Selection of Pectinolytic Yeast from Liberica Green Coffee Beans (Coffea liberica)

Abstract

Liberica coffee has an inferior quality when compared to arabica and robusta coffee. This flavour can be improved through a fermentation process involving indigenous microbes, one of which is a group of pectinolytic yeasts. Therefore, this study aimed to obtain yeast isolates with pectinolytic activity. Green bean samples were used for yeast isolation using YEPD agar media. Selected yeast isolates were screened for their pectinolytic activity semi-quantitatively using the well-diffusion method and quantitatively using the dinitrosalicylic acid (DNS) method. A total of six yeast isolates with different colony morphological characters were obtained and referred to as isolates Y1, Y2, Y3, Y4, Y5, and Y6. The isolates suspected to produce pectinase enzyme due to a clear zone around the well are Y2, Y3, Y4, and Y5. Y5 had the highest pectinolytic index, 022 and 0,73 on the second and fifth days of incubation, respectively. The four selected isolates were then screened quantitatively and showed that Y2 had the highest pectinase enzyme activity with a value of 12,66 ± 0,17 U/mL. The results showed that four yeast isolates from Liberica green coffee beans had pectinolytic activity with the highest enzyme activity found in Y2.