Investigation on the safety and probiotic potentials of yoghurts sold in Owerri metropolis in Imo State Nigeria

Investigation on the microbial safety and probiotic potentials of different yoghurt brands sold in Owerri, Imo State Nigeria, was carried out using standard microbiological procedures. Ten each, of five different brands of commercially available yoghurt packaged in plastic containers were purchased from the street vendors and shopping malls in Owerri metropolis. The mean total count of samples on Brain Heart Infusion (BHI) and De Mann Rogosa Sharpe (MRS) agar media ranged from 2.0×107 to 6.0×108 and 1.0×108 to 5.4 × 108 cfu/ml respectively. The yoghurt isolates were identified as Streptococcus and Lactobacillus species; these isolates were resistant to commonly used antibiotics and inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa from clinical samples. No viable growth of isolates was observed in simulated gastric fluid of pH 1.5 to 2.5. Slight decrease in viable count of Lactobacillus spp. from 4.0×107 to 3.0×107 cfu/ml and Streptococcus spp. from 3.0×108 to 2.0×108 cfu/ml was observed in bile of pH 8.28 to 8.30. The isolates were recovered from faecal samples two weeks after ingestion with mean count ranging from no growth (zero) to 5.8×108 cfu/ml on MRS agar media. The isolates were found to exhibit some probiotic potentials and no pathogen was isolated from samples. It is recommended that strains of microorganisms that can deliver full probiotic potentials to consumers be used in commercial yoghurt productio