Uso da espectrometria de massas com ionização por eletrospray no estudo da influência da irrigação e da resistência ao fungo Hemileia vastatrix Berk. Et Br. em grãos verdes de Coffea arabica.

Abstract

The growth of irrigated coffee farming areas and the development of new technolo-gies comes providing increased productivity and quality of the final product. Howev-er, a precise modelling of irrigation influence on the chemical changes of the Arabi-ca coffee is limited. In this study, were analyzed by direct infusion electrospray ioni-zation mass spectrometry (ESI-MS), ten different varieties of Coffea arabica L., culti-vated under distinct water regimes (irrigated and not-irrigated). The major constitu-ents identified in the methanolic extracts of green beans, in positive and negative modes, were: choline; trigonelline; sucrose; βN-arachinoyl-5-hidroxytryptamide; βN-behenoyl-5-hidroxytryptamide; palmitoyl-linoleoyl (PL); dilinoleoyl (LL); dipalmitoyl-linoleoyl (PPL); palmitoyl-dilinoleoyl (PLL), quinic acid, cafeoilquinic acid, dicafeoilquinic acid and three new compounds identified for the first time in the green coffee matrix: triacylglycerol (TG 54:6), phosphoethanolamine (PE, 40:7) and 1-hexadecyl-2-dodecanoyl-glycero-3-phosphate. It was possible to efficiently sort the groups of irrigated and non-irrigated at 95% of confidence using PLS-DA (Partial Least Squares Discriminant Analysis), in order to obtain all the minimum require-ments for evaluation of efficiency of the rating model of coffees. The sucrose (ion m/z 381) and the ion m/z 431 (not identified) suffered a negative influence of irriga-tion, while trigonelline (ion m/z 138 and ion m/z 176) and the ion m/z 723 (not identi-fied) were correlated positively with irrigation. The cup test showed that the coffees cultivated in not-irrigated regime had slightly larger cupping notes that the ones cul-tivated under irrigation, probably because they presented higher sucrose content. Additionally, it was evaluated the influence of resistance of studied varieties to the fungus Hemileia vastatrix BerK. Et Br. on chemical composition of green beans. It was observed that the chemical profile of grains of resistant varieties does not change significantly from profile of susceptible varieties.