Low pH-assisted hydrothermal extraction approach to recover bioactive compounds from date seeds for their potential application in emulsion stabilization

Abstract

Date seeds, a major byproduct of the date palm industry, despite recent attempts at valorization, yet remain an underexploited economic resource. This study evaluated whether date seeds can be valorized by low pH-assisted hydrothermal extraction to yield date seed extract (DSE) that is rich in bioactive compounds and capable of stabilizing emulsions. Using an I-optimal design, the effects of extraction time (30–150 min), temperature (30–50 °C), pH (1–6), and date seed concentration (DSC, 5–25 %) were evaluated to maximize bioactive compounds in the extract evaluated as total polyphenol content (TPC) and minimize Sauter mean diameter (D[3,2]) of emulsion. All parameters significantly influenced TPC and D[3,2], with time and temperature positively impacting both. The effects of pH and DSC followed quadratic trends, with optimal values balancing bioactive release and emulsion droplet size. The predictive response surface models effectively captured these trends, enabling process optimization. Emulsions stabilized with optimized DSE exhibited good storage stability under neutral to mildly acidic conditions, however, their stability decreased with increasing salt concentrations. These findings support the potential valorization of date seeds by low pH-assisted hydrothermal extraction to recover bioactive compounds as well as to stabilize emulsions. Further studies are recommended to improve salt stability and expand functional applications of DSE-stabilized emulsions in complex food or pharmaceutical systems.