Effect of nisin and its combination with sodium chloride on the survival of Listeria monocytogenes added to raw buffalo meat mince

Antilisterial activity of nisin (Nisaplin), alone at concentrations of 400 and 800 IU/g and in combination with 2% sodium chloride was incorporated in raw buffalo meat mince. Samples of the raw meat mince were inoculated with 10(3) colony forming units (cfu)/g of L. monocytogenes and stored at 4 deg rees C for 16 days and at 37 degrees C for 36 h. Initial estimates of pH, e xtract release volume, mesophilic and psychrophilic counts were found to be 5.74, 48 mi, 3.5x10(5) and 1.0x10(5) cfu/g of meat,respectively. The growt h of L. monocytogenes in the treated groups was significantly (P < 0.05) in hibited compared to the control group. The degree of inhibition increased w ith increasing concentration of nisin and decreasing storage temperature. A ddition of 2% sodium chloride in combination with nisin increased the effic acy of nisin at both storage temperatures. The pH in the treated groups rem ained significantly lower (P < 0.01) than in the control groups at both 4 a nd 37 degrees C. (C) 2000 Elsevier Science Ltd. All rights reserved.