“All oat!” Optimizing the spray drying process for oat oil emulsions stabilized by cellulose nanocrystals and methylcellulose

Oil-filled powders are increasingly important as nutraceutical use expands across food, cosmetic, and pharmaceutical sectors. Oat products are attractive for such applications due to their high antioxidant content, however oat oil (a grain refining by-product) remains challenging to stabilize because it readily oxidizes and thus has not previously been converted into a dry, reconstitutable powder. Here, we report a fully bio-based encapsulation platform in which oat oil is stabilized by cellulose nanocrystals (CNCs), food-grade methylcellulose, and tannic acid. Emulsion stability was evaluated for cold-pressed and solvent-extracted oat oils, with cold-pressed exhibiting superior stability. Spray drying was systemically optimized using a design-of-experiments (DOE) approach to quantify the effects of CNC content and processing parameters on powder yield and quality. The optimized powders achieved yields up to 82%, oil contents of 89%, moisture contents below 2%, and rapid reconstitution into stable emulsions, with CNC content identified as the dominant factor governing performance. CNCs were also extracted directly from oat hulls and applied to produce an "All Oat!" encapsulation system in which both stabilizer and oil come from a single biomass source. Overall, this work establishes a scalable, energy-efficient, carbohydrate-driven route to high-oil-loading powders that meets the growing demand for surfactant-free, sustainable formulations.