RESUMEN
Pumpkin pies were sampled and screened for presence of Bacillus cereus . Pies were obtained from a cross-section of distribution outlets including: two major chain supermarkets, an independently owned supermarket with in-store bakery and a major chain supermarket that distributes products baked at a central distribution center. Water activity (aw) and pH were determined on each sample. B. cereus was isolated on KG agar incubated at 30 C for 24 h. Intraperitoneal injections in mice were used to determine pathogenicity of the isolates. Pumpkin pies inoculated with B. cereus were incubated at 4, 25 or 35 C. B. cereus grew well at 25 C. D-values in minutes for B. cereus in pumpkin pie were 40 at 100 C, 10.5 at 108 C, and 7 at 124 C. Under normal baking conditions, the internal temperature of the pie reaches 108 C for approximately 1 min. Therefore it appears that the spores would survive baking. Potassium sorbate (0.25%) or refrigeration temperature inhibited growth of B. cereus .
RESUMEN
The ability of pumpkin pies as prepared and distributed in the food distribution system to support growth of selected food pathogens was studied. Products were puchased from a cross-section of retail outlets. Microbial quality of the products was determined. One of four samples contained high levels of coliforms and Staphylococcus aureus . Salmonella was not detected in any of the samples. Samples were inoculated with Salmonella typhimurium and S. aureus and incubated at 4, 25 and 35 C. Water activity (aw), pH and S. aureus enterotoxin were measured. Pumpkin pies supported growth of the pathogens at 25 and 35 C. Data revealed if contaminated and held at room temperature, pumpkin pies could present a public health hazard. Growth of pathogens is inhibited at refrigeration temperatures. Enterotoxin was present in samples containing S. aureus . Potassium sorbate (0.25%) inhibited growth of S. typhimurium but not S. aureus . Refrigeration is recommended for pumpkin pies to eliminate the possible health hazard.