即食凉拌食品中微生物污染调查分析及大肠菌群限量探讨

Evaluation of microbiological contamination and coliform safety limit in cold ready-to-eat (RTE) foods

目的了解即食凉拌食品中微生物污染状况,为制定即食凉拌食品微生物限量标准提供依据。方法采用国家食源性疾病监测网监测方案和《中华人民共和国国家标准食品卫生微生物学检验方法》(GB/T4789-2003)检测凉拌食品中的沙门氏菌、志贺氏菌、O157∶H7/NM、单核细胞增生李斯特氏菌和大肠菌群。结果29家零售加工单位即食凉拌食品受大肠菌群污染差异无统计学意义(χ2=5.60,P>0.05),其零售的76份即食凉拌食品样品中均未检出目的致病菌。大肠菌群是主要污染菌,阳性率为71.05%,其中中式凉拌菜阳性率为70.23%,高于西式沙拉的68.97%,差异无统计学意义(t=0.92,P>0.05),菌浓度差异无统计学意义(t=0.7,P>0.05)。超市零售加工的中式凉拌菜大肠菌群阳性率高于普通饭店和中高级饭店,差异有统计学意义(χ2=7.00,P<0.05),平均菌浓度差异有统计学意义(F=11.06,P<0.01)。结论大肠菌群是凉拌食品主要的污染菌,应尽快出台即食凉拌食品卫生标准,建议即食凉拌食品大肠菌群限量≤100MPN/g。

Objective To investigate the microbiological quality of cold ready-to-eat （RTE） foods,so as to provide reference for determining maximum levels of contaminants in these foods. Methods Cold RTE food samples were examined for Salmonella, Shigella, E. coli O157 ： H7/NM, Listeria monocytogenes and colfforms, in accordance with the National Foodborne Disease Surveillance System guidelines and the national standard GB/T4789-2003. Results No contamination of Salmonella, Shigella ,E. coli O157： H7/NM and Listeria monoeytogenes was found in the 76 food samples collected from 29 manufacturers. The overall incidence of coliforms was 71.05% , showing no difference among the manufacturers （X^2 = 5.60 ,P 〉 0.05）. There were no significant differences between the Chinese-style cold dish and western-style salad in the incidence of coliforms （70. 23 % vs 68. 97 % , t = 0. 92, P 〉0. 05） and in the concentration of coliform count （ t = 0. 7,P 〉 0.05）. The Chinese-style cold dish sold in supermarkets had a higher incidence rate and mean concentration of coliforms than that of those served in restaurants （X^2 = 7.00, P 〈 0. 05 ; F = 11.06, P 〈 0.01 ）. Coliforms are the major bacterial contaminant in cold RTE foods. It is suggested that the safety limit of coliforms be set at ≤ 100 MPN/g 〉 for cold RTE foods.