Abstract: The effects of antifreeze proteins (AFP) on the quality changes of pork during freezing were investigated in comparison to those of the commercial antifreeze agent alginate (4 mg/mL). Samples with no added AFP were used as a control. The effects of adding different amounts of AFP (0.05, 0.1, 0.2, and 0.3 mg/mL) on the quality, physicochemical properties of myofibrillar proteins, microstructure, and water distribution of frozen pork were investigated. The results showed that AFP decreased the water loss of frozen pork, which was beneficial to maintaining pork color and microstructure. Addition of AFP at 0.3 mg/mL had the highest cryoprotective effect on the cooking loss, thawing loss and color characteristics of pork during frozen storage, followed by AFP at 0.2 mg/mL and alginate at 4 mg/mL. The shear force and total sulfhydryl content of myofibrillar proteins in the 0.2 and 0.3 mg/mL AFP groups were significantly higher than those of the control group (P < 0.05). nuclear magnetic resonance imaging (NMRI) discovered that the infiltration of AFP reduced the loss of bound and immobile water in pork. Scanning electron microscopy showed that in the presence of 0.2 mg/mL AFP, the arrangement of muscle fibers was orderly, appearing more compact and denser. Overall, AFP addition had a positive effect on improving the quality of frozen pork and might have the potential of being a safe and efficient cryoprotection method.

Key words: antifreeze proteins; frozen pork; water distribution; myofibrillar protein; microstructure