Control of mycobiota and mycotoxins contaminating popcorn grains

Sixty-six species and one varity belonging to 22 genera were recovered from 20 samples of ‎popcorn grains collected from different stores in Assuit Governorate during four seasons from ‎winter 2018 to Autumn 2019 on dichloran rose bengal chloramphenicol agar (DRBC) and ‎dichloran glycerol agar (DG18) media. The most common genera of mycobiota are Aspergillus ‎followed by Fusarium, Cladosporium and Penicillium. The prevalent species were represented by ‎Aspergillus niger, A. flavus, Cladosporium cladosporioides and Fusarium oxysporum. All ‎collected samples of popcorn were free from detectable amounts of mycotoxins. Among 30 ‎isolates represented 3 species (Aspergillus flavus, A. versicolor and Fusarium verticilloides) only ‎two isolates of Aspergillus flavus were potent to produce Aflatoxin B1. The inhibitory effect of ‎two spices and two essential oils against the growth of the two aflatoxin producers and their ‎abilities for producing aflatoxin as biocontrol agents were examined. Clove was found to be the ‎most effective spice which completely inhibited the growth the two fungal isolates at ‎concentration of 1.0 %. Also, clove essential oil at concentration of 1.0 % showed strong ‎antifungal effect against the two tested fungi. On the other side, each of the two fungal strains ‎could not be produced any detectable amount of aflatoxin in presence of each of the two spices ‎or the two essential oils tested. These results could be useful for rural communities to prevent the ‎contamination of fungi and their toxins in different grains and/or seeds by a simple, safe and ‎low-cost method. ‎