包装方式对牛排贮藏期间微生物数量和演替的影响

Effect of Packaging Atmospheres on Microbial Counts and Succession in Beef Steaks during Storage

为研究包装方式对牛排贮藏期间的品质、微生物数量和演替的影响,牛排分别采用50%O2气调包装(50%O2+30%CO2+20%N2)和真空包装在0~4℃下贮藏21 d,并检测贮藏期间pH值、肉色、微生物数量和微生物多样性。结果表明:50%O2气调包装组比真空包装具有更好的护色效果;贮藏21 d时,与真空包装组相比,气调包装组菌落总数、乳酸菌数和假单胞菌数降低;两种包装的微生物多样性均随时间延长呈现先升高后降低的趋势,且真空包装牛排比50%O2气调包装牛排具有更复杂的微生物多样性;牛排的初始微生物主要由不动杆菌属、苍白杆菌属、栖热菌属和金黄杆菌属组成,随着贮藏时间的延长,肉食杆菌属逐渐成为真空包装牛排的优势菌群,而环丝菌属、沙雷氏菌属和乳杆菌属则成为50%O2气调包装牛排的优势菌群;贮藏7~14 d是牛排中微生物种类产生变化的关键时间点;相比于真空包装牛排,50%O2气调包装牛排中的微生物群落具有更低的糖代谢和更高的蛋白质代谢能力。本研究结果明确了不同贮藏方法下牛排的品质变化和微生物的演替规律,为定向抑制牛排中的微生物、延长产品货架期提供了参考。

In order to investigate the effect of different packaging methods on meat quality,microbial counts and microbial community succession in beef steaks during storage,meat samples were stored in modified atmosphere(50%O2+30%CO2+20%N2)or vacuum at 0-4℃and evaluated for pH,meat color,microbial counts and bacterial diversity after 0,3,7,14 and 21 days.The results showed that modified atmosphere packaging(MAP)maintained meat color better than vacuum packaging(VP).On day 21,the total viable count,lactic acid bacterial count and Pseudomonas spp.count in the MAP group decreased as compared to those in the VP group.The microbial diversity in both groups increased at first and then decreased as storage time was extended,being more complex in the VP group than in the MAP group.The initial bacterial community in steaks was dominated by Acinetobacter,Ochrobactrum,Thermus and Chryseobacterium,and then Carnobacterium gradually became the dominant microorganism in the VP group,while Brochothrix,Serratia and Lactobacillus eventually became the dominant microorganisms in the MAP group.The storage time from day 7 to 14 was the critical period for the changes in microbial species in beef steaks.Higher protein and lower carbohydrate metabolism levels in the MAP group were found compared with the VP group.The results from this study may provide a reference for targeted inhibition of microorganisms in beef steaks and prolonging the shelf life.