Extratos hidroalcóolicos de jabuticaba, uva e hibisco nanoencapsulados: aplicação como antimicrobiano e como enriquecedor de tapioca

Abstract

The growing demand for foods that offer health benefits has encouraged the development of products enriched with bioactive compounds. However, the instability of these compounds in food systems represents a challenge. Nanoencapsulation technology emerges as a solution to overcome these limitations, promoting greater stability and effectiveness of bioactive compounds. In this context, this study aims to evaluate the bioactive potential of the residues (peels and seeds) from grape and jabuticaba fruits, as well as hibiscus (calyx and seed fruit), and to encapsulate these compounds followed by their return to the food matrix through the enrichment of cassava starch. All raw materials were processed into flours and characterized in terms of proximal and physicochemical composition, revealing particularities among them. Mineral profiles, carbohydrates, phenolic compounds, flavonoids, and organic acids were determined, along with the quantification of bioactive compounds such as chlorophyll, carotenoids, anthocyanins, and flavonoids. Extracts (water, 10% ethanol, 50% ethanol, 70% ethanol, and 80% ethanol) were produced to evaluate antioxidant activity and determine the best concentration for extraction by maceration and percolation. The best solvents for grape peel and seed flour (80% and 10% ethanol), jabuticaba peel and seed (50% and 80% ethanol), and hibiscus calyx and seed fruit (80% and 10% ethanol) were determined and characterized. Functional group analyses of pre- and post-extraction flours were performed by FTIR-ATR, as well as of crude and concentrated extracts. Finally, antimicrobial activity was assessed. The results showed that the flours are excellent nutritional sources, with seed portions presenting the highest levels of most minerals. Grape and jabuticaba peel flours exhibited the highest concentrations of carbohydrates (fructose, glucose, and sucrose). The main organic acids were tartaric and ascorbic acids, and the main phenolic compounds present in the flours were catechin and gallic acid. The maceration + percolation extraction method was effective in recovering and preserving phenolic compounds from the flours, with higher results for jabuticaba peel and seed. Regarding antimicrobial activity, only the concentrated jabuticaba seed extract was able to inhibit the growth of Salmonella choleraesuis (500 µg mL−1), Escherichia coli (500 µg mL−1), Klebsiella pneumoniae (1000 µg mL−1), and Bacillus subtilis (1000 µg mL−1). The nanoencapsulation of concentrated extracts showed variations in encapsulation efficiency (13.61% to 87.54%) and particle size (545.85 nm to 1539.96 nm), with grape and jabuticaba peel nanoparticles demonstrating the highest bioactive compound retention and thermal stability after being applied to tapioca. These samples also caused significant visual changes, such as reduced luminosity and increased saturation. The results suggest that these nanoparticles are promising for enriching foods and improving their functional and visual properties.