Development of instant whole grain highland barley: Insights into the effects of drying methods on molecular...

The soak-steam-dry approach was applied to prepare instant whole grain highland barley, elucidating the effects of different drying methods (hot-air, infrared, microwave-assisted hot-air, and freeze-drying) on its molecular structure, digestibility, and rehydration behavior. Dehydration significantly altered water mobility and disrupted microstructure, causing reduced viscosity, elevated pasting temperature, improved thermostability, and modified starch molecular order, which strengthened digestion resistance and shaped rehydration performance. Freeze-drying effectively preserved chemically bound water and endosperm integrity, reduced molecular order, and enhanced thermostability, while microwave-assisted hot-air and infrared drying promoted more ordered structure formation. Infrared drying caused the largest changes in pasting characteristics and increased resistant starch by 33.96% (p < 0.05). Upon rehydration (80 °C and 100 °C), all grains became chewier, with freeze-dried grains rehydrating fastest (∼66.67% time reduction), making it most suitable for instant product development. This study highlights the critical role of drying in shaping the functionality of instant whole grains.