This study aims to optimize the ultrasound-irradiation combined pretreatment conditions to enhance the liquid egg white (LEW) foamability and investigate the changing mechanism about the physical and structural properties of LEW during the processing. Results indicated that the foamability of the LEW was increased by ultrasound-irradiation combined pretreatment to the highest value of 92.6% (irradiation dose = 33 kGy, ultrasound time = 6 min, and ultrasound power = 300 W). Three significant proteins in LEW (ovalbumin, ovotransferrin, and lysozyme) were chosen to explore the change law on their physical and structural properties. Results indicated that ultrasound-irradiation combined pretreatment increased the solubility and reduced the pH and particle size of ovalbumin and lysozyme, thus enhancing the foamability of LEW. Furthermore, the fluorescence spectra changes implied the un-folding and destruction of ovalbumin, ovotransferrin, and lysozyme during the ultrasound-irradiation combined pretreatment. Moreover, circular dichroism spectroscopy analysis revealed that the pretreatment decreased α-helix and β-sheet of the ovalbumin, ovotransferrin, and lysozyme, which bring out the improvement of LEW foamability. The present study indicated that ultrasound-irradiation combined pretreatment had the potential to be implemented to enhance the foamability of LEW.
Keywords: foamability; liquid egg white; physical properties; structural change; ultrasound-irradiation pretreatment.
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