Growth inhibition of Listeria monocytogenes by commercial nisin and lacticacid 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 co unt 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 inh ibition, as the count of pathogen registered only a slight increase whereas . in control groups, the count increased by more than 4 log cycles. The deg ree of inhibition increased with increase in the concentration of nisin and decrease in the storage temperature, pH in treatment groups remained signi ficantly lower (P<0.01) than the control groups at 4 degrees C and 37 degre es C. Addition of lactic acid (2%) resulted in slight brownish discoloratio n of meat, but there was no disagreeable odour. This combination of food gr ade preservatives has been found to be effective listeriostatic in minced m eat and can be used as adjunct specially in the event of "cold-chain" failu re.