Microbiological feasibility of microwave processing of coconut water

Abstract

Thermal processing of coconut water is designed to ensure safety and stability and microwave may be used as an alternative process. This study evaluated the feasibility of microwave processing of acidified green coconut water (pH 4.30–4.50) concerning inactivation of Bacillus coagulans spores with specific power between 115 and 135 W/mL. Four variables were evaluated (temperature, microwave power, amount, and composition of added acids) according to a central composite design with four replicates at the center point. After holding periods of 5, 10, 15 and 20 min, the reduction in spore population was determined. The only significant variable for spore inactivation was the temperature; consequently, the survival curves were described by Weibull model, which was adjusted in a single-step procedure that integrated the time-temperature profile of 112 experiments. The α value (time of the first decimal reduction) at reference temperature of 90 °C was 33.8 s and the z′ value (temperature required for a 10-fold change in α) was 5.06 °C. The reduction in the population of B. coagulans spores and the kinetics parameters suggest that microwave may be used as a viable alternative for coconut water processing.