Growth inhibition of Listeria monocytogenes by commercial nisin and lactic acid in raw buffalo meat mince

Survivability of Listeria monocytogenes was studied against combination of 400 and 800 IU of commercial nisin (Nisaplin) with a final concentration of 2% Tactic acid incorporated in raw buffalo meat mince stored at 4 degrees C for 16 days and 37 degrees C for 36 h, Initial microbial analysis of meat mince revealed pH, extract release volume, mesophiles and psychrophiles count as 6.04, 47 mi, 37 x 10(4) and 13 x 10(4) cfu/g of meat, respectively. The growth of L. monocytogenes in the treated groups showed significant inhibition, as the count of pathogen registered only a slight increase whereas. in control groups, the count increased by more than 4 log cycles. The degree of inhibition increased with increase in the concentration of nisin and decrease in the storage temperature, pH in treatment groups remained significantly lower (P<0.01) than the control groups at 4 degrees C and 37 degrees C. Addition of lactic acid (2%) resulted in slight brownish discoloration of meat, but there was no disagreeable odour. This combination of food grade preservatives has been found to be effective listeriostatic in minced meat and can be used as adjunct specially in the event of "cold-chain" failure.