Grinding characteristics of some legumes

Legumes/pulses namely, lentil (Lens esculenta), cowpea (Vigna unguiculata), blackgram (Phaseolus mungo), greengram (Phaseolus aureus) and Bengalgram (Cicer arietinum) in their dhal (dehusked split pulse) form were studied for their grinding characteristics from initial coarse grinding to further fine grinding of coarse particles resulting in 860–75 μm and 210–45 μm respectively, using an impact mill. The ground samples were screened and analyzed using differential analysis technique. The results indicated lentil to be the most amenable to grinding resulting in highest increase in surface area and also number of particles, and Bengalgram, the least in this respect. Cowpea, blackgram and greengram showed almost similar behavior with respect to increase in surface area and number of particles on grinding from coarse to finer particles. Though an increase in energy consumption was noted from coarse to fine grinding, it did not entirely depend on their breaking strength either. Analysis of the particle distribution of the ground samples indicated that grinding characteristics depends largely on some inherent property of these legumes and not merely on the size or shape of the samples during grinding.