Flux evaluation based on fouling mechanism in acoustic field-assisted ultrafiltration for cold sterilization of tender coconut water

Membrane-based processing was attempted as a clean, green and energy-efficient method for cold sterilization of tender coconut water (TCW). Ultrafiltration of TCW was carried out at four different pressures employing two different polyethersulfone membranes, using a stirred cell. Permeate flux was evaluated based on different fouling mechanisms which are analysed employing Hermia's model. The objective of the study was to examine the efficacy of ultrafiltration for cold sterilization of TCW while retaining good sensory quality. The effect of acoustic field (ultrasonication) on the performance of ultrafiltration has been evaluated. Permeate flux increased on the application of ultrasonication. Enzyme activities in TCW permeate were found to reduce after ultrafiltration with good sensorial acceptability. Microbial load of TCW after ultrafiltration was observed to decrease from 4.16 to 0.0 log CFU/mL, achieving cold sterilization. Sensorial quality of ultrafiltered TCW was found to be good after three months storage period with zero microbial count.