Unraveling the potential nutritional benefits of fermented date syrup waste: Untargeted metabolomics and carbohydrate metabolites of in vitro digested fraction

•Date syrup waste (DSW) was fermented by 2 yeasts and digested to assess biological activities.•Volatile and phenol compounds and untargeted metabolomics were analyzed.•Fermented DSW had greater polyphenol contents with 9 new volatile compounds.•Bioaccessible portions of FDSW had greater levels of α-amylase inhibition.•Bioaccessible portion of FDSW contained 20 carbohydrate metabolites with biological roles. Valorization of fruit by-products is a crucial area of research for the development of innovative bio-based products. This study investigated the physicochemical properties and health-promoting benefits of date syrup waste, both fermented by Pichia cecembensis or Pichia kudriavzevii (FDSW), and unfermented (CDSW). Metabolomics profiles of these samples were identified post in vitro digestion. FDSW exhibited 42 volatile compounds, including 9 new ones, and contained (-)-epicatechin, tyrosol, and gallic acid. Bioaccessible fractions of FDSW demonstrated substantial α-amylase inhibition, with percentages of 40.7 % and 53.9 %, respectively. FDSW displayed superior cytotoxicity against Caco2 and MCF-7 cancer cell lines, with an average of ∼75 % and 56 %, respectively. Untargeted metabolomics analysis revealed an increase in secondary metabolites, totaling 27 metabolites. LC-QTOF analysis of bioaccessible carbohydrate metabolites in FDSW identified two phytochemical groups, alkaloids, and terpenoids. This study underscores the potential of FDSW for producing value-added bio-based products with desirable characteristics and health benefits.