Ko Kyung Yuk, Park So Ra, Lee Chae A, Kim Meehye
Division of Food Additives and Packaging, Department of Food Safety Evaluation, Ministry of Food Drug Safety, Osongsengmyeong 2-ro, Cheongwon-gun, Chungbuk, 363-700, Korea.
Division of Food Additives and Packaging, Department of Food Safety Evaluation, Ministry of Food Drug Safety, Osongsengmyeong 2-ro, Cheongwon-gun, Chungbuk, 363-700, Korea.
J Dairy Sci. 2015 Mar;98(3):1435-42. doi: 10.3168/jds.2014-8452. Epub 2014 Dec 18.
Nisin, a polypeptide with antimicrobial properties, is known as a natural preservative. It is used in various foods, including dairy products. This study validated a novel procedure using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of nisin A and nisin Z in cow milk. An extraction solution of 0.1 M acetate buffer containing 1 M NaCl (pH 2.0) and MeOH (1:1) was used to extract nisin A and nisin Z from milk samples. After the addition of extraction buffers, the samples were homogenized and centrifuged. The supernatant was filtered and injected for LC-MS/MS analysis. The linearity of the analytical method had a high correlation coefficient (r≥0.9987). The limits of quantitation of nisin A and nisin Z were approximately 12.9 and 10.9 µg/kg, respectively. The accuracy of the analytical method in milk ranged from 90.6 to 103.4% for nisin A and from 83.8 to 104.4% for nisin Z. The coefficient of variation values of intra- and interday in milk determined to be less than 5% in both nisin A and nisin Z. Because the proposed method has comparatively high recovery and low coefficient of variation, it seems appropriate for the determination of nisin A and nisin Z in milk samples. As the quantification of nisin A and nisin Z in milk samples by using LC-MS/MS has only been rarely reported until now, this study provides a meaningful technological advance for the dairy industry.
乳酸链球菌素是一种具有抗菌特性的多肽，被称为天然防腐剂。它被用于各种食品中，包括乳制品。本研究验证了一种使用液相色谱 - 串联质谱法（LC-MS/MS）测定牛奶中乳酸链球菌素A和乳酸链球菌素Z的新方法。使用含有1 M NaCl（pH 2.0）和甲醇（1:1）的0.1 M乙酸盐缓冲液作为提取液，从牛奶样品中提取乳酸链球菌素A和乳酸链球菌素Z。加入提取缓冲液后，将样品均质化并离心。将上清液过滤并注入进行LC-MS/MS分析。该分析方法的线性具有较高的相关系数（r≥0.9987）。乳酸链球菌素A和乳酸链球菌素Z的定量限分别约为12.9和10.9 μg/kg。该分析方法在牛奶中的准确度对于乳酸链球菌素A为90.6%至103.4%，对于乳酸链球菌素Z为83.8%至104.4%。牛奶中乳酸链球菌素A和乳酸链球菌素Z日内和日间的变异系数值均小于5%。由于所提出的方法具有较高的回收率和较低的变异系数，似乎适用于测定牛奶样品中的乳酸链球菌素A和乳酸链球菌素Z。由于迄今为止很少有关于使用LC-MS/MS定量牛奶样品中乳酸链球菌素A和乳酸链球菌素Z的报道，本研究为乳制品行业提供了一项有意义的技术进步。
