Evaluation of a potential starter culture for enhance quality of coffee fermentation

Abstract

The coffee fermentation is characterized by the presence of different microorganisms belonging to the groups of bacteria, fungi and yeast. The objectives of this work were to select pectinolytic microorganisms isolated from coffee fermentations and evaluate their performance on coffee pulp culture medium. The yeasts and bacteria isolates were evaluated for their activity of polygalacturonase (PG), pectin lyase (PL) and pectin methylesterase (PME) and metabolites production. Among 127 yeasts isolates and 189 bacterial isolates, 15 were pre-selected based on their ability to produce PL and organic compounds. These isolates were strains identified as Bacillus cereus, Bacillus megaterium, Bacillus subtilis, Candida parapsilosis, Pichia caribbica, Pichia guilliermondii and Saccharomyces cerevisiae. When cultivated in Coffee peel and pulp media in single culture or two by two mixed inocula, different behavior concerning to PME, PL and PG were found. The two principal components PC1 and PC2 accounted for 45.27 and 32.02 % of the total variance. UFLA CN727 and UFLA CN731 strains were grouped in the positive part of PC1 being characterized by 1,2-propanediol, hexanoic acid, decanoic acid, nonanoic acid and ethyl acetate. The UFLA CN448 and UFLA CN724 strains were grouped in the negative part of PC1 and were mainly characterized by guaiacol, butyric acid and citronellol. S. cerevisiae UFLACN727, P. guilliermondii UFLACN731 and C. parapsilosis UFLACN448 isolates are promising candidates to be tested in future studies as coffee starter cultures.