Phenolic content and α-glucosidase inhibition of tubruk-brew kalosi coffee processed by different post-harvest processing

Abstract

Brewed coffee contains phenolic compounds, a class of bioactive compounds known for their ability to inhibit the alpha-glucosidase enzyme. This study investigates the influence of post-harvest processing on the phenolic content and alpha-glucosidase inhibitory activity of brewed coffee using tubruk method. Arabica coffee from Kalosi Enrekang was utilized, processed using three post-harvest methods: natural, honey, and full-washed. The beans were roasted to a medium level and brewed using the tubruk method. Results revealed that coffee brewed from beans processed using the natural method exhibited the highest phenolic content (3.02 g GAE/100 g) and alpha-glucosidase inhibitory activity (18.48%), compared to those processed with honey and full-washed methods. These findings highlight that post-harvest processing significantly impacts phenolic compound levels and their associated bioactivity. A higher phenolic content in brewed coffee corresponds to an enhanced ability to inhibit the alpha-glucosidase enzyme. Thus, post-harvest processing methods play an important role in determining the functional quality of coffee.