Abstract
Thiolated food-grade biopolymers represent an emerging class of redox-adaptive materials that extend the functional capabilities of conventional hydrocolloids and protein-based structuring agents through reversible covalent interactions. This work provides a systematic, PRISMA-guided synthesis of thiolated food-grade biopolymers, integrating quantitative data on thiol density, speciation, and redox kinetics into a unified structure–mechanism–function framework. Covalent incorporation of sulfhydryl groups enables dynamic disulfide formation and thiol-disulfide exchange, driving time-dependent network evolution, adaptive mechanical reinforcement, and persistent interfacial stabilization under mild aqueous conditions. Across major polysaccharide systems (e.g., chitosan, alginate, pectin, starch, cellulose derivatives), thiol densities span ≈20 μmol g−1 to >5 mmol g−1; however, functional performance is governed primarily by thiol accessibility, oxidation state, and polymer charge environment rather than total thiol content alone. Thiolation induces multi-fold to order-of-magnitude increases in viscoelasticity (G′ ≈102 to >103 Pa; viscosity >104 mPa s), alongside improved encapsulation efficiency and interfacial stability. Key limitations include rapid thiol oxidation at pH ≥ 5, non-linear substitution-performance relationships, and limited control over redox stability. Overall, this systematic analysis establishes design principles for redox-responsive carbohydrate materials while identifying critical barriers to food-system translation.