Method for improving storage and preservation of fresh lilies

Abstract

The invention provides a method for improving storage and preservation of fresh lilies, which comprises the following steps of: soaking the fresh lilies in micro-nano bubble ozone water (O3-MNBW), naturally airing after soaking treatment, and storing under a cold storage condition. The invention also provides a new application of the micro-nano bubble ozone water, namely the application of the micro-nano bubble ozone water in improving the storage quality of the picked fresh lily. According to the method provided by the invention, the weightlessness of the lilium brownii scales is obviously slowed down, the weightlessness, hardness reduction, respiration and browning of the lilium brownii scales are effectively inhibited, the content of soluble solids is maintained, the dip dyeing of pathogenic microorganisms is effectively prevented, and the quality of the lilium brownii scales in the postharvest storage period is obviously improved. Through O < 3 >-MNBW treatment, the sensory evaluation index of the picked fresh lilies is effectively improved, the preservation quality is improved, browning after picking is inhibited, only one-time treatment is needed before storage, and the economic benefit is remarkable. And a novel, economical and effective fresh-keeping mode is provided for the storage period of the picked fruits and vegetables.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fresh lily preservation, and particularly relates to a method for improving the storage and preservation of fresh lilies. BACKGROUND

[0002] Lily is a perennial herbaceous plant of the Liliaceae family and has a long history of cultivation. There are 86 species of wild lilies reported worldwide, and 47 species and 18 varieties of lilies were first discovered in China. Lanzhou lily belongs to the "Sichuan lily" variety and is the only edible lily available today. It is often referred to as "unique lily" due to its excellent quality and high nutritional value. In addition, lanzhou lily polysaccharide has functions such as anti-tumor, anti-oxidation, and anti-inflammatory. In traditional Chinese medicine, Lanzhou lily is often combined with rehmannia to form lily rehmannia decoction, which can effectively improve the symptoms of depression with internal heat due to yin deficiency; Chinese medicine scholars integrate lily anemarrhena decoction and hovenia decoction to obtain a compound preparation, which effectively improves the sleep quality of patients. Therefore, Lanzhou lily is both a medicine and a food, and has a wide research value.

[0003] Currently, the lily cultivation area in Gansu Province reaches 250,000 mu. Lanzhou lily is usually used as a medicine or food and needs to be stored for 4-6 months. During storage, lily bulbs are easily infected by Penicillium and develop penicillium disease, and fungal toxins accumulate in the diseased tissues, which seriously endangers the health of consumers. The inventors' research group previously found that the main pathogenic bacteria causing penicillium disease in Lanzhou lily during postharvest storage is Penicillium gladioli (gladiolus penicillium). The pathogenic bacteria mainly invade through the surface wounds of lily bulbs. At the early stage of infection, there are obvious boundary brown lesions on the surface of the bulbs, and the surrounding tissues are soft. With the extension of storage time, spores accumulate into groups, and gradually a gray-green mold layer appears, the bulbs further rot, and the pathogenic bacteria invade the bulb base, leading to bulb dry rot. The entire rotting process lasts for 60-90 days. If the bulbs are severely mechanically damaged during harvesting, the storage warehouse has high temperature and humidity, and ventilation is poor, etc., the penicillium disease will be more severe, and a large number of bulbs will rot, making tons of lilies unsalable. This causes huge economic losses to farmers and merchants.

[0004] Currently, low-temperature storage is widely used for postharvest storage and preservation of fresh lilies. However, Penicillium can still grow under low-temperature conditions, leading to the occurrence of Lanzhou lily penicillium disease.

[0005] Ozone (O3) is widely used in food industry as a strong oxidant for sterilization. Micro-nano bubble (MNBs) is composed of micro-bubbles (<100 μm) and nano-bubbles (<1 μm), and the size of MNBs is between micro-bubbles and nano-bubbles. Compared with common bubbles, MNBs have more advantages in properties. MNBs have larger specific surface area, longer retention time in water, and more outstanding gas-liquid mass transfer efficiency. Due to the higher Zeta potential, MNBs can exist more stably in water, and can generate hydroxyl radicals when it breaks. The solubility of ozone in water is low, and it is easily affected by temperature and pH value, resulting in a large number of ozone molecules escaping. When ozone is dissolved in MNBs, the amount of dissolved ozone is significantly improved, and the influence of temperature and pH value on the negative efficiency of ozonation is inhibited. At present, micro-nano bubble ozone water (O3-MNBW) has certain application in aquaculture, but there is no report on its application in postharvest storage and preservation of fruits and vegetables. SUMMARY

[0006] The purpose of the present application is to provide a method for improving the storage and preservation of fresh lilies. Another purpose of the present application is to provide a new use of micro-nano bubble ozone water.

