低温下鲜切莲藕菌相分析及货架期评价

采用不同选择性培养基分析真空包装鲜切莲藕的菌相组成,并采用菌落形态、显微形态观察及生理生化方法予以鉴定;建立Gompertz模型揭示莲藕主要腐败微生物在4℃恒温贮藏过程中的变化规律;基于感官分析,确定低温条件下鲜切莲藕货架期的微生物限量。结果发现,真空包装鲜切莲藕中主要菌相为乳酸菌属、肠杆菌科、假单胞菌属、酵母菌属,实验鉴定出乳酸菌属、肠杆菌科、假单胞菌属、酵母菌属各2株;经菌落形态、显微形态观察及生理生化鉴定,均符合相关科属特性。整个贮藏过程中,乳酸菌、肠杆菌、假单胞菌和酵母菌的数量变化趋势基本一致,其中乳酸菌延滞期最短,假单胞菌最大比生长率最高,酵母菌数量优势相对较大。该莲藕产品的货架期为10d左右,所对应的微生物数量级约107CFU/g。

Microflora and shelf life assessment of fresh-cut lotus root at low temperature

Microflora of vacuum-packed flesh-cut lotus root was analyzed and identified using different selective medium, and the bacteria colony were identified by colony morphology, microscopic morphology, physiological and biochemical methods. Gompertz model was established to reveal the changing regulation of varies spoilage microorganism of lotus root in the process of 4℃ constant temperature storage. Based on sensory analysis, the shelf life of flesh-cut lotus root microbial limits was determined under low temperature. The results indicated that main microflora in vacuum packing fresh-cut lotus root was Lactobacillus, Enterobactetiaceae, Pseudomonas and Saccharomycetes. Two strains of each species were detected by colony morphology, microscopic morphology observation, physiological and biochemical observation, the result all conform to the character of rele- vant species and genus. The numbers of variation trend of Lactobacillus, Enterobacteriaceae, Pseudomonas and Saccharomycetes were similar throughout the storage process. Lactobacillus had the shortest lag phase; Pseudomonas had the maximum specific growth rate; yeast had the quantita- tive superiority in the process. The shelf tife was about 10d, and the corresponding magnitude of microorganisms was about 107CFU/g.