Survey On Microorganism Contamination Of Ready-to-Eat Food In Catering Industry And Establishment Of Rapid Detection Methods Of Staphylococcus Aureus

Ready-to-eat food refers to those cooked or uncooked food materials in catering industry.They are prepared by heat-and(or)freezing-treatment and can be consumed immediately without any additional cooking,including pot-stewed fowl,raw water products,and freshly squeezed juices,etc.Nevertheless,these ready-to-eat food may cause bacterial contamination when the hygiene requirements are not standerized.If not controlled properly,the related pathogenic toxins may cause food poisoning and induce the ourbreak of intestinal infectious diseases.In this study,a total of 304 ready-to-eat food samples,including 148 pot-stewed fowl samples,58 water product samples,and 98 squeezed juice samples,were randomly collected in Zhejiang Province.The sampling time was set in March,April,September,and October in 2016.In particular,the total bacteria count(CFU)of Escherichia coli,Salmonella,Staphylococcus aureus,Listeria monocytogenes,and parahaemolytic fungi were detected according to the Chinese National Standards.The pass rates of pot-stewed fowl,raw water products,and freshly squeezed juice were60.68%,82.76%,and 75.51%,respectively.Compared with the qualified rate in autumn(74.55%),those ready-to-eat food produced in spring had a lower pass rate(64.91%).In addition,the degree of microbial contamination of different sites of ready-to-eat food decreased in the following order: sauced meat shop > supermarket >hotel.Amongst all the 304 samples,Escherichia coli was beyond the standard limit in66 samples;Salmonella was detected in 1 sample;Staphylococcus aureus was detected in 5 samples;Listeria monocytogenes was detected in 1 sample;Vibrio hemolyticus was out of range in 4 samples.On the basis of analysis on microbial pollution factors,the following facilities or procedures should be highlighted to control the microbial contamination of ready-to-eat food: that is,the entrance changing facilities,hand washing facilities,normal status of UV sterilization lamps,specialized cold storage facilities,standerized preparation of disinfectant solutions,stacking debris,reasonable room temperature,wearing of masks by practitioners,etc.Furthermore,the highly conserved nuc gene of Staphylococcus aureus was selected as the target gene.Consequently,the reaction conditions for real-time quantitative PCR detection were optimized and a rapid detection method was established.The detecting efficiency was 100% consistent with the Chinese StandardMethod(GB 4789.10-2010).