[0007] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0008] A method for improving the storage and preservation of fresh lilies, wherein fresh lilies are soaked in micro-nano bubble ozone water (O3-MNBW), and then naturally dried after soaking treatment, and stored under refrigeration conditions.

[0009] The method described above, preferably, the concentration of ozone in the micro-nano bubble ozone water is 3-6 mg / L, and the diameter of the micro-nano bubbles is 110 nm-10 μm.

[0010] The method described above, preferably, the soaking treatment time is 2-8 min.

[0011] The method described above, preferably, the temperature of the refrigeration conditions is 0-4 ℃, and the relative humidity (RH) is 50-80%.

[0012] Further, the concentration of ozone in the micro-nano bubble ozone water is preferably 5 mg / L, and the temperature of the refrigeration conditions is 2 ℃, and the relative humidity (RH) is 60%.

[0013] Application of micro-nano bubble ozone water in improving the storage quality of postharvest fruits and vegetables.

[0014] The application described above, preferably, the concentration of ozone in the micro-nano bubble ozone water is 3-6 mg / L, and the diameter of the micro-nano bubbles is 110 nm-10 μm.

[0015] The application as described above, preferably the fruit and vegetable is soaked in the micro-nano bubble ozone water for 2-8 minutes.

[0016] The application as described above, preferably the soaking time is 2-8 minutes.

[0017] The application as described above, preferably the fruit and vegetable is fresh lily, vegetable and fruit, and further the fruit and vegetable is carrot.

[0018] The application has the following beneficial effects:

[0019] The method for improving the storage and preservation of fresh lily can effectively improve the storage quality of fresh lily, can significantly inhibit the occurrence of Lanzhou lily penicillium disease caused by P. gladiol, and O3-MNBW treatment can significantly slow down the weight loss of lily scales, effectively inhibit the weight loss, hardness decrease, respiration and browning of Lanzhou lily scales, maintain the soluble solid content, effectively prevent pathogenic microorganisms from being contaminated, and significantly improve the quality characteristics of Lanzhou lily scales during postharvest storage.

[0020] The application also provides a new use of micro-nano bubble ozone water, which effectively improves the postharvest sensory evaluation index of fruit and vegetable, improves the storage quality of lily scales, inhibits the occurrence of postharvest browning, only needs one-time treatment before storage, and has significant economic benefits. A new, economical and effective preservation method is provided for fruit and vegetable during postharvest storage. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Results of disease control rate of Lanzhou lily scale inoculated with P. gladiol by different concentrations of O3-MNBW treatment;

[0022] Figure 2 Results of disease spot diameter control of Lanzhou lily scale inoculated with P. gladiol by different concentrations of O3-MNBW treatment;

[0023] Figure 3 Photos of disease control of Lanzhou lily scale inoculated with P. gladiol by different concentrations of O3-MNBW treatment;

[0024] Figure 4 Results of weight loss rate of Lanzhou lily scale during postharvest storage by different treatment methods;

[0025] Figure 5 Results of hardness peak value of Lanzhou lily scale during postharvest storage by different treatment methods;

[0026] Figure 6 L value results of color change of Lanzhou lily scale during postharvest storage by different treatment methods;

[0027] Figure 7 The a-values ​​for the color changes of Lanzhou lily scales during postharvest storage under different treatment methods;

[0028] Figure 8 The results of b-values ​​for the color change of Lanzhou lily scales during postharvest storage under different treatment methods;

[0029] Figure 9 Results of BI values ​​for color changes in Lanzhou lily scales during postharvest storage under different treatment methods;

[0030] Figure 10 Images showing the color changes of Lanzhou lily scales during post-harvest storage under different treatment methods;

[0031] Figure 11 The effects of different treatment methods on soluble solids in Lanzhou lily scales during postharvest storage;

[0032] Figure 12 The effects of different treatments on respiration intensity of Lanzhou lily scales during postharvest storage;

[0033] Figure 13 The effects of different treatment methods on the total number of pathogenic microorganisms during postharvest storage of Lanzhou lily scales;

[0034] Figure 14 Radar image for sensory evaluation of Lanzhou lily scales at different post-harvest storage periods. Detailed Implementation

[0035] This invention addresses the current practice in fresh lily scale processing enterprises of using both low-temperature storage and chemical treatment with the fungicide tebuconazole. However, Penicillium, the mold that causes lily mold, can still grow and colonize under low-temperature storage conditions. Furthermore, chemical treatment with fungicides presents problems such as drug residues, environmental pollution, and the development of drug resistance in pathogens. This invention utilizes micro-nano bubble ozone water soaking to treat lily scales, achieving both mold prevention and preservation of freshness and quality, while avoiding the health threats to consumers posed by chemical fungicides.

