Preservative for postharvest bananas and application thereof

Abstract

The invention relates to the technical field of banana preservation, in particular to a postharvest banana preservative and application thereof.The preferable main component of the postharvest banana preservative is quinacridine dihydrochloric acid, and after treatment of the preservative, the disease resistance of banana anthracnose can be improved, the occurrence of postharvest banana rot caused by anthracnose is remarkably reduced, and the banana quality is improved. Black spots on the surfaces of banana peels can be delayed, and the quality of picked banana fruits can be maintained.

Description

[Technical field]

[0001] The invention belongs to the technical field of banana preservation, and particularly relates to a post-harvest banana preservative and application thereof. [Background technology]

[0002] Banana (Musa nana L.) is one of the four major fruits in the world, native to Southeast Asia. Ripe bananas have a fragrant smell and delicate flesh. In addition, bananas are rich in nutrients such as protein, VC, mineral K, and active ingredients such as polyphenols and amines, and have health functions such as anti-oxidation and cardiovascular prevention, so they are deeply loved by consumers.

[0003] Bananas are respiratory climacteric fruits. Once the respiratory peak occurs, the fruit will quickly become soft and rot. Banana anthracnose is one of the most important fungal diseases on bananas and one of the main causes of post-harvest rot in bananas. At first, small brown or dark brown round spots appear on the fruit stalk and peel. Then the spots quickly expand and merge with each other, causing the flesh to rot, seriously affecting the storage, transportation and sales of bananas. In addition, some black spots will appear on the peel of bananas after they mature, affecting the appearance of the banana fruit.

[0004] Therefore, developing post-harvest banana preservation technology is of great significance to improving the shelf life and commodity value of bananas. [Summary of the invention]

[0005] In view of the above, it is necessary to provide a post-harvest preservative for bananas, which can improve the disease resistance of bananas to anthracnose, significantly reduce the occurrence of post-harvest rot caused by anthracnose, and delay the appearance of black spots on the banana peel, thereby maintaining the post-harvest quality of banana fruits.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A banana post-harvest preservative mainly consists of one of quinacrine dihydrochloride, neomycin sulfate and n-hexanol.

[0008] Specifically, the concentration of neomycin sulfate is preferably 3.0 mM, and the concentration of n-hexanol is preferably 0.12%.

[0009] In the present invention, further, the preservative is quinacrine dihydrochloride.

[0010] In the present invention, further, the concentration of quinacridone dihydrochloride is 2.00 mM.

[0011] The invention also provides a method for preserving bananas by using a banana post-harvest preservative. The method specifically comprises the following steps: drying banana fruits, soaking them in the prepared banana post-harvest preservative for 4-6 minutes, taking them out and drying them after soaking, and then sealing and storing them in polyethylene film bags.

[0012] The present invention has the following beneficial effects:

[0013] The present invention provides a banana post-harvest preservative, wherein the main component is selected from one of quinacrine dihydrochloride, neomycin sulfate and n-hexanol. The applicant has many years of experience in banana preservation research and knows that banana anthracnose is a major banana disease caused by C. musae. In the process of banana resisting pathogens, the cell membrane, as the first line of defense in the body, responds quickly when under stress. Phospholipase, as a key enzyme for the cell membrane to resist diseases, can catalyze the hydrolysis of ester bonds in phospholipid molecules, produce second messenger substances for conduction, and quickly make the plant body respond immune. Phospholipase plays an important role in the defense response and growth and development of plants. However, the role of phospholipase is not only positive. While phospholipase protects plants, it also hydrolyzes cell membrane phospholipids, promoting membrane Lipid peroxidation causes oxidative stress, leading to abnormal membrane lipid metabolism and destroying the integrity of cell membranes. Based on this, the preservative described in the present application takes the inhibition of phospholipase activity as the main starting point. Through a large number of experiments, it is concluded that quinacrine dihydrochloride, neomycin sulfate and n-hexanol have an inhibitory effect on phospholipase and can inhibit the growth of C.musae. The optimal concentration is further explored. In further experiments, it is concluded that quinacrine dihydrochloride can inhibit the PLA of C.musae and the PLA of banana peel. It is the most preferred preservative component. After being treated with the preservative, the disease resistance of bananas to anthracnose can be improved, the occurrence of post-harvest rot of bananas caused by anthracnose can be significantly reduced, and the appearance of black spots on the banana peel epidermis can be delayed, thereby maintaining the post-harvest quality of banana fruits.

