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SummaryStructures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α‐helix content decreased and β‐sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics.

BACKGROUND Emulsification is important for food quality and processing functionality. Most emulsification occurs under high‐fat conditions that eventually cause health concerns. Protein emulsifiers also have drawbacks such as lower dispersity. This study considered the effects of different high‐speed shear homogenization (HSH) speeds on the emulsifying and structural properties of myofibrillar proteins (MPs) under low‐fat conditions. RESULTS High‐speed shear homogenization significantly increased the emulsifying activity and emulsifying stability of MPs at lower speeds (8000 to 14 500 rpm). The primary structure of MP was not altered significantly by HSH, whereas its secondary, tertiary, and quaternary structures were changed. Particle size decreased first and then increased significantly, and reached a minimum when the HSH speed was 14 500 rpm. The absolute zeta potential values increased significantly and the dendritic fibrous structure of sample was destroyed when the speed exceeded 14 500 rpm. High‐speed shear homogenization (14 500 rpm) decreased the particle size and unfolded the protein, which improved the emulsifying properties of MPs. Excessive HSH speeds (20 500 rpm or higher) caused an aggregation of MP molecules, which was not conducive to improving their emulsifying properties. CONCLUSION Optimal HSH speed was achieved at 14 500 rpm to modify MPs' emulsifying and structural properties under low‐fatconditions. © 2019 Society of Chemical Industry

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The effects of camellia oil (CO) addition (0-50 mgÁmL −1 ) on the properties, structures and molecular forces of chicken myofibrillar protein (MP) gel induced by microwave heating were studied. Results indicated that the hardness, gumminess, chewiness and water holding capacity of the gel (50 mgÁmL −1 MP) were the highest after 40 mgÁmL −1 CO addition. For 40 mgÁmL −1 CO addition, the gel network was more homogeneous, and the hydrophobic interaction of MP reached the maximum according to the S 0 -ANS values, while electrostatic repulsion was the minimum according to the zeta potential. The α-helix content decreased and the β-sheet content increased as CO concentration increased from 0 to 40 mgÁmL −1 . Increased CO induced the unfolding of MP molecules and exposure of internal hydrophobic groups, which affected the hydrophobic interaction and the gel properties. To conclude, 40 mgÁmL −1 of CO was the optimal amount to prepare composite gel when MP was 50 mgÁmL −1 .