Growth kinetics of Salmonella spp. pre- and post-thermal treatment

• Published in: International journal of food microbiology 2006-05, Vol.109 (1), p.54-59
• Main Authors: Juneja, Vijay K., Marks, Harry M.
• Format: Article
• Language: English
• Subjects: bacterial contamination; Biological and medical sciences; Colony Count, Microbial; culture media; Exponential growth rates; food contamination; Food industries; Food Microbiology; food pathogens; food preservation; Fundamental and applied biological sciences. Psychology; heat tolerance; heat treatment; Hot Temperature; inactivation temperature; Kinetics; Lag phase; mathematical models; microbial growth; Models, Biological; pathogen survival; plate count; predictive microbiology; Salmonella; Salmonella - growth & development; Salmonella typhimurium; serotypes; Serotyping; viability
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2006.01.009

This paper reports estimated growth kinetic parameters for a cocktail of stationary phase Salmonella serotypes, pre- and post-thermal inactivation treatment. Cells were grown in brain–heart infusion broth at 25 or 37 °C and then destruction of the cells was quantified at 55 °C using a submerged coil heating apparatus. The surviving cells (about 1–2 log 10 cfu/ml) were subsequently grown at 25 or 37 °C. The results indicated that lag phase duration times for the post- heat treated cells increased at 25 and 37 °C by about 6.2 h and at least 3 to 4 h, respectively, and thus the increases appear to be truly different. However, when considering the ratios of the lag phase duration times for post-treated to pre-treated cells, a significant difference was not found, where estimated ratios could exceed 4. Estimated exponential growth rates, EGR, were not affected by the treatment, where for 37 °C, EGR was estimated to be 0.9 log 10 (cfu/ml)/h, and at 25 °C, the EGR was estimated at 0.45 log 10 (cfu/ml)/h.