Fungicidal Potential of Essential Oils in Organic Corn Grains during Storage

also have a significant economic impact on cereal growers and food processors due to grain lossand product recall. Synthetic fumigant is usually used to control mold growth during grainstorage, but it is not permitted for organic grains. Therefore, the objective of this study was toinvestigate the antifungal potential of some essential oils (EOs) for organic corn grain protectionat storage temperature 25 and 35°C and water activities 0.85 and 0.9 by a simulated fumigationmethod. A 4x2x2 experimental design was used. The three factors were the types of EOs(cinnamon, clove, oregano and thyme oils), storage temperature (25 and 35°C) and water activity(aw) (0.85 and 0.9). Organic corn grains were weighed into a set of glass jars and adjusted to thedesired water activity (aw). EOs were diluted to 10% using 10% DMSO, 0.5 mL diluted EO wasadded to a cotton ball taped to the lid. The jars were capped immediately and stored at thedesired temperature for 7-35 days. Samples treated with fungicide Pyraclostrobin and 10%DMSO were used as positive control and negative control, respectively. Mold growth wasmonitored every 7 days by photographing and aflatoxins in the samples were determined byultra-high-performance-liquid-chromatography (UPLC). The study found that the mold growthand aflatoxin contents of corn grains were affected by the type of EO, storage temperature andmoisture or water activity. At 25°C and aw=0.85, the negative control was molded at day 28,while others were not molded; aflatoxin B1 and B2 were almost unchanged in positive controland cinnamon oil treated samples; aflatoxin G1 and G2 were below the detection limit inpositive-control and EO-treated samples. At 35°C, the negative-control was molded in 7 days ataw=0.9 and 14 days at aw=0.85, while samples treated with fungicide and cinnamon oil were notmolded until day 28 and 35, respectively. The lowest aflatoxin B1 concentration was detected inthe samples treated with cinnamon oil, oregano oil and positive control. The results indicated thatcinnamon oil and oregano oil at a concentration 0.4 mL/100g corn grains have great potential toreplace toxic fumigants to protect organic grains from mold and mycotoxin contamination duringstorage.