Lc pak millex system

The HPLC-grade water was obtained from a LC-Pak™ Millex system (Millipore Corporation, Billerica, MA, USA). Formic acid, MS grade methanol, citric acid, galacturonic acid, malic acid, glucose, sucrose, gallic acid, and caffeine were obtained from Sigma-Aldrich, St. Louis, MO, USA. Quinic acid, catechin, procyanidin B 1 , procyanidin C 1 , kaempferol glucoside, kaempferol, rutin, and quercetin rhamnoside were obtained from PhytoLab, Vestenbergsgreuth, Germany. The ''Degla-Beida'' dates used in this study present a dry nature and a hard texture, that are found in the palm groves of South-East Algeria. The choice of this variety is justified by its relative abundance on the national territory, its low market value, its long shelf life due to its dry nature, its taste and nutritional quality (energy source represented by its high sugar content) (Djaoud et al., 2020) . The dates were washed with tap water followed by distillated water, pitted and deposited in a drying oven at 40°C until up to a constant weight. Then, the dried samples were ground into a fine powder, which was passed through a standard sieve (125 µm diameter) and only the fraction with the particle size≤125 µm was used. Finally, the powder was stored in the darkness (Djaoud et al., 2019) .