α-tocopherol content and oxidative stability of egg yolk as related to dietary α-tocopherol

Hens fed diets with 0.0, 7.5, 15.0, 30.0, 60.0 and 120.0 mg supplemental alpha-tocopherol/kg feed produced egg yolks with 25, 30, 35, 45, 50 and 75 mu g/g yolk, respectively. The correlation coefficient between dietary alpha-tocopherol (mg/kg diet) and egg yolk alpha-tocopherol (mu g/g egg yolk) after 28 days feeding was 0.99. The supplemented dietary alpha-tocopherol had an effect on the alpha-tocopherol in egg yolk (P<0.05). The oxidative stability of yolk was determined by measuring the oxygen and volatile compounds in the headspace of bottled yolk. alpha-Tocopherol had an effect on the stability of yolk as an antioxidant at 25, 45 and 50 mu g/g yolk and a prooxidant at 75 mu g/g Or above (P<0.05). The addition of 60.0 mg alpha-tocopherol/ kg diet resulted in the best egg yolk stability. The correlation coefficient between headspace oxygen disappearance and volatile compound formation in the headspace of bottled egg yolk was 0.84.