Study of α-, γ-, and δ-tocopherols in the oxidative stability of lard

Effects of α-, γ-, and δ-tocopherols at 0, 50, 100, 250, 500, and 1,000 ppm on the oxidative stability of lard during storage in the dark at 55°C for 7 days were studied by determining headspace oxygen content and peroxide value. The headspace oxygen content of the lard without tocopherol addition decreased from 21.1 to 14.4% and the peroxide value increased from 2.5 to 15.4 meq/kg lard for 7 days. The headspace oxygen depletion and the peroxide value of lard decreased by the addition of α-tocopherol at 50 ppm, but significantly increased at 250, 500, or 1,000 ppm. As the concentration of γ-tocopherol or δ-tocopherol increased, the headspace oxygen depletion and the peroxide value decreased. α-Tocopherol at 250 ppm acted as a prooxidant in the autoxidation of lard. The concentrations of γ- or δ-tocopherol to be applied to improve the autoxidative stability of lard may be 100–250 ppm.