Dairy, Food and Environmental Sanitation

Abstracts - September, 2001

Delamination in High Density Polyethylene Surfaces and the Influence of Multilayered Upper Surfaces on the Deterioration Process

The Relationship between Standard Plate Counts and Coliform Counts
in Raw Milk

Food Safety in Arizona: An Update

Delamination in High Density Polyethylene Surfaces and the Influence of Multilayered Upper Surfaces on the Deterioration Process

Ricky P. Kane,1 Paul D. Hildebrand,2 Paula Allan Wojtas,2 and Joellen M. Feirtag3*
1-Canadian Food Inspection Agency, Box 670, Kentville, Nova Scotia B4N 3X9, Canada;
2-Agriculture & Agri-Food Canada, Atlantic Food and Horticulture Research Centre,
3-2 Main St., Kentville, Nova Scotia B4N 3X9, Canada; and 3Department of Food Science
and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, MN 55108

SUMMARY
Polyethylene, a thermoplastic discovered in 1933, is widely used in a variety of food equipment contact surfaces. Polyethylene has been shown to break down rapidly on the contact interface through a delamination mechanism. Previous observations of in-use samples indicate that delamination after the initial surface incision is an important factor in food contact surface deterioration. This deterioration can lead to a food safety risk, because it may not be possible to clean and sanitize such a surface completely. The molecular structure of polyethylene is a regular oriented crystal lattice, but if the molecules lose energy quickly during molding, the interconnected lattice does not form to the required degree. The reason for the deterioration pattern observed might be directly tied the molecular configuration of the crystal matrix. The objectives of this study were to (i) search for the presence of multilayered structures in the contact interfaces of polyethylene surfaces that may be contributing to rapid deteriorative changes of surface structures, (ii) evaluate the effects of various cleaning procedures following initial knife cuts into the upper surface layers, and (iii) compare samples to a refurbished sample (from which outer layers had been removed) to gain insight into the influence of multilayered structures on surface delamination. Understanding and verifying the link between the delamination phenomenon and the multilayered appearance of upper surface layers allow the control of deterioration by refurbishing the plastic links before use. These results could contribute significantly to food safety analysis of plastic food contact surfaces.

The Relationship between Standard Plate Counts and Coliform Counts
in Raw Milk
Michael Costello, Richard H. Dougherty, and Dong-Hyun Kang,*
Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6376

SUMMARY
The Standard Plate Counts (SPC) and coliform counts of 200 raw milk samples were determined. Analysis of the results showed an association between the SPC and the coliform counts. The relationship between SPC and coliform numbers was highly correlated (y= 0.864 ¥ + 2.374; y= log CFU/ml for SPC and ¥ = log CFU/ml for coliforms; r = 0.82). SPC numbers were classified into five categories; SPC class 1 (log CFU/ml < 2), class 2 (log CFU/ml ≥ 2 and < 3), class 3 (log CFU/ml ≥ 3 and < 4), class 4 (log CFU/ml ≥ 4 and < 5), and class 5 (log CFU/ml ≥ 5 and < 6). The average coliform counts were 0.0, 0.69, 1.17, 1.88, and 2.73 log CFU/ml in SPC class 1, 2, 3, 4, and 5, respectively. There was strong agreement between SPC classes and average coliform numbers. These data suggest that it is possible to estimate coliform counts based on SPC of raw milk.

Food Safety in Arizona: An Update
Ralph Meer,1* Scottie Misner1, and Mary Meer2
1-Department of Nutritional Sciences, University of Arizona, 309 Shantz Bldg., Tucson, AZ 85721; 2-Department of Support Services, University Medical Center, Tucson, AZ 85724

SUMMARY
In Arizona, the Department of Health Services, in conjunction with 15 county health departments, operates sanitation programs that cover food, bottled water, hotels and motels, trailer parks, children’s camps, public schools, and swimming pool maintenance. In 2000, food facilities represented two-thirds of all regulated facilities. The number of food establishments increased 10% over the previous year, with 70,000 inspections being conducted at more than 30,000 food establishments. An enforcement action to achieve regulatory compliance was required at only 1.5% of establishments, a reduction of approximately 40% from the previous year. The proposed Arizona Food Code 2000, a modified version of the FDA’s 1999 Model Code, will go into effect in October 2001. The new Arizona Code will not allow direct bare hand contact with ready-to-eat foods except for washing raw produce or when otherwise approved, and Arizona’s requirement for hot holding food will be 130°F. From the limited data available (1998 and 1999), the incidence of confirmed cases of illness due to selected pathogens appears to have declined, with the exception of campylobacteriosis in Arizona and salmonellosis at the FoodNet sites. Information on lab-confirmed cases of foodborne illness outbreaks in Arizona (1998 through 2000) indicates that the only fatalities observed were associated with listeriosis.