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M. GAENZLE, Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag / For Centre, Edmonton, AB T6G 2P5, Canada The use of high hydrostatic pressure for food preservation offers the possibility to reduce the energy requirement for food processing and enables the inactivation of bacterial endospores, microorganisms and enzymes while affecting food quality to a lesser extent than conventional heat treatments. Pressure at ambient temperature (<50° C) in the range of 400 to 800 MPa eliminates vegetative bacteria. The inactivation of bacterial endospores requires a combination of pressure with moderate heat. Commercial applications of pressure processes to achieve commercial sterility are currently hampered by the lack of data concerning the inactivation of Clostridium botulinum endospores (1). We compared the spore resistance of 7 C. botulinum strains to that of 20 strains of Bacillus ssp. and Thermoanaerobacterium thermosaccharolyticum with respect to treatments with pressure and temperature in the range of 600 to 800 MPa and 80 to 116° C in mashed carrots. A large variation was observed in the pressure resistance of spores and their reduction by treatments with 800 MPa/70° C for 4 min ranged from more than 6 log to no reduction. Spores C. botulinum TMW 2.357 were more resistant than spores from all other strains with the exception of B. amyloliquefaciens. Inactivation of these spores by 5 log required 800 MPa and >100° C. The heat resistance of spores did not correlate with the pressure resistance, neither within strains of C. botulinum nor when C. botulinum spores were compared to spores of Bacillus ssp. or T. thermosaccharolyticum. B. amyloliquefaciens TMW 2.479, which forms highly pressure resistant spores, is proposed as a non pathogenic target organism for pressure processes.
Session 9, Mechanisms and modeling of bacterial spore inactivation by high pressure processing
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |