鲜乳保鲜技术的研究——Nisin、溶菌酶、抗坏血酸复合型保鲜试验

RESEARCH ON FRESH-KEEPING TECHNIQUE IN FRESH MILK -THE COMPOSITE FRESH-KEEPING EXPERIMENT OF NISIN,LYSOZYME AND ASCORBIC ACID

研究了在10℃条件Nisin、溶菌酶、抗坏血酸3种复合型保鲜剂对鲜乳的保鲜效果,采用L9(34)正交试验设计确定各因素及水平之间的不同比例,每隔2d对乳进行感官指标、相对密度、酸度、菌落总数以及大肠菌群的测定,结果表明:试验组中第2组效果较好,其酸度仍在正常范围内,其他各试验组酸度的变化趋势是先上升达到22°T后下降,其机理有待进一步探讨;通过三因素对相对密度的方差分析可知F<F0.05差异不显著,表明所添加的复合型保鲜剂对乳相对密度基本没有影响;菌落总数与大肠菌群的变化情况与前述的基本相似;这进一步说明,乳酸链球菌素,溶菌酶,抗坏血酸的共同使用对抑制乳中细菌的生长繁殖和防腐保鲜具有重要的作用。通过综合直观分析法,对各因素的K,k及R值的大小进行有关的分析可知:在鲜乳中加入100mg/kgNisin、33.50u/mL溶菌酶、0.15g/kg抗坏血酸保藏效果最佳。

The experiment studied the effect of Nisin, lysozyme and ascorbic acid on fresh-keeping in milk. Through orthogonal design of L9（3^4）, the different proportions of three factors and three levels were designed. At interval two days ,measurement of the indexes of sensory,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 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, results of testing relative density were analyzsed by variance. The variance was not significant （F〈F0.05）. The results tested colony group and colibacillus groups indicated the 2nd treatment was optimum in keeping milk fresh. This showed that Nisin ,lysozyme and ascorbic acid had significant effect on inhibiting the bacterium growth and the fresh-keeping. Through visualized analysis of the orthogonal experiment, the optimum proportions of three fresh-keeping agents was： Nisin 100mg/kg＋Lysozyme 33.50u/mL＋ Ascorbic acid 0.15g/kg.