Modelling the inactivation kinetics of Leuconostoc mesenteroides, Saccharomyces cerevisiae and total coliforms during ozone treatment of sugarcane juice

Abstract

The efficacy of ozone treatment against Leuconostoc mesenteroides (LM), Saccharomyces cerevisiae (SC) and total coliforms (TC) was investigated. The effects of three ozone doses per unit volume (ODV), 0.12, 0.28 and 0.45 mg/min ml on microbial disinfection were studied. At the end of treatment (50 min), maximum reductions of LM (2.8 log), SC (2.18 log) and TC (3.4 log) were achieved with ODV of 0.45 mg/min ml. Various non-linear models, viz., Weibull+tail, Coroller, Geeraerd, Cerf, modified Gompertz and log-logistic were attempted to elucidate inactivation kinetics of microorganisms. The microbial tailing behaviour was well described by model parameters, like, tailing ratio, residual population and minimum cell concentration. The sensitive and resistant fractions of microbial population were characterized by the estimated scale parameter and destruction rate constants. Statistical measurements (adjR²: 0.97–0.999) and validation indices (accuracy factor: 1.02–1.27, bias factor: 0.965–1.25) indicated satisfactory performance of all models. The Akaike's theory was employed for model selection. Coroller model was identified as the most accurate model for LM and TC showing the lowest Akaike increment in 71.82% and 54.67% of the inactivation curves, respectively. Log-logistic model was selected as the best-fit model for SC owing to its reliability in describing 81.37% of their survival curves.