Fitoquímicos bioativos e potencial antioxidante do resíduo agroindustrial do pedúnculo do caju (Anacardium occidentale L.).

Abstract

The agro-industrial residues consisting of bark and seed, usually concentrate significant amounts of bioactive phytochemicals often have superior antioxidant capacity found in the pulp of the fruit. Due to this fact, this study aimed evaluate the antioxidant potential of cashew waste from the industrial processing of frozen fruit pulp. The residue was dried in an air circulating oven (50° C) until moisture content below 10%. The flour obtained was subjected to determination proximate composition and content of the main bioactive phytochemicals and optimize the process to obtain extracts. To determine the ideal processing conditions for preparing extracts with high total phenolic content and high antioxidant capacity the 24-1 fractional factorial design and the central composite rotational design (DCCR) was applied for each type of solvent (acetone and methanol). Stirring time (30 to 90 minutes), processing temperature (30 to 50 °C), solvent concentration (50% to 90%) and Stirring speed (100 to 300 rpm) were used as independent variables, and the total phenolic content and percentage of DPPH radical scavenging were used as dependent variables. The extracts obtained using the optimized extraction process were subjected to determination of scavenging capacity DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS•+ (2,2 '-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) and inhibition of oxidation of co-oxidation system β-caroteno/ácido linoleic acid. The residue showed less than 10% moisture, 0.36 water activity, 9.65% protein content, 5.43% lipids and 76.68% carbohydrates in addition to ascorbic acid (78.5 mg.100g-1), total carotenoids (67.20 mg.g-1), total anthocyanins (36.05 mg.100g-1), flavonols (109.03 mg.100g-1), condensed tannins (313 mg.100g-1) and phenolic (1975.64 mg.100g-1). The variables did not influence the extraction of phenolic compounds by employing methanol as solvent extractor, independent of process conditions, but were significant when the extraction process used acetone. Extracts with high levels of polyphenols and strong scavenging capacity DPPH (> 80%) was obtained by employing acetone 55%, time 30 minutes, temperature of 30°C and agitation of 150 rpm. Hydroacetonic and hydromethanolic extracts, obtained by sequential extraction process, were combined and subjected to antioxidant assays for free radical scavenging in a model system (DPPH and ABTS) and antioxidant assays in lipid systems (coupled oxidation of B-carotene/linoleic acid). The extracts exhibited good efficiency against DPPH (EC50 of 57.38 and TEC50 <0.5 minutes), strong scavenging this radical (80.74 to 93.2%) and positive correlation between the total phenolic content and DPPH• scavenging capacity, and expressive ABTS•+ scavenging ability (7506.49 TEAC mol / g). In system β-carotene / linoleic acid the extract exhibited antioxidant action intermediate (62.75%), proving to be efficient in blocking the start of the oxidation reaction (F1 <1), but the propagation phase was not as effective (F2> 1). Based on these results, it is evident that the waste cashew presents as a source of bioactive compounds with good antioxidant potential that can be used in developing new products or as raw material for extraction of antioxidant compounds to be applied in food, in order to deter lipid oxidation in total replacement and / or partial to synthetic antioxidants.