Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2009 May;26(5):583-94. doi: 10.1080/02652030802641898.
The elucidation of chemical pathways and the identification of intermediates leading to vinylogous compounds such as acrylamide by the Maillard reaction have proven challenging. This study was conducted to assess the formation of styrene from L-phenylalanine, employing binary mixtures of the amino acid heated together with simple C(3)-sugar analogue (1-hydroxyacetone) or methylglyoxal. The formation of the corresponding vinylogous product, i.e. styrene, was measured under different moisture, pH, and temperature conditions. The formation of intermediates over time was monitored by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) together with the target compound styrene. Two intermediates, i.e. 1-phenethylaminopropan-2-one and 2-phenylethylamine, play a role in the formation of styrene, the latter of more importance in high-moisture systems, whilst the former favours the release of styrene in low-moisture systems. The model further showed that Strecker-type reactions are of less importance in the formation of styrene, as the yield from single immediate precursors was maximally 0.03 mol%. The low conversion rate of L-phenylalanine to the vinylogous product and existing data on the occurrence of free L-phenylalanine in food plants suggests that the amounts of styrene expected in foods subjected to thermal treatment are negligible.
阐明导致丙烯酰胺等乙烯基化合物的化学途径和中间产物一直具有挑战性。本研究旨在评估 L-苯丙氨酸与简单的 C(3)-糖类似物（1-羟基丙酮）或甲基乙二醛形成苯乙烯的情况。在不同的水分、pH 值和温度条件下，测量了相应的乙烯基产物，即苯乙烯的形成情况。通过气相色谱-质谱联用（GC-MS）和液相色谱-质谱联用（LC-MS）以及目标化合物苯乙烯，监测了中间体随时间的形成情况。两种中间体，即 1-苯乙基丙-2-酮和 2-苯乙胺，在苯乙烯的形成中起作用，后者在高水分系统中更为重要，而前者有利于在低水分系统中释放苯乙烯。该模型还表明，Strecker 型反应在苯乙烯的形成中作用不大，因为单一直接前体的产率最高为 0.03 mol%。L-苯丙氨酸向乙烯基产物的转化率较低，以及在食品植物中存在游离 L-苯丙氨酸的现有数据表明，在经受热处理的食品中，预计苯乙烯的含量可以忽略不计。
