Optimization of maltodextrin–gum arabic–whey protein systems for freeze-drying microencapsulation of young barley leaf extract

Abstract

Young barley leaves are rich in bioactive compounds but highly prone to oxidation, necessitating stabilization for functional food applications. This study encapsulated barley leaf extract using maltodextrin (MD), whey protein isolate (WPI), and gum arabic (GA), and optimized wall-material ratios through freeze-drying and response surface methodology (RSM). Model fitting confirmed strong statistical performance, with significant quadratic models (p < 0.05), non-significant lack-of-fit, R² values up to 0.99, and adequate precision above 40, ensuring reliable prediction across the design space. Experimentally, MD-rich formulations achieved the highest microencapsulation yield (∼89%), while encapsulation efficiency (83.67–89.98%) maximized in a ternary MD–WPI–GA blend (67.66 : 16.67 : 16.67). Moisture content (10.22–11.29%), water activity (0.34–0.40), and particle size (34.50–37.59 µm) indicated good storage stability and structural integrity. Solubility reached 75.29% in MD–GA systems, and the highest glass transition temperature occurred in the ternary blend, reflecting enhanced thermal stability. Bioactive preservation was substantial, with total phenolic content (∼70 mg GAE per g) and antioxidant activity (∼80%) maintained effectively. Overall, MD contributed to high yield, GA to emulsion stability, and WPI to improved film-forming and antioxidant protection. The optimized microcapsules demonstrated strong stability and functional potential for use in nutraceuticals, functional foods, and instant beverage formulations.