Natrajan N, Sheldon B W
Department of Food Science, North Carolina State University, Raleigh 27695-7624, USA.
J Food Prot. 2000 Sep;63(9):1189-96. doi: 10.4315/0362-028x-63.9.1189.
Nisin is an antimicrobial peptide produced by the food-grade microorganism Lactococcus lactis subsp. lactis. This peptide inhibits many gram-positive bacteria, and when combined with chelating agents it inhibits gram-negative bacteria such as Salmonella sp. The efficacy of packaging films treated with nisin-containing formulations to reduce Salmonella contamination of fresh broiler drumstick skin and increase the refrigerated shelf life was investigated. Three films (5.1 cm2) of varying hydrophobicities (polyvinyl chloride [PVC], linear low density polyethylene, nylon) were coated with one of three liquid formulations (pH 3.5 to 3.8) composed of 100 microg/ml nisin and varying concentrations of citric acid, EDTA, and Tween 80. The treated films were applied either wet or dry to 5.1-cm2 broiler drumstick skin samples inoculated with a nalidixic acid-resistant (NAr) strain of Salmonella Typhimurium. After incubation at 4 degrees C for 24 h the populations of surviving Salmonella TyphimuriumNAr organisms were recovered from the skin and film samples using a rinse procedure and enumerated on brain heart infusion agar containing 800 ppm NA. Log reductions (untreated versus treated skin) in Salmonella TyphimuriumNAr populations ranged from 0.4 to 2.1. Treatment formulation compositions and wet versus dry treatment application also influenced the extent of kill. The shelf life of refrigerated broiler drumsticks was extended by 0.6 to 2.2 days following a 3-min immersion in a nisin-containing treatment solution and subsequent storage in a foam tray pack containing a nisin-treated PVC overwrap and a nisin-treated absorbent tray pad. These findings demonstrated that Salmonella Typhimurium and spoilage microorganism populations on the surface of fresh broiler skin and drumsticks can be significantly reduced using immersion treatments, absorbent tray pads, and packaging films treated with nisin-containing formulations.
乳酸链球菌素是由食品级微生物乳酸乳球菌乳酸亚种产生的一种抗菌肽。这种肽能抑制许多革兰氏阳性菌，与螯合剂联合使用时还能抑制革兰氏阴性菌，如沙门氏菌属。研究了用含乳酸链球菌素制剂处理的包装膜对减少新鲜肉用仔鸡腿皮肤沙门氏菌污染及延长冷藏保质期的效果。选用三种不同疏水性的薄膜（5.1平方厘米）（聚氯乙烯[PVC]、线性低密度聚乙烯、尼龙），分别用由100微克/毫升乳酸链球菌素以及不同浓度柠檬酸、乙二胺四乙酸和吐温80组成的三种液体制剂（pH 3.5至3.8）之一进行包被。将处理过的薄膜湿用或干用在接种了耐萘啶酸（NAr）鼠伤寒沙门氏菌菌株的5.1平方厘米肉用仔鸡腿皮肤样品上。在4℃下孵育24小时后，采用冲洗程序从皮肤和薄膜样品中回收存活的鼠伤寒沙门氏菌NAr菌，并在含800 ppm萘啶酸的脑心浸液琼脂上计数。鼠伤寒沙门氏菌NAr菌数量的对数减少量（未处理皮肤与处理后皮肤）在0.4至2.1之间。处理制剂的组成以及湿用与干用处理方式也会影响杀灭程度。将肉用仔鸡腿在含乳酸链球菌素的处理溶液中浸泡3分钟，随后储存在装有经乳酸链球菌素处理的PVC外包装和经乳酸链球菌素处理的吸水托盘垫的泡沫托盘包装中，冷藏肉用仔鸡腿的保质期可延长0.6至2.2天。这些研究结果表明，采用浸泡处理、吸水托盘垫以及用含乳酸链球菌素制剂处理的包装膜，可以显著减少新鲜肉用仔鸡皮肤和腿表面的鼠伤寒沙门氏菌及腐败微生物数量。
