Selection and Characterization of Non-Saccharomyces Yeast Strains for Potential Use in Arabica and Conilon Coffee Fermentations

Abstract

Customized fermentation approaches are necessary due to the differences in the characteristics of Coffea arabica (Arabica) and Coffea canephora (Conilon) coffees. Therefore, this work aimed to select and characterize new non-Saccharomyces yeast strains with potential use as starter cultures for Arabica and Conilon coffee fermentation, using a coffee peel and pulp medium (CPM). Fifty-six yeast strains were assessed for pectinolytic activity, and 34 were selected for further evaluation in CPM. Their performance was assessed based on population growth, °Brix, pH, and production of organic acids. Seventeen strains showed significant growth in Arabica CPM and eight in Conilon CPM, ranging from 10.96% to 18.38%. Nine yeast strains showed higher organic acid production in Arabica and five in Conilon, ranging from 0.826 to 1.336 g/L. Volatile compound production was also evaluated, with 44 compounds detected in Arabica and 61 in Conilon fermentations, showing strain-dependent profiles. Meyerozyma guilliermondii CCMA1737, Meyerozyma caribbica (CCMA1993, CCMA1617, CCMA1992, CCMA1950, and CCMA1735), Pichia kluyveri CCMA1658, Cystofilobasidium ferigula CCMA1647, and Hanseniaspora uvarum CCMA1944 were considered the most promising candidates for fermentations with Arabica coffee. Hanseniaspora uvarum (CCMA1895 and CCMA1944), Rhodotorula mucilaginosa CCMA1663, P. kluyveri CCMA1652, and M. caribbica CCMA1950 were considered the most promising candidates for Conilon fermentation. For the first time, H. uvarum and R. mucilaginosa were selected as potential starter cultures for Conilon coffee fermentation. Future studies should evaluate the suitability of these selected yeasts as starter cultures in coffee fermentation.