Oxidative changes and weakened gelling ability of salt-extracted protein are responsible for textural losses in dumpling meat fillings during frozen storage

The objective of the study was to investigate the contribution of oxidation and rheological behaviour of proteins present outside the meat particle (OMP) and those remaining inside the meat particle (IMP) in dumpling meat fillings. The −7 °C sample fillings stored for 180 d had a significantly lower breaking strength and water-holding capacity than those stored at −18 °C and −7 °C/−18 °C (P < 0.05). Microscopy of stained samples showed significant fat exudation in the high (−7 °C) and fluctuating (−7 °C/−18 °C) temperature treatments during storage, coinciding with decreased thermal stability of OMP. There was a more abundant carbonyl production in OMP than in IMP (P < 0.05). The storage modulus G′ in OMP was significantly lower than that in IMP. Moreover, SDS-PAGE showed that −7 °C and −7 °C/−18 °C samples produced more insoluble protein aggregates. These findings indicate that oxidative damage and reduced gelling potential of OMP proteins led to reduced textural properties in frozen dumplings.