Caracterização química e potencial antioxidante de produtos e subprodutos de uva

Abstract

Brazil is considered a country with great diversity of fruits, and the grape in this scenario is highlighted as one of the most consumed fruits in the world. Among the derivatives that can be used of this fruit is the juice that has been gaining market space, and presents an estimable value, being equalized in terms of constituents the own fruit. During the processing of grape juice an expressive amount of residues are generated signaling environmental pollutants. In turn, these byproducts have a high aggregate commercial value because they are residues rich in bioactive compounds as sources of natural antioxidants capable of combating the oxidative damages that free radicals cause to our cells. Considering this, this work has proposed to investigate the physico-chemical and antioxidant characteristics of the Isabel grape, as well as its juice microfiltered by Membrane Separation Process (MSP) and the flour obtained as a by-product of this. In addition, optimize the best antioxidant-extracting solvent fraction of fermented and unfermented Bordô seed, evaluate antioxidants and quantify fatty acids of the oil obtained from that seed by cold pressing method. Finally, determine the content of trans-resveratrol present in these products and by-products. The antioxidant activity was determined by the methods of DPPH, ABTS and FRAP and supplemented with phenolic compounds and flavonoids. The optimization of the extraction took place through statistical planning of simplex-centroid mixing type, which made possible the analysis of the effect of solvents water, ethanol and acetone, as well as their mixtures on these responses. The fatty acid composition was determined by gas chromatography. For the determination of trans-resveratrol in the samples, a high-performance liquid chromatograph was used and quantified by external calibration. The microfiltered and retained juice in the membrane (retentate) presented good stability of antioxidant compounds during the storage period, highlighted the retentate juice. For the fermented and non-fermented Bordô grape seeds the extracts containing the ternary fraction of the solvents showed higher antioxidant activity, however the non-fermented seed had better antioxidant contents and also better results in the quantification of trans-resveratrol. Fermented and unfermented Bordô seed oil had high concentrations of polyunsaturated fatty acids, especially linoleic acid, and the antioxidant content of this oil was moderate for both.