Changes in the Chemical Compound and Sensory Profiles of Liberica Fermentation (Coffea liberica) with Cellulolytic Bacteria Alcaligenes sp and Exiguobacterium indicum

Abstract

Jambi Province, particularly in Tanjung Jabung Barat Regency, Indonesia, is a crucial producer of Liberica coffee known as Liberika Tungkal Komposit (Libtukom). This variety of Liberica coffee (Coffea liberica) thrives in lowland regions, particularly peatlands. It grows best in slightly acidic soil with a pH between 6.0 and 6.5, which helps the plant absorb nutrients and resist pests more effectively. A significant post-harvest method to improve the quality and yield of Liberica coffee involves fermentation using cellulolytic bacteria, Alcaligenes sp. And Exiguobacterium indicum, found in civet digestive tracts. Fermentation enhances the coffe’s flavor, aroma, and quality, mimicking that of civet coffee. The primary objective of this study was to refine the sensory characteristics of Liberica coffee, improve its proximate composition, preserve its bioactive compounds, and boost its antioxidant properties. The fermentation was conducted over 24 hours and 48 hours periods, with roasting temperatures set at light (170 ºC), medium (190 ºC), and dark (210 ºC). The process began with the preparation of bacterial inoculum, followed by fermentation, roasting, and grinding. Sensory evaluation, proximate analysis, and chemical profiling (via FTIR, LC-MS, antioxidant activity, and total phenolic content) were then performed. The findings revealed that fermented Liberica coffee exhibited improved sensory attributes, achieving specialty-grade status at medium roasting temperatures. There was a decrease in moisture and ash content, an increase in fat content, and a reduction in carbohydrate and protein levels. The FTIR analysis showed the preservation of existing compounds, while LC-MS identified bioactive components based on their retention times and molecular weights. Additionally, the fermented coffee demonstrated increased antioxidant activity and total phenolic content compared to non-fermented samples. This study highlights the potential of fermentation technology to enhance the quality and health benefits of Liberica coffee significantly.