Efeitos na coloração, atividade antioxidante, e composição fenólica no suco de uva (Vitis Labrusca L.), enriquecido de termomaceração dos subprodutos de prensagem

Abstract

Grape juice is among the top growing juice consumption in recent years. The countries that stand out are the United States and Brazil, where the American varieties of the species Vitis labrusca L. are widely cultivated. Grapes are one of the richest sources of phenolic compounds among fruits and therefore have been extensively studied because of their potential beneficial effects on human health. They emphasize the ability to prevent diseases associated with oxidative stress, including cancers , cardiovascular diseases and neurodegenerative diseases. The grapes used in the experiment were of the Isabel species Vitis Labrusca of the 2018 crop year, in the state of Rio Grande do Sul, Southern Brazil, in the Serra Gaúcha. The technique of aqueous maceration with pectolitic enzymes was used to recover the compounds present in the skins and seeds from the cold press process, the pressing cake was exposed for 5 hours in agitation, aligned to high pressures generated by piston and hydraulic unit in Pilot press equipment at temperature up to 60 ° C and later concentrated to the original brix of the fruit in rotavapor equipment at a temperature not exceeding 65 ° C. Regarding the results, a significant difference was observed between practically all the analyzed parameters, demonstrating the presence of compounds in grape pomace due to their incomplete extraction during processing. As for the total polyphenol content (IPT), the juice sample considered as the final product composed of the proposed blend of 70% juice of 1st extraction plus 30% of juice of 2nd extraction resulted in 47 IPT, 791 mg / l in anthocyanins total, as for color, the results suggest more bluish tones in comparison to juice of 1st extraction and intensity (420 + 520 + 620 nm) of 1.532. The highest correlation observed in antioxidant activity was for the ABTS test with the content of phenolic compounds (r = 0.99511), suggesting that these compounds have high free radical sequestration capacity and, therefore, important sources of antioxidants, of great importance to the food industry.