Microencapsulação de extratos metanólicos de amora-preta (rubus fruticosus) e ácido gálico.

Abstract

The blackberries fruits are a high food source of phenolic compounds such as gallic and þ-hydroxybenzoic acids and epicatechina. Among them, gallic acid is found in greater abundance. These compounds exhibit antioxidant properties; however, due to the presence of unsaturated bonds in its molecular structure, they are vulnerable to the action of oxidizing agents such as light, heat, oxygen and moisture. An alternative to maintain the stability of these compounds is to provide its protection in a polymer matrix, which remain protected until the time that these compounds are released from this matrix. Thus, the objective of this study was microencapsulate gallic acid in the matrixes β-cyclodextrin (β-CDS), chitosan (C), xanthan (X) and the phenolic extract of blackberry in the presence of these polymers and also in xanthan and chitosan hydrogel (H), to confirm the encapsulation by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis Techniques (TGA), to determine the antioxidant activity, to evaluate the controlled release of phenolic compounds and determine the efficiency of encapsulation. It was concluded that the gallic acid was encapsulated in the matrices C, β-CDS and X by lyophilization method, as well as the extract phenolic of blackberry in these same matrixes and additionally in the H matrix. The encapsulated showed distinct characteristics to the gallic acid and phenolic extract in its pure form, being proved by the techniques of SEM, DSC and TGA. The encapsulation of gallic acid was obtained in the chitosan matrix greater encapsulation efficiency, with the capsules formation with characteristic shape and greater protection of the core, according to the results of DSC and TGA, is also maintained the antioxidant activity. In relation to the blackberry phenolic extract capsules have the formation of shaped characteristic matrices with chitosan and xanthan. The encapsulation efficiency was dependent on the compounds coating used. The highest antioxidant activity was fairly related to the presence of phenolic compounds, gallic acid and epicatechina, the microcapsules coated with β-cyclodextrin and xanthan. The controlled release of the phenolic extract of the capsules was influenced by coating, as well as the solvent and pH.