Ramsaran H, Chen J, Brunke B, Hill A, Griffiths M W
Department of Food Science, University of Guelph, ON, Canada.
J Dairy Sci. 1998 Jul;81(7):1810-7. doi: 10.3168/jds.s0022-0302(98)75750-9.
Pasteurized and raw milks that had been inoculated at 10(4) cfu/ml with bioluminescent strains of Listeria monocytogenes and Escherichia coli O157:H7 were used in the manufacture of Camembert and Feta cheeses with or without nisin-producing starter culture. Survival of both organisms was determined during the manufacture and storage of Camembert and Feta cheeses at 2 +/- 1 degree C for 65 and 75 d, respectively. Bacterial bioluminescence was used as an indicator to enumerate the colonies plated on selective Listeria agar and on MacConkey agar. Escherichia coli O157:H7 survived the manufacturing process of both cheeses and was present at the end of the storage period in greater numbers than in the initial inoculum. At the end of 75 d of storage, E. coli O157:H7 was found in the brine of Feta cheese. The counts of L. monocytogenes increased as the pH of the Camembert cheese increased, and there were significant differences between the counts from samples taken from the inside and the counts from samples obtained near the surface of the cheese. The Feta cheese that contained nisin was the only cheese in which L. monocytogenes was at the level of the initial inoculum after 75 d of storage.
将每毫升接种10⁴ 菌落形成单位（cfu/ml）的发光单核细胞增生李斯特菌和大肠杆菌O157:H7的巴氏杀菌乳和生乳，用于制作有无产乳链菌肽发酵剂的卡门贝奶酪和费塔奶酪。分别在2±1摄氏度下制作和储存卡门贝奶酪65天、费塔奶酪75天的过程中，测定这两种微生物的存活情况。细菌生物发光用作指标，对接种在选择性李斯特菌琼脂和麦康凯琼脂上的菌落进行计数。大肠杆菌O157:H7在两种奶酪的制作过程中均存活下来，并且在储存期结束时的数量比初始接种量更多。在储存75天后，在费塔奶酪的盐卤中发现了大肠杆菌O157:H7。随着卡门贝奶酪pH值升高，单核细胞增生李斯特菌的计数增加，并且从奶酪内部取样的计数与从奶酪表面附近取样的计数之间存在显著差异。含有乳链菌肽的费塔奶酪是储存75天后单核细胞增生李斯特菌数量维持在初始接种量水平的唯一一种奶酪。
