Application of ambient ionization mass spectrometry to detect the mycotoxin roquefortine C in blue cheese

Authors: Maragos, Chris

Submitted to: Food Analytical Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2021
Publication Date: 11/4/2021
Citation: Maragos, C.M. 2021. Application of ambient ionization mass spectrometry to detect the mycotoxin roquefortine C in blue cheese. Food Analytical Methods. 15:751-760. https://doi.org/10.1007/s12161-021-02165-3.
DOI: https://doi.org/10.1007/s12161-021-02165-3

Interpretive Summary: Harmful secondary metabolites produced by fungi, mycotoxins, are found worldwide in a multitude of products. Roquefortine C (ROQC) is a mycotoxin produced by Penicillium roqueforti, the major fungus used to ripen blue-veined cheeses. An ARS researcher at Peoria, Illinois, developed a method to facilitate the screening for this toxin in blue cheeses. The method was able to detect the toxin at levels typically found in blue cheeses. The technology that was used was a form of direct analysis in real time-thermal desorption- mass spectrometry (DART-TD-MS). Results from the DART-TD-MS method agreed well with results from a reference method that used liquid chromatography - mass spectrometry (LC-MS). These results help to establish the DART-TD-MS technology as a more rapid, easier to use way to detect this toxin in cheeses.

Technical Abstract: Harmful secondary metabolites produced by fungi, mycotoxins, are found worldwide in a multitude of products. Roquefortine C (ROQ-C) is a mycotoxin produced by Penicillium roqueforti, the major fungus used to ripen blue-veined cheeses. To facilitate the screening of cheeses for ROQ-C, a method based upon the ambient ionization technique of direct analysis in real time-mass spectrometry (DART-MS) was developed. The method involved extraction with acetonitrile/water, removal of interferences with a cleanup column, and application to test strips. Thermal desorption was used to facilitate volatilization and ionization of the ROQ-C. The limits of detection and quantitation were 0.011 and 0.036 µg/mL, respectively, equivalent to 0.06 µg/g and 0.18 µg/g in cheese. Average recoveries at concentrations from 0.5 to 5 µg/g ranged from 80.2 to 87.4%. The assay was validated as a screening assay, with a cut-off value of 0.31 µg/g and a t-statistic of 25.95 at this level, indicating a very low probability of false positives (p'<'.00001). Results from the DART-TD-MS method were compared to results from an LC-PDA-MS method for 64 naturally contaminated cheeses. The two methods were in good agreement, with r2'='0.9152, suggesting that the DART-MS method can be used to screen for ROQ-C in blue cheeses.