Alginate-Based Encapsulation of Phenolic Compounds: Insights Into Gastrointestinal Stability, Release Behavior, and...

The inherent instability of dietary phenolics under gastrointestinal conditions has prompted interest in alginate-based encapsulation to enhance their stability, delivery, and bioaccessibility. This review critically evaluates recent in vitro studies, revealing that most rely on static digestion models and primarily use direct spherification, with limited investigation of alternative structuring strategies. Formulation approaches often include fillers (e.g., inulin, pectin, xanthan, and psyllium) and surface coatings such as chitosan to improve structural integrity, although their impact on release modulation is generally modest. Alginate systems consistently exhibit pH-responsive behavior, limiting release in gastric conditions while promoting release in the intestinal phase, largely governed by matrix properties rather than compound-specific factors. Encapsulation generally improves phenolic bioaccessibility compared to nonencapsulated systems; however, the extent of improvement varies depending on formulation design and matrix interactions. Reported antioxidant activity changes are also inconsistent, reflecting differences in analytical methods and digestion-induced transformations. Although most studies focus on hydrophilic phenolics, recent evidence indicates that alginate systems can also modulate the release of lipophilic compounds via structured delivery approaches. Future research should prioritize dynamic digestion models, real food matrices, and in vivo studies to better represent physiological conditions and improve the relevance of findings.