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This study aimed to address the effects of frozen storage temperature and duration on the changes in physicochemical properties of beef myofibrillar protein. The beef was stored at −1, −6, −9, −12, and −18°C for 28, 84, 126, 168, and 168 days, respectively. The myofibrillar protein of beef samples denatured gradually with the extention of storage period. Regarding the samples stored at temperature range of −12∼−1°C, higher storage temperature resulted in more severe denaturation (the myofibrillar protein exhibited lower sulfhydryl content, Ca2+-ATPase activity, ionic bonds, hydrogen bonds, and higher surface hydrophobicity). Particularly, difference in −12 and −18°C did not yield significant effects upon the protein properties throughout 168-day storage P>0.05. These results indicated that lowering freezing temperature may not minimize myofibrillar protein denaturation in a limited storage duration, which was also confirmed by the quality properties of beef.

Cooking meat at different temperatures resulted in loss of fluids and alterations in its textures. This work signifies the effect of different cooking temperatures on the volumetric changes and biophysical properties of breast meat blocks obtained from broilers and yellow-feather chicken (YFC). Shrinkage in the length and volume of meat blocks of broilers were higher, whereas YFC showed an increase in cross-sectional area. At each cooking temperature (60°C, 70°C, 80°C, 90°C, and 100°C), mostly there were significant differences (p< .05) in volumetric changes found between the meat block of both breeds. Results from the biophysical properties indicated that the cooking of broilers meat below 80°C increases its hardness, the opposite was observed for YFC. Cooking at 100°C produced more hardness in YFC meat than broilers (34.15 N vs 26.80 N) (p< .05). Moreover, cooking at higher temperature produced early gel properties in broilers than YFC meat. SDS-PAGE results revealed a similar trend for both breeds except cooking at 100°C where broilers have more band intensities than YFC. LF-NMR (low-field nuclear magnetic resonance) and MRI (magnetic resonance imaging) data suggested that after cooking at each temperature YFC reserved more water than broilers. Physical meat quality traits have correlations with volumetric changes and cooking temperatures. Cooking of YFC meat at 90°C and 100°C has demonstrated similar correlation patterns with physical quality traits. Overall, cooking at 100°C caused more undesirable changes in YFC than broilers meat blocks. Therefore, it is suggested that cooking at 90°C could be a better temperature for YFC meat.

The effects of freezing temperature on the microstructure and moisture migration of beef were investigated, aiming to provide the potential theoretical basis for the beef storage. Drip loss, surface hydrophobicity, and secondary structure of myofibrillar proteins, ice crystal, and micro- and ultrastructure of meat were analyzed at 4°C, −1°C, −6°C, −9°C, −12°C, and −18°C, respectively. Results indicated that the drip loss and surface hydrophobicity of samples stored at −12°C were significantly lower than that stored at 4°C and −1°C (p0.05). Result from Fourier transform infrared spectroscopy suggested that protein denaturation occurred after storage. There was an increase in α-helices and decline in random coil at lower temperature (−12°C and −18°C). It was indicated that the samples stored at −12°C and −18°C could effectively restrain the denaturation of protein and maintain the stability of secondary structure. The analysis of the ice crystal and micro- and ultrastructure of the muscle indicated that the structure of samples stored at −12°C and −18°C had more integrity and was complete than that stored at 4°C and −1°C. The spaces (water “reservoir” and “channel”) where was the origination of drip were small. Furthermore, the results of low-field nuclear magnetic resonance and 1H magnetic relaxation image showed that the freezing at −12°C could inhibit the migration of immobilized water to free water.