Obtenção, caracterização e microencapsulação de extrato de erva-mate (Ilex paraguariensis)

Abstract

The interest in extracting bioactive compounds from natural sources has increased because its functional and technological effects. Among the natural sources of bioactive compounds, the yerba mate (Ilex paraguariensis A.St.-Hil.) is composed of phenolic compounds, flavonoids, alkaloids and terpenes, as well as vitamins and minerals. The yerba mate culture is the agricultural activity present mainly in northwestern Argentina, eastern Paraguay and Southern Brazil. The states of Paraná, Santa Catarina and Rio Grande do Sul are the largest producers and consumers, with their exploitation mainly in small and medium-sized farms. This agricultural activity has great social and economic importance. The objective of this study was to obtain mate extract with high concentration of bioactive compounds, as well as microencapsulate and characterizate them. Different samples of yerba mate were used, one of it was collected in natura and oven dried (F) and three samples from commercial brands, named M, T and S were purchased in local commerce. Different solvents were used (100% water, 100% ethanol and 50% water: 50% ethanol) with Dubnoff bath at 50 ° C for 5 hours for yerba mate extract (YME) preparation. The YME were characterized by the analysis of total solids, soluble solids (°Brix), pH, titratable acidity, total phenolic compounds, flavonoids and antioxidant activity (AA), using the DPPH• and DPPH• radicals scavenging, and the best YME was encapsulated. The encapsulation was carried out by extract and material mixture follow by freeze drying. Arabic gum and fructooligosaccharide (FOS) were used as wall materials in the proportions: 100% FOS (I), 25% gum arabic and 75% FOS (II), 50% FOS and 50% gum arabic (III), 25% FOS and 75% gum arabic (IV) and 100% gum arabic (V). The microcapsules were characterized by analysis of total phenolic compounds, flavonoids, antioxidant activity by and DPPH• radicals scavenging and thermal stability by Differential Scanning Calorimetry (DSC). The solvent solution water: ethanol (50%, v: v) was selected as this mixture resulted in higher concentration of total phenolic compounds and flavonoids. Among the types of yerba mate DPPH studied, differences between the samples (p <0.05) were observed, and the lowest bioactive composition were found in dry leaves (F). The commercial yerba mate T was chosen, which presented, with lower total solids content and higher soluble solids content (°Brix). There was a difference (p<0.05) on the content of phenolic compounds between the encapsulated samples and the control (YME freeze dried), suggesting that the microencapsulation was able to protect the polyphenols present in the extract. The addition of the encapsulating agents in all the formulations studied produced microcapsules with more concentrations of flavonoids than the YME freeze dried (p<0.05). Data from the evaluation of the antioxidant DPPH• activity showed differences between the control and treatments. The highest AA of ABTS•+ scavenging was in treatments and the lowest AA in control. Confirmation of the encapsulation of the YME in the Arabic gum and fructooligosaccharide matrices was performed by thermal analysis using DSC. The microparticles of encapsulated YME have the potential to be used in the food industry as a natural source antioxidant, collaborating with the control of oxidation in different foods matrixes.