Roasted date palm seeds (Phoenix dactylifera) as an alternative coffee: chemical composition and bioactive properties

Abstract

Less used date palm fruits, as Bouhattam variety, are being converted into coffee through a roasting thermal process. Therefore, laboratory assays were conducted to investigate chemical and cytotoxic proprieties of this commercial coffee. Mineral content determination showed that roasted seeds of Bouhattam were a source of K+ and Ca2+. Date seed powder was fractionated successively using organic solvents of increasing polarity (cyclohexane, CYHA; dichloromethane, DCM; and methanol, MeOH). While the best yield was recorded for CYHA fraction, the MeOH extract showed the strongest antioxidant activity associated with highest total polyphenol content (TPC) (56.7 mg eq GAE/g dry wt). LC-MS analysis revealed that two major phenolic compounds were identified in methanolic extract: protocatechic acid (67.6 mg/100 g dry wt), which is generally found in tea and quinic acid (39.5 mg/100 g dry wt), known as the main compound of coffee beans. Vitamin E was identified only in the MeOH extract and vitamin K1 was identified in DCM and CYHA ones. GC-MS data showed that the roasted date seed coffee was decaffeinated, and the most volatile compounds were identified as fatty acids in the CYHA extract. All tested organic extracts against MCF-7 and HCT-116 cell lines displayed lower cytotoxicity. Taken together, obtained results argued that roasted seed powder of Bouhattam variety is an excellent decaffeinated beverage enriched with polyphenols and vitamins concomitant with high antioxidant potential and lower cytotoxicity.