humidity.

[0096] Weigh regularly: Take out the tomatoes at set time intervals (such as every day or every week) and weigh the current weight (Wt) of each tomato using an electronic balance. Record the data of each weighing. Repeat measurement: Repeat step 3 until the end of the experiment.

[0097] (3) Determination of fruit soluble solids

[0098] The steps for determining the soluble solids content in tomato fruit can be summarized as follows:

[0099] Collect juice: Take 5 tomato fruit samples and use a spoon to squeeze and collect the juice. Add sample: Add the juice dropwise onto the detection mirror of the refractometer, making sure there are no bubbles. Aim at the light source: Hold the refractometer level with the light source, and adjust the eyepiece diopter until the black and white dividing line is clearly visible. Read the data: Read the reading on the scale, which is the soluble solids content (expressed as mass fraction %). Repeat the measurement: Repeat the steps 2 to 4 times to obtain a more accurate result. Calculate the average value: Add the three measured values ​​and divide by 3 to get the average value.

[0100] (4) Determination of total phenols and flavonoids

[0101] Fruit and vegetable tissues are rich in secondary metabolites such as phenols and flavonoids, which have an important impact on the storage, processing, nutritional value and medical and health care effects of fruits and vegetables.

[0102] Methanol was used to extract total phenols and flavonoids from fruits and vegetables, and their absorbance was measured at a specific wavelength by a UV-visible spectrophotometer, and the content was calculated by comparing with the standard curve. This method is simple and has good reproducibility.

[0103] (5) Determination of malondialdehyde (MDA)

[0104] MDA is harmful to the plasma membrane and organelles of fruits and vegetables because it can react with biomacromolecules such as proteins and nucleic acids, changing their structure or causing them to cross-link, thus losing their normal function. In addition, MDA also affects the stability of cellulose and the synthesis of proteins.

[0105] In order to accurately measure the content of MDA, the thiobarbituric acid (TBA) reaction method is usually used. However, the soluble sugars in fruits and vegetables will interfere with this reaction, so it needs to be corrected by a specific formula. The correction method usually involves measuring the absorbance at three wavelengths (450nm, 532nm and 600nm) and using a specific formula to remove the interference of sugar.

[0106] (6) Determination of total protein content

[0107] Weigh 2.0 g of fruit and vegetable sample tissue, add 5 mL of distilled water or buffer, grind into a homogenate, centrifuge at 4°C, 12000 x g for 20 min, collect the supernatant as the soluble protein extract, and store at low temperature for later use.

[0108] Take 1.0 mL of sample extraction supernatant (appropriately diluted according to protein content), put it into a stoppered test tube, add 5.0 mL of Coomassie Brilliant Blue G-250 solution, mix thoroughly, let stand for 2 minutes, and then measure the absorbance value at a wavelength of 595 nm in the same way as the standard curve. Repeat three times.

[0109] (7) Peroxidase (POD) assay

[0110] Peroxidase (POD) plays a key role in fruits and vegetables. As fruits and vegetables grow, mature, age, encounter external stimuli, pathogen infection, or changes in storage and processing conditions, POD activity will be adjusted accordingly to respond. Peroxidase catalyzes hydrogen peroxide to oxidize phenolic substances to form aldehyde compounds, which can further condense or combine with other molecules to form darker compounds. In particular, peroxidase can catalyze hydrogen peroxide to oxidize guaiacol to 4-o-methoxyphenol. The product is reddish brown and has a maximum light absorption at a wavelength of 470nm. Therefore, the activity of peroxidase can be evaluated by measuring the absorbance of this product by colorimetry. Weigh 5.0g of fruit and vegetable tissue samples, place them in a mortar, add 5.0mL of extraction buffer, grind them into a homogenate under ice bath conditions, centrifuge them at 4℃ and 12 000x g for 30min, collect the supernatant as the enzyme extract, and store them at low temperature for later use. Take a test tube, add 3.0mL 25mmol / L guaiacol solution and 0.5mL enzyme extract, 200uL 0.5mol / L H2O2. Mix the solution quickly to start the reaction, and start timing immediately. Pour the reaction mixture into a colorimetric cup and place it in the sample chamber of the spectrophotometer. Using distilled water as a reference, start recording the absorbance value of the reaction system at a wavelength of 470nm after 15s of reaction as the initial value, and then record it every 1min, measure continuously, and obtain data for at least 6 points. Repeat three times.

