Influence of natural coffee drying process on the physical characteristics and sensory quality of beans Influencia del proceso de secado del café natural en las características físicas del grano y la calidad sensorial

Natural coffee (NC) is noted for its differential sensory descriptors in fragrance/aroma and flavor attributes compared to washed coffees. Among the procedures to get it, drying is a critical factor for its quality assurance. In order to evaluate the effect of coffee drying on NC quality, 5 treatments that consisted of an initial sun drying (S), supplemented with mechanical drying (M): S45%+M, S50%+M, S55%+M, S100%, M100% and a control that corresponded to 100% mechanically dried washed coffee (LM) were evaluated. In the different treatments, NC reached an adequate final moisture content (10-12%) between 9 and 17 days. This performance was described based on a logarithmic function and an R2 > 0.92. For LM, coffee required an average of 4 days of drying, which was explained by a third degree polynomial R2: 0.999. In general, NC showed adequate water activity content. With respect to bean physical variables, average shrinkage was 50.7%, and healthy beans was 42.6%, while defective beans had values between 2.6% and 6.6%. Regarding sensory quality, the average total score of the SCA (Specialty Coffee Association) for LM was 82.9 and for NC was 83.9, with outstanding descriptors in fragrance/aroma of chocolate, fruit, caramel, and honey, as well as sweet pulp and wine notes. The results show that an adequate drying process allows obtaining NC with remarkable physical and sensory quality.