title: Antimicrobial efficacy of emulsified essential oil components against weak acid-adapted spoilage yeasts in clear and cloudy apple juice.
abstract: The antimicrobial activity of oil-in-water emulsions containing dual combinations of the essential oil components cinnamaldehyde, perillaldehyde, and citral was examined against two acid-resistant yeast strains (Zygosaccharomyces bailii) in beverage systems composed of diluted clear or cloudy apple juice and in a Sabouraud dextrose broth model. Antimicrobial properties of an encapsulated oil-in-water emulsion and of essential oil components dissolved in 10% dimethyl sulfoxide were compared using plate counts and turbidity measurements. Growth curves were modulated to qualitatively assess differences in antimicrobial efficacy. The impact of the presence of a beverage emulsion without essential oils (unloaded; 5% oil and 1% modified starch, pH 3.0) on the antimicrobial efficacy also was investigated. Dual combinations of essential oil components were sufficient to completely inhibit and/or kill yeast cells in diluted apple juice and Sabouraud dextrose broth systems at very low concentrations (100 to 200 μg/ml). However, the combination of perillaldehyde and citral had the weakest antimicrobial effect; a concentration of 400 μg/ml was necessary to prevent yeast growth in beverages, and up to 800 μg/ml was required in systems to which an unloaded emulsion had been added. The antimicrobial activity of essential oil components did not differ in diluted clear and cloudy apple juices and was not affected by being added in emulsified form or dissolved in dimethyl sulfoxide as long as there was no unloaded emulsion also present. These results indicate that formulations of essential oil combinations encapsulated together in emulsions are highly effective for inhibiting and/or killing microorganisms in real beverage systems.
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Myriam
authors.initials: M
authors.lastname: Loeffler
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Sophia
authors.initials: S
authors.lastname: Beiser
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Sarisa
authors.initials: S
authors.lastname: Suriyarak
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Gibis
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. j.weiss@uni-hohenheim.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives* / Q000494:pharmacology; D000080462:Acyclic Monoterpenes; D000935:Antifungal Agents / Q000494:pharmacology*; D001628:Beverages / Q000032:analysis / Q000382:microbiology*; D027845:Malus / Q000737:chemistry / Q000382:microbiology*; D039821:Monoterpenes / Q000494:pharmacology*; D009822:Oils, Volatile / Q000494:pharmacology*; D020068:Zygosaccharomyces / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000080462:Acyclic Monoterpenes; D000935:Antifungal Agents; D039821:Monoterpenes; D009822:Oils, Volatile; C033342:perillaldehyde; D000171:Acrolein; C012843:cinnamaldehyde; C007076:citral