Effect Of Ethanol Treatment On Quality And Microorganism Of Fresh Cut Lettuce And Its Mechanism

Fresh cut fruits and vegetables is a nutritious,convenient,ready to eat,high quality fresh product.With the continuous development of society,consumers are more interested in fresh cut fruits and vegetables,and the proportion of fresh cut products in the world food market is increasing.But the head lettuce is difficult to clean and the pretreatment is troublesome,so the circulation of head lettuce in the market is limited.Fresh cut head lettuce solves the market problem which is easy to be damaged by machinery and difficult to process.The tissue cells of cut lettuce were destroyed,which led to a series of physiological and biochemical reactions,affecting the freshness,quality and nutritional characteristics of head lettuce.Therefore,it is important to study the quality retention and microbial growth of fresh cut heading lettuce.In this study,the fresh cut lettuce was fumigated with different concentration of ethanol,and the storage quality,physiological metabolism and microbial growth of fresh cut heading lettuce during storage were analyzed.Experimental results show that:1.The sensory score of fresh cut lettuce kept decreasing during storage,while 2mL/L and 4mL/L ethanol treatment could slow down the sensory score,but 6mL/L ethanol was not conducive to the storage of fresh cut head lettuce,2mL/L and 4mL/L ethanol treatment also can alleviate the rising rate of weight loss;delay the reduction of soluble solids content;inhibition of fresh cut lettuce during storage of chlorophyll a,B loss of vitamin C consumption;the rate of decline slowed;curb the rising of fresh cut lettuce during storage of conductivity;while inhibiting the respiration rate of rise.2.During the storage period of fresh cut lettuce,4mL/L concentration in the ethanol treatment group was the lowest,and the inhibition rate of O2-· MDA production was the best.Ethanol treatment with 2mL/L and 4mL/L can inhibit the increase of PPO activity,maintain POD activity,maintain CAT activity during storage,and maintain SOD activity effectively.3.In this experiment,the total number of colonies in fresh cut lettuce for zeroth days was 3.26×105CFUg-1,and that of 6mL/L ethanol treatment group was the best.The number of coliform bacteria decreased continuously in storage period,and no coliform bacteria were detected in sixth days in the ethanol treatment group,while the blank control group did not detect coliform bacteria in eighth days.This experiment was not detected by Listeria monocytogenes,but still continue to focus on.