Physicochemical comparison of aqueous extracts from Peruvian coffee husks (Caturra, Catimor and Geisha) varieties

Abstract

The study aimed to determine and compare the physico-chemical characteristics of coffee husks aqueous extracts corresponding to three Peruvian varieties of Arabica coffee: Caturra, Catimor and Geisha. Each sample was dehydrated at 45 °C for 10 hours, ground, sieved and dissolved in 2.5% w/w water. Aqueous extracts were obtained and analyzed for pH, total solids (TS), whiteness index (WI), reducing sugars (RS), total phenols (TP) and reducing power (RP) for the antioxidant activity The influence of coffee varieties, particle sizes (0.097, 0.033, and 0.0139in) and extraction temperaturas (60 and 80 ºC) on the physicochemical characteristics of their corresponding extracts was determined by factorial analysis. Correlation between TP and RP was significant while RS and TP showed an inverse relationship. Cluster values indicate similarity between Geisha extracts at 60 and 80 °C and the corresponding Catimor extracts at 80 °C. Differences were observed between the Catimor extracts at 60 °C and Caturra at 60 and 80 °C. Based on these results, the extracts exhibit distinctive intrinsic characteristics. The Caturra extracts at 60 °C showed the highest antioxidant capacity, while the Catimor extracts at 60 °C or 80 °C exhibited the highest WI (water holding capacity) and pH values. Additionally, the Geisha extracts displayed the highest amount of RS (reducing sugars). These findings are of utmost significance for the development of novel products using Peruvian coffee husks, encompassing beverages, concentrated juices, and the enhancement of coffee quality offered in coffee shops. These developments can be guided by the physicochemical characteristics obtained in this study.