Abstract
The effects of preheating on the digestibility of ovalbumins (OVAs) derived from five poultry eggs were examined by the treatments with simulated gastric (SGF) and intestinal (SIF) fluids and compared to those of chicken.
Similar to chicken OVA, the duck, Japanese quail, guinea fowl and turkey OVAs were relatively resistant to SGF on preheating below 65°C, getting susceptible to SGF from 70°C to 80°C, and then their digestibility decreased at more than 90°C. Ostrich OVA was relatively resistant to SGF on preheating at 80°C or lower but its digestibility markedly improved by preheating at more than 90°C.
The poultry OVAs except for duck OVA were relatively resistant to SIF without preheating as well as chicken OVA but their digestibility by SIF became higher than that of chicken above 60°C of preheating. Duck OVA was rapidly digested by SIF regardless of the preheating temperatures.
Since OVA was a major protein in the poultry eggs examined here, preferable heat treatments would be from 70°C to 80°C for duck, Japanese quail, guinea fowl and turkey eggs and more than 90°C for ostrich egg in order to enjoy nutritional benefits.
