| Abstract
| - Concord grape juice with 20% polymeric and 60% monomeric anthocyanin (Acy) forms wasultrafiltrated using polyvinylidene fluoride flat sheet membranes ranging from 10 to 1000K molecularweight cutoff (MWCO) to obtain different permeate and retentate fractions. Permeate flux, membraneresistance, Acy rejection, fouling, Acy content and composition, color properties, and antioxidant activity(AOX) were characterized. Results showed that permeate flux declined with lower MWCO, whilemembrane resistance increased and related exponentially with fouling. Anthocyanin membranerejection differed for polymeric and monomeric Acy forms. Polymeric Acy increased (36−66%) andmonomeric Acy decreased (12−20%) in retentate fractions with membrane pore size of <100KMWCO, while polymeric Acy decreased (11−28%) and monomeric Acy increased (5−7%) in permeatefractions. Fraction properties showed that AOX related linearly with the total phenolic content, whilelightness and chroma color properties related linearly to the monomeric Acy content. These resultsindicate that ultrafiltration can be used to tailor monomeric and polymeric Acy fractions with potentialeffects in color and bioactive properties. Keywords: Grape anthocyanin composition; fractionation; ultrafiltration; color; membranes;antioxidants
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