[0036] The present application is researched through a large number of experiments, first, P. gladioli is inoculated on Lanzhou lily scale tissue by loss, then the loss inoculated Lanzhou lily is treated by using different concentrations of micro-nano bubble ozone water, the disease occurrence of lily after inoculation during storage is observed, so as to screen the best micro-nano bubble ozone water treatment concentration. Then the effects of micro-nano bubble (MNBW), ozone gas fumigation (O3), sterile water treatment and micro-nano bubble ozone water (O3-MNBW) on the weight loss rate, hardness, color, total number of colonies, respiration intensity, soluble solids and sensory evaluation indexes of Lanzhou lily during postharvest storage are compared, and the best postharvest storage preservation mode of Lanzhou lily is determined, so as to promote the development and application of O3-MNBW in the food industry. The present application research finds that O3-MNBW can effectively improve the postharvest storage quality of fruits and vegetables.

[0037] The following examples are used to further illustrate the present application, but should not be construed as limiting the present application. Modifications or substitutions made to the present application without departing from the spirit and essence of the present application shall all belong to the scope of the present application.

[0038] If not specifically indicated, the technical means used in the examples is the conventional means familiar to those skilled in the art, and unless otherwise specified, the reagents used in the examples are analytical pure or above, such as anhydrous glucose analytical pure (AR) which can be purchased from Shandong Yifike Trading Co., Ltd., nutrient agar biological reagent (BR) which can be purchased from Shanghai Yuanye Biotechnology Co., Ltd., anhydrous ethanol analytical pure (AR) which can be purchased from Nanjing Chemical Reagent Co., Ltd., sodium chloride analytical pure (AR) which can be purchased from Jinan Meihui Chemical Co., Ltd., Tween-80 analytical pure (AR) which can be purchased from Linyi Guoli Chemical Co., Ltd.; the experimental instrument model and source used in the examples are micro-nano bubble generator RJN-MN-300 Shanghai Rujing Environmental Protection Technology Co., Ltd., water-cooled oxygen gas source ozone generator RJC-YC-20 Shanghai Rujing Environmental Protection Technology Co., Ltd., air source ozone generator OSAN-CFG Ausan Environmental Protection Technology Industry Co., Ltd., portable CO2 detector GW-2032 Wuhan Ganwei Technology Co., Ltd., fruit hardness tester GY-4 Zhejiang Top Instrument Co., Ltd., handheld refractometer WZ-103 Youlaibo Technology Co., Ltd., precision colorimeter CS-210 Hangzhou Caipu Technology Co., Ltd., circulating water type multi-purpose vacuum pump SHB-III Zhengzhou Great Wall Scientific Industrial & Trading Co., Ltd., refrigerator GELIDER Zhu Hai GELIDER Group Co., Ltd.

[0039] Example 1

[0040] 1.1 Materials

[0041] 1.1.1 Experimental materials

[0042] Fresh Lanzhou lily was purchased from Lanzhou Qilihe lily planting base, and the lily bulb tissues with equal size, no mechanical damage and no obvious pests and diseases were selected.

[0043] PDA medium formula: potato 200 g, glucose 20 g, nutrient agar 17 g, water 1000 mL, natural pH.

[0044] The Penicillium gladioli strain was provided by the Department of Chemistry, Gansu Agricultural University, which was isolated and purified from the lily bulb tissues with typical symptoms of blue mold disease, and was identified as Gladiolus penicillium through morphology and molecular biology. After the strain was cultured on PDA medium for 7 days, the surface spores were scraped and prepared into a spore suspension of 1×10 6 CFU / mL with sterile water for standby.

[0045] 1.2 Method

[0046] 1.2.1 Preparation method of MNBW and O3-MNBW

[0047] Both MNBW and O3-MNBW were prepared by a micro-nano bubble generator-oxygen source ozone generator combined device. The micro-nano bubble rapid generator was turned on, and the water inlet was adjusted to 8 L / min. When the beaker appeared dense bubbles and presented white emulsion, the ozone gas generator was turned on, and the gas inlet was adjusted to 8 L / min, to obtain O3-MNBW with a concentration of 8 mg / L, and MNBW(micro-nano bubble water) with a diameter of 110 nm-10 μm.

