Validation of a heat, moisture and gas concentration transfer model for soybean (Glycine max) grains stored in plastic bags (silo bags)

A model of respiration rate of soybean as a function of temperature, moisture content and O2 level was used to predicted gas concentrations in the interstitial air. Average CO2 and O2 concentrations were compared with measured data. As mean grain temperature was below 15 °C for most of the storage period, O2 consumption and CO2 production were low. O2 level was about 19-20% V/V for dry soybean (13% w.b.) and about 16-17% V/V for wet soybean (15% w.b.). Predicted CO2 concentration varied from 1% V/V for dry soybean (13% w.b.) to 2% V/V points for wet soybean (15% w.b.). Though CO2 relative differences were high, the general trends of measured gas evolution were compatible with the simulated ones, indicating that the changes in CO2 and O2 concentrations during storage were satisfactorily predicted by use of the proposed correlations.