The chemical composition and quality of the Parainema coffee cultivar under different shading conditions, as assessed by a leaf flavonol optical index

The introgressed cultivar of Parainema coffee was studied in two Honduras plantations that differed in their tree-shading system, namely intercropping as opposed to agroforestry. The cumulative sunlight effect on plants was determined by means of a non-destructive index of leaf flavonols, applied here for the first time to the coffee culture. The coffee seeds selectively harvested from shaded and full sunlight plants were analyzed for both their chemical composition and the derived cup quality. The high and constant shading of the agroforestry system determined both the heaviest coffee beans and an excellent rating of the beverage. Green beans under shade contained higher levels of caffeine and lower levels of trigonelline and mono-caffeoylquinic acids (other than chlorogenic acid) than those from sun-exposed plants. Banana-tree shading produced no differences in the green bean chemicals with respect to sunlight. The employed leaf flavonol optical index allowed to quantify the spatial variability of shading within the coffee plantations. Regardless of the light regime and site, Parainema coffee was classified as a "specialty", an aspect that, together with its high seed weight and resistance to disease, can further favor its spread among coffee producers.