Compração química dos grãos de café (Coffea Arabica), sadio e seus grão PVA (pretos, verdes, ardidos) oriundo do Sul de Minas e do Cerrado Mineiro, submetidos a diferentes graus de torrefação

Abstract

Coffee is considered one of Brazil s most important commodities and, therefore, its quality is very important. This product must present physical, chemical and sensorial properties according to established standards to reach the quality degree for exportation. Among the several factors that influence the quality of coffee, the presence of defective beans (black, green and sour beans (BGS)) must be avoided. Thus, the aim of this dissertation was to obtain a chemical differentiation between good and defective roasted beans. To study that, samples from Minas Gerais s cerrado and from the South of this state were used. They were roasted until three different degrees (mild, medium and strong roasting). The results showed that beverages prepared from BGS beans were more acid due to fermentative processes, and more astringent due to higher content of phenolic compounds, proanthocyanidins and chlorogenic acids. Moreover, the presence of defective beans reduces the essential oil concentration, but increases the content of undesirable substances for the aroma, as low molecular weight aldehydes and sulfides. These beans are rich in olefins and saturated chains. However, the matrixes of the defective and good beans are similar, being basically composed by sugars, phenols, carboxylic acids and caffeine.