Natural antimicrobials: Effect of Microgard™ and nisin against Listeria innocua in liquid cheese whey

Antimicrobial activity of Microgard™ individually or in combination with nisin against Listeria innocua in liquid cheese whey (LCW) was investigated. Microgard™ did not reduce the initial count of L. innocua during storage at 7, 12, 20 and 25 °C, and showed a response similar to the untreated whey. In comparison, nisin exhibited an immediate bactericidal effect that was followed by regrowth of L. innocua. Initially, a significant antagonistic effect was detected when Microgard™ was combined with nisin in all systems evaluated. However, during storage, different responses were observed. Some combinations were more effective than single treatments, providing an adequate control of L. innocua. The combination of Microgard™ and nisin appears to be a feasible means for extending the shelf life of liquid cheese whey.