The optimal conditions for the extraction of polyphenolic compounds from hard
Syrian wheatvarieties (Hourani, Doma1,Bohoos11) were determined using response
surface methodology. A Central Composite Design was used to investigate the effects of
thr
ee independent variables, namely solvent concentration, extraction temperature and
time on the response phenolic content. The independent variables were at three levels and
their actual values selected on the basis of preliminary experimental results. A secondorder
polynomial model was used for predicting the response.
Regression analysis showed that more than 95-97% of the variation was explained by
the models. The optimal conditions for phenolic compounds extraction were found to be
acetone concentration of 49.5 %v/v, extraction temperature of 55.5°C, extraction time of
42.5min, for wheat. Under the optimum conditions the corresponding predicted response
values for polyphenolic compounds were 0.976 mg EGA forHourani, 0.947 mg EGA
forDoma1 and 1.316 mg EGA for Bohoos11. The phenlics were extracted under optimum
conditions to check the validity of model, and the experimental values were 0.969±0.05
,0.932±0.03 and 1.214±0.06 mggalic acid equivalent /g dry weight from wheatvarieties
(Hourani, Doma1,Bohoos11) respectively. The good agreement between predicted and
,experimental values indicated suitability of the model employed and the success of
response surface methodology in optimizing the extraction conditions.
