title: Combined pressure-thermal inactivation kinetics of Bacillus amyloliquefaciens spores in egg patty mince.
abstract: Bacillus amyloliquefaciens is a potential surrogate for Clostridium botulinum in validation studies involving bacterial spore inactivation by pressure-assisted thermal processing. Spores of B. amyloliquefaciens Fad 82 were inoculated into egg patty mince (approximately 1.4 x 10(8) spores per g), and the product was treated with combinations of pressure (0.1 to 700 MPa) and heat (95 to 121 degrees C) in a custom-made high-pressure kinetic tester. The values for the inactivation kinetic parameter (D), temperature coefficient (zT), and pressure coefficient (zP) were determined with a linear model. Inactivation parameters from the nonlinear Weibull model also were estimated. An increase in process pressure decreased the D-value at 95, 105, and 110 degrees C; however, at 121 degrees C the contribution of pressure to spore lethality was less pronounced. The zP-value increased from 170 MPa at 95 degrees C to 332 MPa at 121 degrees C, suggesting that B. amyloliquefaciens spores became less sensitive to pressure changes at higher temperatures. Similarly, the zT-value increased from 8.2 degrees C at 0.1 MPa to 26.8 degrees C at 700 MPa, indicating that at elevated pressures, the spores were less sensitive to changes in temperature. The nonlinear Weibull model parameter b increased with increasing pressure or temperature and was inversely related to the D-value. Pressure-assisted thermal processing is a potential alternative to thermal processing for producing shelf-stable egg products.
authors.affiliation: Department of Food Science and Technology, Ohio State University, Columbus 43210-1007, USA.
authors.forename: S
authors.initials: S
authors.lastname: Rajan
authors.forename: J
authors.initials: J
authors.lastname: Ahn
authors.forename: V M
authors.initials: VM
authors.lastname: Balasubramaniam
authors.forename: A E
authors.initials: AE
authors.lastname: Yousef
mesh_terms: D001407:Bacillus / Q000502:physiology*; D015169:Colony Count, Microbial; D004531:Eggs / Q000382:microbiology*; D006358:Hot Temperature; D006874:Hydrostatic Pressure; D007700:Kinetics; D016014:Linear Models; D013171:Spores, Bacterial / Q000254:growth & development