title: Modeling the efficacy of triplet antimicrobial combinations: yeast suppression by lauric arginate, cinnamic acid, and sodium benzoate or potassium sorbate as a case study.
abstract: The growth of four spoilage yeasts, Saccharomyces cerevisiae, Zygosaccharomyces bailii, Brettanomyces bruxellensis, and Brettanomyces naardenensis, was inhibited with three-agent (triplet) combinations of lauric arginate, cinnamic acid, and sodium benzoate or potassium sorbate. The inhibition efficacy was determined by monitoring the optical density of yeast cultures grown in microtiter plates for 7 days. The relationship between the optical density and the sodium benzoate and potassium sorbate concentrations followed a single-term exponential decay model. The critical effective concentration was defined as the concentration at which the optical density was 0.05, which became an efficacy criterion for the mixtures. Critical concentrations of sodium benzoate or potassium sorbate as a function of the lauric arginate and cinnamic acid concentrations were then fitted with an empirical model that mapped three-agent combinations of equal efficacy. The contours of this function are presented in tabulated form and as two- and three-dimensional plots. Triplet combinations were highly effective against all four spoilage yeasts at three practical pH levels, especially at pH 3.0. The triplet combinations were particularly effective for inhibiting growth of Z. bailii, and combinations containing potassium sorbate had synergistic activities. The equal efficacy concentration model also allowed tabulation of the cost of the various combinations of agents and identification of those most economically feasible.
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Dai
authors.forename: Mark D
authors.initials: MD
authors.lastname: Normand
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
authors.forename: Micha
authors.initials: M
authors.lastname: Peleg
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D055168:Brettanomyces / Q000187:drug effects / Q000254:growth & development; D002934:Cinnamates / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004338:Drug Combinations; D004357:Drug Synergism; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D005516:Food Microbiology; D005520:Food Preservatives / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007848:Laurates / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development; D020160:Sodium Benzoate / Q000494:pharmacology; D013011:Sorbic Acid / Q000494:pharmacology; D015003:Yeasts / Q000187:drug effects* / Q000254:growth & development; D020068:Zygosaccharomyces / Q000187:drug effects / Q000254:growth & development
chemical_list: D000935:Antifungal Agents; D002934:Cinnamates; D004338:Drug Combinations; D005520:Food Preservatives; D007848:Laurates; C029010:cinnamic acid; D020160:Sodium Benzoate; D013011:Sorbic Acid