MALDI-Imaging Mass Spectrometry of Ochratoxin A and Fumonisins in Mold-Infected Food.

RATIONALE: Mycotoxins are toxic secondary metabolites produced by various fungi. Their distribution within contaminated material is of high interest to obtain insight into infection mechanisms and the possibility of reducing contamination during food processing.

METHODS: Various vegetable foodstuffs were infected with fungi of the genera Fusarium and Aspergillus. The localization of the produced mycotoxins was studied by matrix assisted laser desorption ionization time of flight imaging mass spectrometry (MALDI-MSI) of cryosections obtained from infected material. The results were confirmed by HPLC-electrospray ionization triple quadrupole mass spectrometry (HPLC/MS/MS).

RESULTS: The mycotoxins ochratoxin A (OTA) and fumonisins of the B- and C-series (FB1 , FB2 , FB3 , FB4 , FC2/3 , and FC4 ) as well as partially hydrolyzed fumonisins (pHFB1 , pHFB2 , pHFB3 , pHFC1 , and pHFC2/3 ) could successfully be detected by MALDI-IMS in mold-infested foodstuffs. The toxins are distributed differently in the material: OTA is co-localized with visible fungal spoilage while fumonisins could be detected throughout the whole sample.

CONCLUSIONS: This work shows the applicability of MALDI-Imaging Mass Spectrometry (MALDI-MSI) to mycotoxin analysis. It has been demonstrated that the analyzed mycotoxins are differently distributed within moldy foodstuffs. These findings show the potential of MALDI-MSI for the localization of these hazardous compounds in various plant tissues.