Ice Crystal Regulation in Aquatic Products via Physical-Field-Assisted Freezing: Mechanisms and Research Progress

Aquatic products provide one-fifth of global animal protein and are rich in long-chain n-3 polyunsaturated fatty acids. Their fragile muscle structure, high moisture, unsaturated lipids, and endogenous enzymes make them prone to quality loss during freezing. Traditional freezing forms large uneven ice crystals, causing 10%-25% drip loss and rapid lipid oxidation even under standard cold-chain conditions. Various physical-field-assisted freezing methods can regulate supercooling, ice nucleation, and unfrozen water distribution to optimize ice crystal formation. This review analyzes freezing-induced damage from microstructural damage, water migration, molecular instability, and species-specific biochemistry and evaluates technologies by mechanism validity, applicable range, species adaptability, and practical operability. Final product quality is largely determined by the degree of supercooling at nucleation, the rate of latent-heat removal during crystal growth, and the extent of field-induced perturbation to native proteins and lipids. Excessive treatment intensity will trigger tissue deterioration. Currently, high-pressure and continuous ultrasound-assisted freezing have mature mechanisms and applicable parameters, suitable for high-value aquatic products despite limited production capacity. By contrast, magnetic and low-frequency electric field-assisted freezing lack solid theoretical support, with unstable practical effects. This article classifies these techniques by mechanism, operation range, and engineering practicability and puts forward targeted application strategies and standardized research norms. Future studies should resolve contested mechanisms, test hybrid protocols under factorial designs, harmonize reporting standards, and validate scale-up performance.