Effect of Pulsed Light Treatment for the Preservation of Coconut Inflorescence Sap

The present study aims to investigate the impact of pulsed light (PL) treatment on the preservation of coconut inflorescence sap. In order to avoid fermentation of the sap, the freshly collected sap was exposed to various PL process parameters such as the input voltage, which is supplied to the lamp from 500 to 1500 V; the exposure time for treatment ranges from 60 to 180 s; and the distance of the lamp to the treatment chamber, which is selected from 50 to 150 mm. Using Box-Behnken design, the process parameters, such as 1000 V of input voltage, 100 mm of distance and a treatment time of 120 s were optimised based on the physico-chemical and microbial properties. Maximum log reduction of 3.57 log cfu/ml in total plate count and 2.79 log cfu/ml in yeast and mould were observed at the optimum condition. The quality parameters, such as pH and TSS do not have significant effect (p < 0.05) over the treatment. The colour difference value (Delta E) was 0.92, which is mildly noticeable, whereas the turbidity reduced to 42%, total sugars to 6.34% and reducing sugar reduced to 13.58%, with a significant effect (p < 0.05) over the PL treatment. From the results obtained, it was determined that pulsed light technology might be used as a preservation approach for coconut sap with the minimum effect on its quality parameters.