Nadathur S R, Zhou L, Lowry R R, Bakalinsky A T
Department of Food Science and Technology, Oregon State University, Corvallis 97331, USA.
J Dairy Sci. 1998 Mar;81(3):664-71. doi: 10.3168/jds.S0022-0302(98)75621-8.
Reconstituted nonfat dry milk was treated with different amounts of lipase from Pseudomonas fluorescens. Hexane extracts of treated milks were dissolved in dimethylsulfoxide and assayed for antimutagenicity using the Ames test (Salmonella typhimurium TA 100) against N-methyl, N'-nitro, N-nitrosoguanidine. Anti-N-methyl, N'-nitro, N-nitrosoguanidine activity increased significantly as the amount of added lipase increased. At the highest lipase concentration tested, activity increased 5-fold, suggesting that liberated fatty acids contributed to the increased antimutagenicity. The activities of mixtures of pure fatty acids on antimutagenesis were examined using the Ames test. At the lowest concentrations tested, mixtures of palmitic and stearic acids and mixtures of palmitic and isopalmitic acids exhibited greater activity than did the individual acids. At all doses tested, mixtures of the monoacylglycerides of palmitic and stearic acids exhibited the same activity as the individual components. Quantification of fatty acids in milk and yogurt by gas chromatography indicated a 2 to 20-fold greater content of free fatty acids in yogurt. The increase in free fatty acids may contribute to the increase in antimutagenicity of yogurt relative to that of milk.
用不同量的荧光假单胞菌脂肪酶处理复原脱脂奶粉。将处理过的牛奶的己烷提取物溶解在二甲基亚砜中，并使用艾姆斯试验（鼠伤寒沙门氏菌TA 100）检测其对N-甲基、N'-硝基、N-亚硝基胍的抗诱变性。随着脂肪酶添加量的增加，抗N-甲基、N'-硝基、N-亚硝基胍活性显著增加。在测试的最高脂肪酶浓度下，活性增加了5倍，这表明释放的脂肪酸有助于抗诱变性的增加。使用艾姆斯试验检测了纯脂肪酸混合物的抗诱变活性。在测试的最低浓度下，棕榈酸和硬脂酸的混合物以及棕榈酸和异棕榈酸的混合物比单一酸表现出更高的活性。在所有测试剂量下，棕榈酸和硬脂酸的单酰甘油混合物与单一成分表现出相同的活性。通过气相色谱法对牛奶和酸奶中的脂肪酸进行定量分析表明，酸奶中游离脂肪酸的含量比牛奶高2至20倍。游离脂肪酸的增加可能有助于酸奶相对于牛奶抗诱变性的增加。
