Food Protection Trends

Abstracts - June 2005

Incidence of Listeria and Listeria monocytogenes on Processed Aquacultured Channel Catfish Fillets

Evaluation of Thermometers for Measuring the Cooking Temperature of Meat

The Transmission of Surrogate Norwalk Virus – From Inanimate Surfaces to Gloved Hands: Is It a Threat?

Incidence of Listeria and Listeria monocytogenes on Processed Aquacultured Channel Catfish Fillets

STEPHENIE DRAKE and DOUGLAS L. MARSHALL*

Department of Food Science, Nutrition, and Health Promotion, Mississippi Agricultural and Forestry Experiment Station, Mississippi State University, Box 9805, Mississippi State, MS 39762-9805 USA

SUMMARY
Wholesale purchase decisions of aquacultured channel catfish are increasingly relying on microbial testing for the genus Listeria in raw products.The goal of the present work was to determine whether Listeria incidence correlates with Listeria monocytogenes incidence on catfish fillets. A secondary objective was to compare two different methods (biochemical based vs. fatty acid based) for their ability to identify L. monocytogenes. One hundred channel catfish fillets were obtained from a commercial processing facility and 100 fillets were obtained from 4 local retail facilities. The incidence of Listeria species (ELISA method) and Listeria monocytogenes (ELISA plus either a biochemical screen or gas chromatography-fatty acid methyl ester (GC-FAME) analysis) was determined on each fillet. Although the ELISA-Biochemical method had more false positives (5%) L. monocytogenes identifications than the ELISA-GC-FAME method (0%), both methods gave similar incidence levels, 42.5 and 37.5%, respectively. The incidence of Listeria and L. monocytogenes on processing plant fillets (58% and 2%) was lower than on retail fillets (91% and 73%). Genus testing for Listeria was not a reliable indicator for the presence of L. monocytogenes on processing plant sourced fillets.

Evaluation of Thermometers for Measuring the Cooking Temperature of Meat

Denyse I. LeBlanc, 1* Bernadette Goguen, 1 Réjeanne Dallaire, 2 Mary Taylor, 3 Dan Ryan, 4 and Mark Klassen 5

1-Agriculture and Agri-Food Canada, Université de Moncton, Moncton, New Brunswick, Canada E1A 3E9
2-École des sciences des aliments, de nutrition et d’études familiales, Université de Moncton, Moncton, New Brunswick, Canada E1A 3E9
3-Agriculture and Agri-Food Canada, Atlantic Food and Horticulture Research Centre, Kentville, Nova Scotia, Canada B4N 1J5
4-Department of Mathematics and Statistics, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada C1A 4P3
5-Beef Information Centre, 215 – 6715 8th NE, Calgary, Alberta, CanadaT2E 7H7

SUMMARY
Six models of fork thermometers / indicators and six models of digital instant-read probe-style thermometers, available to consumers in Canadian department stores, were evaluated to determine their accuracy in measuring a safe end-point temperature when cooking meat. The study found that both fork and probe-style thermometers are accurate in estimating the cooking temperature of meat, as long as they are properly used.

Fork thermometers that show a doneness level rather than a digital temperature may lead consumers to overcook the meat to ensure that the required temperature has been reached. Also, the temperature range associated with each doneness level varies considerably from one model to another and does not always match the recommended temperatures generally associated with each doneness level. This can lead to confusion. Finally, some models of fork thermometers cannot be easily stored, as their tines are too long or too large, or the device is too long, or the handle is too large.

Digital probe thermometers are suitable for all foods and are easy to read. Because the probe is smaller than the fork thermometer tines, the response time of digital probe-style thermometers is shorter and the temperature readings are more accurate. The fact that they are shorter than the fork thermometers may be a disadvantage when the temperature of meat on the barbeque grill is being measured.

The Transmission of Surrogate Norwalk Virus – From Inanimate Surfaces to Gloved Hands: Is It a Threat?

Daryl S. Paulson *
BioScience Laboratories, Inc., 300 North Willson Ave., Bozeman, MT 59715, USA

SUMMARY
The United States Food Code requires that workers wear gloves while working with ready-to-eat foods. However, it has been observed that those wearing gloves do not always adhere to good hygienic practices (e.g., wearing gloves while counting money, petting animals, and using the bathrooms and not subsequently changing the gloves before contacting food and/or food service utensils). There has been little focus on the transfer of viruses to gloved hands. The objective of this research was to determine the amount of virus transferred from contaminated surfaces to gloved hands. Results from this exploratory work showed that a significant viral load (4 to 5 logs) was transferable.