Effects of freeze-thaw cycles on physicochemical properties and structure of cooked crayfish (Procambarus clarkii)

Abstract To explore the damage mechanisms of freeze-thaw cycles on cooked crayfish in frozen storage, changes in the physicochemical properties and structure of cooked crayfish during the freeze-thaw cycles were investigated. The physicochemical properties of cooked crayfish changed significantly after five freeze-thaw cycles. The moisture content, water holding capacity, pH, and textural properties were decreased, while the total color difference, drip loss, and protein and lipid oxidation were significantly increased (P < 0.05). LF-NMR and MRI verified the water loss, and SDS-PAGE showed denaturation/degradation of myofibrillar proteins (MPs). Multiple freeze-thaw cycles promoted the transition from α-helix to β-turn in the secondary structure, the unfolding of tertiary structure, and a significant change in the chemical forces of MPs. SEM results revealed a disruption in the microstructure of muscle fibers. Repeated freeze-thaw cycles reduced the moisture content and distorted the structure of MPs in cooked crayfish, resulting in the disruption of physicochemical properties and its structure. Graphical Abstract