el-Gazzar F E, Bohner H F, Marth E H
Department of Food Science, University of Wisconsin-Madison 53706.
J Dairy Sci. 1992 Jan;75(1):43-50. doi: 10.3168/jds.S0022-0302(92)77736-4.
Tyndallized samples of unfiltered skim milk and retentate (concentrated fivefold or twofold by volume) and permeate from UF skim milk were inoculated with 5.5 x 10(3) to 1.5 x 10(5) cfu/ml of Listeria monocytogenes strains California or V7 together with 4 x 10(7) to 2.3 x 10(8) cfu/ml of mesophilic lactic acid bacteria. Numbers of L. monocytogenes (McBride Listeria agar) and lactic acid bacteria (all purpose Tween agar) were determined after 0, 6, 12, 24, 30, and 36 h of incubation at 30 degrees C. Lactic acid bacteria significantly inhibited or inactivated L. monocytogenes in all three products. Inactivation was greater in permeate (6.77 orders of magnitude) than in unfiltered skim milk (3.67 orders of magnitude) or in retentate (4.21 orders of magnitude). Degree of inactivation in retentate was related to the extent of concentration. Inactivation was not complete, and L. monocytogenes survived in these products during fermentation for up to 36 h. When fermented products were refrigerated (4 degrees C), L. monocytogenes survived for 4 to 6 wk in skim milk, 3 to 5 wk in retentate, and 1 wk in permeate. At refrigeration temperature, length of survival was dependent on type of product and strain of the pathogen.
将未过滤的脱脂牛奶、截留物（体积浓缩五倍或两倍）以及超滤脱脂牛奶的渗透物进行间歇灭菌处理，然后接种5.5×10³至1.5×10⁵ cfu/ml的单核细胞增生李斯特氏菌加利福尼亚菌株或V7菌株，同时接种4×10⁷至2.3×10⁸ cfu/ml的嗜温乳酸菌。在30℃培养0、6、12、24、30和36小时后，测定单核细胞增生李斯特氏菌（麦克布莱德李斯特氏菌琼脂培养基）和乳酸菌（通用吐温琼脂培养基）的数量。乳酸菌在所有三种产品中均显著抑制或灭活了单核细胞增生李斯特氏菌。渗透物中的灭活程度（6.77个数量级）大于未过滤的脱脂牛奶（3.67个数量级）或截留物（4.21个数量级）。截留物中的灭活程度与浓缩程度有关。灭活并不完全，单核细胞增生李斯特氏菌在这些产品发酵过程中可存活长达36小时。当发酵产品冷藏（4℃）时，单核细胞增生李斯特氏菌在脱脂牛奶中存活4至6周，在截留物中存活3至5周，在渗透物中存活1周。在冷藏温度下，存活时间取决于产品类型和病原体菌株。
