Mapping the Aspergillus niger metabolite biomarkers for in situ and early evaluation of table grapes contamination

Abstract Aspergillus niger volatilome was recently explored using advanced gas chromatography tools tandem with multivariate analysis, which allowed to propose a molecular biomarker pattern for this fungus. A. niger is a ubiquitous fungus responsible for food contamination, being reported as one of the main agents of the black mold disease, a serious post-harvest pathology of table grapes. In this work the metabolite pattern already proposed was tested in three different conditions, i.e., by using : (i) 1 day of growth time for A. niger cultures; (ii) 1 day of growth time through A. niger cultures obtained from previously contaminated grapes and iii) in situ SPME approach directly on previously contaminated table grapes with A. niger. Supervised multivariate analysis was performed which revealed that after 1 day of inoculation it was possible to detect the A. niger biomarkers, which allows to infer its presence. Furthermore, the follow-up of this set of metabolites showed that they can be employed to confirm the presence of the pathogen in two varieties of table grapes. The results obtained confirm the potential applicability of the pattern of A. niger biomarkers to early detect the fungi (after 1 day of contamination) and also may be further explored for access food susceptibility to fungi contamination, based on a direct analysis of food item and taking advantage of the high sensitivity of the GC×GC-ToFMS.