[0111] 1. Tomato appearance diagram

[0112] like Fig.11 As shown in the figure, PE and BOPE film packaging delayed the color change of tomatoes compared with the control group. In the first 0-2 days of storage, the color and maturity of tomatoes in all treatment groups were similar, but after 4-6 days of storage, the tomatoes in the control group changed from red to green the fastest. In the late storage period (8-12 days), compared with unpackaged tomatoes and tomatoes packaged with PE only, the tomatoes in the BOPE packaging group had better skin condition and no obvious wrinkles.

[0113] 2. Tomato weight loss rate

[0114] like Fig.12 As shown in the figure, the weight loss rates of tomato fruits packaged with PE or BOPE films were 1.23% and 0.43%, respectively. Compared with the CK group, the weight loss rates of tomato fruits treated with PE and BOPE films were significantly reduced (p<0.05), and the effect of BOPE was better than that of PE.

[0115] 3. Tomato Hardness

[0116] like Fig.13 As shown in the data, with the extension of storage time, the firmness of tomato fruit gradually decreased. Compared with the control group, the degree of firmness reduction in PE and BOPE treatments was significantly slower (p<0.05). In addition, on the 6th and 8th days after storage, the effect of BOPE treatment was higher than that of PE, which indicates that BOPE has a good effect in maintaining fruit firmness and effectively delaying fruit softening.

[0117] 4. Soluble solids content of tomatoes

[0118] As the tomato fruits gradually matured, the soluble solids content of the samples in each experimental group showed a trend of first increasing and then decreasing. Fig.14 As shown, the soluble solids accumulation in tomato fruits treated with BOPE was higher than that in the control group.

[0119] 5. Total phenols and flavonoids content in tomatoes

[0120] like Fig.15 and Fig.16 As shown in the figure, the total phenolic and flavonoid contents of tomato fruits under all treatment conditions increased first and then decreased throughout the storage period, and basically reached a peak on the 4th day. The peak values ​​of total phenolic contents of tomato fruits wrapped in PE film and BOPE film were 3.17 mg / g and 3.49 mg / g, respectively, and the peak values ​​of flavonoid contents were 1.45 mg / g and 1.56 mg / g, respectively, which were significantly higher than the CK peak values.

[0121] 6. Soluble protein content of tomatoes

[0122] During storage, the soluble protein content of tomato fruit usually shows a continuous upward trend. Fig.17 As shown, the soluble protein content increased with the extension of storage time, and the soluble protein content of tomatoes packaged in BOPE was higher than that in PE and the control group.

[0123] 7. MDA content in tomatoes

[0124] like Fig.18As shown, compared with the control group, the rate of increase of MDA content in the BOPE-treated group was significantly slower, with the MDA content of the control group reaching 0.64 μmol / kg on the 8th day, the MDA content of the PE group reaching 0.61 μmol / kg, and the MDA content of the BOPE-treated group only reaching 0.54 μmol / kg.

[0125] 8. Tomato POD Activity

[0126] like Fig.19 As shown in the figure, the POD activity in tomato fruit gradually increased during storage, reaching the highest level on the 4th day, and then decreased. During the same storage period, the POD activity of tomatoes treated with BOPE was higher than that of the PE group and the control group. BOPE treatment increased the activity of POD enzyme in fruit tissue, which helped to enhance the antioxidant capacity of the fruit and its resistance to adverse stress.

[0127] This example compares the effects of the control group, PE film packaging group, and BOPE film packaging group on the quality of tomato fruit during storage. The results show that BOPE film packaging has the best preservation effect on post-harvest tomatoes. The research results are as follows:

[0128] (1) BOPE film packaging extends the storage period of post-harvest tomatoes and the hardness of tomato fruits;

[0129] (2) BOPE film packaging delayed the increase of weight loss rate of post-harvest tomatoes and the loss of soluble protein and soluble solids;

[0130] (3) BOPE film can inhibit the formation of free radicals in tomatoes, thus delaying the ripening process of tomato fruits and playing a certain role in preserving freshness;

[0131] (4) BOPE film delayed the increase of MDA content in postharvest tomatoes and maintained high POD activity during storage.

[0132] The above description is only used to explain the preferred embodiments of the present invention, and is not intended to limit the present invention in any form. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included in the scope of protection intended by the present invention.

Claims

1. A method for extending the shelf life of agricultural products using BOPE film, characterized in that: The tomato and strawberry fruits are packaged using BOPE film.

2. The method for extending the shelf life of agricultural products using BOPE film according to claim 1, characterized in that: Use BOPE film to package ripe fruits to extend their shelf life.

3. The method for extending the shelf life of agricultural products using BOPE film according to claim 1, characterized in that: The agricultural products are strawberries or tomatoes.

Images