以富含多不饱和脂肪酸（UPFA）的核桃油为油相，采用超高压微射流均质机制备油包水（W/O）乳液，分别添加非极性抗氧化剂α-生育酚及其极性对应物—6-羟基-2,5,7,8-四甲基色烷-2-羧酸（Trolox）于乳液中，45 ℃避光保存，检测乳液初级氧化产物—脂质氢过氧化物与次级氧化产物-顶空己醛含量，探究抗氧化剂极性对W/O乳液稳定性影响。结果表明，10~1000 μM，α-生育酚与Trolox对W/O乳液脂质氢过氧化物和己醛的形成都具有抑制作用，其中Trolox抗氧化性随浓度的增大而提升，而较高浓度的α-生育酚（500~1000 μM）反而降低其对脂质氢过氧化物的抑制作用；α-生育酚分布于乳液油水界面浓度小于极性抗氧化剂Trolox，导致非极性抗氧化剂α-生育酚活性低于极性抗氧化剂Trolox；乳液水相pH 3.0时，Trolox抗氧化性高于水相pH 7.0，水相pH通过影响Trolox在W/O乳液各相分布，从而影响其抗氧化性。

Walnut oil is rich in polyunsaturated fatty acid (PUFA) and was employed as the oil phase in order to prepare water-in-oil (W/O) emulsions using a ultrahigh pressure microfluidizer. The nonpolar antioxidant α-tocopherol and its polar counterpart 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) were added into the emulsions separately. These samples were stored in the dark at 45 ℃. The content of the primary oxidation products (lipid hydroperoxides) and the secondary oxidation products (headspace hexanal) were determined in order to evaluate the influence of antioxidant polarity on the lipid oxidative stability in W/O emulsions. Both α-tocopherol and Trolox (10~1000 μM) reduced the formation of lipid hydroperoxides and hexanal in the W/O emulsions. Trolox had a concentration-dependent antioxidant activity, whereas the inhibitory effect of α-tocopherol on the formation of lipid hydroperoxides was reduced at a relatively high concentration (500 to 1000 μM). The α-tocopherol concentration was lower than the polar oxidant Trolox for the partitioning in the oil-water interface of the emulsion, suggesting that the non-polar antioxidant α-tocopherol had lower activity than the polar antioxidant Trolox. The antioxidant activity of Trolox was higher when the pH of the aqueous phase of the emulsion was 3.0 compared to a pH of 7.0. The aqueous phase pH affected the antioxidant activity of Trolox through its partitioning in each phase of the W/O emulsion.

陕西省科技厅农业攻关（2014K01-10-04）