Determination of minimum inhibitory concentrations of liquid smoke fractions

The minimum inhibitory concentrations (MIC) of 9 liquid smoke fractions against pathogenic and food spoilage organisms were determined using broth or agar dilution methods. Extract F1 (highest carbonyl content and lowest pH) was most effective against all microorganisms. MIC of F1 was 0.75% against Lactobacillus plantarum; 1.5% against Listeria innocua M1, Salmonella, Escherichia coli 8677, Saccharomyces cerevisiae, and Aspergillus niger; and 2% against Pseudomonas putida. The least effective smoke fraction F9 had MIC >9% against most organisms tested, had high pH, low phenols, and low carbonyls. Growth curves of individual bacteria and yeast below the MIC exhibited a prolonged lag phase that increased with increasing smoke concentrations.