Dual enzyme-modified porous starch granules with α-glucan coating: Structure-function tailoring for enhanced...

Porous starch granules (PSGs) with tailored pore structures were produced by a one-pot dual enzymatic hydrolysis system. Combining α-amylase with glucoamylase (α/g-PSGs) yielded higher hydrolysis efficiency and larger, interconnected pores compared with β-amylase (α/β-PSGs), resulting in enhanced water-holding (477%) and oil-holding (348%) capacities. α/g-PSGs were coated with α-glucans synthesized by amylosucrase. The amylosucrase-mediated glucan coating reduced crystallinity (38% → 19%) and increased long-chain glucans (DP ≥ 37), leading to an amorphous and flexible matrix. The α-glucan-coated PSGs (C-PSGs) were evaluated as carriers for probiotics. Encapsulation of Lacticaseibacillus spp. and Bifidobacterium longum improved survival under stress conditions. Under acid and bile stress, C-PSGs maintained 90% viability, showing a 5-10% higher survival rate compared with uncoated PSGs. Under heat and oxygen stress, C-PSGs preserved 85-90% survival while free cells decreased to 55-60%. These findings show that the α-glucan coating provides digestive resistance and protection against stress. Real-time monitoring via a Thunder imaging system confirmed strain-dependent growth and the structural integrity of encapsulated probiotics. These results demonstrate that C-PSGs effectively enhance probiotic stability and serve as multifunctional carriers for bioactive materials.