Matrix‐Guided Stabilization of Plant Bioactives in Nutrition Powders: Protein–Polyphenol Interactions, Encapsulation Design, and Shelf‐Life Analytics

ABSTRACT Nutrition powders are used to deliver plant bioactives, but apparent stability is often overstated when it is inferred from encapsulation efficiency, day‐zero retention, or bulk antioxidant assays alone. This review develops a matrix‐guided framework for plant‐bioactive nutrition powders, focusing on protein‐polyphenol interactions, carrier matching, encapsulation design, powder formation, shelf‐life analytics, and reconstitution performance. The main weakness in the field is not the lack of encapsulation strategies, but the tendency to treat early retention values as shelf‐life evidence. The review argues that stability claims require three connected checks: chemical retention, powder physical state, and functional performance after reconstitution. The central trade‐off is that mechanisms that appear protective in one matrix may create a different failure mode in another. Protein binding may preserve phenolics while lowering extractability; carbohydrate matrices may immobilize water while failing to support lipophilic actives; and emulsion‐based systems may improve dispersion while increasing oxidation risk. This review proposes an evidence chain that deliberately limits stability claims to what has been validated across chemistry, powder physics, and use‐stage performance. Nutrition‐powder stability is claimed only when chemical retention, physical state, and application performance are evaluated together.