Modelling of polyphenol recovery from olive pomace by response surface methodology

Factorial design and Response Surface Methodology (RSM) were used to model the recovery of polyphenols from olive pomace (OP) by solvent extraction. Experiments carried out according to a Central Composite Design (CCD) allowed evaluation of the effects of temperature (T), extraction time (E), solvent composition (C) and liquid-to-solid ratio (R) on the yield of polyphenol extraction. Statistical analysis of the results showed that T was the most influential factor, followed by E, R and C. A reduced polynomial model was developed by the stepwise regression method. The model was checked by performing validation experiments both inside and outside the factorial region. A very good agreement was observed between experimental and calculated extraction yields, thus supporting the use of the model to quantitatively describe the recovery of polyphenols from OP.