Antimicrobial Activity of Binary and Ternary Mixtures of Vanillin, Citral, and Potassium Sorbate in Laboratory Media and Fruit Purees

The susceptibility of Escherichia coli, Salmonella enteritidis, Saccharomyces cerevisiae, and Zygosaccharomyces bailii to binary and ternary mixtures of potassium sorbate (KS), vanillin (V), and citral (C) was evaluated according to the Berenbaum experimental design, in laboratory media. For some V/C combinations, KS inhibitory concentrations were determined in agarized melon and mango purees by the spiral gradient endpoint (SGE) method. In laboratory media, inhibitory antimicrobial combinations were generally additives. For the yeasts, some synergistic effects were observed. All Berenbaum mixtures which resulted inhibitory in laboratory media were confirmed in the fruit purees. When the SGE method was used, several inhibitory ternary mixtures were found. The lowest inhibitory KS concentrations, estimated for a given V/C combination, corresponded to the bacteria assayed in melon puree. Z. bailii was not inhibited at any condition. Some synergistic antimicrobial combinations (595 ppm V + 251 ppm C + 8 ppm KS in melon and 280 ppm V + 123 ppm C + 8 ppm KS in mango purees) could be useful to achieve a desired inhibitory effect in fruit pur,es while reducing their concentrations.