IAFP 2009 Program Book and Abstract Book - AB181

P3-88 Cold Tolerance of Clostridium perfringens Induced by GRAS Substances Norma L. Heredia, SANTOS GARCIA and Julio Limon Universidad A. De Nuevo Leon, San Nicolas, South Introduction: C. perfringens is an anaerobic, spore-forming foodborne pathogen that occurs in a variety of foods. Symptoms associated with poisoning are caused by Clostridium perfringens enterotoxin (CPE) that is expressed during sporulation of enterotoxigenic strains (Heredia and Labbé 2001). Physical and chemical treatments are used in food processing to eliminate or reduce the presence of pathogens and spoilage microorganisms. Sodium benzoate and potassium sorbate are GRAS (Generally Recognized As Safe) substances and are commonly used as preservatives (USFDA 2003). Purpose: In this work we investigate the effect of GRAS substances on cold tolerance of strains of Clostridium perfringens. Methods: Maximal concentrations recommended for foods of sodium benzoate, potassium sorbate, sodium nitrite, monosodium glutamate, or mixtures of those were added to cultures, and their effect on C. perfringens tolerance to 10°C was evaluated. The effect of a previous shock at 28°C was also determined. Results: Growth of C. perfringens was not inhibited by the substances examined. Sodium nitrite, applied at maximal permitted concentrations, increased C. perfringens survival at 10°C. Mixtures of GRAS compounds either had no clear effect or caused an increase of tolerance to 10°C. A pre-shock (28°C) of the cultures treated with sodium benzoate, sodium nitrite or monosodium glutamate increased survival and stimulated growth of the cultures treated at 10°C. Significance: We conclude that the addition of GRAS substances, including sodium benzoate, potassium sorbate, sodium nitrite, and monosodium glutamate, to cultures of C. perfringens can influence their cold tolerance. In some cases, these substances that would normally eliminate microorganisms can increase tolerance, permitting survival at low temperatures. The acquired cold tolerance of C. perfringens by these preservatives could represent a significant hazard. P3-89 Effects of Temperature and pH on the Thermal Inactivation of Bacillus pumilus, B. licheniformis, B. subtilis and B. megaterium JOY E. GAZE and Andres Rodriguez-Lozano Campden BRI, Microbiology, Chipping Campden, United Kingdom Introduction: Bacillus pumilus, B. licheniformis, B. subtilis, and B. megaterium have been traditionally associated with the spoilage of food products; however, more recently there has been an increased concern for the potential food safety implications associated with these species. Purpose: The purpose of this study was to obtain heat resistance data relevant to food pasteurization regimes and to model the effects of temperatures and pH on the survival of the spores of these four bacilli. Methods: A surface response design was used to determine the thermal resistance across a range of temperature (93 to 107°C) and pH (3.6 to 6.4). The results were analyzed using Minitab 15 Statistical Software and a predictive model for each of the four Bacillus species studied was proposed. Results: When these sets of data are compared, the results show a consistent decrease in the D value with decrease in pH. For example, the D values for the four species heated at 95°C at a pH of 6 were 4.56, 3.51, 8.60, and 5.70 compared with 1.30, 2.20, 2.39, and 1.02 at pH 4 for Bacillus pumilus, B. licheniformis, B. megaterium and B. subtilis, respectively. When the log of D was plotted against temperature and pH, the models were able to predict thermal death of 91, 89, 94 and 94% for B. pumilus, B. licheniformis, B. megaterium and B. subtilis, respectively. For B. pumilus, a linear relationship was seen for log D versus pH and temperature. For B. megaterium, B. subtilis and B. licheniformis, the pH showed a quadratic effect. An interaction with pH and temperature was seen for B. megaterium and B. subtilis. Significance: Readjusting the processing parameters by increasing the temperature or reducing the product pH will allow a reduction in the number of these food spoilage and potential pathogenic organisms surviving in the final product. P3-90 Time-temperature Profiling Associated with Preparation and Storage of Powdered Infant Formula: Implications for Microbial Safety ELIZABETH C. REDMOND and Christopher J. Griffith University of Wales Institute Cardiff, Cardiff School of Health Sciences, Cardiff, United Kingdom Introduction: Powdered infant formula (PIF) is not sterile and UK recommendations are that powdered infant feeds are reconstituted using boiled water > 70°C (cooled for 30 min). If it is not possible to reconstitute feeds immediately before use, made-up feeds should be refrigerated and transported in a cool bag for 4 h were recorded using miniature dataloggers (accuracy ± 0.5°C). Initial temperatures of feeds ranged from 70°C. Microbial counts of feeds reconstituted with this water were 4 h was conducive for microbial growth. No Enterobacteriaceae or S. aureus were isolated. Abstract Book — 181 Poster

IAFP 2009 Program Book and Abstract Book

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