Dried dates: polar phenols and their fate during in vitro digestion

Abstract

The present study aimed to evaluate the polar phenolic content of dried dates from three varieties and to determine their polar phenol bioaccessibility, using a static model of in vitro digestion. Dried date total phenol content was 55–71 mg GAE/100 g; total flavanol content was 0.2–0.4 mg CE/100 g, total flavone/flavonol content was 8–14 mg RE/100 g. Dates from the Ajwa and Safawi varieties presented the higher total phenol and flavone/flavonol content as compared with dates from the Jomara variety. Flavonoids together with benzoic acids and cinnamic acids were present in all date varieties. Among the compounds identified, gallic acid predominated in Ajwa variety (4.56 ± 0.11 mg/100 g), caffeic acid in Safawi (3.59 ± 0.02 mg/100 g), and neochlorogenic acid in Jomara (1.05 ± 0.10 mg/100 g). Simulated gastrointestinal digestion revealed that date polar phenols were bioaccessible. A 37–70% release was observed post oral digestion, in terms of total phenolic content, that further increased post gastric (> 100%). Total phenols and total flavones/flavonols were found to enter the simulated epithelial cell wall. p-Coumaric acid, ferulic acid, myricetin, and quercetin were identified and quantified in all simulated digestion phases.