In vitro peptic digestion of ovomucin-depleted egg white affected by pH, temperature and pulsed electric fields

The effect of pH (4, 5, 7, and 9) combined with either heat (60, 80°C for 10min) or pulsed electric fields (PEF) (1.4-1.8kV/cm, 260-690kJ/kg) treatments on the in vitro peptic digestion of ovomucin-depleted egg white was investigated. Protein digestibility, unaffected by 60°C heating, was increased by heating at 80°C, which caused protein aggregation and solution turbidity. Compared to ovalbumin and lysozyme, ovotransferrin was more susceptible to pepsinolysis. Susceptibility to pepsinolysis of ovalbumin and lysozyme was markedly enhanced by heating at 80°C, compared to either 60°C heating or PEF processing. MALDI-MS identified proteolytic fragments from ovalbumin and lysozyme, exhibiting varied resistance to pepsinolysis. PEF processing at ∼690kJ/kg and pH 4 increased protein digestibility to a similar level to that obtained after heating at 80°C, with negligible solution turbidity, showing potential for the production of digestible protein drinks with good consumer visual appeal owing to their clarity.