Assessment of mould contamination and mycotoxin occurrence in cherry, blackcurrant and grape berries during storage

Introduction. Fresh fruits are susceptible to fungal contamination at multiple stages, including cultivation, harvesting, transport, marketing, and storage by consumers. Identification of fungal contaminants is important because certain moulds can grow and produce mycotoxins, while certain yeasts and moulds may lead to fruit spoilage, resulting in reduced product quality and economic losses. Their naturally low pH further increases their susceptibility to fungal spoilage (1). Aim of the study. To evaluate the prevalence of moulds and mycotoxins in cherries, blackcurrants, and grape berries in relation to berry pH. Methods and materials. Fresh berries (cherries, blackcurrants, and grapes) were obtained from local farmers' markets. Yeast and mould counts were enumerated according to the standard Microbiology of food and animal feeding stuffs - Horizontal method forthe enumeration ofyeasts and moulds (ISO21527-2:2008). Mould genera were identified and characterised based on colony morphology and light microscopy. pH was measured using a WTW InoLab pH 720 pH meter. Mycotoxins were determined by thin-layer chromatography according to the Romer Labs (USA) method. Results. The total yeast and mould counts ranged from 4.68 to 6.27 ± 0.28 log10 CFU/g in blackcurrant samples, from 3.22 to 5.72 ± 0.48 log10 CFU/g in grape samples, and from 2.30 to 2.68 ± 0.08 log10 CFU/g in cherry samples (p <0.05). ThepH values ranged from 3.75 to 3.78 in grape samples, from 3.44 to 3.47 in cherry samples, and from 3.53 to 3.54 in blackcurrant samples. A weak positive correlation between yeast and mould counts and pH values was observed (r = 0.232), although the relationship was not statistically significant (p > 0.05). The following mould genera were identified: Penicillium, Cladosporium, Mucor, Rhizopus, Botrytis, Fusarium, and Monilia. The samples were predominantly contaminated with Penicillium (62%) and Cladosporium (22%) (p > 0.05). the saiiples Zearalenone (ZEN) and deoxynivalenol (DON) concentrations ranged from 165 to 250 µg/kg and LOD to 125 µg/kg in cherry samples, from 165 to 200 µg/kg and 125 µg/kg in grape samples, and from LOD to 130 µg/kg and LOD to 125 µg/kg in blackcurrant samples. Conclusions. The study demonstrated that yeast and mould contamination levels differed significantlyamong the analysed berry types (p < 0.05), with the highest counts detected in blackcurrant samples and the lowest in cherry samples. A weak positive correlation between pH values and yeast and mould counts was observed; however, this relationship was not statistically significant (p > 0.05), indicating that pH was not a determining factor for fungal contamination in the analysed samples. The predominant mould genera identified werePenicillium and Cladosporium. Afiatoxin B1 (AFL B1) was not detected in any of the samples, whereas zearalenone (ZEN) and deoxynivalenol (DON) were present in varying concentrations across allberry types. No statistically significant relationship was observed between yeast and mould counts and mycotoxin concentrations (p> 0.05).