Exploratory evaluation of dry fermentation of specialty coffee from Nariño-Colombia, -using wet and honey-like methods

Abstract

The aim of this investigation was to compare the quality of coffee produced by dry fermentation using wet and honey-type methods in three farms located in southwestern Colombia through an ex post facto study. Specialty coffee was produced and studied according to a post-harvest protocol that utilized traditional practices. The study revealed that the quality of coffee is primarily affected by postharvest processing (57.6%) and the coffee farm (37.9%). The honey-like processing method employed on La Mina farm obtained the highest overall quality score, as determined by the Specialty Coffee Association (SCA). The variation in the cup quality occurred due to the variation in the different attributes. The overall impression, fragrance/aroma, body, and flavor were the primary contributors to the total score quality variance (34.9%), whereas acidity, aftertaste, and balance accounted for 26.1% of the total variance. Regarding the environmental, physicochemical, and microbiological parameters, the principal component analysis showed that the bottom temperature (BT), surface temperature (ST), middle temperature (MT), aerobic mesophilic bacteria (AMB), and °Bx accounted for 29.5% of the variance. Also, yeast, pH, LAB, and AAB accounted for 27.3% of the total variance. The highest correlation with the final cupping score was recorded for MT, ST, environmental temperature (ET), BT, Enterobacteria, and relative humidity (RH). Pre-fermentation was found to increase the microbial count, and longer dry fermentation durations of depulped coffee promoted the growth of beneficial microbial populations. The process revealed interesting relationships between temperature-AMB and degrees Brix (°Bx), and between yeast-lactic acid bacteria (LAB) and acetic acid bacteria (AAB).