Evaluation of a fluorodensitometric method for analysis of ergosterol as a fungal marker in compound feeds

Ergosterol is the principal sterol of fungi and plays an essential role as a component of the cell membrane and other cell constituents. This molecule is considered a good marker of fungal contamination in foods and feeds. This paper reports a rapid and sensitive method to test ergosterol content in compound feeds based on fluorodensitometry after thin-layer chromatography (TLC) separation. This method involves a thermal treatment of TLC plates that leads to the formation of a highly fluorescent ergosterol derivative. Such a dosage allows ergosterol testing in any naturally contaminated samples (limit of detection: 1 ppm of ergosterol) and gives results in close agreement with high-pressure liquid chromatography determination. Moreover, values obtained on mixed feeds for animals at different steps of fungal contamination are linked to quantitative development of storage fungi, evaluated by mycological technique, reinforcing the interest of a rapid method for measuring this fungal marker.