Plant polysaccharides as natural cryoprotectants: From structure to antifreeze mechanisms in frozen food systems.

Freezing, while a key food preservation method, often induces quality deterioration due to uncontrolled ice crystal growth, water migration, and disruption of structural integrity in food matrices. Developing effective cryoprotective strategies is therefore essential for maintaining the quality and stability of frozen foods. Although traditional cryoprotectants are effective, their high sweetness and calorie content limit wider use. Natural plant polysaccharides have thus emerged as promising sustainable alternatives, yet the links between their complex structures and multifaceted antifreeze mechanisms remain unclear. This review critically discusses recent advances in plant-derived polysaccharides for cryoprotection, with emphasis on how structural features, including molecular weight, branching, chain flexibility, and functional groups, may influence cryoprotective performance through different mechanisms. A four-dimensional framework is proposed-encompassing ice crystal inhibition, water mobility regulation, macromolecular stabilization, and viscoelastic network formation-and compared across food matrices. In addition, we summarize recent advances in the application of polysaccharides across various frozen food systems, including frozen meat and seafood products, frozen dough and bakery products, ice cream and dairy-based products, and plant-based products. Findings show that polysaccharides act synergistically to control ice behavior, water distribution, and macromolecular stability, performing as dynamic phase regulators rather than mere physical stabilizers. Their efficacy depends on both structural features and matrix complexity, underscoring the need for system-specific design. Future work should focus on structure-activity relationships in complex systems to enable rational design of efficient, multifunctional natural cryoprotectants.