Optimization of fermentation conditions of naturally processed Arabica coffee (Coffea Arabica) in Uganda

Abstract

Coffee is very popular due to the unique sensory characteristics of its brew. This research aimed to determine the best fermentation method and duration for Arabica coffee with respect to its volatile, physicochemical, and sensory components. Gas chromatography/mass spectrophotometry (GCMS) was used to examine volatile chemicals that had been extracted using solid-phase micro extraction (SPME). Descriptive sensory evaluation with 8 trained panelists was used to assess the cup quality. Response Surface Methodology and Principle Component Analysis were used for data analysis. Significant models were generated to describe the relationship between fermentation time, fermentation type, and the physicochemical, and sensory properties as well as volatile compounds of Arabica coffee. Both fermentation type and time had an impact on sensory qualities such as fragrance/aroma, flavor, sweetness, acidity, body, balance, aftertaste, uniformity, and cleanliness. The optimum fermentation time and fermentation type were 16.8 hours and spontaneous fermentation respectively. Principle component analysis was performed to relate sensory attributes with physicochemical properties and volatile compounds. Furaneol, coffee temperature, 3-ethyl-2-hydroxy-2-cyclopenten-1-one, and acetaldehyde were positively correlated to each other. 1-(1H-pyrrol-2-yl)-ethanone, furan were related, 3-hydroxy-2-butanone, acetic acid, brix, 2,3-pentanedione and ethyl isovalerate, 2,3-butanedione (diacetyl), 2-methylbutanal, 3-methylbutanal were positively correlated, and there was a positive correlation between 2-butanone, pH, pyrazines.