Schroeder Maria T, Becker Eleonora Miquel, Skibsted Leif H
Department of Food Science, Food Chemistry, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
J Agric Food Chem. 2006 May 3;54(9):3445-53. doi: 10.1021/jf053141z.
During repeated deep-fat frying of potato slices at 163 degrees C in yellow or red palm olein of comparable fatty acid profiles, the oxidative stability (peroxide value and anisidine value) of the palm oleins was similar, and in yellow palm olein, the rate of antioxidant depletion decreased in the order gamma-T3 > alpha-T3 > delta-T3 (T3, tocotrienol). In red palm olein, which had a total tocopherol/tocotrienol content of 1260 vs 940 ppm in yellow palm olein and a corresponding longer induction period in the Rancimat stability test at 120 degrees C, only depletion of gamma-T3 was significant among the phenols during frying and slower as compared to that in yellow palm olein. The carotenes in the red palm olein were depleted linearly with the number of fryings, apparently yielding an overall protection of the phenols. In antioxidant-depleted palm olein and in phospholipid liposomes with added increasing concentrations of phenols, gamma-T3 was found to be a better antioxidant than alpha-T3. alpha-T3 and alpha-T (T, tocopherol) had a similar antioxidant effect in antioxidant-depleted palm olein in the Rancimat stability test, while in the liposomes the ordering as determined by induction period for the formation of conjugated dienes was gamma-T3 > alpha-T3 > alpha-T. The addition of 100-1000 ppm beta-carotene to antioxidant-depleted palm olein or liposomes (lycopene also tested) did not provide any protection against oxidation. In the liposomes, synergistic interactions were observed between beta-carotene or lycopene and alpha-T, alpha-T3, or gamma-T3 for carotene/phenol ratios of 1:10 and 1:2 but not for 1:1. In chloroform, carotenes were regenerated by tocopherols/tocotrienols from carotene radicals generated by laser flash photolysis as shown by transient absorption spectroscopy, suggesting that carotenes rather than phenols are the primary substrate for lipid-derived radicals in red palm olein, in effect depleting carotenes prior to phenols during frying. Regeneration of carotenes by the phenols also explains the synergism in liposomes. In the laser flash photolysis experiments, gamma-T3 was also found to be faster in regenerating carotenes than alpha-T3 and alpha-T.
在163摄氏度下，使用脂肪酸组成相近的黄色或红色棕榈油反复对土豆片进行深度油炸时，这两种棕榈油的氧化稳定性（过氧化值和茴香胺值）相似。在黄色棕榈油中，抗氧化剂消耗速率的下降顺序为γ-生育三烯酚>α-生育三烯酚>δ-生育三烯酚（T3，生育三烯酚）。红色棕榈油的总生育酚/生育三烯酚含量为1260 ppm，而黄色棕榈油为940 ppm，在120摄氏度的Rancimat稳定性测试中具有相应更长的诱导期。在油炸过程中，红色棕榈油中只有γ-生育三烯酚的消耗显著，且与黄色棕榈油相比消耗较慢。红色棕榈油中的类胡萝卜素随着油炸次数呈线性消耗，这显然对酚类起到了整体保护作用。在抗氧化剂耗尽的棕榈油和添加了浓度不断增加的酚类的磷脂脂质体中，发现γ-生育三烯酚比α-生育三烯酚是更好的抗氧化剂。在Rancimat稳定性测试中，α-生育三烯酚和α-生育酚（T，生育酚）在抗氧化剂耗尽的棕榈油中具有相似的抗氧化效果，而在脂质体中，根据共轭二烯形成的诱导期确定的顺序为γ-生育三烯酚>α-生育三烯酚>α-生育酚。向抗氧化剂耗尽的棕榈油或脂质体中添加100 - 1000 ppm的β-胡萝卜素（也测试了番茄红素）并不能提供任何抗氧化保护。在脂质体中，当胡萝卜素/酚类比例为1:10和1:2时，观察到β-胡萝卜素或番茄红素与α-生育酚、α-生育三烯酚或γ-生育三烯酚之间存在协同相互作用，但1:1比例时没有。在氯仿中，通过激光闪光光解产生的胡萝卜素自由基可被生育酚/生育三烯酚再生胡萝卜素，瞬态吸收光谱显示了这一点，这表明在红色棕榈油中，胡萝卜素而非酚类是脂质衍生自由基的主要底物，实际上在油炸过程中胡萝卜素比酚类先被消耗。酚类对胡萝卜素的再生也解释了脂质体中的协同作用。在激光闪光光解实验中，还发现γ-生育三烯酚比α-生育三烯酚和α-生育酚更快地再生胡萝卜素。
