Physicochemical Characteristics of Coffea liberica Cascara Kombucha: Effects of Sugar Concentration and Fermentation Duration
Keysha Lathifiah Az Zahra, Tunjung Mahatmanto*, Wenny Bekti Sunarharum, Indria Purwantiningrum

Department of Food Science and Biotechnology
Faculty of Agricultural Technology, Universitas Brawijaya
Jalan Veteran, Malang 65145, Jawa Timur, Indonesia
*Email: tjmahatmanto[at]ub.ac.id

Abstract

Cascara, the dried skin of coffee cherries, represents up to 18% of the total mass of coffee cherries and is often discarded despite being rich in bioactive compounds such as flavonoids, chlorogenic acid, caffeic acid, and caffeine. While its use in tea infusions is growing, limited studies have explored its application in fermented probiotic beverages such as kombucha. Here, we studied the effects of different sugar concentrations and fermentation durations on the physicochemical characteristics of kombucha from the cascara of liberica coffee. Using a factorial randomized block design, the kombucha was prepared with 1% (w/v) cascara and 10% (v/v) starter, then analyzed for pH, total acidity, total sugar, alcohol content, and antioxidant activity. Statistical analysis showed that both factors significantly influenced all parameters. Longer fermentation and higher sugar concentration increased total acidity, alcohol content, and antioxidant activity, while lowering pH and total sugar. These results indicate that sugar concentration and fermentation time can be optimized for desirable acidity, sweetness, and functional benefits of cascara kombucha. The development of cascara-based products offers a strategy to valorize waste in the coffee industry, supporting both environmental sustainability and specialty market diversification.

Keywords: cascara- Coffea liberica- kombucha- waste valorization

Topic: Food science and biotechnology