Because the E. coli group refers to a group of bacteria related to stool pollution with certain characteristics, that is, the Gram -negative germiosilus of Gram -based germinated germiamia with gas -producing gesture of lactose production at 37 ° C. Therefore, the detection of the colorectal flora is generally performed in accordance with its definition. The testing method of import and export food colorectal flora adopted in China mainly includes national standards and industry standards formulated by the former State Commercial Inspection Bureau. The two standard methods are slightly different in the detection program. (1) National standards: National standards adopt three steps, namely: lactose fermentation test, separation training, and confirmation test. The lactose fermentation test: After the sample is diluted, select three dilution degrees, and each dilution degree to inoculate tri -tube lactose gallbladder fermentation tubes. Cultivate 48 ± 2h at 36 ± 1 ℃ to observe whether it is produced. Sepan cultivation: Turn the cultivation of gas production tubes on Yonghongmei Blue Graphite tablet, and cultivate 18-24h at 36 ± 1 ℃ to observe the formation of the colonies. Crofin test: Pick the suspected colonies on the tablet and observe Gram -dyeing. At the same time, the lactose fermentation tube is 36 ± 1 ℃ to cultivate 24 ± 2h to observe the gas production situation. Report: According to the number of positive pipes of E. coli, check the MPN table and report the MPN value of the Escharian flora per 1ml (g). For specific operations, see gb4789.3-2010 "The National Standard Food Sanitary Microbiology Test of the People's Republic of China" Standard, equivalent, use the US FDA standard method to detect E. coli in exported foods. This method adopts two steps: G speculation test: After the sample is diluted, select three dilution degrees, and each dilution degree to inoculate tri -tube LST soup. Cultivate 48 ± 2h at 36 ± 1 ℃ to observe whether it is produced. Keng test: Incubate the gas -producing green lactose gallbladder salt (BGLB) soup tube, cultivate 48 ± 2h in 36 ± 1 ° C to observe whether the gas is produced. BGLB is positive. Check the MPN table and report the mpn value of the colonic flora in each ml (g) sample. The specific operations see SN0169-92 "The People's Republic of China Import and Export Commodity Inspection Industry Standard Export Foods, Enterobacter Fun, Gan Gravococcius and E. coli"
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