Determinação de compostos fenólicos na farinha da cebola roxa do gênero Allium cepa

Abstract

Natural flavonoids are distinguished by their pharmacological properties, which can be found in a variety of vegetables, fruits and some medicinal plants. Flavonoids are used in the formulation of various drugs because of their physico-chemical and pharmacological properties, in addition to their high antioxidant power. One of the main sources of flavonoid is in the purple onion (Allium cepa), which has in its composition the major amount of flavonoid quercetin, which due to this characteristic, is a very studied vegetable. The objective of this work is to determine the phenolic compounds in the flour of the purple onion of the genus Allium cepa, to obtain methanolic extracts; to study stability and to verify the presence of phenolic compounds. Moisture determinations and confirmation of the presence of phenolic compounds were carried out via spectroscopy in the UV-Visible region. The extracts of the purple onion obtained via methanolic proved the presence of phenolic compounds from the folinCiocalteu reagent. The results showed that folin-ciocalteu Reactant occurs phenolics in the samples, since the band formed at 760 nm, is indicative of the reduction of the metals (Molybdenum-Mo and Tungsten-W) present in the folin reagent, which are reduced by the hydroxyls present in the phenolic compounds and that degradation of the samples occurs when analyzed in the long term. According to the experiments, it is possible to verify the majority quantity of water with a mean value of 89.15%. Evaluating the methanolic extract it was realized that the extracts should be analyzed in a short time due to the degradation of their constituents. With the use of the Folin - Ciocalteu Reagent it was possible to confirm the presence of phenolic compounds since the band formed at 760 nm is an indication of the reduction of the metals (Mo and W) present in the Folin reagent, which were reduced by the hydroxyls present in the compounds phenolics.