Cascas liofilizadas de manga Tommy Atkins: teor de fitoquímicos bioativos e potencial antioxidante

Abstract

This work had as objective to characterize of freeze-dried bark of mango Tommy Atkins, come from organic farming, and defining the conditions of the polyphenols extraction process. The peels were crushed and the flour was submitted to the determination of proximate composition, minerals and bioactive phytochemicals and antioxidant potential employing techniques titrimetric, spectrophotometric and chromatographic. To define the optimal conditions of the process was applied the of factorial design 2² as independent variables: temperature 25-50° C and time stirring 30 to 90 min), and as response the total phenolics concentration in the extract. This experimental design was applied in the following process types: a) Extraction sequentially- hydroacetonic solution (80%), followed by hydromethanolic solution (80%); b) Extraction sequentially- hydromethanolic solution (80%), followed by hydroacetonic solution (80% ); c) Extraction non-sequential-hydroacetonic solution (80%) and d) extraction non-sequential- hydromethanolic solution (80%). The extracts were submitted to antioxidant assays, capture radicals in model system (DPPH, ABTS, ORAC) and antioxidant assays in lipid systems (coupled oxidation of β -carotene-linoleic acid, peroxidation of linoleic acid - ferric thiocyanate method, and accelerated storage test in an oven) and high performance liquid chromatography analyses for identification of polyphenols. The mango flour showed high levels of carbohydrates, potassium, sodium, calcium and phosphorus, total phenolics, ascorbic acid and β-carotene. The factorial design defined as the ideal sequential extraction (80% methanol, followed by 80% acetone) and the following process conditions: temperature 37.5°C and 25ºC; time stirring of 30 and 60 min, whose extracts showed, respectively, higher total phenolic content (2407.16μg. mL-1) (Ext-5), and increased sequestration capacity DPPH (95%) (Ext-7). Both extracts exhibited significant antioxidant capacity against free radicals ABTS, DPPH and ORAC, and in lipid system. The chromatographic analysis revealed the presence in both extracts of the phenolic acids (benzoic acid and cinnamic acid derivatives), flavonoids and a xanthone, but with quantitative and qualitative differences between the profiles of the extracts. Synaptic acid, syringic acid, taxofoline, isoquercetine and mangiferin were the major constituents of these extracts. Thus, considering the chemical composition and antioxidant capacity, the agro-industrial waste of Tommy Atkins mango emerges as a potential source of natural antioxidant.