Muthukumarasamy Parthiban, Han Jung H, Holley Richard A
Department of Food Science, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
J Food Prot. 2003 Nov;66(11):2038-44. doi: 10.4315/0362-028x-66.11.2038.
Two naturally occurring antimicrobial agents were tested in packages of refrigerated ground beef for their ability to reduce the viability of Escherichia coli O157:H7 during storage. Allyl isothiocyanate (AITC) and Lactobacillus reuteri were tested separately and together for their action against a cocktail of five strains of E. coli O157:H7 in ground beef held at 4 degrees C for 25 days. Ground beef prepared from whole, raw inside round beef roasts was inoculated with low (3 log CFU/g) or high (6 log CFU/g) levels of the E. coli O157:H7 mixture. The beef was treated with AITC (about 1,300 ppm), L. reuteri, or both, along with 250 mM of glycerol per kg of meat at two levels (3 and 6 log CFU/g) and according to a design that yielded 8 controls plus 10 different treatments. Samples were analyzed for E. coli O157:H7 survivors, numbers of total bacteria, and lactic acid bacteria on days 0 to 25 at 5-day intervals. L. reuteri at both input levels with glycerol killed E. coli O157:H7 at both inoculated levels before day 20. AITC completely eliminated E. coli O157:H7 at the low-inoculum level (3 log CFU/g) and reduced viability >4.5 log CFU/g at the high-inoculum level (6 log CFU/g) by the end of the storage period. The combination of L. reuteri and AITC did not yield an additive effect against E. coli O157:H7 viability. L. reuteri in the presence of glycerol was highly effective against E. coli O157:H7 in ground beef during refrigerated storage (4 degrees C) in modified atmosphere packages. Sensory testing is planned to evaluate effects of treatments.
对两种天然存在的抗菌剂进行了测试，评估它们在冷藏碎牛肉包装中降低大肠杆菌O157:H7在储存期间生存能力的效果。分别对异硫氰酸烯丙酯（AITC）和罗伊氏乳杆菌进行了测试，并将两者联合测试，观察它们对在4℃下保存25天的碎牛肉中五种大肠杆菌O157:H7菌株混合物的作用。用整只生的内圆烤牛肉制备碎牛肉，并接种低水平（3 log CFU/g）或高水平（6 log CFU/g）的大肠杆菌O157:H7混合物。碎牛肉用AITC（约1300 ppm）、罗伊氏乳杆菌或两者进行处理，同时每千克肉添加250 mM甘油，添加量分为两个水平（3和6 log CFU/g），按照一种设计方案，产生8个对照组和10种不同处理。在第0至25天期间，每隔5天对样品进行大肠杆菌O157:H7存活菌数、总细菌数和乳酸菌数的分析。在第20天之前，两种接种水平下添加甘油的两种罗伊氏乳杆菌输入量均能杀死两种接种水平的大肠杆菌O157:H7。AITC在低接种量水平（3 log CFU/g）下完全消除了大肠杆菌O157:H7，在储存期结束时，在高接种量水平（6 log CFU/g）下使生存能力降低>4.5 log CFU/g。罗伊氏乳杆菌和AITC的组合对大肠杆菌O157:H7的生存能力没有产生相加效应。在气调包装中冷藏储存（4℃）期间，存在甘油的罗伊氏乳杆菌对碎牛肉中的大肠杆菌O157:H7非常有效。计划进行感官测试以评估处理效果。
