Effects of the moisture content on the sorption and desorption behaviour of fumigants on grain with special reference to 1,1,1,-trichloroethane

A method is described for carrying out experimental studies on the interaction of fumigant vapours with food commodities under conditions of controlled moisture content. The amount of 1,1,1‐trichloroethane adsorbed by wheat and maize during fumigation increased with the moisture content of the grain, but during subsequent airing, it was lost more rapidly from grain of higher moisture content. Except with the driest grain used, the rate of loss of fumigant was usually more rapid at 25°C than at 10°C. When samples of wheat and maize were dried slowly during airing, the rate of loss of 1,1,1‐trichloroethane was considerably reduced, almost none being lost in an initial 2‐week period of re‐equilibration. Some parameters affecting the sorption and loss of fumigants by food commodities are discussed, together with constraints in the interpretation of experimental data.