Food Protection Trends

Abstracts - August 2005

Irrigation Treatments and the Presence of Escherichia coli on Ontario Field Strawberries

Secret Shopper: Grocery Store Employee Food Handling Practices from a Customer’s Perspective

Microflora Isolated from Mexican Mennonite-style Cheeses

Irrigation Treatments and the Presence of Escherichia coli on Ontario Field Strawberries

TING ZHOU1, ROBIN MCKELLAR,* SANDRA JONES,2 PAM FISHER,2 HONGDE ZHOU,3 KELLEY KNIGHT,1and XIU-ZHEN LI1

Food Research Program, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, Ontario, Canada N1G 5C91, Ontario Ministry of Food,2 School of Engineering, University of Guelph,3 Guelph, Ontario, Canada

SUMMARY
Consumer demand for fresh and minimally-processed fruits and vegetables is increasing. Outbreaks of foodborne illness have been attributed to these products, and in some cases irrigation practices have been implicated in the transfer of pathogens
from contaminated water to the crop. We therefore examined the influence of irrigation methods and water quality on the incidence of Escherichia coli on Ontario-grown strawberries. Three irrigation methods were investigated: trickle irrigation with well water, trickle irrigation with surface water, and overhead irrigation with surface water. Both strawberry and water samples were taken from at least 5 producers for each irrigation system at early, middle and late periods in the harvesting season. E. coli was present in approximately half of the surface water samples at levels of 0.07–2.45 log cfu 100 ml-1, although, E. coli was not found on fruit treated with surface water. E. coli (1.17–2.64 log cfu g-1) was found on three samples of fruit that had been irrigated with well or municipal water. Irrigation water generally met the revised 2002 Canadian Water Quality Guidelines (maximum of 100 E. coli per 100 ml). Overhead irrigation with surface water does not seem to result in transfer of E. coli to berries; however, further experimentation is warranted.

Secret Shopper: Grocery Store Employee Food Handling Practices from a Customer’s Perspective

Lisa Mathiasen and Douglas Powell1

University of Guelph, Food Safety Network, Guelph, ON N1G 2W1, Canada

SUMMARY
Food safety is critical along the entire agri-food chain, but it should be emphasized particularly in grocery stores because this may be the last opportunity to prevent food from becoming contaminated before it is purchased. The responsibility for safe food handling has increased for the newer North American supermarkets, which offer a variety of additional food services and products. This research reports on food handling trends discovered by observing the food handling practices of grocery store employees and by inquiring about specific food safety -related topics in supermarkets across southern Ontario. Ten researchers, trained to portray customers, visited 13 randomly selected supermarkets in Southern Ontario, three times. Observations and information were evaluated against the content of supermarket training programs and current literature. The triangulation of results was used to establish and confirm the observed trends. During the store visits, a number of poor food handling practices were observed including improper glove use; cross contamination between raw and ready-to-eat meats and poultry; improper food storage; and poor personal hygiene. In addition, although many grocery store employees appeared confident in their food safety knowledge, when asked for storage and handling advice, many were unaware of the proper methods within their department and were willing to offer incorrect advice. This advice often conflicted with the food handling information posted throughout the grocery store. This research highlights the need for more interactive training specific to individual departments within a supermarket, and will help in the improvement of training resources for grocery store food handlers.

Microflora Isolated from Mexican Mennonite-style Cheeses

Angela L. Bricker,*1 Diane L. Van Hekken,1 Victor M. Guerrero,2 and Alfonso A. Gardea2

1United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038; 2Centro de Investigación en Alimentación y Desarrollo, A.C. CIAD, Unidad Cuauhtémoc, Av. Río Conchos s/n, Parque Industrial, Apartado Postal 781, 31570 Cd. Cuauhtémoc, Chihuahua, México

SUMMARY
Microflora isolated from 10 freshly manufactured Mexican Mennonite-style cheese samples were compared to assess the relative importance of various types of bacteria in the manufacture of the cheese. Eight of the commercially manufactured samples were made from raw milk, while two were made from pasteurized milk inoculated with mixed commercial starter cultures. Generally, coliforms, enterococci, and coagulase-positive staphylococci were present in raw milk cheeses but not in pasteurized milk cheeses. Levels of mesophilic and thermophilic lactococci did not differ greatly between the two groups, being present at relatively high levels (106–108 colony forming units per gram) in all samples. Thermophilic lactobacilli were slightly less prevalent in pasteurized milk cheeses (1–1.5 log10 fewer bacteria), while levels of mesophilic lactobacilli and Leuconostoc spp., as well as non-Lactobacillus mesophiles, were significantly lower in a single pasteurized sample (4–5 log10 reductions). This survey of the groups of bacteria present in Mennonite-style cheeses demonstrated the variety of microflora that may be found even in a single type of cheese. The distinction between raw milk and pasteurized milk cheeses, as well as between the two pasteurized milk cheeses, demonstrates the potential for using pasteurized milk to produce typical Mennonite-style cheese with a greatly lowered bacterial content.