Effect of loading weight and grinding time on size reduction of cardamom, clove and cumin using a knife mill.

摘要

A study on size reduction processes of three spices, cardamom, clove and cumin, as influenced by loading weight and grinding time were carried out using a knife mill. The efficiency (E), size reduction rate (R_t), selectivity function (S_i) and cumulative size reduction function (B_i,j) were used as response parameters to assess the size reduction performance. A polynomial curve fitting was developed by using Microsoft Excel on cumulative size reduction function (B_ij) and efficiency (E). The mass of feed material loaded were 30, 50 and 70 g with grinding time operation of 1, 3 and 5 min. It was observed that as time of grinding increased, size of spices decreased up to three min and then become unchanged. Among the three spices, cardamom achieved the highest size reduction as evaluated by efficiency and size reduction rate. The suggested loading weight and grinding time were 30 g and 3 min irrespective of the type of spice used. The data of cumulative size reduction function and efficiency fitted well to second-order polynomial equation with the highest goodness of fit. This study indicated that the size reduction/grinding using knife mill greatly influenced by the physical and chemical properties of materials instead of size reduction technique and equipment used.