Pasteurization of kava juice using novel continuous flow microwave heating technique

This study was aimed to investigate the effect of continuous flow microwave heating on the reduction of microorganisms in kava juice to extend the shelf life. Chemical and microbial properties of treated juices were analyzed using key parameters such as microbial counts, kavalactones, and pectin methylesterase activities. The microbial population was reduced from 3.3×106 to 5×105, 8×103, and 4.5×102 CFU/mL at 41.4, 52.3, and 65.2°C, respectively. The amounts of kavalactones such as kavain (K), demethoxyyangonin (DMY), and yangonin (Y) were kept constant or increased after pasteurization at different treatment temperatures. The effect of microwave heating on the pectin methylesterase activities decreased significantly from 83 to 34% by increasing the temperature values from 41.4 to 65.2°C, enhancing juice cloud stability. The developed pasteurization technique is expected to deliver the adequate lethal effect to the kava juice without major deterioration of food quality.