Extraction of polyphenols from white distilled grape pomace: optimization and modelling.
Both ethanolic and aqueous extraction were carried out in a laboratory-scale vertical extractor to obtain polyphenols from distilled grape pomace of Vitis vinifera var. "Albariño". An experimental design was performed to analyse the effects of flow (2 ml/min and 4 ml/min) and temperature (40 degrees C and 50 degrees C). Yields of polyphenolics from aqueous extraction were much higher (up to 30-fold) than those of ethanolic extraction, in contrast with previous results obtained by us from batch extraction of different grape varieties. Polyphenols extraction was modelled by application of second Fick's law to spherical particles of 0.5 mm diameter, so obtaining the effective diffusion coefficient as parameter. The mass transfer coefficients were also estimated, giving as result that the external mass transfer resistance was negligible. Correlation coefficients ranged 0.989-0.9999. Effective diffusivity values in water extraction assays were between 0.6x10(-11) m(2)/s and 2.1x10(-11) m(2)/s. Using ethanol as solvent, the effective diffusivity was lower, between 0.1x10(-11) m(2)/s and 0.76x10(-11) m(2)/s.
Guerrero
M Sánchez
MS
Department of Chemical Engineering, School of Engineering, USC, Rúa Lope Gómez de Marzoa, s/n. 15782, Santiago de Compostela, Spain.
Torres
J Sineiro
JS
Nuñez
María José
MJ
D005419:Flavonoids / Q000737:chemistry*; D007220:Industrial Waste; D007700:Kinetics; D008956:Models, Chemical; D010636:Phenols / Q000737:chemistry*; D059808:Polyphenols; D013997:Time Factors; D027843:Vitis / Q000737:chemistry*; D014920:Wine
D005419:Flavonoids; D007220:Industrial Waste; D010636:Phenols; D059808:Polyphenols