A Fructo-oligosaccharides and whey protein matrix significantly enhances stability and gastrointestinal retention of bioactive substance anthocyanin

Abstract Black soybean anthocyanin extract (BAC), possessing significant physiological activity, suffers from intrinsic structural instability and high sensitivity to environmental degradation, limiting its food applications. To overcome this barrier, this study engineered protective microcapsules using fructo-oligosaccharides (FOS), whey protein (WP), and FOS-WP complex as encapsulating matrices, fabricated via freeze-drying. Comprehensive characterization revealed the FOS-WP composite wall material achieved excellent encapsulation efficiency (94.21 %) and payload capacity (5.46 %), yielding optimally sized particles (46.5 µm). Crucially, FOS-WP microencapsulation conferred exceptional stability enhancements: anthocyanin retention surged to 85.6 % during simulated gastrointestinal digestion (vs. 59.6 % for free BAC) and demonstrated remarkable stability in model beverage systems (97.6 % vs. 68.8 % at 4 °C; 54.3 % vs. 44.2 % at room temperature after 8 d of storage). This study establishes the FOS-WP synergistic encapsulation system as a highly effective strategy for stabilizing vulnerable bioactive anthocyanins, which could provide technical support for industrial application of BAC in food processing.