Mycobiota of berry fruits– levels of filamentous fungi and mycotoxins, composition of fungi, and analysis of potential health risk for consumers

Abstract

Introduction and Objective. The aim of the study was to determine the presence, concentration and generic composition of filamentous fungi. Selected mycotoxins were also determined: total aflatoxins and deoxynivalenol. Materials and method. In 2017–2018, 40 samples of strawberry fruits and 40 samples of red raspberry fruits were collected. In 2019–2020, 37 samples of fresh strawberry fruits and 41 samples of fresh red raspberry fruits were collected on conventional farms located in eastern Poland and 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 using macroscopic and microscopic methods. Samples were also analysed for the presence of aflatoxin B1, total aflatoxin and deoxynivalenol using ELISA tests. Results. The median concentrations of fungi were moderate or low: 3.079 and 3.491 log10 CFU g-1 for strawberries and raspberries, respectively. Fungi of the genus Cladosporium prevailed in the mycobiota of berry fruits, accounting for 84.3% of total isolates in raspberries and 34.8% in strawberries. The occurrence of total aflatoxins was detected in the majority of tested samples (73.2% in raspberries and 70.3% in strawberries) but never exceeded the level of 4.0 µg kg-1 assumed as safe. Deoxynivalenol has been detected only in raspberries with the prevalence of 58.5%. Its median concentration was 242.0 µg kg-1 and in 7 out of 41 samples (17.0%) exceeded the level of 750.0 µg kg-1, assumed as safe. Conclusions. Filamentous fungi and mycotoxins occurred in the examined berries at levels that mostly do not represent a health risk for immunocompetent people, but might pose such risk for immuno-compromised and/or atopic consumers.