Analysis And Improvement Of Detection Method Of Salmonella In Food

Foodborne disease is one of the most common problems that most people concerned in the world today.Salmonella is one of the most important foodborne pathogen.The food poisoning and contamination of eggs and meat products caused by Salmonella have damaged the health of human beings.In recent years,with the development of enzyme-linked immunosorbent assay(ELISA)and PCR technology,all kinds of salmonella detection technology are emerging.But the domestic and international standard testing method is still given priority to conventional culture method.But conventional culture method detection cycle is time-consuming,and false negative rate is high.The existence of a variety of other miscellaneous bacteria in selective isolation media leads to large amount of biochemical identification and big workload.In addition,ELISA and PCR equipments are more expensive,which make them not convenient in food testing.This research is divided into two parts.In the first part,based on the simulation of the process of natural samples contaminated with Salmonella,three kinds of Salmonella-contaminative samples were analyzed: meat(chicken and ham duck),egg products(eggs and cakes),and mixed products(salad and bento).According to the processing technic,these 6 samples can be divided into two classes:(1)cold processed products: chicken,eggs,and salad;(2)hot processed products: ham duck,cakes and bento.Salmonella was added to food products to simulate the process of natural contamination.Conventional culture method was used to detect Salmonella in the food samples.Results show that besides Salmonella Pullorum detection rate is low,other Salmonella detection rates are higher.The Salmonella detection rate is 83.3% in both cold processed products and hot processed products.Meat and egg products’ Salmonella detection rates are higher,while Salmonella detection rate of egg products is low.The second part,combined with domestic and foreign relevant Salmonella detection method,an improved Salmonella detection method was set up to achieve same specificity and accuracy.The Salmonella enrichment incubation time is reduced from 8 to 18 h to 8 h.SX2 was used instead of standard selective enrichment media TTB and SC,and selective isolation medium XLD and Salmonella chromogenic medium were used instead of HE and BS.In summary,the improved method saved 1 ~ 2 days,and optimized the detection process,particularly Salmonella chromogenic medium and XLD reduced the interference of miscellaneous bacteria,thus the workload of biochemical identification was reduced.