Brief Description of the Drawings

[0014] Figure 1 The effects of different concentrations of QU, NE and Hex on C. musae and the calculation of IC50;

[0015] Figure 2 The effect of the inhibitor on the phospholipase activity of C. musae and banana fruit;

[0016] Figure 3 The effects of different concentrations of QU, NE and Hex on banana anthracnose;

[0017] Figure 4 The effect of the optimal QU concentration on the appearance of bananas;

[0018] Figure 5The effect of optimal QU, NE and Hex concentrations on banana anthracnose is shown in the banana appearance diagram;

[0019] Figure 6 This is a numerical comparison chart of the effects of optimal QU, NE and Hex concentrations on the lesion diameter of banana anthracnose. [Specific implementation method]

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0021] Embodiment 1:

[0022] This embodiment provides a post-harvest banana preservative, wherein the main component of the preservative is quinacrine dihydrochloride, and the concentration of the quinacrine dihydrochloride is preferably 2.00 mM.

[0023] Embodiment 2:

[0024] This embodiment provides a post-harvest banana preservative, wherein the main component of the preservative is neomycin sulfate, and the concentration of the neomycin sulfate is preferably 3.0 mM.

[0025] Embodiment 3:

[0026] This embodiment provides a post-harvest banana preservative, wherein the main component of the preservative is n-hexanol, and the concentration of the n-hexanol is preferably 0.12%.

[0027] The present application also provides a method for preserving bananas, specifically, using the banana post-harvest preservative described in Examples 1-3 to preserve the harvested bananas. Specifically, after drying the bananas, soak them in the prepared banana post-harvest preservative for 4-6 minutes, take them out after soaking, dry them, and then seal them in polyethylene film bags for storage.

[0028] Test example:

[0029] In order to illustrate the effect of this application, the applicant conducted the following experiments:

[0030] Test 1:

[0031] 1. Test materials

[0032] Test strain: banana anthracnose fungus (Colletotrichum musae, C. musae) 31249 strain, which was preserved in the laboratory of the Institute of Agricultural Products Processing, Guangxi Academy of Agricultural Sciences for future use.

[0033] Plant experimental materials: Bananas of the "Guijiao No. 1" variety were selected. The ripe fruits were picked in the orchard of Tanluo Town, Nanning City, Guangxi, and immediately transported to the Agricultural Products Processing Research Laboratory of Guangxi Academy of Agricultural Sciences. Bananas with uniform size and maturity, free of mechanical damage and pests were selected for cleaning, and then soaked in 0.5% sodium hypochlorite solution for 30 seconds for disinfection.

[0034] Test reagents and instruments: as shown in Table 1 and Table 2:

[0035] Table 1 Test reagents

[0036]

[0037]

[0038] Table 2 Test equipment

[0039]

[0040] 2. Test methods

[0041] (1) In vitro experiments

[0042] 1.1 Analysis of the concentration effect of different concentrations of preservatives on the mycelium diameter and spore production of C. musae

[0043] Quinacridone dihydrochloride (QU), neomycin sulfate (NE) and n-hexanol (Hex) solutions were filtered through a 0.45 μm Millipore filter and then added to the sterilized PDA medium and mixed. The final concentrations of QU were 0.01, 0.10, 0.50, 1.00, 1.50 and 2.00 mM, the final concentrations of NE were 0.50, 1.00, 1.50, 2.00, 2.50 and 3.00 mM, and the final concentrations of Hex were 0.01%, 0.02%, 0.04%, 0.08%, 0.10% and 0.12%, with sterile water as the control. PDA medium containing preservative was poured into a culture dish. After the culture medium solidified, the bacterial cake was connected to the center of the culture medium and placed in an inverted culture at 28°C. The mycelial growth diameters on the 3rd, 4th and 5th days were observed and measured.

[0044] The QU, NE and Hex solutions were filtered through a 0.45 μm Millipore filter and then added to the sterilized PDB medium and mixed. The final concentrations of QU were 0.01, 0.10, 0.50, 1.00, 1.50 and 2.00 mM, the final concentrations of NE were 0.50, 1.00, 1.50, 2.00, 2.50 and 3.00 mM, and the final concentrations of Hex were 0.01%, 0.02%, 0.04%, 0.08%, 0.10% and 0.12%, with sterile water as a control. Take the cultured C. musae strain, gently scrape the fungal spores on the surface of the culture medium with an inoculation loop under sterile conditions, count them under an optical microscope with a hemocytometer, and adjust the spore concentration to 1×10 6 The spores and PDB medium were mixed at a volume ratio of 1:1000 and then incubated at 28°C and shaken at 200 rpm. The spore counts were measured on the 3rd, 4th and 5th days.

