Physicochemical properties, microstructure and protein characteristic of frozen chicken feet as affected by different thawing methods

In this study, the effects of six thawing methods (flowing water thawing, FWT; water immersion thawing, WIT; room temperature air thawing, RTAT; low temperature air thawing, LTAT; ultrasonic-assisted thawing, UAT; and microwave thawing, MT) on water holding capacity (WHC), shear force, tissue microstructure, thiobaric acid active substances (TBARS), myofibrillar fragmentation index (MFI), protein secondary structure and myofibrillar protein (MP) oxidation of frozen chicken feet were investigated. The results demonstrated that UAT improved the sample tenderness with a minimum shear force of 775.67 +/- 63.30 g. The WHC of the UAT sample also presented a high level; the thawing and cooking losses reached 4.20 +/- 0.33% and 3.23 +/- 0.35%, respectively. Although the LTAT sample presented a lower loss in the thaw (2.72 +/- 0.23%) and a high alpha-helix content (30.54 +/- 1.69%), it showed a significantly higher TBARS value (0.62 mg MDA/kg) (P < .05). On the other hand, it was observed a significant inhibition of fat oxidation in the FWT sample (0.19 +/- 0.01 mg MDA/kg) (P < .05). However, the SDS-PAGE diagram showed that the MPs in this sample exhibited a significant degradation. Furthermore, the MT process could lead to partial overcooking of the chicken feet, resulting in poor physicochemical properties. Overall, the results indicate that the UAT method could be the most recommended process to thaw chicken feet, providing optimal tenderness with more intact microstructure and less MP degradation. This study provides relevant evidence, for consumers and industrial practice, regarding thawing methods that can be applied to frozen chicken feet