Improvement and mechanism of emulsifying properties of liquid egg yolk by ozonation technology
Zhe Li, Yi Sun, Haobo Jin, Qi Wang, Yongguo Jin, Xi Huang, Long Sheng
Abstract
This study introduced a novel non-thermal approach to improve the emulsifying properties of liquid egg yolk by ozonation technology. The best emulsifying performance was obtained following 20 min of ozone treatment. The emulsification activity, emulsion stability, creaming index and emulsion capacity were significantly (P < 0.05) increased by 42.2%, 175.0%, 35.0% and 42.4%, respectively. The structural changes of egg yolk proteins were monitored by UV spectroscopy, endogenous fluorescence spectroscopy, circular dichroism and zeta potential to investigate the formation mechanisms of improved emulsifying properties. Results showed that the moderate ozonation treatment (≤20 min) exposed more interior hydrophobic groups of egg yolk proteins and increased protein flexibility. Micro-rheology results indicated that ozonation could significantly improve the viscoelasticity of egg yolk emulsions. Accordingly, the egg yolk emulsion droplets observed by microscopy appeared to be smaller and more uniformly distributed after moderate ozone treatment, which had a positive effect on the emulsifying properties.