Effects of treatment with lysozyme and nisin on the microflora and sensory properties of commercial pork.

A mixture of lysozyme and nisin at a ratio of 3:1 (w/w) and at a surface concentration of approximately 260 microg/cm2 was effective in controlling the growth of lactic acid bacteria, lactic acid bacteria able to grow in the presence of acetate and Brochothrix thermosphacta on naturally contaminated pork loins that were stored in vacuum packages at 2 degrees C for up to 6 weeks. When loins were removed, cut into chops, and displayed in a retail display case, the efficacy of the antimicrobial mixture decreased with increasing display time. At most sampling times, bacterial numbers were lower in treated samples than in untreated samples. The numbers of Enterobacteriaceae were higher in treated samples than in untreated samples. The growth of Enterobacteriaceae may have been reduced as a result of antimicrobial activity of the lactic acid bacteria because when the growth of lactic acid bacteria was inhibited by the antimicrobial treatment, the Enterobacteriaceae were able to grow to higher numbers. Sensory evaluation of the loins showed no difference between treated and untreated samples, but aerobically displayed chops treated with antimicrobial had more prevalent off-odours and reduced odour acceptability than untreated samples.