HEAT RESISTANCE OF G. STEAROTHERMOPHILUS AND C. SPOROGENES IN CARROT AND MEAT ALGINATE PUREES HUSSEIN F. HASSAN and HOSAHALLI S. RAMASWAMY 1 Department of Food Science and Agricultural Chemistry, McGill University, Macdonald Campus, 21111 Lakeshore Road, Ste Anne de Bellevue, Quebec H9X 3V9, Canada 1 Corresponding author. TEL: 514-398-7919; FAX: 514-398-7977; EMAIL: hosahalli.ramaswamy@mcgill.ca Accepted for Publication October 1, 2010 doi:10.1111/j.1745-4549.2011.00519.x ABSTRACT The main objective of this study was to investigate the heat resistance of nonpatho- genic, heat-resistant Geobacillus stearothermophilus and Clostridium sporogenes spores in meat and carrot alginate purees. Alginate is used as a viscosity modifier in liquid foods and has been used to fabricate thermally stable and firm simulated par- ticles for biological validation studies of thermal processing, when conventional temperature gathering is not possible. Pureed carrot and meat were mixed with sodium alginate and inoculated with high concentrations of spores of G. stearother- mophilus or C. sporogenes and filled into capillary tubes, flame sealed and heat treated in an oil bath for different times at selected temperatures. D values were computed from the slopes of log(N/N0) versus time, and z values from log(D) versus tempera- ture curves. For meat alginates, D values for G. stearothermophilus ranged between 1.9 min and 40.8 min with a z value of 11.7C and D values for C. sporogenes ranged between 0.9 min and 28.7 min with a z value of 10.1C. For carrot alginates, D values for G. stearothermophilus ranged between 1.9 min and 42.6 min with a z value of 11.5C and D values for C. sporogenes ranged from 1.1 min and 31.0 min with a z value of 10.2C. The results were also fitted to Weibull model, but the model did not result in any better fit than the conventional first-order model. PRACTICAL APPLICATIONS Thermal process establishment is generally based on gathered time temperature data from test cans under real processing conditions.There are many situation like aseptic processing, continuous flow biaxial rotary processing, etc. in which such tempera- ture measurements are often difficult. Biological validation is generally considered useful in such processes to validate the processes as well as computer simulations. Such concepts have been tried to some limited extent in the past. With new thermal processing equipment and processes surfacing time and again, such concepts need to be redesigned. In order to successfully use such applications, thermal destruction kinetics data under controlled conditions are needed. This study provides thermal destruction kinetics baseline data for one such study making use of alginate- impregnated meat and carrot-simulated particles. Further, the study compare two modeling procedures: the conventional first-order log-linear model versus the log- nonlinear Weibull models. INTRODUCTION Thermal processing is a traditional, yet among the most effec- tive, methods to preserve foods. Stumbo (1973) defined thermal processing as “the application of heat for the purpose of shelf life extension and promotion of safety of food.” Destruction of spoilage and pathogenic microorganisms in canned foods, and thus achieving safety and shelf stability, is the main objective of thermal processing (Ramaswamy and Marcotte 2005). The main pathogen of public concern in Journal of Food Processing and Preservation ISSN 1745-4549 376 Journal of Food Processing and Preservation 35 (2011) 376–385 © 2011 Wiley Periodicals, Inc.