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Kinetics of the ozone gas reaction in popcorn kernels

Silva, M.V.A., Faroni, L.R.A., Sousa, A.H., Prates, L.H.F., Abreu, A.O.
Journal of stored products research 2019 v.83 pp. 168-175
air, electrical conductivity, exposure duration, grain quality, insects, models, mortality, ozonation, ozone, popcorn, popping, reaction kinetics, seeds, water content
The objectives of this work were to determine the saturation times for popcorn kernels exposed to different concentrations of ozone gas (O3) in a constant flow; to study the kinetics of the ozone gas decomposition in the grain mass; and to ascertain the ozone treatment effect on grain quality. In order to promote saturation and to study the decomposition reaction kinetics, samples of popcorn kernels were exposed to ozone gas or atmospheric air (control) at a specific flow rate of 0.33 m3 min−1 t−1, and concentrations of 500, 2200, and 4500 μg L−1. The popping expansion volume, water content and electrical conductivity of the ozonized popcorn kernel samples were considered to investigate the effect of ozone treatment on popcorn quality. The effect of ozone treatment on insect mortality was also evaluated. The grain masses treated at ozone concentrations of 500, 2200, and 4500 μg L−1 reached the saturation condition after 10, 3.1, and 2.1 h, respectively. At all concentrations considered, the decomposition kinetics of the ozone gas when in contact with the saturated grain mass was best explained by a first-order model. The decomposition rate constants were equal to 0.13, 0.11, and 0.12 min−1, for the concentrations of 500, 2200, and 4500 μg L−1, respectively. At these ozone levels, the quality analyses of the popcorn grains did not reveal alterations that could compromise the product commercially. Nevertheless, the concentrations of 500, 2200, and 4500 μg L−1 proved to be lethal to the insects at the exposure times corresponding to the saturation in each case.