2.2. Detection and enumeration of Salmonella
All of the samples were subjected to qualitative and quantitative
analysis for Salmonella. Qualitative analysis was performed according
to National Food Safety Standards of China document GB 4789.4-
2010. A 25 g sample was randomly collected from each RTE food
product and was pre-enriched in 225 ml of buffered peptone broth
(Huankai, Guangzhou, China). One millilitre cultureswere incubated
in 10 ml of selenite cystine broth (SC) (Huankai) at 37 C and 10ml of
tetrathionate brilliant green broth (TTB) at 42 C for 24 h, respectively.
Loopfuls of SC and TTB cultures were streaked onto xyloselysine-
tergitol 4 (XLT4) selective agar plates (Difco, Detroit, MI,
USA) and chromogenic Salmonella agar plates (Huankai), then
incubated at 37 C for 24 h. Presumptive colonies were picked from
each plate, stabbed into a triple sugar iron slant (Huankai), and
incubated at 37 C for 24 h. Isolates with typical Salmonella phenotypes
were further confirmed using API 20E test strips (bio-
Merieux, Marcy-l'Etoile, France). The levels of Salmonella in the