Nielsen Søren D, Knudsen Lotte J, Bækgaard Line T, Rauh Valentin, Larsen Lotte B
Department of Food Science, Aarhus University, Agro Food Park 48, 8200 Aarhus N, Denmark.
Arla Foods Innovation Centre, Agro Food Park 19, 8200 Aarhus N, Denmark.
Foods. 2022 Mar 22;11(7):897. doi: 10.3390/foods11070897.
A liquid chromatography-mass spectrometry method based on multiple reaction monitoring (MRM) was developed for the simultaneous quantification of markers representing two potentially competing pathways, the Maillard reaction and the dehydroalanine pathway. The two pathways involve the same residues in the proteins to some extent, namely, the essential amino acid lysine, as well as free-amino terminals available on proteins and polypeptides, competition between the two pathways in food systems may occur. The developed method comprises the following markers of the Maillard reaction: furosine, N-ε-(carboxyethyl)lysine (CEL) and N-ε-(carboxymethyl)lysine (CML), together with the dehydroalanine reaction pathway markers; lanthionine (LAN) and lysinoalanine (LAL), as well as lysine itself. The validated method was then used for the absolute quantification of heat-induced protein modifications in model systems of micellar casein and whey protein isolates (MCI and WPI, respectively) in the presence or absence of lactose. As expected, the Maillard reaction markers furosine, CEL and CML increased during the applied heat treatment in the presence of lactose, whereas the dehydroalanine markers, LAN and LAL increased with heating in both MCI and WPI, both in the presence and absence of lactose, although at lower levels in the presence of lactose, confirming the competing state of the two pathways.
建立了一种基于多反应监测（MRM）的液相色谱-质谱方法，用于同时定量代表两条潜在竞争途径（美拉德反应和脱氢丙氨酸途径）的标志物。这两条途径在一定程度上涉及蛋白质中的相同残基，即必需氨基酸赖氨酸，以及蛋白质和多肽上的游离氨基末端，因此在食品体系中这两条途径之间可能会发生竞争。所开发的方法包括以下美拉德反应的标志物：呋喃果糖胺、N-ε-（羧乙基）赖氨酸（CEL）和N-ε-（羧甲基）赖氨酸（CML），以及脱氢丙氨酸反应途径的标志物；羊毛硫氨酸（LAN）和赖氨酸丙氨酸（LAL），还有赖氨酸本身。然后，将经过验证的方法用于在有或没有乳糖存在的情况下，对胶束酪蛋白和乳清蛋白分离物（分别为MCI和WPI）的模型系统中热诱导的蛋白质修饰进行绝对定量。正如预期的那样，在有乳糖存在的情况下进行热处理时，美拉德反应的标志物呋喃果糖胺、CEL和CML增加，而脱氢丙氨酸的标志物LAN和LAL在MCI和WPI中加热时均增加，无论有无乳糖存在，尽管在有乳糖存在时水平较低，这证实了两条途径的竞争状态。
