Superfine Grinding of Oat Powder for Filtration-Free Oat Milk Production: Effects on Powder Properties, In Vitro Digestion, and Oat Milk Quality

Oat milk (OM) has gained popularity as a plant-based dairy alternative; however, conventional filtration-based production removes oat pulp, leading to β-glucan loss and processing waste. This study investigated the effects of particle size reduction by different grinding techniques on the powder properties and in vitro digestion characteristics of oat powder (OP), and it evaluated the applicability of superfine OP to filtration-free OM production. OP was prepared at three particle sizes: coarse, fine, and superfine, using a blender, ultra-centrifugal mill, and ball mill, respectively. Decreasing particle size improved hydration properties, including water absorption capacity, swelling capacity, and water solubility. During in vitro digestion, OP-superfine showed higher dialyzable protein fraction, β-glucan extractability, and digestion extract viscosity than OP-coarse, indicating an enhanced release of proteins and viscosity-contributing soluble components. When applied to OM, OP-superfine increased viscosity, Brix, turbidity, and suspension stability, while particle size had only a minor influence on pH. Sensory evaluation showed that OM prepared with OP-superfine had reduced grittiness and throat-feel intensity while maintaining relatively high sweetness. These findings suggest that superfine grinding is a promising strategy for producing filtration-free OM with improved digestion-related properties, physical stability, and sensory quality.