Influence of whey protein-xanthan gum stabilized emulsion on stability and in vitro digestibility of encapsulated astaxanthin

The combination of proteins and polysaccharides has potential to act as good emulsifiers and stabilizers. The aim of this study was to evaluate the stability of the emulsion system stabilized by whey protein isolate (WPI) (2–5 wt%) and xanthan gum (XG) (0.25 and 0.5 wt%). Furthermore, the influence of WPI-XG emulsion system on the thermal stability of incorporated astaxanthin under different storage temperatures (5, 25, 37, 55 and 70 °C) and in vitro digestion were investigated. The emulsion system with higher XG concentration (0.5 wt%) exhibited the highest viscosity, emulsion stability, and creaming stability. The WPI-XG stabilized emulsion exhibited higher stability of astaxanthin at lower storage temperature (5, 25 and 37 °C) with 10–12% astaxanthin loss during 15 days of storage. During in vitro digestion, emulsion stabilized by WPI-XG demonstrated influence on droplet digestion process, significantly (p˂0.05) lower lipid digestibility and lower astaxanthin digestion (12.6%) in comparison to emulsion stabilized by WPI alone. This research study provides platform for designing fortified food or beverage systems incorporated with hydrophobic bioactive compounds for better stability and delivery to target sites.