Extração assistida por ultrassom e caracterização de compostos bioativos da casca de uva preta cultivar vitória (Vitis vinifera L.)

Abstract

Brazilian viticulture generates large volumes of agro-industrial waste, such as grape skins and pomace, which, if improperly disposed of, can have environmental impacts. However, these residues are rich in lignocellulosic and bioactive compounds of interest to the food, pharmaceutical, and cosmetics industries. In this context, the present study aimed to extract and characterize phenolic compounds and antioxidants from black grape skins Vitória type (Vitis vinifera L.) through ultrasound-assisted bath extraction, evaluating the influence of different solvent conditions (water, ethanol, and acetone), concentration, extraction time, and temperature. The experimental process included assays for determining antioxidant activity (DPPH), quantifying total phenolic compounds (Folin Ciocalteu), analyzing tannins (vanillin-HCl), as well as spectroscopic (UV-Vis, FTIR), chromatographic (GC-MS) characterization, and photodegradation under ultraviolet light. The results showed that hydroethanolic and hydroacetonic solvents at intermediate concentrations (20–70%) provided the highest yields of total phenolics (up to 316.7 mg GAE/L) and tannins (up to 8,697.9 mg catechin/L), with high antioxidant activity (EC50 up to 0.086 µg/mL). The use of pure solvents (100%) and high temperatures (60 °C) resulted in partial loss of bioactive activity, suggesting thermal degradation. The lignocellulosic composition of black grape skin showed contents of 25.7% extractives, 33.5% cellulose, 21.8% lignin, and 19.1% hemicellulose. GC-MS analyses revealed that ethanolic extracts were characterized by the presence of coumarins and niacinamide, while acetonic extracts concentrated condensed phenolics and squalene. The solvent selectivity was confirmed by FTIR and UV-Vis. The conclusion is that ultrasound-assisted extraction under optimized conditions represents a sustainable and efficient strategy for recovering target molecules, contributing to the valorization of wine residues and aligning with the Sustainable Development Goals (SDG 3 – Good Health and Well-Being, which seeks to ensure healthy lives and promote well-being for all; SDG 9 – Industry, Innovation and Infrastructure, which aims to increase access for small industries and other enterprises to financial services and their integration into value chains and markets; and SDG 12 – Responsible Consumption and Production, which proposes to ensure sustainable patterns of production and consumption by promoting the efficient use of natural resources, waste reduction, and the adoption of sustainable business practices throughout the production chain) by proposing innovative solutions for the industry, promoting responsible consumption, and promoting health benefits.