Colour changes in pulses fumigated with different metal phosphide formulations

Many phosphine-emitting products are used globally to control insect pests in dried vegetables, grains and pulses. However, variation in phosphide formulations is associated with colour change in many pulses. This study evaluated the effect of fumigation using Mg₃P₂ containing ammonium carbamate; AlP containing no ammonium carbamate and pure ammonium carbamate on colour of diferrent pulses. Different pulses showed different reactions towards fumigation with phosphine. A distinctly darker discolouration was observed in broad beans and lentils when fumigated with ammonium carbamate containing Mg₃P₂ and pure ammonium carbamate, whereas there were no apparent colour changes in white kidney beans, soybeans and green peas. The use of ammonium carbamate-free AlP resulted in no changes in any of the pulses. Therefore, formulation type of the phosphine product plays a major role in the visible colour change of the pulses.