Biochemical composition of green and roasted coffee beans and their association with coffee quality from different districts of southwest Ethiopia

Quality is a key criteria that can help producers win the global coffee market. Coffee quality can be expressed by physical, organoleptic as well as biochemical compositions. To determine biochemical compositions and antioxidant activity in green and roasted coffee and their correlation with cup quality samples were collected from nine districts of BenchMaji and Sheka zones. Significant variation in trigonelline, chlorogenic acids and caffeine content were observed among coffee samples. The result on dry matter basis range of trigonelline, chlorogenic acids and caffeine varied from 0.80 to 1.08 g/100g, 2.80–5.42 g/100g and 0.85–1.73 g/100g of green coffee, respectively. Antioxidant activity of green and roasted coffee showed highly significant differences across districts. Due to roasting, trigonelline, chlorogenic acids and antioxidant activity were lower in roasted coffee as compare to green coffee. Correlations between cup quality and some chemical composition of coffee vividly showed that the biochemical content of beans can significantly influence coffee quality. Biochemical compositions can be used in predicting the quality of coffee and has special importance in determining the quality of coffee diversity in the BenchMaji and Sheka zones.