Current retail food distribution practices, microbial quality of bakery products, and the potential for growth of food borne pathogens (Staphylococcus aureus, Salmonella typhimurium, and Bacillus cereus) were examined using pumpkin pie as a model. The pumpkin pies, as obtained from the retail outlets, showed contamination with food pathogens. The aerobic plate counts reached high numbers (up to 10⁹/g) when stored at 25°C for the specified shelf life as indicated by pull dates. S. aureus was isolated from one sample and B. cereus from two samples of pumpkin pie. Baking conditions were sufficient to destroy IS. aureus and Salmonella typhimurium but not spores of B. cereus. The presence of S. aureus indicated post-processing contamination. When inoculated with S. aureus, Salmonella typhimurium and B. cereus, pumpkin pie supported the growth of all these organisms when stored at 25°C. When stored at severe abuse conditions (35°C), pumpkin pie supported the growth of S. aureus and Salmonella typhimurium but not B. cereus. Refrigeration at 4°C controlled the growth of the pathogens studied. The addition of 0.25% potassium sorbate to the pie filling inhibited the growth of Salmonella typhimurium and B. cereus but not S. aureus at 25°C. The findings of this study indicated a lack of knowledge regarding safe food handling practices among bakers. Current distribution practices indicated that pumpkin pies were often displayed at room temperature from two to five days. If contaminated, the product could become a public health hazard. / Graduation date: 1981

Published Article / The genus Chryseobacterium is often found in food and is regarded as a food spoilage organism. In this study, the source of the chryseobacteria was uncertain. As an exploratory investigation, the potential source of chryseobacterial contamination was determined. Total bacteria counts and yellow-pigmented colony counts were performed. Chryseobacterium species were present on poultry carcasses at all stages of processing. Total Chryseobacterium counts increased from 5.6 to 11.8 % after the brine injection stage. A significant increase in total Chryseobacterium counts (20.0 and 25.2 %) in the processing waters occurred where cutting up of the carcasses was involved. It is speculated that live chickens are the source of contamination.

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Because Mexican foods have been implicated in a number of outbreaks of foodborne illness in the United States, production procedures used in Mexican restaurants were investigated by interviewing four managers. Two major problems identified through these interviews were failure to cool large quantities of beans rapidly and failure to reheat beans thoroughly before placement on the steam table. Experiments were designed to study the effects of varying temperatures, duration of incubation, and the location in the product as it might affect aeration on growth of B. cereus and C. perfringens, singly and combined, in cooked mashed pinto beans. Growth of both B. cereus and C. perfringens was rapid at 37°C, with numbers of cells associated with illness reached in 4 and 6 hours, respectively. B. cereus may present more of a health hazard, since obvious signs of spoilage did not occur in these beans until 12 hours, whereas C. perfringens caused obvious spoilage of beans within 6 to 8 hours. At 23°C with B. cereus, the numbers associated with illness were found at 12 hours. However, the beans appeared to be spoiled before this level was reached with C. perfringens at 24 hours. Aeration, as indicated by location in the jar, appeared to have more of an effect on B. cereus growth than on C. perfringens, but good growth of the two species occurred in both top and bottom locations. Restaurant samples of bean dip and mashed beans were analyzed for contamination with B. cereus and C. perfringens. Total aerobic and anaerobic counts were determined. Only two of the 42 samples were found to contain B. cereus or C. perfringens and these were present in low numbers. The total aerobic and anaerobic counts varied from less than 100 to 100,000,000 per gram: chiefly lactic acid bacteria which appeared to be related to the seasoning ingredients. However, one batch of bean dip and one of mashed beans were found to contain large numbers of coagulase-positive S. aureus (>100,000/g). / Graduation date: 1982

Thesis (M.S.) in Food Science and Human Nutrition--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 146-178).

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Graduation date: 1972