[0048] 1.2.2 Screening of optimal bacteriostatic concentration of O3-MNBW

[0049] Adjust the gas inlet flow of the oxygen source ozone gas generator, and prepare O3-MNBW with different concentrations(2, 3, 4, 5, 6, 8 mg / L), and set the same volume of MNBW as a control. Select the lily bulb tissues with uniform size and similar skin color, 20 pieces for a group, a total of 7 groups. Each group of lily bulb tissues was soaked in 0.1% sodium hypochlorite solution for 12 min, washed with sterile distilled water for 3 times, and dried at room temperature(20℃, 30% RH). Use a sterilized pipette tip to make a hole on all lily bulb tissues(1 mm in diameter, 4 mm in depth), and inoculate 1×10 6P. gladioli spore suspension of 20 μL CFU / mL was inoculated in the center of the well and incubated in a constant temperature incubator (25°C, 50% RH) for 10 h in the dark. After P. gladioli spores were fully attached to the inside of the well, each group of lily scales was treated with the above-mentioned concentrations of O3-MNBW and control MNBW for 8 min. After treatment, the lily scales were again naturally dried. The lily scales were placed in a "LOCK & LOCK" fresh-keeping box and stored at room temperature for 12 d, and samples were taken every 3 d. The disease incidence was calculated using the following formula (1) by measuring the lesion diameter using the cross method. Each treatment was repeated 3 times, and the optimal bacteriostatic concentration of O3-MNBW was selected.

[0050]

[0051] To screen the optimal O3-MNBW treatment concentration, lily scales inoculated with P. gladioli were treated with 2, 3, 4, 5, 6, and 8 mg / L O3-MNBW for 8 min, and then removed. The lily scales were dried at room temperature and then stored at room temperature (20°C, 50-55% relative humidity). As the storage time increased, the disease incidence results are shown in Figure 1 , and the lesion diameter results are shown in Figure 2 . The vertical lines in the figure represent the standard error (±SE), and different letters represent significant differences (p < 0.05). Both the disease incidence and lesion diameter results showed an upward trend. At the beginning of storage, the lily scale penicillium disease was relatively light, and at 12 d of storage, the disease incidence and lesion diameter of each group reached a peak. The lesion diameter of the remaining treatment groups and the CK group was more than 2 cm, except for the 5 mg / L treatment group, which had an average lesion diameter of 1.73 cm. In addition, the disease incidence of the 5 mg / L treatment group was also lower than that of the other treatment groups and the CK group (p < 0.01). The 2, 6, and 8 mg / L treatment groups began to develop disease at 1 d, and the disease incidence was 20%, 28%, and 32%, respectively, at 3 d. The 5 mg / L treatment group began to develop disease slowly at 3 d, and the disease incidence of the 3 mg / L treatment group was more than 60% at 12 d of storage. The disease incidence of the CK, 4, 6, and 8 mg / L treatment groups was more than 80%, and the disease incidence of the 5 mg / L treatment group was only 35%. The color change of the lily scales during storage is shown in Figure 3As shown in the figure, during storage, each group of lily scales produced pink patches and browned at room temperature, and the 5 mg / L treatment group could significantly inhibit the occurrence of browning. The results showed that the use of O3-MNBW treatment had a good control effect on the occurrence of penicillium disease during the postharvest storage of Lanzhou lily. Among them, the treatment effect of 5 mg / L O3-MNBW was the best. The mechanism of action may be that O3-MNBW acts on the phospholipid bilayer of the cell membrane of the pathogenic bacteria, leading to membrane damage, cell content leakage, affecting the exchange of substances inside and outside the cell, and then inducing the death of pathogenic bacteria cells.

[0052] 1.2.3 Effect of O3-MNBW on quality indicators and sensory evaluation of Lanzhou lily during storage

[0053] In order to more clearly understand the effect of O3-MNBW on Lanzhou lily during postharvest storage, the weight loss rate, hardness, browning degree, soluble solids, total number of pathogenic microbial colonies, respiration intensity, quality indicators and sensory evaluation of Lanzhou lily scales during postharvest storage were determined, a total of NBSW soaking for 5 min, 5 mg / L ozone gas fumigation for 20 min, O3-MNBW (5 mg / L) soaking for 5 min, and distilled water soaking for 5 min as control, a total of four groups. Lily scales were not inoculated and placed in a 1L "LOCK & LOCK" fresh-keeping box under cold storage conditions (2℃, 60% RH) for 90 days. The selection of lily scales and the calculation of weight loss rate refer to 1.2.2. Each group consisted of 20 lily scales, and each treatment had three replicates. In the first 28 days, sampling was performed every 7 days, and in the last 60 days, sampling was performed every 14 days, and the data were recorded continuously until the 90th day. All the following data were calculated using Excel 2021 to calculate the mean and standard deviation, plotted using origin2021, and analyzed for significant differences using SPSS21.0 (p<0.05). The specific results are as follows:

[0054] 1.2.3.1 Weight loss rate

[0055] The weight loss rate was sampled at the time intervals described in 1.2.3, measured using a precision analytical balance, and recorded. Each group of samples was repeated three times, and the weight loss rate of Lanzhou lily scales was calculated using formula (2) as follows:

[0056]

