Bletilla striata Polysaccharide: Structural Characteristics, Chemical Modification Strategies, and Dual-Field Application Progress in Biomedicine and the Food Industry

Bletilla striata polysaccharide (BSP), a bioactive glucomannan derived from the traditional Chinese medicinal herb Bletilla striata, has garnered increasing attention in both the biomedical and food sectors due to its unique physicochemical properties and diverse biological activities. While existing reviews have partially covered BSP’s structural features or single-field applications, a systematic review integrating its structure–activity relationship, full-spectrum chemical modification strategies, and parallel advances in the dual core fields of biomedicine and the food industry remains lacking. This review systematically consolidates recent advances in BSP research, focusing on three interconnected aspects: (1) the structure–activity relationships of BSP, highlighting how molecular weight (104–105 Da), monosaccharide composition (mainly glucose and mannose with variable ratios), glycosidic linkages, and higher-order self-assembled structures (e.g., triple-helix conformation) dictate its functionality in biological systems and food matrices; (2) chemical modification strategies—including carboxymethylation, graft copolymerization, cross-linking, polysaccharide–trace element complexation, phosphorylation, acetylation, and cholesterylation—that overcome intrinsic limitations of native BSP to enhance solubility, targeting, bioactivity, and food-related functional properties; and (3) the expanding applications of BSP and its derivatives in biomedicine (hemostatic materials, tissue engineering scaffolds, drug delivery systems, immunomodulation, and antitumor effects) and in the food industry (as natural stabilizers, emulsifiers, functional additives, and bio-based packaging components). Compared with previously published reviews, this work establishes a complete closed-loop logical system from structural characterization to rational modification and cross-field application and provides the most up-to-date systematic summary of BSP research. Key challenges—such as an incomplete understanding of structure-function correlations, insufficient pharmacokinetic data, and a lack of standardized quality control—are discussed, and future research directions are proposed. This review aims to provide a systematic theoretical basis for advancing BSP as a versatile multifunctional material for applications in functional foods, nutraceuticals, and biomedical fields.