Recovery of Cold Shocked Salmonella sp, Isolated from Burger, Using Different Substrates

Abstract

The aim of this study was to design a medium for the true bacterial loud in frozen meat.The study was carried out in the period from June to October 2009.The injured bacteria on frozen meat like burger, showed a remarkable reduction in their viable count number. This is in turn will lead to underestimation of the true bacterial load. Consequently, this will lead to passing food as fit for human consumption while it is not passable. XLD medium was used for the growth of Salmonella sp shocked cells. The suggested media consisted of sodium pyruvate at the concentrations 0.5, 1.0 and 1.5%. Vitamin B6 and B12 in the concentrations of 1, 2 and 3ml were added singly or simultaneously with sodium pyruvate. Salmonella was subjected to shock at -20,-30 and -40oC for one hour and then inoculated in the different media. The loss in viability with B6 was 4.8% at -20oC, 9.7% at -30oC and 26.3% at -40oC. The loss in viability with B12 was 0.98% at -20oC, 2.5% at -30oC and 14.8% at -40oC. The loss in viability with sodium pyruvate was 2.0% at -20oC, 25.2% at -30oC and 26.8% at -40oC.When sodium pyruvate was added in 0.5% recovery was 93.9%, in 1% recovery was 94.0% and in 1.5% recovery was 92.9%. When sodium pyruvate was added in 0.5% with B6 (1ml) recovery was 97.5% while B12 (1ml) was 99.6% an improvement of recovery was noticed. It is suggested that when counting bacteria in frozen foods e.g. burger medium containg sodium pyruvate and B12 should be included.