Influence of Milling Speed on Proximate Composition of Pearl Millet Flour during Storage

Abstract

To assess the effect of milling speeds on shelf-life and proximate composition of flour, pearl millet (Pennisetum glaucum), one of the most extensively grown type of millet was selected. Pearl millet flour was prepared using low speed mini flour mill at 75 and 115 rpm and the results were compared with the flour prepared using commercial flour mill. The performance of flour mill was evaluated on the basis of recovery of flour, rise in temperature of flour after milling, time taken for milling, particle size distribution and different quality parameters viz., moisture, protein, crude fat, ash, fiber, carbohydrates and free fatty acids (FFA). The whole pearl millet flour was packed in high density polyethylene (HDPE), lower density polyethylene (LDPE) plastic jars and stored for 50 days at ambient conditions. The recovery of flour was the the higher (95.26%) at 75 rpm speed than at 115 rpm although the time taken was more i.e. 25 min. but the rise in temperature during milling was very less (13.45°C) as compared to the commercial mill where the temperature rose upto 36.5°C. The moisture content and FFA increased significantly (P<0.05), whereas the protein, fat and ash content decreased significantly (P<0.05) with increase in storage time. Further, the moisture content, FFA, crude protein and fat content were affected significantly (P<0.05) whereas, the fiber and ash contents were effected non-significant (P<0.05) by both the storage time and packaging material. The pearl millet flour prepared at low speed (rpm) was light brown in color as compared to higher speed (rpm) which was dark brown. Pearl millet flour prepared at 75 rpm and stored in low density polyethylene LDPE packaging material of (200 gauge) was found the best in quality among those milled at 115 rpm and 400 rpm, followed by packaging HDPE packs.