[0045] 1.2 Effects of preservatives on phospholipase activity in C. musae and banana fruit

[0046] After solidification, sterile cellophane was spread on the PDA medium, and then C.musae cake was inoculated into the medium and inverted for culture at 28°C. When C.musae was cultured to the 5th day, the mycelium was collected for use. The collected mycelium was crushed in liquid nitrogen with a mortar, 0.01g of mycelium was weighed, 100μL of BPS with pH 7.8 was added, and the mycelium was further ground thoroughly with an electric sample grinder. Centrifuged at 4500r / min for 15min at 4°C, the supernatant (containing crude enzyme solution of PLA, PLC and PLD) was taken for use. After adding IC50 concentration of PL preservative to the crude enzyme solution, the PLA, PLC and PLD of C.musae were determined by ELISA. Samples were taken from the dried banana peels, frozen through with liquid nitrogen, and stored at -80°C for use. Weigh 0.10g banana peel, add 1mL BPS of pH 7.8, mix well with a vortexer, centrifuge at 4500r / min and 4℃ for 15min, take the supernatant (containing crude enzyme solution of PLA, PLC and PLD) for later use. Add PL preservative with 5 times IC50 concentration to the crude enzyme solution, and measure PLA, PLC and PLD of C.musae by ELISA.

[0047] (2) In vivo test on banana

[0048] 2.1 Analysis of pathogenicity of C. musae to banana fruit mediated by different concentrations of preservatives

[0049] After drying, bananas were ripened by adding ethylene gas for 18 hours. After ripening, they were randomly divided into 15 groups (0, 1, 2, 3 and 4 mM MQU groups, 0, 2, 3, 4 and 5 mM NE groups, 0.00%, 0.10%, 0.12%, 0.24% and 0.48% Hex groups), with 12 fruits in each group. After drying, banana fruits were treated with simulated mechanical injury. Three holes were punched with a stainless steel puncher starting from the middle of the banana at an interval of 3 cm. Each wound was 2.00 mm deep and 2.00 mm in diameter, and 20 μL of the prepared agent was added. After the agent was absorbed, 10 μL of a concentration of 1×10 6 cfu / mL C.musae suspension, and after the bananas completely absorbed the suspension, they were sealed in 0.03 mm thick polyethylene film bags and stored in an incubator at 28°C with relative humidity maintained at 85% to 90%. The lesion diameters were observed and measured on days 0, 1, 3, and 5.

[0050] 2.2 Effect of optimal concentration of preservative on the appearance of spots on banana fruit peel

[0051] Bananas were dried and ripened with ethylene gas for 18 hours. They were randomly divided into 4 groups (Control, QU, NE and Hex groups), with 12 bananas in each group. They were soaked in water and a certain concentration of QU, NE and Hex at a pressure of 0.06 MPa for 5 minutes. After drying, they were sealed in 0.03 mm thick polyethylene film bags and stored in an incubator at 28°C with a relative humidity of 85-90%. The appearance of the banana peels was observed and measured on days 0, 1, 3 and 5.

[0052] Excel 2019 was used to process the data. All data were the mean ± standard deviation (SE) of three parallel analyses, and graphs were drawn using Origin 2022. SPSS26 software was used for variance analysis of the data, and Duncan's method was used to analyze the significant differences in the data (p < 0.05 was a significant difference, and p < 0.01 was an extremely significant difference).

[0053] 3. Test results

[0054] (1) In vitro test results:

[0055] 1.1 Effects of different concentrations of preservatives on mycelial diameter and spore production of banana anthracnose fungus and calculation of IC50:

[0056] QU, NE and Hex treatments had a concentration-dependent effect on the growth of C. musae; Figure 1 (a), (b), and (c) show that as the concentrations of QU, NE, and Hex increase, the diameter of C. musae hyphae growth decreases. Figure 1(d), (e), and (f) show that QU, NE, and Hex can significantly inhibit spore production. Figure 1 (g), (h), and (i) show that the IC50 of QU is 1.00mM; the IC50 of NE is 5.00mM; and the IC50 of Hex is 0.08%. These results show that different phospholipase preservatives can inhibit the growth of C.musae, which provides an experimental basis for using PL preservatives as agents to prevent and control banana anthracnose.

[0057] 1.2 Effects of preservatives on phospholipase activity in C. musae and banana fruit:

[0058] In this experiment, C. musae was used as the strain material, and the extracted PL crude enzyme solutions (PLA, PLC and PLD) were treated with different PL preservatives at IC50 concentrations. Figure 2 (a), (b) and (c) show that QU can inhibit the PLA of C.musae, NE cannot inhibit the PLC of C.musae, and Hex can inhibit the PLD of C.musae. Figure 2 (d), (e) and (f) show that QU can inhibit the PLA of banana peel, NE can inhibit the PLC of banana peel, and Hex cannot inhibit the PLD of banana peel.

