Photochemical trans-/cis-Isomerization and Quantitation of Zearalenone in Edible Oils

• Published in: Journal of agricultural and food chemistry Vol. 60; no. 47; pp. 11733 - 11740
• Main Authors: Köppen, Robert, Riedel, Juliane, Proske, Matthias, Drzymala, Sarah, Rasenko, Tatjana, Durmaz, Vedat, Weber, Marcus, Koch, Matthias
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 28.11.2012
• Subjects: Biological and medical sciences; bottles; Cannabis; corn oil; Corn Oil - chemistry; Drug Stability; Fat industries; fluorescence; Food industries; Food toxicology; Fundamental and applied biological sciences. Psychology; glass; high performance liquid chromatography; irradiation; Isomerism; mass spectrometry; nuclear magnetic resonance spectroscopy; Photochemistry; Plant Oils - chemistry; Seeds - chemistry; solvents; Sunlight; supermarkets; surveys; X-ray diffraction; zearalenone; Zearalenone - analysis; Zearalenone - chemistry; occurrence; analysis; Fusarium mycotoxins; food; Mycotoxin; Zearalenone; Cis trans isomerization; Edible oil; Fungi; Toxin; Surveillance; Fusarium; Fungi Imperfecti; Food; Quantitative analysis
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf3037775

The emphasis of the present work was to investigate the photochemical conversion of trans- to cis-zearalenone in edible oils under real-life conditions. For quantitation purposes a cis-zearalenone standard was synthesized and characterized for its identity and purity (≥95%) by 1H NMR, X-ray crystallography, HPLC fluorescence and mass spectrometric detection. In a sample survey of 12 edible oils (9 corn oils, 3 hempseed oils) from local supermarkets all corn oils contained trans-zearalenone (median 194 μg/kg), but no cis-zearalenone was detected. For alteration studies trans-zearalenone contaminated corn oils were exposed to sunlight over 4 and 30 weeks, revealing an obvious shift toward cis-zearalenone up to a cis/trans ratio of 9:1 by storage in colorless glass bottles. Irradiation experiments of trans-zearalenone in different organic solvents confirmed the preferred formation of cis-zearalenone possibly caused by entropic effects rather than by enthalpic entities as investigated by quantum chemical and classical force field simulations.