Antioxidant properties and bioaccessibility of coffee beans and their coffee silverskin grown in different countries

Abstract

In this study, 7 Arabica (A) and 3 Robusto (R) green coffee beans (GCB) grown in different countries were used. These beans were roasted (RCB), and their coffee silverskin (CSS) produced during roasting was separated. The objective of the study was to determine the total phenolic contents, antioxidant capacities and bioaccessibility of green coffee beans and roasted coffee beans and their coffee silverskin. Three different antioxidant capacity determination methods (ABTS, CUPRAC, FRAP) were used for the determination of the antioxidant capacity; the Folin-Ciocalteau method was employed for the determination of the total phenol content (TPC); and the in-vitro enzymatic extraction method was applied for the determination of the bioaccessibility. The average bioaccessibility values of the TPCs of the GCB and RCB and their coffee silverskin were determined to be 50.05%, 41.45%, and 39.18%, respectively. The highest % bioaccessibiliy results for CSS were determined in the Ethiopia coffee for Arabica species and in the Indonesia-grown coffee for Robusta species. The highest % bioaccessibiliy in the green and roasted coffee beans of Arabica species was determined in the Kenya and Costa Rica coffees, while in Robusta species, it was determined in the India coffee. In general, although the total phenolic content and antioxidant capacity of the coffee beans were found to be higher in the Robusta, the Arabica was found to be higher in terms of % bioaccessibility results. As a result, it is recommended to use GCB and RCB and their CSS in the development of foods and beverages with functional properties.