Elucidation of the mechanism of formation of thermally generated volatile and non-volatile Maillard reaction products using isotope labeling technique combined with ESI-TOF MS/MS and GC/MS analysis.

使用同位素标记技术结合 ESI-TOF MS/MS 和 GC/MS 分析，阐明热产生的挥发性和非挥发性美拉德反应产物的形成机制。

• 批准号: RGPIN-2014-03834
• 负责人: Yaylayan, Varoujan
• 金额: $ 2.19万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610674
• 关键词: Elucidation; mechanism; formation; thermally; generated

Sugars and amino acids are the key components responsible for the generation of distinctive aroma and color of food products subjected to thermal processing. Many unpleasant-tasting raw foods can be transformed by the interaction of sugars and amino acids (known as Maillard reaction) into desirable products via processes such as bread baking, coffee roasting and chocolate manufacture. Under physiological conditions, many body proteins also can be modified through similar interaction with sugars, specially, in diabetic patients that may result in the impairment of physiological and immunological functions. Unfortunately, this same chemical interaction is also responsible for the thermal generation of food toxicants during cooking such as heterocyclic amines, acrylamide, furan and glycotoxins. Understanding the mechanism by which many of the above mentioned critical food components are formed can contribute to our ability to control their generation. Finding optimal conditions to lower the levels of different toxicants and at the same time retain the Maillard-derived aroma compounds and hence improve the quality and safety of foods, is one of the main challenges of the food industry today. The long term objective of the applicant is to study the origin and the mechanism of formation of volatile and non-volatile compounds formed through the use of model systems. The applicant has developed a convenient method of introducing 13C- and 15N-labeled atoms into the reaction products, through carrying out the reactions with specifically labeled sugars (13C-1, 13C-2, …13C-6) and amino acids (15N, 13C-1, 13C-2 etc) using Pyrolysis-GC/MS as an integrated reaction, separation and identification system. The pyrolysis is conducted between 100-250oC for 20 seconds and requires only sub-milligram quantities of the expensive labeled precursors, thus reducing drastically the cost and time needed to carry out such experiments. Pyrolysis at 250°C for 20 seconds has been shown to mimic heating at 110oC for 1h. One of the advantages of using labeled reactants is that all the C- and N-atoms of a reaction product can be traced back to their origin in the starting material. This can permit elucidation of the mechanism of their formation and structural assignment of their mass spectral fragments. Using the above approach the applicant was able to elucidate the mechanism of formation of various thermally generated volatile and semi-volatile compounds relevant to food such as acrylamide, furan, pyrazines, etc. However, the polar residue remaining after the pyrolysis also contains considerable amount of chemical information in the form of labeled polar products. The short term objectives of the applicant is (1) to analyze these residues in selected model systems for their non-volatile components in addition to the volatiles. The strategy of analyzing the same sample for the volatiles and its residue for non-volatiles allows identification of label incorporation patterns of compounds in both fractions without having to perform additional experiments with costly labeled precursors and to mechanistically link the two pathways. The non-volatile residue can be a rich source of information regarding the origin of color, taste and toxicity due to recently identified link between the levels of consumption of heated foods (fried, grilled, etc.) and chronic diseases associated with aging. (2) To study the influence of selected food matrix components such as phenolics, salts etc on the direction of the Maillard reaction. These parameters have not been studied systematically.

糖和氨基酸是热加工食品产生独特香气和颜色的关键成分。许多味道不好的生食可以通过糖和氨基酸的相互作用（称为美拉德反应）转化为理想的产品，如面包烘焙，咖啡烘焙和巧克力制造。在生理条件下，许多身体蛋白质也可以通过与糖类似的相互作用而被修饰，特别是在糖尿病患者中，这可能导致生理和免疫功能的损害。不幸的是，同样的化学相互作用也是在烹饪过程中产生食物毒物的原因，如杂环胺，丙烯酰胺，呋喃和糖毒素。了解上述许多关键食物成分形成的机制有助于我们控制它们的生成。寻找最佳条件来降低不同有毒物质的水平，同时保留美拉德衍生的芳香化合物，从而提高食品的质量和安全性，是当今食品行业的主要挑战之一。 申请人的长期目标是研究通过使用模型系统形成的挥发性和非挥发性化合物的来源和形成机制。申请人已经开发了一种将13 C-和15 N-标记的原子引入反应产物中的方便方法，通过使用热解-GC/MS作为集成的反应、分离和鉴定系统与特异性标记的糖（13 C-1、13 C-2、. 13 C-6）和氨基酸（15 N、13 C-1、13 C-2等）进行反应。热解在100- 250 ℃之间进行20秒，并且仅需要亚毫克量的昂贵的标记前体，从而大大降低了进行此类实验所需的成本和时间。在250°C下热解20秒已被证明模拟在110 ° C下加热1小时。使用标记的反应物的优点之一是反应产物的所有C-和N-原子可以追溯到它们在起始材料中的来源。这可以允许阐明其形成的机制和其质谱片段的结构归属。使用上述方法，申请人能够阐明与食品相关的各种热生成的挥发性和半挥发性化合物（如丙烯酰胺、呋喃、吡嗪等）的形成机理。然而，热解后剩余的极性残留物也以标记极性产物的形式包含大量的化学信息。申请人的短期目标是（1）在选定的模型系统中分析这些残留物的非挥发性组分以及挥发物。分析同一样品的挥发物及其残留物的非挥发物的策略允许鉴定两种馏分中化合物的标记掺入模式，而不必使用昂贵的标记前体进行额外的实验，并机械地连接两种途径。非挥发性残留物可以是关于颜色、味道和毒性起源的丰富信息来源，因为最近确定了加热食品（油炸、烧烤等）的消费水平与食物的毒性之间的联系。以及与衰老有关的慢性疾病。(2)研究食品基质中酚类物质、盐类物质等对美拉德反应方向的影响。这些参数尚未得到系统的研究。