Structure elucidation of transformation products of toxic plant alkaloids in stored or processed foods
Final Report Abstract
Pyrrolizidine alkaloids (PAs), tropane alkaloids (TAs) and colchicine (COL) are plant compounds that are toxic to humans and animals and can be found as contaminants in food or animal feed. Processing of food can influence the content of these alkaloids. The current project aimed to investigate how storage and processing affect the levels of PAs, TAs or COL during the respective processes. Of particular interest was whether the alkaloids at reduced levels in food are degraded or form compounds with food components and can therefore no longer be detected analytically using conventional methods. Initially, an analytical method using mass spectrometry (MS) were developed to determine the alkaloids in food relevant to the project. It was found that, depending on the method used, certain alkaloids can be chemically modified. In the first sub-project, PAs were added to honeys and stored for up to four weeks. The PA content was analysed at regular intervals. Results showed that certain PAs, namely PA N-oxides, were only found to a significantly reduced extent over time. In order to identify any degradation compounds, the honey samples were analysed using specialised, so-called non-targeted, high-resolution (HR) MS methods. The data is currently being analysed. The next sub-project investigated the fate of TAs when bread is baked. For this purpose, millet and buckwheat flours were mixed with TA solutions or ground seeds of TA-containing thornapple plant and baked. In addition, it was investigated whether fermentation with yeast or sourdough has an influence on the TA content. Preliminary results showed that the TAs, especially the TA N-oxides, were differently stable in bread crumb or crust. The different types of fermentation also resulted in varying levels of reduced TA content. Overall, the baking process reduced the TA levels in the breads. In this sub-project, too, selected samples were analysed using HRMS methods and the data are currently being evaluated. The third sub-project investigated the stability of PAs, TAs and COL in milk during the preparation of yoghurt. The alkaloids were added to long-life / UHT retail milk which was used to produce yoghurt using various commercially available culture mixes. It was shown that the levels of PA and TA N-oxides in particular decreased. The amines of these N-oxides that were not added to the milk were detected in the yoghurt, so that it can be assumed that the alkaloids were converted into each other by chemical reduction. In contrast, COL was not affected by the yoghurt production.
Publications
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Fate of Food-Relevant Toxic Plant Alkaloids during Food Processing or Storing and Analytical Strategies to Unveil Potential Transformation Products. Journal of Agricultural and Food Chemistry, 70(20), 5975-5981.
Kaltner, Florian
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Stabilität von Pyrrolizidinalkaloiden und Pyrrolizidinalkaloid‐N‐Oxiden bei der Herstellung von Rührjoghurt. Lebensmittelchemie, 76(S2).
Klein, L. M.; Nöbel, S.; Schrader, K.; Baumann, E.; Gabler, A. M.; Rychlik, M.; Gottschalk, C. & Kaltner, F.
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Stabilität von Pyrrolizidinalkaloiden und Pyrrolizidinalkaloid‐N‐Oxiden bei der Herstellung von Rührjoghurt aus Ziegenmilch. Lebensmittelchemie, 77(S3).
Klein, L. M.; Nöbel, S.; Schrader, K.; Knappstein, K.; Lamp, J.; Balázs, B.; Rychlik, M.; Guldimann, C.; Gottschalk, C.; Kaltner, F. & Gabler, A. M.
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Challenges in the analysis of pyrrolizidine alkaloids in foods. Advances in Food Safety Conference, 08.11.2023, Móstoles, Spanien
Florian Kaltner
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The (in)stability of pyrrolizidine and tropane alkaloids during food storage and processing: An issue for food safety? Analytica Conference, 09.03. - 12.03.2024, München
Florian Kaltner
