A method for producing a proanthocyanidin extract is described. The method comprises: (a) providing a volume of proanthocyanidin-containing liquid feedstock； (b) passing the proanthocyanidin-containing liquid feedstock to an ultrafiltration feed tank； (c) filtering the material in the ultrafiltration feed tank through an ultrafiltration membrane system to fractionate the material into a proanthocyanidin-reduced permeate stream and a proanthocyanidin-enriched retentate stream； (d) collecting the proanthocyanidin-reduced permeate stream； and (e) passing the proanthocyanidin-enriched retentate stream to the ultrafiltration feed tank until the volume of proanthocyanidin-containing liquid feedstock is exhausted and thereafter collecting the proanthocyanidin-enriched retentate stream.
