Survival of Shiga-toxin producing Escherichia coli (STEC)‎ during storage of Karish cheese

Abstract EN

Non O157:H7 Shiga-toxin- Producing Escherichia coli (STEC) is a major foodborne pathogen that causes severe disease in humans ranged from mild gastroenteritis to critical illness and death.

This study investigated survival of (STEC) during storage of experimentally manufactured kareish cheese.

Cheese were prepared using pasteurized milk inoculated with 2 STEC strains (O26& O111) at (9 log10 CFU/g) with and without yogurt starter culture (Lactobacillus.

bulgaricus and Streptococcus.

thermophilus) & 3% NaCl, then expulsion of whey and stored at refrigerator.

The obtained results revealed that mean STEC counts (log10 CFU/g) were 6.46±5.66 , 6.06 ± 5.75 at zero time then reached 8.01±7.69, 8.07 ± 7.76 ( their maximum count) on 12 th day of storage, finally decreased to 4.63±4.55, 4.34 ± 4.08(at 21th day) in (O26&O111) treated groups with starter culture.

Concerning (O26&O111) untreated groups, the mean STEC counts were 6.67±5.32, 6.50±5.98 at zero time then reached to 9.08±8.65, 9.11±8.90 on 12 th day, finally decreased to5.53±4.85, 5.61±4.82 at 15 th day of storage at refrigerator.

Effect of starter culture on survival of STEC were highly significant (P< 0.05).In conclusion presence of starter culture in manufactured Karish cheese significantly enhanced reduction of Non O157:H7 STEC counts over its storage time.