Levels of filamentous fungi and selected mycotoxins in leafy and fruit vegetables and analysis of their potential health risk for consumers

Introduction and Objective. The aim of the study was to determine the presence, concentration and generic composition of filamentous fungi. Considering the significant role of mycotoxins in the pathogenicity of fungal contaminants of vegetables, the scope of the study was extended by determination of aflatoxins and deoxynivalenol. Materials and method. In the years 2019-2020, samples of vegetables (lettuce, spinach, tomato, red pepper) collected on conventional farms located in eastern Poland were subjected to mycological examination. The concentration and species composition of filamentous fungi were determined by the method of plate dilutions on malt agar. The isolated strains were identified with the use of macroscopic and microscopic methods. Samples were also analyzed for the presence of aflatoxin B1 (AFB1), total aflatoxin (AFT) and deoxynivalenol (DON) using the immunoenzymatic ELISA method. Results. The median concentrations of filamentous fungi ranged from 2.778-3.204 log10 CFU g-1. Overall, 40 fungal species were identified in the examined vegetables, of which 38 are classified as potentially pathogenic for humans. The mean prevalence values for AFB1 and AFT were moderate or high (16.0-60.0% and 57.8-75.6%, respectively) and very low for DON (0-2.2%). The median concentrations of filamentous fungi, AFB1 and AFT were distinctly greater in leafy vegetables than on non-leafy tomato and pepper fruits, and the differences were highly significant (P<0.001). Conclusions. The levels of filamentous fungi and mycotoxins in Polish vegetables could be classified as moderate or low. The abundant presence of species with various pathogenic abilities may pose a risk for some categories of people consuming raw vegetables, mostly for immuno-compromised persons or atopics susceptible to food allergy caused by ingested moulds.