Reduction of Brochothrix thermosphacta on beef surfaces following immobilization of nisin in calcium alginate gels

Authors

C. N. Cutter, USDA-ARS
G. R. Siragusa, USDA-ARS

Date of this Version

1996

Document Type

Article

Citation

Published in Letters in Applied Microbiology (1996) 23: 9-12

Abstract

Lean and adipose beef carcass tissues inoculated with Brochothrix thermosphacta (BT) (approx. 4·50 log₁₀ cfu cm^-2) were left untreated (U) or treated with 100 µg ml^-1 nisin (N), calcium alginate (A) or 100 µg ml^-1 nisin immobilized in a calcium alginate gel (AN). Tissue samples were refrigerated after treatments and bacterial populations and nisin activity were determined at 0, 1, 2 and 7 d. U, A and N treatments of lean and adipose tissues did not suppress bacterial growth (>6 log₁₀ cfu cm^-2 by day 7) while treatments of lean and adipose tissues with AN suppressed bacteria ( > 2·42 log₁₀ cfu cm^-2 by day 7). Bacteriocin titres from both tissues were higher in AN vs N samples after the 7 d incubation. This study demonstrates that immobilization of nisin in a gel may be a more effective delivery system of a bacteriocin to the carcass surface than direct application.