Food Protection Trends - November 2010 - 707

Kirsten Hirneisen, from the University of Delaware, presented her research on the hydroponic internalization of enteric viruses into green onions and spinach. Hepatitis A virus and murine norovirus were shown to internalize into young green onion and spinach plants grown hydroponically. Both viruses were found to be present in the edible portions. Carol D’Lima of the University of California-Davis, discussed “Controlled Environment Assessment of Preharvest Internalization and Transference of Salmonella into Melon Vines from Irrigation Water Using a Tube Nucleation Assay.” This work showed that a high dose of Salmonella into the soil via irrigation water can result in immediate, but transient, transfer into melon vines. David Ingram of the USDA ARS presented “The Effect of Total Organic Carbon Content and Repeated Irrigation on the Persistence of Escherichia coli O157:H7 on Baby Spinach.” Spinach was inoculated at levels of E. coli O157:H7 in compost tea that are acceptable for coliform counts (26 CFU/100 mL) of irrigation water. After 24 hours, spinach was acceptable for harvest. Manan Sharma of the USDA-ARS presented “Effect of Modified Atmosphere on Persistence and Virulence Expression of Escherichia coli O157:H7 on Shredded Lettuce.” Dr. Sharma showed that the packaging atmospheres of fresh-cut lettuce may affect the ability of E. coli O157:H7 to cause illness. Scott Moosekian, a graduate student at Michigan State University, discussed his work on the “Inactivation of Escherichia coli O157:H7 on Spinach and Parsley Using Low-energy x-ray Irradiation.” Results indicate low-energy x-ray irradiation could be an effective method for inactivating E. coli O157:H7 on spinach and parsley. “Inactivation of Salmonella on Tomato Surfaces Using Gaseous Chlorine Dioxide Treatment” was presented by Bassam Annous from the USDA-ARS-ERRC. Results showed that gaseous ClO2 treatment was effective at reducing Salmonella on tomatoes.

T5 — Meat and Poultry Claudia Bravo and Iryna Sybirtseva
Amit Morey, Auburn University, talked about growth patterns of S. Typhimurium and Heidelberg in BHI, non-sterile chicken slurry (CS) and on chicken carcasses stored for 6 days at various temperatures. There was no difference in Salmonella populations in BHI and CS over a storage period at all temperatures. An increase in Salmonella count was observed only when carcasses were stored at 10°C. Tim B. Mohr, USDA-FSIS, analyzed ALLRTE and RTE001 sampling programs (2005—2008) for Salmonella species. Results showed low incidence (0—0.13%) of Salmonella samples with use of both programs. Michael Musgrove, USDA-ARS, discussed Salmonella isolated from the shell egg processing environment, showing that improvements can be made with sanitation. Wash tanks and drains are the major reservoirs, and more effective sanitation is needed for washing equipment and eggs. Vania Ferreira, Escola Superior de Biotecnologia, CBQF, discussed the incidence (60%) of persistent and sporadic L. monocytogenes strains in a Portugal fermented meat sausage facility, related to phage resistance; no significant association of strain persistence to lysogenicity was found.

Shiowshun Sheen, USDA-ARS, characterized the behavior of chlorine-exposed L. monocytogenes on RTE meat products stored at 4, 8, and 16°C. The growth rate of the pathogen increased with an increase in temperature and decreased with an increase in chlorine level. Kristina Barlow, USDA-FSIS, presented a comparison of data from FSIS routine (RLm) and intensified sampling programs (IVT) for L. monocytogenes in RTE establishments. Positives percentages were higher for IVT programs than RLm programs. FSIS uses both sampling results to identify cross-contamination and protect public health. Kevin Church, Microbial-Vac Systems, Inc., discussed the performance of the M-Vac method compared with methods using cellulose sponges. The device was successfully in recovering bacteria from the meat surfaces and may reduce the risk of spreading contamination. Michael de la Zerda, IEH Labotarories, compared excision n60 pieces, surface sampling (SS) and core drilling (CD). SS recovered more microorganisms than core drilling and n60, the last two sampling methods being similar. Jeef Bussey, Bureau of Microbial Hazards, showed data on C. difficile prevalence in ground meat (n = 368): veal, beef, pork, lamb and chicken. The highest prevalence was 7.5% in ground chicken and 22% in ground lamb. 11 of 12 isolates were toxigenic. Anthonic Pavic, University of New South Wales, discussed data on Salmonella vaccines; results showed that the vaccine decreased overall flock prevalence of Salmonella and that S. Typhimirium is titre dependant. Also, maternal antibody transfer offers moderate protection to the chicks, and extracted IgY is not harmful to chicks. Jeremy W. Chenu, University of New South Wales, explained the difficulty in recovering spiked C. jejuni from chick paper under hatchery incubation conditions. Results indicated that C. jejuni became uncultarable as the paper dried. The cells survive under modified atmosphere, as in humidity hatchery incubators C. jejuni, where persistence was shown. Wendy Lauer, Bio-Rad Laboratories, closed the session with an overview about DNA extraction with the iQ PCR kit. The study was a modified DNA extraction protocol indicated by AOAC approved kit. Results showed a good performance of the kits.

T6 — Produce and Communication Outreach and Education Helen Barela and Brita Ball
“Pathogen Presence and Indicator Organism Levels during Turned Pile Composting of Broiler Litter and Aerated, Static Pile Composting of Mixed Feedstocks” was presented by A. Adhikari, A. Bary, C. Cogger and K. Killinger, Washington State U, Pullman, WA. Active composting decreases indicator organism and pathogen counts. Composting to PFRP requirements does not prevent pathogen presence in the compost. “Produce Microbial Quality is Associated with Surface Microbial Contamination in Packing Sheds: An Assessment of Risk Factors for Produce Contamination,” was discussed by J. Leon, E. C. Ailles, K. A. Etienne, L. M. Johnston, L. A. Jaykus and C. L. Moe, Emory U, Atlanta, GA. Microbial levels in produce increase from farm to packing shed/box. Indicator organisms presence on equipment are associated with microbial levels on produce. NOVEMBER 2010 | FOOD PROTECTION TRENDS

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Food Protection Trends - November 2010

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