Combined pressure-thermal inactivation kinetics of Bacillus amyloliquefaciens spores in egg patty mince

• Published in: Journal of food protection Vol. 69; no. 4; pp. 853 - 860
• Main Authors: Rajan, S, Ahn, J, Balasubramaniam, V.M, Yousef, A.E
• Format: Journal Article
• Language: English
• Published: Des Moines, IA International Association of Milk, Food and Environmental Sanitarians 01.04.2006
• Subjects: Bacillus - physiology; Bacillus amyloliquefaciens; bacterial contamination; bacterial spores; Biological and medical sciences; Clostridium botulinum; Colony Count, Microbial; Egg and egg product industries; eggs; Eggs - microbiology; food contamination; Food industries; food pathogens; food processing quality; Fundamental and applied biological sciences. Psychology; heat inactivation; heat treatment; high pressure treatment; Hot Temperature; Hydrostatic Pressure; inactivation temperature; Kinetics; Linear Models; minced foods; nonlinear models; patties; plate count; predictive microbiology; Spores, Bacterial - growth & development; Bacillales; Egg; Egg product; Bacteria; Bacillus amyloliquefaciens; Kinetics; Bacillaceae; Inactivation; Pressure; Spores
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028x-69.4.853

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 (z(T)), and pressure coefficient (z(P)) 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 z(P)-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 z(T)-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.