[0057] The weight loss rate is one of the important indicators for evaluating the quality of fruits and vegetables during postharvest storage. Due to respiratory metabolism and water transpiration, Lanzhou lily will experience weight loss during storage, which can cause lily scales to wilt and shrivel, thereby reducing the quality of lily and affecting the shelf life of Lanzhou lily. The effects of different treatment methods on the weight loss rate of Lanzhou lily during postharvest storage are as followsFigure 4 As shown in the figure, vertical lines represent standard error (±SE), different letters represent significant differences (p<0.05), MNBW: micro-nano bubble water treatment, O3: 5mg / L ozone gas fumigation, CK: distilled water treatment, O3-MNBW: 5mg / L micro-nano bubble ozone water treatment. During the whole storage period, the weight loss rate of Lanzhou lily scales showed an overall upward trend. Under cold storage conditions, the weight loss rate of Lanzhou lily scales in the early stage increased slowly, and rapidly increased after 28d, reaching a peak at 90d. The weight loss rate of lily scales was significantly lower than that of the CK control and MNBW, O3 treatment groups (p<0.01) compared with the O3-MNBW treatment group. The weight loss rate of the CK control group increased rapidly and the increase was larger at 21d. At 56d, the weight loss rate of the CK control group was 23%, while the MNBW, O3, and O3-MNBW treatment groups were 14%, 13%, and 11%, respectively. The increase in the MNBW and O3 treatment groups was larger after 56d. At 90d, the weight loss rate of the CK control group reached 38%, while the MNBW and O3 treatment groups both exceeded 20%, and the O3-MNBW treatment group was only 17%, which was 0.45 times that of the CK control group. Therefore, the O3-MNBW treatment group can effectively slow down the weight loss of Lanzhou lily during postharvest storage.

[0058] 1.2.3.2 Hardness

[0059] Hardness was measured using a fruit hardness tester (GY-4). Each treatment group of lily scales was measured three times. The measurement parameters were: penetration depth 4mm, pre-measurement and post-measurement rates both 1mm / s, and mid-measurement rate 3mm / s. The results were expressed in (N).

[0060] Hardness is one of the important indicators for measuring the maturity of fruits and vegetables and the quality of postharvest storage. The effects of different treatments on the hardness of Lanzhou lily during postharvest storage were as follows Figure 5As shown in FIG. 6, the vertical line in the figure represents the standard error (±SE), and different letters represent significant differences (p<0.05); MNBW: micro-nano bubble water treatment, O3: 5 mg / L ozone gas fumigation, CK: distilled water treatment, O3-MNBW: 5 mg / L micro-nano bubble ozone water treatment. The results showed that with the increase of storage time, the hardness showed a downward trend as a whole, and the hardness of the MNBW, O3, and O3-MNBW treatment groups was better than that of the CK control group. The initial hardness of lily scales was 11.75 N, and the hardness of the CK control group began to decrease at 3d, and the hardness decreased greatly, and at 90d, it was only 20% of the initial hardness value. During 1-7d, there was no significant difference between the O3 treatment group and the MNBW treatment group compared with the O3-MNBW treatment group, and after 14d, the hardness value of the O3 treatment group and the MNBW treatment group decreased rapidly. At 90d, the hardness value of the CK control group was 2.3N, and the hardness of the O3, MNBW, and O3-MNBW treatment groups was 5.1N, 3.6N, and 6.8N, respectively. Compared with the CK control group at 7d, the hardness of the O3 treatment group, the MNBW treatment group, and the O3-MNBW treatment group decreased by 91%, 56%, and 69%, respectively. However, the hardness of the O3-MNBW treatment group only decreased by 42%. According to the above results, there was a significant difference (p<0.05) between the O3-MNBW treatment group and the CK group during the entire storage period. O3-MNBW treatment can effectively slow down the decrease of lily scale hardness during storage.

[0061] 1.2.3.3 Color

[0062] Color determination was determined by using a precision color difference meter, and L*, a*, and b* values were read in the CIE color system. The browning index (BI value) was calculated by the following formulas (3) and (4).

[0063]

[0064] Color is an index for sensory evaluation of the quality of fruits and vegetables. The effects of different treatment methods on the color of Lanzhou fresh lily during postharvest storage are shown in FIG. 7. Figure 6-10 As shown in FIG. 7, the vertical line in the figure represents the standard error (±SE), and different letters represent significant differences (p<0.05), MNBW: micro-nano bubble water treatment, O3: 5 mg / L ozone gas fumigation, CK: distilled water treatment, O3-MNBW: 5 mg / L micro-nano bubble ozone water treatment. The effects of different treatment methods on the color L* value of Lanzhou lily scales are shown in FIG. 8. Figure 6As shown, the L* value represents brightness; a higher value indicates whiter and brighter lily scales. During post-harvest storage, the L* value generally decreased with increasing storage time. The O3-MNBW treatment group was significantly better than the MNBW, O3, and CK control groups. From day 7 to day 56, the L* values ​​of the MNBW and O3 treatment groups decreased slowly. After day 56, the decrease in L* value increased. At day 42, the L* value of the CK control group dropped sharply to 42.76, which was due to severe browning of the bulb leaves caused by Penicillium infection during storage. At day 90, the L* values ​​of the MNBW, O3, and CK treatment groups were 49.75, 59.1, and 27.89, respectively. The L* value of the O3-MNBW treatment group was 65.68, significantly higher than the other treatment groups and the CK control group (p<0.05).

