Growth inhibition of lactic acid bacteria in ham by nisin: A model approach

• Lactic acid bacteria are the main spoilage in vacuum-packed sliced cooked ham.
• Experimental design strategy suggests that nisin can reduce L. sakei growth.
• A model approach to predict LAB growth in vacuum-packed sliced cooked ham
• The addition of nisin in ham showed the reduction of total lactic acid bacteria.
• LAB growth inhibition in MRS broth by nisin and validation in food matrix

Lactic acid bacteria (LAB) have been described as spoilage organisms in vacuum-packed cooked ham. A Fractional Factorial Design was performed to investigate the relative merits of sodium chloride, sodium lactate, sodium tripolyphosphate, sodium erythorbate, nisin and pediocin, in limiting the Lactobacillus sakei growth in broth culture. This allowed rejection of sodium chloride, sodium lactate and sodium erythorbate (no significant effects on growth), and a Central Composite Rotatable Design broth culture study was performed comparing the effects of nisin and pediocin. From this study, nisin was identified as a more important variable for inclusion into a cooked ham model (significant effects on growth parameters: logarithmic increase in the population, exponential microbial growth rate and lag phase extension). The validation of this outcome in a model formulation of vacuum-packed sliced cooked ham (0.001%, 0.007% and 0.013% of nisin) stored for 60 days, confirmed the inhibitory effect of nisin on total LAB growth.