Ozone Effect on Fungi Proliferation and Genera Susceptibility of Treated Stored Dry Paddy Rice (Oryza sativa L.)

This work reports the ozone (O3) gas effects on stored dry paddy rice (Oryza sativa L.) mycoflora (fungi reduction/genera susceptibility/yeast) and humidity microorganism proliferation factors (moisture content [mc]/water activity [aw]. From the three O3 concentrations applied (10, 20 and 40 mg/L – groups I, II and III, respectively) on silos stored rice (n = 10), it was observed a rather high reduction on the total fungi load especially in group III from an initial count of 3.0 × 105 down to 1.4 × 102 cfu/mL. Regarding the samples naturally contaminated fungi genera isolated, they were Aspergillus, Penicillium, Acremonium, Alternaria and Aureobasidium (a yeast‐like fungi), as well as yeast, which were reduced after O3 treatment. Despite this, some strain gas susceptibility differences were observed as follows (decreasing order): Acremonium > Alternaria > Aureobasidium > Aspergillus > Penicillium. As expected, mc and aw reduced after gas treatment, which was proportional to the time of exposure and O3 gas stream flow rate applied on the rice stored samples. O3 treatment showed to be an effective green alternative tool to reduce paddy stored rice contamination and keep safety during storage. Practical Applications The O3 gas treatment showed to be an effective green alternative tool to avoid paddy stored rice fungi growth, especially toxigenic species responsible for mycotoxin formation in the paddy rice, and to keep safety during storage. Excess ozone is decomposed rapidly to O2, thus no food residue is left.