[0065] The effects of different treatment methods on the a* and b* values ​​of Lanzhou lily scale color are as follows: Figure 7 , Figure 8 As shown in the figure, a* value represents the red-green value; b* value represents the yellow-blue value. With increasing storage time, the a* and b* values ​​of Lanzhou lily scales generally showed an upward trend. Compared to the MNBW treatment group and the CK control group, the a* and b* values ​​of lily scales treated with O3 and O3-MNBW increased more slowly in the early stages of storage. At 21 days, the lily scales in the CK control group underwent browning, producing a few pink patches, which led to significantly higher a* and b* values ​​than those treated with MNBW, O3, and O3-MNBW. At 90 days, the a* values ​​of the MNBW, O3, CK, and O3-MNBW treatment groups were 12.79, 9.17, 14.11, and 6.89, respectively; and the b* values ​​were 23.18, 20.63, 27.03, and 19.41, respectively. The a* and b* values ​​of the O3-MNBW treatment group were significantly lower (p<0.05) than those of the other treatment groups and the CK control group.

[0066] The effects of different treatment methods on the browning index (BI) value and color changes of Lanzhou lily scales are as follows: Figure 9 As shown in Figure 10, the BI value gradually increased with increasing storage time. At 28 days, browning appeared in the lily scales of the MNBW and O3 treatment groups and the CK control group, especially in the CK control group, where the BI value was significantly higher than that of the O3-MNBW treatment group. At 42 days, severe browning appeared in the lily scales of the CK control group, and the BI value increased sharply. From 42 to 90 days, browning gradually appeared in the lily scales of the MNBW and O3 treatment groups, and the BI value increased slowly. At 90 days, the BI value of the CK control group was 111.22, while the BI value of the O3-MNBW treatment group was only 40% of that of the CK control group. Furthermore, at 90 days, no significant browning was observed in the Lanzhou lily scales treated with O3-MNBW. In conclusion, the O3-MNBW treatment of Lanzhou lily scales can maintain its original color to the greatest extent and slow down the occurrence of browning.

[0067] 1.2.3.4 Soluble solids

[0068] Soluble solids determination was carried out by using hand refractometer, 10 pieces of Lily scales were randomly selected from each treatment group, juice was squeezed and filtered after adding appropriate sterile water, 20 μL of the filtrate was taken and placed in the hand refractometer (WZ-103) to read the value, the result was expressed as (%), each treatment group was repeated three times.

[0069] Soluble solids is an important evaluation index to measure the maturity, taste and nutritional components of fruits and vegetables during postharvest storage. The effect of different treatments on the soluble solids content of Lanzhou Lily scales during postharvest storage is shown in Table 1.2.3.4. Figure 11 The soluble solids content of MNBW and O3-MNBW treatment groups showed an upward trend first and then a downward trend, while the CK group showed a downward trend during the whole postharvest storage period. The soluble solids content of each group was basically unchanged in the first 7 days, and the soluble solids content of MNBW and O3-MNBW treatment groups began to rise at 14d, while the soluble solids content of the Lily scales of the CK control group continued to decrease. The reason may be that during postharvest storage, the respiration of Lily scales was inhibited by MNBW, O3 and O3-MNBW treatment, which promoted the degradation of pectin, cellulose and other substances in the cells of Lily scales to polysaccharides, and the degradation rate was greater than the consumption rate of respiration. Therefore, the soluble solids content of Lily scales treated by MNBW and O3-MNBW increased from 7d to 21d. From 21d to 90d, with the increase of storage time, polysaccharides were consumed by respiration, and the soluble solids content gradually decreased. At 70d, the soluble solids content of each group decreased significantly. After 90d of storage, the soluble solids content of Lily scales treated by O3-MNBW was 2.4%, and the soluble solids content of Lily scales treated by MNBW and O3 and the CK control group was less than 2%. The soluble solids content of Lily scales treated by O3-MNBW was significantly higher than that of Lily scales treated by MNBW, O3 and the CK control group. In summary, O3-MNBW treatment can effectively maintain the soluble solids content of Lanzhou Lily during postharvest storage.

[0070] 1.2.3.5 Respiration intensity

[0071] Respiration intensity determination was carried out by using portable CO2 detector, Lily scales were placed in a sealed container, and portable CO2 detector was used to measure every 20min, each treatment group was repeated three times. The respiration intensity calculation formula is as follows (5):

[0072]

[0073] In the formula: N1, N2 represent the value of portable CO2 detector before and after reading / ppm, V represents the volume of the sealed container / L, m represents the mass of Lily scales / kg, t represents the measurement time / h.

