A process of extracting procyanidins by alkaline hydrolysis. In particular, a procyanidin-containing material, pomace or residue is treated with an alkali, such as sodium or potassium hydroxide, for a predetermined amount of time and at a predetermined temperature to release procyanidins bound to polysaccharides and/or proteins of the cell wall or depolymerize polymeric procyanidins. After the procyanidins are released by alkaline hydrolysis, the extracts are acidified to obtain a pH level where the procyanidins do not degrade. The process of extracting procyanidins may be utilized to estimate the total amount of bound procyanidins in a plant material, enhance the bioavailability of beneficial procyanidins monomers and/or to treat the residue remaining after conventional solvent extraction for increased procyanidin extraction.
