RESUMO
Multi-response optimization of hot pressurized liquid extraction (HPLE) was applied for the first time to obtain maqui (Aristotelia chilensis [Mol.] Stuntz) leaf extracts. The total polyphenol content (TPC), the antioxidant capacity (AC) as well as the total polyphenol purity of the maqui leaf extracts were accurately predicted (RSD < 8%) at the evaluated extraction scales. The optimum HPLE conditions that prioritized TPC and AC equally (OPT1) recovered ~3 times more TPC (205.14 mg GAE/g leaves) than maqui leaf extracts obtained by maceration, while the extract that prioritized purity over TPC and AC presented the highest purity (36.29%) and an EC50 ~3 times lower than currently reported values. It was found by multi-response optimization that maqui leaves and HPLE are among the best natural sources and extraction techniques, respectively, to recover protocatechuic acid, quercetin, and catechin.
RESUMO
The evolution of polyphenolic compounds and sensory properties of wines obtained from Grenache grapes, either untreated or treated with pulsed electric fields (PEF), in the course of bottle aging, as well as during oak aging followed by bottle aging, were compared. Immediately prior to aging in bottles or in barrels, enological parameters that depend on phenolic extraction during skin maceration were higher when grapes had been treated with PEF. In terms of color intensity, phenolic families, and individual phenols, the wine obtained with grapes treated by PEF followed an evolution similar to untreated control wine in the course of aging. Sensory analysis revealed that the application of a PEF treatment resulted in wines that are sensorially different: panelists preferred wines obtained from grapes treated with PEF. Physicochemical and sensory analyses showed that grapes treated with PEF are suitable for obtaining wines that require aging in bottles or in oak barrels.