Non-linear models for microbial inactivation kinetics in kiwifruit juice using cold plasma treatment: the combined impact of applied voltage, juice depth and treatment time

Cold Plasma (CP) is an innovative non-thermal technique that maintains the quality of foods. The kinetics of natural microbiota viz. aerobic mesophiles (AM) and yeasts & molds (YM) were examined within the domain of 18-30 kV, 2-10 mm juice depth, and 0-4 min treatment time. A log reduction of 3.08 and 2.32 was achieved for AM and YM, respectively, at 30 kV/2 mm/4 min. The inactivation kinetics for AM and YM were established using different kinetic models, namely Weibull + tail, Geeraerd, log-logistic, biphasic, and Coroller models. First, the suitability of model was determined according to goodness of fit (Coefficient of determination (R2) and root mean square error (RMSE)) and validation indices (accuracy factor (Af) and bias factor (Bf)). The R2, RMSE, Af, and Bf values for the Weibull + tail, log-logistic, and Coroller models ranged between 0.939 and 0.999, 0.001-0.154, 1.001-1.086, and 0.992-1.024, respectively which were reported to be satisfactory in explaining the inactivation kinetics for AM and YM, respectively. Further, the most appropriate model was selected based on Akaike's theory. The log-logistic model was the best fitting for AM and YM inactivation, showing the least akaike weight in 47.33 and 48.82% of the inactivation curves, respectively. The population of AM and YM were significantly affected by CP voltage, juice depth, and treatment time.The population of AM and YM reduced by 3.08 and 2.32, respectively, after CP treatment.The log-logistic model was best fitted for the AM and YM experimental datasets.The YM was more CP-resistant than AM based on inactivation rate and time in log logistic model.