Determination of physical and chemical quality of coffee beans under improved potassium fertilization managements

Abstract

Coffee quality is the key attribute for establishing its price and commercialization. As the classification of coffee quality is a complex process, mainly based on a subjective judgment, difficult to define and measure, a complementary approach to the current procedures involving physical and chemical methods would bring more effectiveness to the process of quality determination. The chemical composition of the coffee bean is influenced by several factors, among them the nutritional management of coffee trees and, the use of potassium chloride (KCl), which has intensified losses in bean quality due to excessive chlorine in its composition. The aim of this study was to evaluate the efficiency of sources and forms of K application in the quality of beans, and assessment of methodologies for determination of physical and chemical qualities of beans. The experiment was conducted with Yellow Ca tuaí cultivar, from 2017 to 2019, in a randomized experimental block design with five replicates. Six treatments were applied, containing proportions of KCl/K2SO4, as follows: T1-100% KCl; T2-75%/25%; T3-50%/50%; T4-25%/75%; T5-100% of K2SO4 and T6-100% of KCl + two foliar K2SO4 applications. The variables addressed in the study were sensory analysis, screen of beans, electrical conductivity (EC), potassium leaching (KL), titratable total acidity (TTA), and coffee bean color. It was verified that KL, EC, and other chromatic parameters were efficient in detecting alterations on coffee bean caused by the use of KC1. Total (T5) or partial (T4) replacement of KC1 by K2SO4 applied to soil improved chemical characteristics and color of coffee beans. Supplemental foliar fertilization with K2SO4 (T6) was efficient to minimize deleterious effects of KCl on quality of coffee beans, improving beverage quality and grain size, especially in high productive harvests.