Alkaline-pH-shifted mung bean protein isolate for spray-dried probiotic encapsulation: Insights into molecular cell wall interactions and oxidative protection

Probiotics suffer low viability from heat and oxidative stress during spray drying. This study evaluated alkaline-pH-shifted mung bean protein isolate (pHMBPI) as an encapsulant for Limosilactobacillus reuteri KUB-AC5, compared with mung bean protein isolate (MBPI) and whey protein isolate (WPI). pHMBPI showed the highest solubility (82.66%), surface hydrophobicity (3574), and ABTS• + scavenging activity (91.62%). pHMBPI-spray-dried cells had the lowest cell wall (25.31%) and membrane injury (10.22%), the highest viable count (1.49 × 10 9 CFU/g) and survival (9.91%). Viability during digestion remained high (8.60 and 8.05 log CFU/g in gastric and intestinal fluids). NMR confirmed reduced lipid peroxidation, preserving 85.2% of bis-allylic protons. Molecular dynamics simulations revealed strong electrostatic interactions between 8S-alpha globulin and cell wall targets, including peptidoglycan, Mub-RV, and SRRP53608. These results identify pHMBPI as a promising encapsulant offering enhanced thermal stability, antioxidant defense, and targeted bacterial surface binding. • pH shifting enhanced encapsulating properties of mung bean protein isolate (MBPI). • pH-shifted MBPI (pHMBPI) reduced lipid peroxidation and probiotic membrane injury. • pHMBPI minimized cell wall damage, improving probiotic survival under heat. • Viable probiotic cells reached 1.49 × 10 9 CFU/g with pHMBPI after spray drying. • MD simulations showed tight 8S globulin-cell wall protein binding under heat.