Methyl beta-cyclodextrin as a booster for the extraction for Olea europaea leaf polyphenols with a bio-based deep eutectic solvent

摘要

A novel deep eutectic solvent (DES) with optimised composition was used to evaluate the effect of methyl beta-cyclodextrin (CD) on the efficiency of polyphenol extraction from Olea europaea leaves (OLLs). The process developed was based on a 2(3) full-factorial design and response surface methodology to assess the simultaneous effect of CD concentration (C-CD), liquid-to-solid ratio (R-L/S ) and temperature (T). Under optimised conditions (C-CD = 9%, R-L/S = 40 mL g(-1), T = 51 degrees C), the yield in total polyphenols (Y-TP) was 116.65 +/- 3.60 mg gallic acid equivalents per g dry weight. This value was significantly higher than that determined for the extraction performed with 60% aqueous ethanol. The extraction kinetics also showed that the extraction rate was slowed down in the presence of CD, yet the higher extraction capacity of the DES/CD medium was confirmed. Characterisation of the extracts obtained with DES/CD and DES by means of liquid chromatography-mass spectrometry demonstrated that there was no selective extraction of any particular polyphenol, suggesting that CD acted merely as an extraction booster.