Evaluation Of Microial And Chemical Risk Factors Of Fresh-Cut Vegetables During Processing And Marketing

Fresh cut vegetables is a new style vegetable product,fresh vegetables were used as raw materials,it was screened,sorted,cleaned,sliced,sterilized,packed and so on during the cold chain conditions,and it was transported into the supermarkets and retail sales.Fresh-cut vegetables were as the raw materials,explore the changes of quality and safety problems during marketing period.Meanwhile research the simulation test of the lettuce and lotus root,explore the change of microorganism after the cleaning agent and procedure,and the microorganism and physio-chemical change during 4? and 25?.The main results are as follows:1.Twenty-one types(282 samples)of fresh-cut vegetables sold at the Nanjing and Shanghai supermarkets were evaluated for aerobic bacterial count,coliform bacteria,Listeria monocytogenes bacteria,nitrites,sulfites,preservatives and other safety indicators.The results showed that,different fresh-cut vegetables were polluted differently,the total number of colonies and the number of bacteria in fresh-cut vegetables were significantly higher than the established safety limits.The total number of colonies was more than 108 CFU/g,and the number of bacteria was more than about 107 MPN/100g.Listeria monocytogenes were found in eight kinds of fresh cut vegetables(leeks,cabbages,greens,Chinese cabbages,Chinese Little Greens,potatoes,water bamboos and balsam pears).Nitrites and sulfites were also found at a low level in the fresh-cut vegetables,sorbitol acid or benzoic acid was found in the low level in four fresh-cut vegetables.Therefore,the fresh-cut vegetables should be supervised and examined strictly during processing and sales.2.The fresh-cut lettuce and lotus root after cleaned sequentially with water,150ppm and 50ppm NaClO was stored at 4? and 25?,respectively.The indices of total bacterial count,coliform group,Listeria monocytogenes,as well as nitrite,the respiration intensity,color,Ascorbic Acid,malondialdehyde(MDA)and superoxide anion were measured and the change trendency was investigated.The results showed that the cleaning agent and procedure was effective to reduced the total bacterial count.The total number of colonies and the number of bacteria of fresh-cut lettuce were only 103 CFU/g and 400 MPN/100g,the total number of colonies and the number of bacteria of fresh-cut lotus root reduced to 102 CFU/g and 300 MPN/100g.Compared with 25?,4? could inhibit the increase of the number of bacteria,at the fifth day the total number of colonies and the number of bacteria of fresh-cut lettuce were 105 CFU/g and 103 MPN/100g,at the seventh day the total number of colonies and the number of bacteria of fresh-cut lotus root were 2.9×104 CFU/g and 4.7x103 MPN/100g,besides low storage temperature could inhibit the contents of nitrite content and it was less than 2 mg/kg and in the range of safety to eat,meanwhile low storage temperature could inhibit respiratory rate,Ascorbic Acid,color,superoxide anion and MDA,and it kept good sensory quality and nutritional value.