Effect of Copper on Fatty Acid Profiles in Non- and Semifermented Teas Analyzed by LC-MS-Based Nontargeted Screening
- Author(s)
- Marc Pignitter, Klaus Stolze, Franz Jirsa, Lars Gille, Bernard A. Goodman, Veronika Somoza
- Abstract
Unsaturated fatty acids are well-known precursors of aroma compounds, which are considered important for green tea quality. Due to the known copper-induced oxidation of unsaturated fatty acids and the broad variability of the amount of copper present in tea infusions, this paper investigates the influence of copper, added at a nontoxic concentration (300 μM) to non- and semifermented teas, on the degradation of fatty acids and fatty acid hydroperoxides thereof. The abundance of fatty acids in green and oolong tea was determined by means of a nontargeted approach applying high-resolution MS/MS. As a result, most of the fatty acids in green and oolong tea were already oxidized prior to copper addition. Addition of 300 μM CuSO4 to the oolong tea sample resulted in a decrease of 13-hydroperoxy-9Z,11E-octadecadienoic acid, an important flavor precursor, from 0.12 ± 0.02 to 0.05 ± 0.01 μM (p = 0.035), and other oxidized fatty acids decreased as well. However, copper-induced degradation of oxidized fatty acids was less pronounced in green tea compared to oolong tea, most likely due to the formation of copper complexes with low-molecular-weight compounds as evidenced by electron paramagnetic resonance spectroscopy.
- Organisation(s)
- Department of Physiological Chemistry, Department of Inorganic Chemistry
- External organisation(s)
- Veterinärmedizinische Universität Wien, University of Johannesburg (UJ), Guangxi University
- Journal
- Journal of Agricultural and Food Chemistry
- Volume
- 63
- Pages
- 8519-8526
- No. of pages
- 8
- ISSN
- 0021-8561
- DOI
- https://doi.org/10.1021/acs.jafc.5b02792
- Publication date
- 09-2015
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 303009 Nutritional sciences, 104002 Analytical chemistry, 104009 Food chemistry
- Keywords
- ASJC Scopus subject areas
- Agricultural and Biological Sciences(all), Chemistry(all)
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/effect-of-copper-on-fatty-acid-profiles-in-non-and-semifermented-teas-analyzed-by-lcmsbased-nontargeted-screening(d95a653d-5d4a-40a6-af3c-15dd8113f365).html