Physical and tapping characteristics of muruchi (Borassus aethiopum) flour as influenced by moisture condition

The influence of moisture content on physical properties and tapping behavior of ‘muruchi' flour was determined with a view to exploring the possibility of efficient handling at industrial scale. The properties measured were geometric mean diameter, geometric standard deviation, estimated surface area and number of particles per unit gram, loose-filled bulk density and tapped bulk density. Experimental data were simulated using log-normal function to estimate maximum percent mass retained and maximum particle size, while in finite compressibility by tapping and degree of difficulty of tapping were estimated using Sone's model. Moisture content had a significant influence on the physical properties of the flour. The geometric mean diameter of particle by mass decreased linearly from 286 to 234 µm as moisture content increased from 6.32% to 10.96% (db) while estimated total surface area and number of particles per gram increased linearly from 396.5 to 582.6 cm2, and 515,188 to 1,675,732 particles respectively. The particle size ranged between 75 and 400 µm, where 300 µm particle size was the modal particle size. The estimated maximum percent mass retained and maximum particle size decreased as moisture content increased. Loose-fill bulk density and tapped density had highest and lowest values of 462.46 and 425.35 kg/m3 and 600.71 to 518.53kg/m3 at 6.32% and 10.96% moisture contents respectively. As moisture content increased from 6.32% to 10.96% (db) the maximum volume reduction ratio by tapping decreased from 0.2302 to 0.1797. The infinite compressibility by tapping decreased as moisture content increased while the degree of difficulty of tapping did not show any definitive variation with moisture variation.