Relations between sensory quality and spectral indices in brazilian arabica coffees

Abstract

This article describes an investigation using spectral indices to characterize coffee production of Brazil, regarding beverage quality and possible correlations with the growing environment. The study evaluated 50 arabica coffee samples, 16 of which were natural process, and 34 were pulped coffes. These samples were originated from growing areas located in different altitude ranges and regions of the municipality, with similar planting spacing and predominance of Catuai cultivars. The samples were subjected to sensory analysis, which revealed that 58% of the samples were classified as specialty coffees: 3 natural, and 26 pulped coffes. Multiple correspondence analysis showed that average spectral indices, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and photochemical reflectance index (PRI), derived from images of the multispectral instrument (MSI), were not associated with the quality parameters of the coffee beverage. In contrast, the plant senescence reflectance index (PSRI) proved to be the relevant factor in the quality of the drink. In summary, the analysis of the relationship between the indices demonstrated that the NDVI, which measures the vegetative vigor of plants, showed an inverse correlation with the PSRI. Additionally, the principal component analysis suggested that samples collected from drier areas differed significantly from other geographic regions.