Ultrasonication Induced Alterations in Physicochemical and Functional Properties of Myosin

Abstract

Background: Several reports have indicated that ultrasonication can change the solubility of muscle proteins and improves the functional properties of meat and isolated muscle proteins. Moreover, available literature suggests that ultrasonication can significantly improve the gelling properties of muscle proteins.

Objectives: The present study was carried out to investigate the effect of low-frequency ultrasonication on the secondary structure of myosin and the impact of these structural changes on solubility and gelling ability.

Methods: Myosin from breast muscles (Pectoralis major) of broiler chicken was extracted and exposed to low-frequency ultrasonication for 30 min. Four aliquots collected at the interval of 5, 10, 20, and 30 min were analysed for change in ATPase activity, sulfhydryl content, surface hydrophobicity, alpha-helicity. The possible impact of these changes on heat-induced gelation was observed through electron micrographs.

Results: Ultrasonication reduced the enzymatic activity of myosin and increased the reactive sulfhydryl content. Decreased α-helicity and increased intrinsic fluorescence displayed significant structural changes at the secondary and tertiary levels. Myosin aggregation, as indicated by electron micrographs, showed a marked decrease. The microstructure of myosin gels displayed a distinct correlation with ultrasonication-induced structural changes. Furthermore, improved microstructure led to a significant increase in the water retention capacity of myosin gels.

Conclusion: In conclusion, ultrasonication of myosin caused a marked change in structure at the tertiary and secondary levels. Structural changes apparently confined within the globular head region and rod portion of myosin were displayed by reduced enzymatic activity and improved gelation/solubility. Results of our study convincingly showed that ultrasonication improved the microstructure of myosin gels resulting in increased WHC.

Keywords: CD-spectra; Chicken myosin; electron microscopy; filament aggregates; fractal dimensions; structural change; ultrasonication.