Tasters’ performance in a coffee quality contest in Brazil

Abstract

The objective of this work was to evaluate the performance of coffee tasters in five annual editions of Minas Gerais Coffee Quality Contest. The repeatability coefficients of the tasters' scores for sensory attributes were estimated, as well as the minimum numbers of tasters required for consistent sensory results, and the groups of tasters by (dis)similarity of sensory scores. For the repeatability analysis, the treatments (coffees) were tested with the repetitions, constituted by the tasters. The repeatability coefficients were estimated using the analysis of variance, principal component and structural analysis methods. The minimum number of tasters was obtained based on pre-established determination coefficients. Euclidean distance matrices between tasters were determined, which were used as a measure of dissimilarity for cluster analysis by the Tocher optimization method. The tasters' performance in five annual editions of Minas Gerais Coffee Quality Contest is reliable using COE or SCA sensory analysis protocols. Although not fully calibrated, most tasters are grouped with similar cupping results. Unless efficient calibration prior to the contest is adopted, the number of tasters to be used in the next contest editions can not be drastically and randomly reduced, since the estimated minimum number varied over the years. Calibration activities are suggested to improve two main aspects of the Minas Gerais Coffee Quality Contest: distinguishing the best coffees and trainning tasters.