Optimizing the extraction of phenolic antioxidants from date palm fruit by simplex-centroid solvent mixture design

Date palm (Phoenix dactylifera L.) fruits are rich in various bioactive compounds, such as phenolic acids, hydroxycinnamates, flavonoid glycosides, coumarins, alkaloids, and proanthocyanidin oligomers. The focus of this study was to develop a simplex-centroid mix design method to identify the most suitable mixture of solvents (water, acetone, and methanol) to extract bioactive compounds from date fruits. Three extraction solvents (water, methanol, and acetone) were investigated during this study to determine, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (free radical DPPH) and ferric reduction ability (FRAP). The results showed that polar mixtures were effective in extracting antioxidant phenolics. The optimum solvent for extraction was Binary mixture water-acetone (50%) presenting TPC, TFC, DPPH and FRAP values of 502.88 mg GAE.100 g^-1 DW, 206.23 mg QE.100 g^-1 DW, 77 0.01% and 1688.66 μmol.100 g^-1 respectively. The results also confirmed a strong correlation between the amount of polyphenols in a given extract and the antioxidant activities observed in the DPPH and FRAP assays. This study presents a pragmatic and efficient way to choose a solvent combination to extract polyphenols from date palm fruits.