Research On Fresh-keeping Technique In Fresh Milk

The experiment studied the effect of Nisin Lysozyme and Ascorbic acid on fresh-keeping in milk. Through orthogonal design of L9(34), the different proportions of three factors and three levels were designed. Nine treatments preservative agents of different proportions were added into fresh milk. At interval two days ,measurement of the indexes of sensory,boiling experiment,relative density,acidity,colony groups and Colibacillus groups respectively were taken in this experiment at storage temperature of 10℃. The results showed that the 2nd treatment was the optimum. After milk sample had been preserved for 15 days, the milk had no abnormal odor. The conclusions drawn through boiling experiment showed the 2nd treatment was the optimum in keeping milk fresh. The acidity of the 2nd treatment was normal value(16°T~18°T). The acidity of other treatments rose up to 22°T then it dropped. The mechanism was probed into further. Relative density slowly increased with storage time prolonging. The results of testing relative density were analyzsed by variance. The variance was not significant (F