Grape fruit is juicy and delicious, rich in various nutrients such as sugar, organic acids, protein, minerals, vitamins, etc., and has high economic and edible value. Grapes belong to non climacteric fruits. Due to their thin skin, rich pulp, and easy dehydration after harvesting, they can experience wilting and browning of the fruit stem, peeling, wrinkling, and rotting of the fruit after 1-2 days of storage at room temperature, greatly reducing the quality and commercial value of grapes. At a storage temperature of 0-1 ℃, the conidia of various pathogens can germinate and the hyphae can grow, which can easily cause fungal diseases such as gray mold and Alternaria rot. Therefore, it is necessary to use preservatives for sterilization and preservation. Therefore, special preservation techniques need to be adopted in the practice of grape preservation and storage.

Acidic electrolyzed water refers to a solution with special functions produced by treating a dilute electrolyte solution with an electric field in a special device, which changes the pH value, oxidation-reduction potential, residual chlorine concentration and other indicators of water. Its main characteristics can be summarized as follows: it has a wide range of sterilization applications; No pollution, no residue; Safe, reliable, non irritating to the skin, non-toxic to the human body, and no accumulated toxicity; Easy to produce and cost-effective. Research has shown that acidic electrolyzed water can quickly kill spoilage bacteria on the surface of fruits, greatly reducing the decay of fruits and vegetables, and has a preservative effect. The experiment used acidic electrolyzed water with different indicators to treat grapes and investigate its effectiveness in grape preservation and preservation.

Experimental materials
The experimental variety is "Jingyou" grape, and the grapes harvested are free from pests and diseases, mold and rot, and mechanical damage. The fruit grains are full and the ear shape is neat and compact.
 
 
Main instruments and equipment
 
Strong acidic electrolyzed water generator
 

The grapes harvested on the same day were soaked in tap water (control) or acidic electrolyzed water with the above three indicators for 10 minutes. After being taken out and dried, they were packaged in corrugated cardboard boxes and stored at room temperature of 25 ℃ and relative humidity of 65% to 75% for one week.

Determination content and method: After treating grape fruits with various solutions, the total number of bacteria and fungi on the surface of grapes was counted by plate colony counting method. The dehulling rate, rot rate, and total loss rate of grapes were investigated during storage.

The determination of microbial indicators: Take about 5Og of grape seeds from each treatment and add them to 100mL of sterile physiological saline containing 0.1% Tween80, shake for 30 minutes, and perform plate colony counting on the solution to separately count the total number of bacteria and mold in the solution.

Determination of decay and threshing rate
Threshing rate (%)=total fruit mass of detached fruit particles processed X100
Rotting rate (%)=total fruit mass of rotten fruit particles treated X100
Total loss rate (%)=threshing rate+decay rate

The statistical analysis of the experimental results was repeated three times for each measurement, and the results were expressed as the mean. The comparison of the mean between treatments was performed using the Duncan method in SPSS 1.1 for WindoWS statistical software for analysis of variance, with a minimum significance level of 5%.

Result and Analysis
Measurement results of total microbial count
Decay is a common problem during grape storage, and controlling decay is an important issue in grape preservation. After being treated with acidic electrolyzed water and tap water, the microbial indicators of grapes are shown in Figure 1 and Figure 2.

 


From Figures 1 and 2, it can be seen that the total number of fungi and bacteria in grapes significantly decreased after treatment with acidic electrolyzed water. After soaking grapes in electrolyzed water with different indicators for 10 minutes, the total number of fungi and bacteria also significantly decreased. After treatment with water No. 3 and No. 2, the decrease reached about 1.5-2 logarithmic values. After treatment with water No. 1, the number of microorganisms decreased by about one logarithmic value, and there were significant differences in the bactericidal effect of acidic electrolyzed water on grape surfaces with different indicators. The main reason for this is that the effective chlorine concentration of water No. 2 and No. 3 is 150-160mg/kg, which is about three times that of water No. 1, and their oxidation-reduction potential is also about 200-300mV higher than that of water No. 1. Therefore, the bactericidal effect of water No. 2 and No. 3 is significantly better than that of water No. 1.
Loss of grape grains
During grape storage, decay and threshing often occur, which directly affect the appearance quality of grape fruits. The experiment recorded the loss of grape grains at the end of storage, as shown in Figure 3.
 
 

At the end of storage, the group without treatment had the most severe grape decay, with a decay rate of 2.9%, mainly due to mold and rot. However, the other groups treated with acidic electrolyzed water had significantly lower decay rates than the control group (P<0.05) due to the extensive killing of surface spoilage microorganisms (see Figures 1 and 2), generally less than 1%, indicating that acidic electrolyzed water can significantly reduce the occurrence of grape decay. The dehulling rate of grapes was also the highest in the control group (treated with tap water), reaching 7.2%, while the dehulling rates of all acid electrolyzed water treatment groups were below 2%. It can be seen that acid electrolyzed water can significantly reduce the dehulling rate of grapes (P<0.05) and reduce the loss of grape grains. The cumulative loss of grapes due to decay and threshing during storage is the total loss rate of grape grains, which ultimately determines the commodity value of grapes after storage. As shown in Figure 3, the control group suffered the most severe loss of grape grains, reaching 10.1%, while the loss rate of each treatment group with acidic electrolyzed water was around 2%. Therefore, it can be seen that acidic electrolyzed water treatment can effectively reduce the loss of grape grains caused by decay and threshing. Compared with the results of microbiological testing, the strong acidic electrolyzed water with a pH of around 2.8 has the strongest bactericidal effect, corresponding to the best anti-corrosion and preservation effect, and the total loss rate of grape fruits treated with it is also the lowest.

conclusion
The above experimental results indicate that acidic electrolyzed water treatment can greatly reduce the number of microorganisms on the surface of grapes, thereby reducing the decay rate of grapes and improving food safety. Acidic electrolyzed water treatment can significantly reduce the threshing rate of grapes during storage, ultimately reducing fruit loss during storage and transportation. At the same time, it can also alleviate the negative effects of using chemical preservatives on human health and the environment. Further research is needed to determine whether acidic electrolyzed water treatment will affect the post harvest physiological activities of grapes, thereby affecting their preservation effectiveness.