title: The effects of citrus extract (Citrox©) on the naturally occurring microflora and inoculated pathogens, Bacillus cereus and Salmonella enterica, in a model food system and the traditional Greek yogurt-based salad Tzatziki.
abstract: The antimicrobial effect of citrus extract (at 1 mL/kg [TC1] and 2 mL/kg [TC2]) on the naturally occurring microflora and inoculated pathogens (Bacillus cereus and Salmonella enterica, at ca. 6 log cfu/g) in the traditional Greek yogurt-based salad Tzatziki during storage under vacuum at 4 or 10 °C was examined. We also examined the effect of citrus extract (Citrox(©)) against the two aforementioned pathogens in tryptic soy broth (TSB). Of the two treatments, TC2 yielded the lowest yeast counts, irrespective of temperature, resulting in approximately 2 (4 °C) and 3 (10 °C) log reductions on the final day of storage (70 and 30 days, respectively). Although panelists preferred the TC1-treated salad, the TC2-treated product was sensorily acceptable. Therefore, at the concentrations used, Citrox had no negative sensorial effect on the Tzatziki. During storage, the Bacillus populations in the Citrox-treated Tzatziki samples progressively decreased, showing major declines from days 12 and 28 (at 10 and 4 °C, respectively). Citrox, especially at 2 mL/kg, had a significant effect on the survival of B. cereus. S. enterica showed major declines in all untreated Tzatziki samples from day 0-70 (4 °C) and from day 0-30 (10 °C), with averages of 2.5 and 2.8 log cfu/g, respectively. The results indicate that Citrox (at 1 and 2 mL/kg) is effective, from a safety standpoint, for reducing Bacillus and Salmonella spp. in Tzatziki. In addition, 2% citrus extract also showed a higher inhibitory effect against B. cereus and S. enterica grown in TSB than 1% citrus extract.
authors.affiliation: Laboratory of Food Chemistry and Food Microbiology, Department of Chemistry, University of Ioannina, GR-45110, Ioannina, Greece.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Tsiraki
authors.affiliation: Laboratory of Food Chemistry and Food Microbiology, Department of Chemistry, University of Ioannina, GR-45110, Ioannina, Greece. Electronic address: isavvaid@uoi.gr.
authors.forename: Ioannis N
authors.initials: IN
authors.lastname: Savvaidis
mesh_terms: D001409:Bacillus cereus / Q000187:drug effects* / Q000254:growth & development; D002957:Citrus / Q000737:chemistry*; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000517:prevention & control; D005519:Food Preservation / Q000379:methods*; D008954:Models, Biological; D010936:Plant Extracts / Q000494:pharmacology*; D019779:Salmonella enterica / Q000187:drug effects* / Q000254:growth & development; D014675:Vegetables / Q000382:microbiology*; D015014:Yogurt / Q000382:microbiology*
chemical_list: D010936:Plant Extracts
keywords: Bacillus; Citrox(©); Deli salad; Salmonella; TSB; Tzatziki