[0074] Respiration as the basis of energy and material for postharvest life activities of fruits and vegetables, the respiration intensity is closely related to the degree of ripening and spoilage of fruits and vegetables. Lanzhou lily belongs to the respiratory climacteric fruit. The effects of different treatments on the respiration intensity of Lanzhou lily during postharvest storage are shown in Figure 12 As the postharvest storage time prolongs, the respiration intensity of MNBW, O3, O3-MNBW treatment groups and CK control group shows a trend of first rising and then falling. At the beginning of storage, the respiration intensity is weak. From 7d, the respiration intensity of each treatment and CK control group gradually increases. At 21d, the respiration intensity of CK control group is 550.56mg CO2 kg -1 h -1 and reaches the peak, at 42d, the respiration intensity of MNBW treatment group is 510.31mg CO2 kg -1 h -1 and reaches the peak, at 56d, the respiration intensity of O3, O3-MNBW treatment groups is 456.84mg CO2 kg -1 h -1 ; 417.86mg CO2 kg -1 h -1 and reaches the peak. During the whole storage period, the respiration intensity of O3-MNBW treatment group is significantly lower than that of other treatment groups (p<0.05). O3, O3-MNBW treatment groups effectively delay the appearance of respiration peak, reduce the respiration intensity of Lanzhou lily during storage, and the respiration intensity peak of O3-MNBW treatment group is lower than that of O3 group. In summary, O3-MNBW treatment is the best treatment to inhibit the respiration intensity of Lanzhou lily during postharvest storage.

[0075] 1.2.3.6 Total number of pathogenic microorganism colonies

[0076] The total number of pathogenic microorganism colonies is determined according to GB 4789-2022 "National food safety standard, food microbiological examination-colony count".

[0077] Fruits and vegetables are easily contaminated by pathogenic microorganisms during picking, storage and processing, leading to rot and deterioration. The total number of microbial colonies is an important quality indicator during postharvest storage of fruits and vegetables, and is also a key factor affecting the shelf life of food. According to industry regulations, fresh fruits and vegetables picked and stored for a period of time, when the total number of pathogenic microorganism colonies exceeds 4lg(CFU / g), are considered "unqualified vegetables" or "spoiled vegetables" and are not allowed to be sold and traded. The effects of different treatments on the total number of pathogenic microorganism colonies of Lanzhou lily during postharvest storage are shown in Figure 13The total number of pathogenic microorganism colonies of the MNBW, O3, O3-MNBW treatment groups and the CK control group showed an upward trend. In the early stage of storage, the total number of pathogenic microorganism colonies of each treatment group increased slowly, and with the increase of storage time, the total number of pathogenic microorganism colonies of the MNBW, O3, O3-MNBW treatment groups and the CK control group increased continuously. At 28d, the total number of pathogenic microorganism colonies of the MNBW treatment group and the CK control group was 4.02lg(CFU / g) and 4.17lg(CFU / g), respectively, which exceeded the industry limit value. Since 14d, the CK control group had serious pathogenic microorganism contamination due to the lack of effective antibacterial treatment measures, and the total number of colonies increased exponentially. At 90d, it reached 6.94lg(CFU / g). At 42d, the total number of pathogenic microorganism colonies of the O3 treatment group was 4.19lg(CFU / g), which exceeded the industry limit value. At 56d, the total number of pathogenic microorganism colonies of the O3-MNBW treatment group was 4.32lg(CFU / g), which first exceeded the industry limit value. At 90d, the total number of pathogenic microorganism colonies of the O3-MNBW treatment group increased to 5.47lg(CFU / g), but was still significantly lower than that of other treatment groups (p<0.05). The results showed that O3-MNBW treatment could effectively inhibit the infection of postharvest pathogenic microorganisms of Lanzhou lily scales and ensure food safety.

[0078] 1.2.3.7 Sensory evaluation

[0079] The sensory evaluation of Lanzhou lily under different treatment methods at different storage periods was determined by a team of ten people who had received professional training (aged from 25 to 40, 5 males and 5 females). The texture, aroma, wilting degree, color, and rotting degree of Lanzhou lily were specifically evaluated. The evaluation results were scored according to Table 1 below (the score was averaged).

