Decontamination of beef carcass tissue with nisin using a pilot scale model carcass washer

Nisin spray treatments were tested for controlling Gram-positive bacteria attached to beef carcass surface tissue using a pilot scale model carcass washer. Section of lean and adipose tissues were inoculated with approximately 4 log₁₀ cfu cm^-2 of Brochothrix thermosphacta, Carnobacterium divergens or Listeria innocua. Following 28°C water or nisin sprays, bacterial populations were enumerated immediately and after incubation for 24 h at 4°C. Spray treatments with water did not significantly alter the bacterial populations at day 0 or 1 (< 1 log₁₀ reduction). However, nisin spray treatments (5000 AU ml^-1) reduced populations by 1·79 to 3·54 log₁₀ cfu cm^-2 at day 0 and by 1·97 to 3·60 log₁₀ cfu cm^-2 at day 1. This study demonstrates that spray washing is an effective means of applying bacteriocins and that these compounds may be useful as sanitizers of red meat carcasses.