Youssef M K, Gill C O, Tran F, Yang X
Agriculture and Agri-Food Canada Lacombe Research Centre, 6000 C & E Trail, Lacombe, Alberta, Canada T4L 1W1; Department of Food Hygiene and Control, Cairo University, 12211 Giza, Egypt.
Agriculture and Agri-Food Canada Lacombe Research Centre, 6000 C & E Trail, Lacombe, Alberta, Canada T4L 1W1.
J Food Prot. 2014 Dec;77(12):2161-7. doi: 10.4315/0362-028X.JFP-14-190.
Vacuum-packaged top butt cuts from a beef packing plant that does not use any carcass decontaminating interventions were assessed for their organoleptic and microbiological properties during storage at 2 or -1.5°C. Cuts stored at 2°C were acceptable after storage for 140 days but were unacceptable after 160 days because of persistent sour, acid odors. Odors of cuts stored at -1.5°C for 160 days were acceptable. The numbers of aerobes on cuts increased from <1 log CFU/cm(2) to 7 or 6 log CFU/cm(2) for cuts stored at 2 or -1.5°C, respectively. The numbers of Enterobacteriaceae increased from <-1 log CFU/cm(2) to 5 or 3 log CFU/cm(2) for cuts stored at 2 or -1.5°C, respectively. Bacteria recovered from initial microflora were, mainly, strictly aerobic organisms. Bacteria recovered from cuts stored for 160 days were mainly Carnobacterium spp. that grew on an acetate-containing agar generally selective for lactic acid bacteria other than Carnobacterium. C. divergens and C. maltaromaticum were recovered from cuts stored at 2°C, but C. maltaromaticum was the only species of Carnobacterium recovered from cuts stored at -1.5°C. No lactic acid bacteria of genera that usually predominate in the spoilage microflora of vacuum-packaged beef at late storage times were recovered from the spoilage microflora. The findings indicate that carnobacteria, initially present at very small numbers, grew exponentially to persistently dominate the spoilage microflora of vacuum-packaged beef cuts of unusually long storage life.
对一家不采用任何胴体去污干预措施的牛肉加工厂生产的真空包装上等牛肩肉切块，在2℃或-1.5℃储存期间的感官和微生物特性进行了评估。在2℃储存的切块在储存140天后仍可接受，但在160天后由于持续存在酸味和酸臭味而不可接受。在-1.5℃储存160天的切块气味可接受。在2℃或-1.5℃储存的切块上需氧菌数量分别从<1 log CFU/cm²增加到7或6 log CFU/cm²。肠杆菌科细菌数量在2℃或-1.5℃储存的切块上分别从<-1 log CFU/cm²增加到5或3 log CFU/cm²。从初始微生物群落中分离出的细菌主要是严格需氧菌。从储存160天的切块中分离出的细菌主要是肉杆菌属，这些肉杆菌在通常对除肉杆菌属以外的乳酸菌具有选择性的含乙酸盐琼脂上生长。从在2℃储存的切块中分离出了分歧肉杆菌和麦芽香肉杆菌，但麦芽香肉杆菌是从在-1.5℃储存的切块中分离出的唯一肉杆菌属物种。在腐败微生物群落中未检测到在真空包装牛肉后期储存腐败微生物群落中通常占主导地位的乳酸菌属。研究结果表明，最初数量极少的肉杆菌属细菌呈指数生长，持续主导了储存寿命异常长的真空包装牛肉切块的腐败微生物群落。
