Tsai G J, Cousin M A
Department of Food Science, Purdue University, West Lafayette, IN 47907.
J Dairy Sci. 1990 Dec;73(12):3366-78. doi: 10.3168/jds.S0022-0302(90)79032-7.
An enzyme-linked immunosorbent assay was developed for the detection of molds in dairy products. New Zealand White female rabbits were immunized with .45 mg of partially purified extracellular antigen from freeze-dried culture filtrates of Aspergillus versicolor, Cladosporium herbarum, Geotrichum candidum, Mucor circinelloides, and Penicillium chrysogenum. Blood was drawn at various intervals, and antibodies were separated and purified. Antibody-peroxidase conjugates were prepared with the following ratios being the optimum ones: A. versicolor 10:20; C. herbarum 5:10; G. candidum 1:10; M. circinelloides 5:5; and P. chrysogenum 10:10. The assays were sensitive within a range of 1 ng to 1 microgram/ml, depending on the mold used. Inhibition tests were done for each mold with concentrations of 0 to 5000 micrograms/ml of antigen. The enzyme-linked immunosorbent assay tests for Cladosporium, Geotrichum, and Mucor were only inhibited by antigens from other species of the same genus; whereas there was crossreaction between antibodies and antigens of species of Penicillium and of Aspergillus. Citrate buffer was best for extracting the mold from cheese and yogurt. The extract was adjusted to pH 7.2 and ELISA was performed. Results showed that these molds can be detected in Cheddar and cottage cheeses and yogurt within 2 d, which is before mold growth is visible in these products.
开发了一种酶联免疫吸附测定法用于检测乳制品中的霉菌。用来自杂色曲霉、草本枝孢霉、白地霉、卷枝毛霉和产黄青霉冻干培养滤液的0.45毫克部分纯化细胞外抗原免疫新西兰白兔。在不同时间间隔采血，分离并纯化抗体。制备抗体-过氧化物酶结合物的最佳比例如下：杂色曲霉10:20；草本枝孢霉5:10；白地霉1:10；卷枝毛霉5:5；产黄青霉10:10。根据所使用的霉菌不同，该测定法在1纳克至1微克/毫升范围内具有敏感性。对每种霉菌进行了浓度为0至5000微克/毫升抗原的抑制试验。对枝孢霉、地霉和毛霉的酶联免疫吸附测定试验仅被同一属其他物种的抗原抑制；而青霉属和曲霉属物种的抗体与抗原之间存在交叉反应。柠檬酸盐缓冲液最适合从奶酪和酸奶中提取霉菌。将提取物调节至pH 7.2并进行酶联免疫吸附测定。结果表明，在切达干酪、农家干酪和酸奶中可在2天内检测到这些霉菌，这早于这些产品中可见霉菌生长的时间。
