Ozone Injection at Low Pressure: Decomposition Kinetics, Control of Sitophilus zeamais, and Popcorn Kernel Quality

This study aimed to characterize ozone gas (O-3) decomposition kinetics when injected at low pressure for controlling Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and its effect on popcorn kernel quality. The ozonation of the kernels was conducted in a 70-L hypobaric chamber, using samples of 5.0 kg of grains packaged in woven polypropylene bags. Firstly, the internal pressure of the chamber was reduced to 250 hPa, and ozone was injected at concentrations of 5.0, 6.7, 8.5, and 13.0 mg L-1 until reaching a pressure of 940 hPa. The ozone concentration decay inside both the chamber and package was continuously monitored. The quality parameters assessed included the expansion volume, moisture content, electrical conductivity, and color of the popcorn kernels. The decomposition kinetics followed a first-order model in all concentrations studied. The values of decomposition rate constant (k) ranged from 0.030 to 0.014 min(-1), inside the package, and from 0.030 to 0.015 min(-1), inside the chamber. The ozone half-lives ranged from 22.7 and 49.8 min, inside the package, and from 20.6 and 46.5 min, inside the chamber. Ozone applied in a low-pressure system at 13.0 mg L-1 controlled 94.45% of the S. zeamais insects in the grain mass. The injection of ozone gas at low pressure did not change the expansion volume, moisture content, and electrical conductivity of the popcorn kernels.

Automated summary

This study characterized the decomposition kinetics of ozone gas in a low-pressure system for controlling Sitophilus zeamais insects in grain mass, without affecting the quality parameters of popcorn kernels.