Extraction and characterization of pectin from coffee (Coffea arabica L.) pulp obtained from four different coffee producing regions

Abstract

The pectin was extracted using H2SO4, HNO3, and HCl from the pulp of four coffee varieties (Harar, Sidama, Jimma, and Guji) collected from different regions of Ethiopia. The effect of extraction temperature, time, solid-to-liquid ratio, types of acid and coffee varieties on the physiochemical properties and yield of pectin were studied. A maximum pectin yield, which was 12.7 %, was obtained from Harar coffee pulp treated with H2SO4. The equivalent weight of the extracted pectin varied from 1111 to 1667 g/mol. The methoxyl contents of the extracted pectin ranged from 4.23 to 7.13 %. The degrees of esterification and anhydrouronic acid of the pectin ranged from 53 to 68.5 % and 35.5 to 68.8 %, respectively. The results show the yield and physiochemical properties of the coffee pulp pectin depend on extraction parameters, acid types, and coffee varieties. Moreover, the pectin extracted from coffee pulp showed strong gelling properties.