title: Growth of food-borne pathogenic bacteria in oil-in-water emulsions: II--Effect of emulsion structure on growth parameters and form of growth.
abstract: The growth rates and yields of Listeria monocytogenes and Yersinia enterocolitica were determined in liquid culture media, and in model oil-in-water emulsions that contained 30, 70 or 83% (v/v) hexadecane. In emulsions with a mean droplet size of 2 microns containing 83% (v/v) hexadecane, the growth of both organisms resulted in decreased yields. Additionally, in these emulsions adjusted to pH 5.0 or 4.4 the growth rate of L. monocytogenes was significantly less than in other model systems which had an aqueous phase of equivalent chemical composition. Microscopic examination of the 83% (v/v) emulsion showed that its microstructure immobilized the bacteria, which were constrained to grow as colonies. Bacteria behaved similarly in model emulsions of either hexadecane or sunflower oil. Manipulation of the droplet size distribution of the emulsions changed the form and rate of growth of bacteria within them.
authors.affiliation: Institute of Food Research, Norwich Laboratory, Colney, UK.
authors.forename: T F
authors.initials: TF
authors.lastname: Brocklehurst
authors.forename: M L
authors.initials: ML
authors.lastname: Parker
authors.forename: P A
authors.initials: PA
authors.lastname: Gunning
authors.forename: H P
authors.initials: HP
authors.lastname: Coleman
authors.forename: M M
authors.initials: MM
authors.lastname: Robins
mesh_terms: D000473:Alkanes / Q000494:pharmacology; D003470:Culture Media; D004655:Emulsions / Q000737:chemistry; D005079:Excipients / Q000494:pharmacology; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development*; D010938:Plant Oils / Q000494:pharmacology; D000077423:Polidocanol; D011092:Polyethylene Glycols / Q000494:pharmacology; D000074242:Sunflower Oil; D013501:Surface-Active Agents / Q000494:pharmacology; D014867:Water; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000254:growth & development*
chemical_list: D000473:Alkanes; D003470:Culture Media; D004655:Emulsions; D005079:Excipients; D010938:Plant Oils; D000074242:Sunflower Oil; D013501:Surface-Active Agents; D014867:Water; D000077423:Polidocanol; D011092:Polyethylene Glycols; C007932:n-hexadecane