Beverly Richelle L, Janes Marlene E, Prinyawiwatkul Witoon, No Hong K
Department of Food Science, LSU Ag Center, 111 Food Science Building, Baton Rouge, LA 70803, USA.
Food Microbiol. 2008 May;25(3):534-7. doi: 10.1016/j.fm.2007.11.002. Epub 2007 Nov 17.
The use of chitosan as an edible film was evaluated for its antimicrobial activity against Listeria monocytogenes (LM) on the surface of ready-to-eat (RTE) roast beef. L. monocytogenes, decimally diluted to give an initial inoculation of >6.50logCFU/g, was inoculated onto the surface of RTE roast beef cubes, and air-dried. The samples were dipped into chitosan (high or low molecular weights) solutions dissolved with acetic or lactic acid at 0.5% (w/v) or 1% (w/v) then bagged and refrigerated at 4 degrees C. The bacterial counts were determined on days 0, 7, 14, 21, and 28. The samples were spread plated onto modified Oxford agar plates and incubated at 37 degrees C for 48h. An initial 6.50logCFU/g of L. monocytogenes inoculated onto the surface of the non-coated RTE roast beef increased too >10logCFU/g by day 28. On day 14, L. monocytogenes counts were significantly different for all the chitosan-coated samples from the control counts by 2-3logCFU/g and remained significantly different on day 28. Our results have shown that the acetic acid chitosan coating were more effective in reducing L. monocytogenes counts than the lactic acid chitosan coating. Our study indicated that chitosan coatings could be used to control L. monocytogenes on the surface of RTE roast beef.
评估了壳聚糖作为可食用膜对即食（RTE）烤牛肉表面单核细胞增生李斯特菌（LM）的抗菌活性。将单核细胞增生李斯特菌进行十倍稀释，使其初始接种量>6.50logCFU/g，接种到RTE烤牛肉块表面，然后风干。将样品浸入溶解有0.5%（w/v）或1%（w/v）乙酸或乳酸的壳聚糖（高分子量或低分子量）溶液中，然后装袋并在4℃下冷藏。在第0、7、14、21和28天测定细菌计数。将样品涂布在改良牛津琼脂平板上，在37℃下培养48小时。接种在未涂覆的RTE烤牛肉表面的初始6.50logCFU/g单核细胞增生李斯特菌在第28天时增加到>10logCFU/g。在第14天，所有壳聚糖涂层样品的单核细胞增生李斯特菌计数与对照计数相比有显著差异，相差2-3logCFU/g，并且在第28天仍然有显著差异。我们的结果表明，乙酸壳聚糖涂层在减少单核细胞增生李斯特菌计数方面比乳酸壳聚糖涂层更有效。我们的研究表明，壳聚糖涂层可用于控制RTE烤牛肉表面的单核细胞增生李斯特菌。
