大豆脂氧合酶与组合脂肪酸底物的体外动力学及其在异味形成中的功能意义。
In vitro kinetics of soybean lipoxygenase with combinatorial fatty substrates and its functional significance in off flavour development.
机构信息
Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India.
出版信息
Food Chem. 2014 Mar 1;146:394-403. doi: 10.1016/j.foodchem.2013.08.100. Epub 2013 Sep 17.
Lipoxygenase (Lox) mediated oxidation of polyunsaturated fatty acids (PUFA) in mature soya seeds results in objectionable flavour. In the present study, Lox isozymes were purified to near homogeneity (107-fold). Lox-2 and 3 displayed remarkable kinetic preference (1.7 and 1.5-fold, respectively) for low PUFA ratios (LA/LeA) (PRs) among the selected PUFA combinations. Lox-1 displayed no specific preference. Pure Lox-1 displayed unbiased response towards substrates with marginal preference (1.2-fold) for linoleic acid at its optimum pH. Volatile compounds profiling showed a direct relationship between PRs and hexanal to trans-2-hexenal (1.47, 2.24 and 18.90 for 2, 7 and 15 PRs, respectively) ratio. The off-flavour determining parameters like TBA value, carbonyl value and lipid hydroperoxides (LHPODs) exhibited significant negative correlation (0.76, 0.74, 0.72; p<0.0001) in selected soya genotypes displaying varied PRs and significant positive correlation (0.89, 0.81. 0.89; p<0.0001) with ratio of PI (polyene index) to PRs - suggesting the plausible significance of PUFA ratios in biological lipid peroxidation.
脂氧合酶（Lox）介导的多不饱和脂肪酸（PUFA）在成熟大豆种子中的氧化导致不良风味。在本研究中，Lox 同工酶被纯化至近均一性（107 倍）。Lox-2 和 3 对所选 PUFA 组合中的低 PUFA 比（LA/LeA）（PRs）表现出显著的动力学偏好（分别为 1.7 和 1.5 倍）。Lox-1 没有表现出特定的偏好。纯 Lox-1 对底物表现出无偏见的反应，对亚油酸的偏好程度略高（最佳 pH 值下为 1.2 倍）。挥发性化合物分析显示，PRs 与己醛到反式-2-己烯醛（2、7 和 15 PRs 分别为 1.47、2.24 和 18.90）的比例之间存在直接关系。不良风味决定参数，如 TBA 值、羰基值和脂质过氧化物（LHPODs）在显示不同 PRs 的选定大豆基因型中表现出显著的负相关（0.76、0.74、0.72；p<0.0001），与 PI（多烯指数）与 PRs 的比值呈显著正相关（0.89、0.81、0.89；p<0.0001）-这表明 PUFA 比在生物脂质过氧化中的可能重要性。
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