Changes to the tropomyosin structure alter the angiotensin-converting enzyme inhibitory activity and texture profiles of eel balls under high hydrostatic pressure.

Changes in the structure of tropomyosin (TM) altered the texture profiles of eel balls and the inhibitory activity of the angiotensin-converting enzyme (ACE). The secondary and tertiary structure of TM was determined after high hydrostatic pressure (HHP) treatment. The correlation between the spatial structure of TM and the texture profiles of eel balls was developed and discussed. The β-sheet was converted to a β-turn and a random coil when treated at HHP (200-400 MPa), meanwhile the α-helix unfolded and was converted into a β-sheet, β-turn and a random coil with treatment at 500 and 600 MPa. The surface hydrophobicity (H0) was increased and the sulfhydryl (SH) content decreased with an increase in the pressure. The results indicated that the texture profiles of eel balls showed a negative relationship with the α-helix, β-sheet and SH content. The texture profiles of eel balls were greatly enhanced after treatment at 500 and 600 MPa, leading to the improved surface network of the eel ball products. The ACE inhibitory activity of TM after HHP treatment exhibited a positive relationship with the β-sheet content in the protein. The ACE inhibitory activity was preserved under 600 MPa.