Effect of solvent, temperature, and solvent-to-solid ratio on the total phenolic content and antiradical activity of extracts from different components of grape pomace.
Grape byproducts were subjected to an extraction process under various different experimental conditions (namely, solvent type, temperature, solvent-to-solid ratio, time contact, and raw material) in order to study the effect of these conditions on the yield of phenolic compounds and the corresponding antiradical activity of extracts. Although the order of decreasing capacity to extract soluble materials was ethanol > methanol > water, methanol was the most selective for extracting phenolic compounds. Temperature and solvent-to-solid ratio were found to have a critical role in extraction efficiency; values of 50 degrees C (between 25 and 50 degrees C) and 1:1 (between 1:1 and 5:1) maximized the antiradical activity of phenolic extracts. In addition, extracts from grape samples previously subjected to distillation reached higher antiradical values in comparison to those coming directly from pressing; in both cases, seed extracts showed better results than those of stem when ethanol or water was employed, whereas the opposite occurred in the case of methanol. These differences were attributed to the different phenolic compositions of the considered fractions.
Pinelo
Manuel
M
Escuela Técnica Superior de Ingeniería, Universidad de Santiago de Compostela, Lope Gómez de Marzoa, 15782 Santiago de Compostela, Spain. mpinelo@usc.es
Rubilar
Monica
M
Jerez
María
M
Sineiro
Jorge
J
Núñez
María José
MJ
D005609:Free Radicals / Q000037:antagonists & inhibitors*; D005638:Fruit / Q000737:chemistry; D010636:Phenols / Q000032:analysis*; D010936:Plant Extracts / Q000494:pharmacology*; D012639:Seeds / Q000737:chemistry; D012995:Solubility; D012997:Solvents; D013696:Temperature; D027843:Vitis / Q000737:chemistry*
D005609:Free Radicals; D010636:Phenols; D010936:Plant Extracts; D012997:Solvents