title: Antimicrobial activity of apple, hibiscus, olive, and hydrogen peroxide formulations against Salmonella enterica on organic leafy greens.
abstract: Salmonella enterica is one of the most common bacterial pathogens implicated in foodborne outbreaks involving fresh produce in the last decade. In an effort to discover natural antimicrobials for use on fresh produce, the objective of the present study was to evaluate the effectiveness  of different antimicrobial plant extract-concentrate formulations on four types of organic leafy greens inoculated with S. enterica serovar Newport. The leafy greens tested included organic romaine and iceberg lettuce, and organic adult and baby spinach. Each leaf sample was washed,  dip inoculated with Salmonella Newport (10(6) CFU/ml), and dried. Apple and olive extract formulations were prepared at 1, 3, and 5% concentrations, and hibiscus concentrates were prepared at 10, 20, and 30%. Inoculated leaves were immersed in the treatment solution for 2 min  and individually incubated at 4°C. After incubation, samples were taken on days 0, 1, and 3 for enumeration of survivors. Our results showed that the antimicrobial activity was both concentration and time dependent. Olive extract exhibited the greatest antimicrobial activity, resulting  in 2- to 3-log CFU/g reductions for each concentration and type of leafy green by day 3. Apple extract showed 1- to 2-log CFU/g reductions by day 3 on various leafy greens. Hibiscus concentrate showed an overall reduction of 1 log CFU/g for all leafy greens. The maximum reduction by hydrogen  peroxide (3%) was about 1 log CFU/g. The antimicrobial activity was also tested on the background microflora of organic leafy greens, and reductions ranged from 0 to 2.8 log. This study demonstrates the potential of natural plant extract formulations to inactivate Salmonella Newport  on organic leafy greens.
authors: Department of Veterinary Science and Microbiology, University of Arizona 1117, East Lowell Street, Tucson, Arizona 85721, USA.
authors: Katherine L
authors: KL
authors: Moore
authors: Jitendra
authors: J
authors: Patel
authors: Divya
authors: D
authors: Jaroni
authors: Mendel
authors: M
authors: Friedman
authors: Sadhana
authors: S
authors: Ravishankar
mesh_terms: D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D005519:Food Preservation / Q000379:methods*; D031584:Hibiscus / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D018545:Lactuca / Q000382:microbiology*; D027845:Malus / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D031658:Olea / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology*; D019779:Salmonella enterica / Q000187:drug effects* / Q000254:growth & development; D018724:Spinacia oleracea / Q000382:microbiology*; D013997:Time Factors
chemical_list: D010936:Plant Extracts; D006861:Hydrogen Peroxide