Eficiência de solventes na obtenção e caracterização de corantes de urucum (bixa orellana l.)

Abstract

The present research aimed to verify the efficiency of different solvents in extraction of pigments from annatto seeds, as well as to product and to verify the characteristics of the obtained colorants. The solvents used were KOH 0.6%, NH4OH 2%, NH4OH ethanolic 2% and commercial ethanol. From data obtained with KOH 0.6% and NH4OH 2% it was possible to produce powdered colorants by spray-drying, and the hydroalcoholic and alcoholic extracts originated pasty colorants. The extraction efficiency was evaluated by residual content of bixin present in the seeds when the extractions were finished. The colorants were characterized through moisture content, total solids, ash, ammonia, potassium and by bixin and norbixin contents. The most efficient solvent was NH4OH ethanolic 2%. The largest bixin content was found in the pasty colorant produced with ethanol (27.7 g.100 g-1), and in spite of what is described on literature, the concentrations of alkali that were used were not enough to convert bixin in norbixin and its salt. The different solvents interfered by increasing the concentration of compounds present in the produced colorants, such as ash, nitrogenated compounds and potassium. In all colorants produced the major pigment was bixin, even if the extracts were obtained by extraction using alkaline solution.