RESUMO
Wine lees are rich in anthocyanins (AC), natural colorants with health promoting properties. The extraction kinetics of AC from different wine lees in conventional solid-liquid extraction were studied for the first time. The influence of parameters such as temperature, solid-liquid ratio (RS-L) and type of solvent (hydro-alcoholic mixtures) was also studied. Furthermore, microwaves (MW) and ultrasounds (US) were used as pre-treatments (a prior step to the conventional extraction) in order to increase AC yield. Maximum extraction yield (2.78â¯mgMALVIDIN-EQUIVALENTS/gDRY-LEES) was achieved after 15â¯min at 25⯰C, with a RS-L of 1/10â¯(g/mL) and with a 50%vol. ethanol mixture. When MW were used AC extraction yield was doubled (6.20â¯mgMALVIDIN-EQUIVALENTS/gDRY-LEES) and the required time to achieve a constant yield was reduced (from 15â¯min to 90â¯s). Meanwhile, US only shortened extraction time in less proportion (from 15 to 5â¯min). Putative identification of main extract compounds was performed by LC/MS-MS.
Assuntos
Antocianinas/isolamento & purificação , Fracionamento Químico/métodos , Micro-Ondas , Ondas Ultrassônicas , Vinho/análise , Antocianinas/análise , Etanol/químicaRESUMO
Aging wine lees are water-wastes produced during the wine aging inside wood barrels that can be considered as alternative sources of bioactive compounds. Phenolic characterization and antioxidant activity (AA) measurements of wines lees solid-liquid extracts have been undertaken on a dry extract (DE) basis. Solvents with different polarities (water, methanol, ethanol, two hydroalcoholic mixtures and acetone) were used. Total phenolic (TPC) and total flavonoid contents (TFC) were determined. The mixture of 75:25(v/v) EtOH:H2O showed the highest values with 254â¯mgGAE/gDE and 146â¯mgCATE/gDE respectively. HORAC, HOSC and FRAP were used to determine the AA of the extracts being also highest for the mixture of 75:25(v/v) EtOH:H2O (4690⯵molCAE/gDE, 4527⯵molTE/gDE and 2197⯵molTE/gDE, respectively). For ORAC method, methanol extract showed the best value with 2771⯵molTE/gDE. Correlations between TPC, TFC, phenolic compounds and AA were determined. Most relevant compounds contributing to AA were identified using data from mass spectrometry, being mainly anthocyanins.