MYCOBIOTA, ANTIOXIDANT ACTIVITY AND PHENOLIC CONTENT OF TOKAJ GRAPE VARIETIES

Abstract

Grape berries provide a natural habitat for diverse microorganisms, including potentially toxinogenic species. This study investigated the exogenous and endogenous mycocenosis of grapes, focusing on Aspergillus and Penicillium species and their toxinogenic potential, alongside the antioxidant profile (antioxidant activity and total polyphenol content) of four grape samples from the Tokaj wine-growing region in 2023. Exogenous and endogenous fungal communities were analyzed using plating methods, with surface disinfection for endogenous mycobiota. Micromycetes were identified morphologically, and yeasts were characterized using MALDI-TOF MS Biotyper. We isolated 458 fungal colonies across four genera (Aspergillus, Penicillium, Rhizopus, and Trichoderma) from exogenous mycocenosis, with Penicillium being the most frequent and abundant. From endogenous mycocenosis, 202 isolates across six genera (Alternaria, Aspergillus, Cladosporium, Penicillium, Rhizopus, and Trichoderma) were identified, with Penicillium dominating. Yeasts detected included Pichia terricola, Aureobasidium pullulans, Hanseniaspora uvarum, and Pichia fermentans. Toxinogenicity testing revealed that Penicillium expansum produced citrinin, while Aspergillus clavatus did not produce patulin under in vitro conditions. The Zéta grape variety showed the highest antioxidant activity (1.49 mg TEAC/g FM) and polyphenol content (3.15 mg GAE/g FM). These findings underscore the dual role of grapes as a source of valuable phytochemicals and a potential habitat for toxin-producing fungi, which could impact grape safety and quality. Future research should explore the relationship between grape microbiome composition and phytochemical profiles, as well as expand the study to other wine-growing regions to support sustainable grape production and food safety.