Standardization of proanthocyanidin extract’s mean degree of polymerization using eutectic solvents

Abstract

Proanthocyanidin’s molecular characteristics, especially mean degree of polymerization (mDP), have a high impact on their anti-inflammatory and antioxidant activities. Nevertheless, the mDP of proanthocyanidin’s extracts obtained from the same plant species can change due to the use of different plant varieties or by using plant material grown in different conditions/locations leading to extracts with compositional variabilities, that conventional extraction techniques cannot overcome, but that have a great impact on final applications.Eutectic solvents are a new class of solvents that can be prepared by combining a wide variety of compounds in variable proportion allowing for their customization to specific applications. By changing eutectic solvent’s composition it is possible to obtain proanthocyanidins with a specific mean degree of polymerization, regardless of the raw material.Herein, the use of a quaternary eutectic solvent system composed by choline chloride, glycerol, water and ethanol that was previously described as an efficient media for the extraction of proanthocyanidins was explored in the standardization of proanthocyanidin extracts’ mDP obtained from grape pomace by means of Response Surface Methodology. By adjusting the content of each eutectic solvent component to different grape pomaces, it was possible to overcome the limitations normally observed with conventional solvents. More specifically, the production of proanthocyanidin extracts with the desired mDP values (6.5 and 7.5 were selected for validation purposes) from three different grape pomaces that would otherwise lead to considerably different results.