Changes in myofibrillar protein gel quality of porcine longissimus muscle induced by its stuctural modification under different thawing methods

The effects of thawing methods (refrigeration thawing (RT, 4 degrees C), water immersion thawing (WT, 18 degrees C), vacuum thawing (VT, 25 degrees C), ultrasonic thawing (UT, 20 degrees C) and microwave thawing (MT)) on the conformation and gel qualities of myofibrillar protein (MP) obtained from porcine longissimus muscle were investigated. The results showed that MP conformation and gel qualities of porcine longissimus muscles by VT and UT were insignificantly changed compared to fresh meat (FM). A significant decrease in free amino groups of MP from MT illustrated that MT induced protein aggregation and oxidation (P < 0.05). The results of circular dichroism (CD) spectra analysis and fluorescence spectroscopy indirectly proved that thawing can cause protein cross-linking and degradation, secondary structure destruction, non-hydrophilic domain exposed and conformational change of samples. The largest changes in solubility, surface hydrophobicity and particle size were obtained with MT. The effects on the conformation and gel quality of MP were verified during thawing process.