Microbial and Chemical Changes during Fermentation of Coconut Water Kefir Beverage

Abstract

This study investigated changes in the microbial growth and chemical characteristics of coconut water kefir (CWK) during fermentation. The carbohydrate profile, in terms of glucose and sucrose consumption, production of carboxylic acids, and changes in amino acid profile, was determined during CWK fermentation over a period of 96 h. The results showed that the kefir grains were able to utilise both glucose and sucrose and produce significant quantities of carboxylic acids after 96 h of fermentation. The total titratable acidity significantly increased throughout 96 h of incubation at 30 °C, which correlated to a significant drop in pH to 2.8 for CWK supplemented with 12 g/L of sucrose. In addition, this was accompanied by a significant increase in lactic acid, acetic acid, and pyruvic acid. During fermentation, a total of eighteen amino acids were generated, with a notable decline observed across all amino acids. Among them, glutamic acid exhibited a higher concentration compared to the other amino acids. The Scanning Electron Microscope (SEM) results confirmed a higher density of lactic acid bacteria (LAB) and acetic acid bacteria (AAB), with fewer yeast cells through morphological identification. Overall, the findings support the notion that coconut water fermented with kefir could be used as a potential functional starter to produce other fermented food products or a refreshing beverage.