Subcritical Water Extraction of Antioxidants from Buckwheat (Fagopyrum esculentum) Hulls

The objective of this research was to evaluate the feasibility of utilising Subcritical Water Extraction (SWE) for the recovery of the phenolic fraction from buckwheat hulls, with the aim to obtain extracts having high commercial value. In particular, the study was conducted and optimised by using Central Composite Design and Response Surface Methodology with respect to specific parameters such as operating temperature and water pH, namely in the range of 100-160°C and 2.5-6.5 respectively, while the extraction pressure was kept constant at 4 MPa. As reference the hulls were extracted also with MeOH, and in order to compare the two different extraction methods, total phenolic content, rutin content and the antioxidant activity of extracts were assessed.