Optimizing Fruit-based Kombucha: The Effect of Substrate Type and Sugar Concentration on Physicochemical Characteristics and Sensory Acceptability

Abstract

Kombucha, a fermented beverage synthesized by Symbiotic Culture Of Bacteria and Yeast (SCOBY), is gaining traction in the circular bioeconomy for its potential to valorize agricultural by-products into sustainable functional foods. However, research on optimizing the fermentation efficiency and sensory properties of fruit-based substrates with varying concentrations of sugars remains limited. This study evaluated the physicochemical properties and sensory acceptability of kombucha from apple and pineapple substrates at 5% and 8% (w/v) initial sugar concentrations. Following a 7-day fermentation period under isothermal ambient conditions, samples were analyzed for potentiometric pH, soluble solids (°Brix), CIELAB color, and sensory liking (n=45) on a 9-point hedonic scale. All samples achieved optimal pH (2.8–3.0), effectively inhibiting pathogen growth. The 5% sugar variants are showed faster °Brix decline, indicative of efficient fermentation. Pineapple kombucha at 5% sugar scored highest in overall liking (6.20 ± 1.74), outperforming other substrates. These findings confirm that fruit-based kombucha is a microbiologically stable functional beverage, with a 5% sugar concentration in pineapple substrates optimizing both the synergy between bioprocess efficiency and palatability.