[0080] Table 1 Sensory evaluation criteria for Lanzhou lily

[0081]

[0082]

[0083] Sensory evaluation is an important step for quickly judging the quality change of fruits and vegetables during postharvest storage, feeding back the storage results, and evaluating the shelf life. It plays a certain guiding role in determining the reasonable storage conditions of postharvest fruits and vegetables. The sensory evaluation of Lanzhou lily under different treatment methods during postharvest storage is shown in Table 2. Figure 14 In the early stage of storage, 7d-14d, the five sensory evaluation indicators of the MNBW, O3, O3-MNBW treatment groups and the CK control group were good, and the radar Figure 5The edge shape is relatively complete, and after 14d, the smell, texture form, color, and rot degree do not change obviously, and with the increase of storage time, the pentagonal shape is further distorted, and the smell, texture, texture form, color, and rot degree scores are continuously decreased. The Lanzhou lily scale treated by O3-MNBW is obviously better than the MNBW, O3, and CK control groups, and conforms to the radar chart trend.

[0084] The present application inoculates Lanzhou lily with P. gladiol, the pathogen with the strongest pathogenicity of Lanzhou lily penicillium disease, and then treats the inoculated Lanzhou lily with P. gladiol with different concentrations of O3-MNBW, analyzes the incidence and lesion diameter of lily scale during the storage stage after inoculation, and the results show that 5mg / L O3-MNBW can significantly and effectively inhibit the occurrence of Lanzhou lily penicillium disease during postharvest storage.

[0085] MNBW, O3 fumigation, sterile water and 5mg / L O3-MNBW are used to treat non-inoculated Lanzhou lily, and the quality changes of the Lanzhou lily are analyzed after a certain period of storage. The weight loss rate, hardness, color, soluble solids, respiration intensity, total number of pathogenic microorganisms and sensory evaluation are important quality indicators for evaluating the shelf life and commodity value of Lanzhou lily during postharvest storage. The results show that 5mg / L O3-MNBW soaking for 5min can effectively reduce the water evaporation of Lanzhou lily scale, significantly reduce the weight loss rate, slow down the decrease of lily scale hardness, maintain the original color, prevent browning, maintain the content of soluble solids, inhibit respiration, delay the appearance of respiration peak, inhibit pathogenic microorganisms, and improve the quality of Lanzhou lily during postharvest storage.

[0086] The method of micro-nano bubble ozone water provided by the application utilizes the larger specific surface area of micro-nano bubbles, the longer retention time in water, the higher gas-liquid mass transfer efficiency, and the higher Zeta potential of micro-nano bubbles, so that the micro-nano bubbles can exist more stably in water. Meanwhile, the small bubbles generated by dissolving ozone in micro-nano water can produce active free radicals on one hand, and the active free radicals have strong oxidation ability, which can not only kill the microorganisms on the surface of lily scale tissue by acting on the phospholipid bilayer of the pathogenic microorganisms on the surface of lily scale tissue, but also effectively remove the free radicals generated on the surface of lily scale tissue, delay aging and browning of lily scale during postharvest storage; on the other hand, the micro-nano bubble ozone water can improve the permeability and penetration of water, and prolong the contact time of ozone molecules and the surface of lily scale tissue. Therefore, the micro-nano bubble ozone water treatment of Lanzhou fresh lily significantly slows down the weight loss of lily scale, effectively inhibits the decrease of weight loss and hardness, respiration and browning of Lanzhou lily scale, maintains the soluble solid content, effectively prevents pathogenic microorganisms from being infected, and significantly improves the quality and morphology of Lanzhou lily scale during postharvest storage. The method of treating fresh lily by using the micro-nano bubble ozone water provided by the application has the characteristics of greenness, safety, environmental protection and high efficiency compared with the chemical sterilizing agent used in the current production, and is a new technology for postharvest storage and preservation of fresh lily scale that is more acceptable to consumers.

Claims

1. A method for improving the storage and preservation of fresh lily bulbs, characterized in that, Fresh lily is soaked in micro-nano bubble ozone water, and then naturally dried and stored under refrigeration.

2. The method of claim 1, wherein, The concentration of ozone in the micro-nano bubble ozone water is 3-6 mg / L, and the diameter of the micro-nano bubble is 110 nm-10 μm.

3. The method of claim 1, wherein, The soaking time is 2-8 min.

4. The method of claim 1, wherein, The temperature of the refrigeration condition is 0-4 ℃, and the relative humidity is 50-80%.

5. The method of claim 1, wherein, The concentration of the micro-nano bubble ozone water is 5 mg / L, the temperature of the refrigeration condition is 2 ℃, and the relative humidity is 60%.

6. Application of micro-nano bubble ozone water in improving postharvest storage quality of fruits and vegetables.

7. Use according to claim 6, wherein The concentration of ozone in the micro-nano bubble ozone water is 3-6 mg / L, and the diameter of the micro-nano bubble is 110 nm-10 μm.

8. The use according to claim 6, wherein Fruits and vegetables are soaked in the micro-nano bubble ozone water.

9. Use according to claim 8, wherein the compound is ###0002### The soaking time is 2-8 min.

10. The use according to claim 6, wherein The fruits and vegetables are fresh lily, vegetables and fruits.

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