title: Application of cranberry concentrate (Vaccinium macrocarpon) to control Escherichia coli O157:H7 in ground beef and its antimicrobial mechanism related to the downregulated slp, hdeA and cfa.
abstract: The possible use of cranberry concentrate (CC) as a natural food preservative was studied by examining its antimicrobial effect on the growth of Escherichia coli O157:H7 inoculated in ground beef, its organoleptical effect on beef patties, and its antimicrobial mechanism on the gene regulation level. Inoculated ground beef was added with CC and stored at 4 degrees C for 5 days. Bacteria were detected on day 0, 1, 3, and 5. Cranberry concentrate (2.5%, 5%, and 7.5% w/w) reduced total aerobic bacteria 1.5 log, 2.1 log, and 2.7 log CFU/g and E. coli O157:H7 0.4 log, 0.7 log, and 2.4 log CFU/g, respectively, when compared to the control on day 5. Fifty panelists evaluated the burgers supplemented with CC. No differences in appearance, flavor, and taste were found among burgers with 0%, 2.5%, and 5% CC. The expression of E. coli O157:H7 cyclopropane fatty acyl phospholipid synthase (cfa), hypothetical protein (hdeA), outer membrane porin protein C (ompC), hyperosmotically inducible periplasmic protein (osmY), and outer membrane protein induced after carbon starvation (slp) genes with or without CC (2.5% v/v) treatment was investigated by quantitative real-time PCR. Compared to the control, slp, hdeA, and cfa were markedly downregulated, ompC was slightly downregulated, while osmY was slightly affected.
authors.affiliation: Department of Food Science and Human Nutrition, The University of Maine, 5735 Hitchner Hall, Orono, ME 04469-5735, USA. vivian.wu@umit.maine.edu
authors.forename: Vivian C H
authors.initials: VC
authors.lastname: Wu
authors.forename: Xujian
authors.initials: X
authors.lastname: Qiu
authors.forename: Benildo G
authors.initials: BG
authors.lastname: de los Reyes
authors.forename: Chih-Sheng
authors.initials: CS
authors.lastname: Lin
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Pan
mesh_terms: D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D005506:Food Contamination / Q000517:prevention & control; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D006801:Humans; D008461:Meat Products / Q000382:microbiology*; D010936:Plant Extracts / Q000494:pharmacology*; D016133:Polymerase Chain Reaction / Q000379:methods; D013696:Temperature; D013997:Time Factors; D029799:Vaccinium macrocarpon / Q000737:chemistry*
chemical_list: D005520:Food Preservatives; D010936:Plant Extracts