Eosin methylene blue agar emb

The enumeration of TPC, Escherichia coli and Staphylococcus aureus counts and detection of Salmonella and Bacillus cereus were performed according to ICMSF (23 ). Twenty-five grams of the 300 g of food sample was homogenised with 225 mL of buffered peptone water for 2 min in a sterile stomacher bag using a stomacher. Homogenised samples were then serially diluted with 1% sterile peptone water up to 10⁻⁴ dilutions. Then, 0.1 mL of the samples at each dilution factor was transferred onto their selective agars. Plate count agar (PCA; Oxoid, UK) was used for TPC, eosin methylene blue agar (EMB; Oxoid, UK) was used for Escherichia coli, and Baird Packer Agar (BP Agar; Oxoid, UK) was used for Staphylococcus aureus. The detection of Salmonella and Bacillus cereus was performed using xylose lysine deoxycholate agar (XLD; Oxoid, UK) and Bacillus cereus selective agar base (BCSA; Oxoid, UK), respectively. All medium plates were incubated at 37 °C for 24 h–48 h, except the PDA plates which were incubated at 37 °C for 5 days. Only 25–250 colonies on the plates were counted using a colony counter (Today’s Instruments, Taiwan). Results were expressed as colony forming units per gram (CFU/g). Isolates microbial were identified by cultural, morphological and physiological characteristics as described in media supplier (Oxoid, UK).

All samples were inoculated into Trypticase soy broth tubes and were incubated at 37 °C for 24 h. A loop-ful from the previously incubated tubes were streaked onto MacConkey agar plates (Oxoid Ltd., Cairo, Egypt) and Eosin methylene blue agar (EMB) (Oxoid) and were incubated aerobically at 37 °C for 24 h. Suspected colonies were purified through subculture on MacConkey agar plates and were examined for morphology and phenotype traits according to Collee et al. [23 ].