[0059] (2) In vivo test results of banana:

[0060] 2.1 Effects of different concentrations of preservatives on banana anthracnose:

[0061] Figure 3 The effect of different concentrations of QU, NE and Hex on banana anthracnose (the banana fruit was treated with simulated mechanical injury). Figure 3 It can be seen that different phospholipase preservatives can inhibit the lesion diameter of banana anthracnose at appropriate concentrations. The optimal concentrations of QU, NE and Hex were found to be 2mM, 3mM and 0.12% respectively.

[0062] 2.2 Effect of optimal concentration of preservative QU on spots on banana fruit peel:

[0063] It is known from the above test that QU can inhibit PLA in banana peel. In order to further study the effect of preservatives on the appearance of bananas, the applicant further treated banana fruits with the optimal concentration of preservative 2.0 mM QU, and used the observation and measurement of the color of the peel appearance as the evaluation index. Figure 4 The effect of the optimal QU concentration and blank control on the appearance of bananas. Figure 4 The comparison showed that within 5 days, the QU group was able to maintain the appearance of bananas and reduce the occurrence of black spots on bananas compared with the control group.

[0064] Test 2:

[0065] Based on Experiment 1, the applicant further tested the pathogenicity of C. musae to banana fruit under the mediation of the optimal concentration inhibitor. Specifically, the bananas were dried and then ripened with ethylene gas for 18 hours. After ripening, they were randomly divided into 4 groups (Control, QU, NE and Hex groups), with 25 bananas in each group. After drying, the banana fruits were treated with simulated mechanical injuries. A stainless steel puncher was used to punch 3 holes at intervals of 3 cm from the middle of the banana. Each wound was 2.0 mm deep and 2.0 mm in diameter, and 20 μL of the prepared agent was added. After the agent was absorbed, 10 μL of a concentration of 1×10 6 cfu / mL C.musae suspension, and after the bananas completely absorbed the suspension, they were sealed in 0.03 mm thick polyethylene film bags and stored in an incubator at 28°C with a relative humidity of 85-90%. The lesion diameters were observed and measured on days 0, 1, 3, and 5.

[0066] Figure 5 The effect of optimal QU, NE and Hex concentrations on banana anthracnose is shown in the banana appearance diagram. Figure 6 This is a numerical comparison chart of the effects of optimal QU, NE and Hex concentrations on the lesion diameter of banana anthracnose.

[0067] Lesion diameter refers to the size of the lesion formed after pathogens infect plant tissues. By comparing data with different lesion diameters, we can better understand the infection pattern of pathogens and the development trend of the disease. Figure 5 and Figure 6 It can be seen that on the first day, the banana peel was green, the fruit morphology was intact, and there were no obvious disease characteristics. There was no significant difference in the diameter of the lesions of bananas in all treatment groups. From the third day, the difference gradually appeared, and the lesion diameter gradually increased. Among them, the lesion diameter of bananas in the Control group was the largest, showing a significant difference from other treatment groups. At the end of storage, the lesion diameter of the Control group was 6.844±0.36mm, which was 50.58%, 23.25%, and 52.78% higher than the lesion diameters of the QU (3.38±0.38mm), NE (5.25±0.44mm), and Hex (3.23±0.25mm) groups, respectively. This result shows that compared with the Control group, the preservative treatment of banana fruits in each group can significantly slow down the occurrence of banana diseases. However, the disease of fruits treated with NE was more serious than that of the QU and Hex groups. This may be because NE excessively inhibited PL activity, hindered the normal disease resistance signal transmission mediated by PL, and reduced the disease resistance of banana fruits.

[0068] Combined with the above experiments, 2.00 mM quinacrine dihydrochloride can inhibit the PLA of C. musae and the PLA of banana peel, and is the most preferred preservative component. After being treated with the preservative, the disease resistance of bananas to anthracnose can be improved, the occurrence of post-harvest rot of bananas caused by anthracnose can be significantly reduced, and the appearance of black spots on the banana peel can be delayed, thereby maintaining the post-harvest quality of banana fruits.

[0069] The above-mentioned embodiments merely express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it should not be understood as limiting the scope of the present invention.

Claims

1. A banana post-harvest preservative, characterized in that: The preservative is mainly composed of one of quinacrine dihydrochloride, neomycin sulfate and n-hexanol.

2. The postharvest preservative for bananas according to claim 1, characterized in that: The preservative is quinacrine dihydrochloride.

3. The banana postharvest preservative according to claim 2, characterized in that: The concentration of quinacridone dihydrochloride is 2.00 mM.

4. A method for preserving bananas using the banana postharvest preservative as claimed in claim 1.

5. A method for preserving bananas using the banana post-harvest preservative as claimed in claim 3.

6. The method according to claim 4 or 5, characterized in that: The method specifically comprises the following steps: drying the bananas, soaking them in a prepared banana post-harvest preservative for 4-6 minutes, taking them out and drying them, and then sealing and storing them in polyethylene film bags.

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