Characterization of biotransformation, transmission and elimination processes in humans: Influence on the odorant and metabolite profiles of breath, urine and human milk

越来越多的研究报告称，生物转化过程可能会导致气味物质的实质性修改，但也会导致食物摄入的无味挥发性物质。此外，文献中已经描述了由于生理过程而从无气味前体中新形成的气味物质。为了描述这些过程，对大蒜的感官相关物质及其潜在代谢物进行了监测，不仅存在于母乳中，还存在于受试者的尿液和呼气中。在我们之前的项目BU 1351/15-1中，我们全面调查了一起涉及生蒜干预的食品相关情况，从而将干预数据与相应的对照实验进行了比较。对食用生蒜前后采集的母乳进行感官评估，结果表明，食用大蒜约2.5小时后，牛奶的气味发生了变化，可以检测到大蒜/卷心菜般的气味。采用气相色谱-质谱联用嗅觉仪(GC-MS/O)，可在食用大蒜后的母乳和尿样中检出3种大蒜代谢产物，即烯丙基甲硫醚(AMS)、烯丙基甲基亚砜(AMSO)和烯丙基甲基砜(AMSO2)。然而，AMS是唯一散发出明显大蒜气味的气味活性代谢物；另外两种代谢物即使在高浓度下也是无味的。这三种代谢物在特定体液中的排泄率与时间有很强的相关性，不同受试者之间以及同一受试者在不同测试日期的排泄率也不同。同时，我们应用质子转移反应-质谱仪(PTR-MS)和呼气末潮气采样系统相结合，对受试者的肺泡空气与大蒜摄入量进行了采样。分析显示，食用大蒜的测试者呼出的呼气中出现了AMS和甲硫醇，但不同的人排泄率也非常不同。这些发现表明，一方面，生大蒜的挥发性气味部分被强烈代谢，但另一方面，大蒜衍生的代谢物通过不同的体液有相似的排泄途径。基于这些前提，现在建议在真实条件下监测烘烤和煮熟大蒜的生物转化和传递以及消除过程；因此，大蒜气味和代谢物将再次得到定性和定量的监测，但也是在时间分辨的基础上。这种方法将使我们能够阐明潜在的时间动力学，再次比较母乳、尿液和呼吸的生理介质，并将从新鲜大蒜获得的知识转化为与加工大蒜相关的影响。

An increasing number of studies report biotransformation processes that may lead to substantial modification of odorants but also odorless volatile substances that are ingested with food. Also, neo-formation of odorants from non-odorous precursors due to physiological processes has been described in the literature. To characterize these processes, sensorially relevant substances of garlic, together with their potential metabolites, are monitored in human milk, but also in urine and exhaled breath of human subjects. In our previous project Bu 1351/15-1 we comprehensively investigated a food-relevant situation involving intervention with raw garlic, thereby comparing data from the intervention with the respective control experiments.The sensory evaluation of the human milk taken before and after the consumption of raw garlic showed that the odor of milk taken about 2.5 h after garlic consumption was altered, and that a garlic/cabbage-like odor was detectable. Using gas chromatography-mass spectrometry/olfactometry (GC-MS/O), three garlic-derived metabolites, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO2), could be identified in breast milk and urine samples after raw garlic intake. However, AMS was the only odor active metabolite emitting a clear garlic-like smell; the two other metabolites were odorless even at high concentrations. The excretion rates of the three metabolites into the specific bodily fluids were found to be strongly time-dependent and differed between the individual test persons as well as for one individual at different test days. In parallel we applied proton transfer reaction-mass spectrometry (PTR-MS) coupled with a breath end tidal sampling system for the sampling of alveolar air of test persons in relation to garlic intake. The analysis revealed the appearance of AMS and methanethiol in the exhaled breath of test persons consuming garlic, but again with very different excretion rates for different individuals. These findings demonstrate that, on the one hand side, the volatile odorant fraction of raw garlic is strongly metabolized, but, on the other side, that there are similar excretion pathways for garlic-derived metabolites via different bodily fluids.Based on these premises, biotransformation and transmission, as well as elimination processes are now proposed to be monitored under real-life conditions for roasted and cooked garlic ingestion; thereby, garlic odorants and metabolites will again be monitored qualitatively and quantitatively, but also on a time-resolved basis. This approach will enable us to elucidate the underlying temporal kinetics, again comparing the physiological media breast milk, urine and breath, and to translate the knowledge gained with fresh garlic into effects that are related to processed garlic.