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|a Acetic acid and lactic acid can inhibit growth of Gram negative bacteria particularly a pathogenic species. In food industries acetic acid and lactic acid were used as preservative. Current study is to immerse beef carcasses in acetic acid and lactic acid with E. coli strains BL21 (DE3), DH5a and an unknown strain. Beef carcass pieces were immersed in the E. coli suspension which contained (107 CFU/ml) for 30 seconds and left for 2 hours to allow E. coli to settle down on the surface of beef carcass. The beef carcass pieces were thereafter immersed in 1.0, 2.0 and 3.0% solutions of acetic acid and 1.5, 2.5 and 3.5% solutions of lactic acid for 30 seconds, then tap water was used to wash the samples. A clean specimen 5 x 5 cm was put on the surface of each sample. The count of E. coli on beef surface immersed in 1.0, 2.0 and 3.0% of acetic acid reduced by 0.87, 1.33 and 1.73 log CFU/ cm2, respectively also reduced by 1.1, 1.9 and 2.47 log CFU/cm2 for 1.5, 2.5 and 3.5% of lactic acid, respectively. The results showed that concentration of acetic acid and lactic acid had a significant effect to reduce E. coli count. The results also proved that lactic acid had greater effect on non-pathogenic E. coli rather than acetic acid.
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