Effects of high hydrostatic pressure on secondary structure and emulsifying behavior of sweet potato protein

Abstract

In this study, secondary structures of sweet potato protein (SPP) after high hydrostatic pressure (HHP) treatment (200–600 MPa) were evaluated and emulsifying properties of emulsions with HHP-treated SPP solutions in different pH values (3, 6, and 9) were investigated. Circular dichroism analysis confirmed the modification of the SPP secondary structure. Surface hydrophobicity increased at pH 3 and decreased at 6 and 9. Emulsifying activity index at pH 6 increased with an increase in pressure, whereas emulsifying stability index increased at pH 6 and 9. Oil droplet sizes decreased, while volume frequency distribution of the smaller droplets increased at pH 3 and 6 with the HHP treatment. Emulsion viscosity increased at pH 6 and 9 and pseudo-plastic flow behaviors were not altered for all emulsions produced with HHP-treated SPP. These results suggested that HHP could modify the SPP structure for better emulsifying properties, which could increase the use of SPP emulsion in the food industry.

Keywords:

• sweet potato protein
• high hydrostatic pressure
• circular dichroism
• emulsion

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

The authors gratefully acknowledge Natural Science Funding of China [project 31371878] and the earmarked fund for the China Agriculture Research System [CARS-11-B-19]. We also thank the Fundamental Research Funds for the Central Public Scientific Research [2012ZL036].