Avaliação de Três Técnicas de Isolamento de Polifenóis: aplicação em amostras de chocolate meio amargo

Abstract

Polyphenols were intrinsic components of the cocoa; therefore, derivative products of cocoa, like chocolate, can be considered functional food, bringing beneficial effects to costumer's health, as it is suggested for red wine and green or black tea. Nutrition and medicine areas have dedicated special attention to these components. That is due to evidences that polyphenols can act as potential antioxidants, and that they can carry out an important function in the reduction of the risk or delay of the development of diseases, like the cardiovascular ones, cancer and other ones related to aging; and yet, that they can modulate essential biological processes mammals in vivo. The first objective of this work was to evaluate novel stationary phases for the isolation of polyphenols, by the use of polyurethane foam and of a polymeric resin (XAD-16). Therefrom, to determine the best phase by comparison of performance with the one of a phase previously described in literature (C18), by high-performance liquid chromatography (HPLC). Once the phase is chosen, the second objective is to isolate polyphenols from chocolate samples. An index was established to monitor the performance by the ratio P/C, the ratio of heights or absorbances (mAU) of the largest peak among the ones attributed to polyphenols and the largest peak among the ones attributed to carbohydrates. The chosen column was XAD-16, given the observed separation of the polyphenols and reprodutibility of elutions, which was confirmed by triplicate procedures. The polymeric resin XAD-16 was shown as a quite effective way to isolate polyphenols from carbohydrates because the latter are eluted with water while the polyphenols are retained. Subsequent methanol elution was considered quite appropriate for the recovery of polyphenols, because the chromatograms of the fractions obtained yielded P/C ratios much higher than 100%, even considering very small contents of polyphenols.