Influence of Single-and Double-Stage Hammer Grinding on Quality Attributes of Turmeric Powder

Physical properties of turmeric rhizomes such as length, width, thickness, geometric mean diameter, sphericity, surface area, volume, bulk density, true density, porosity, angle of repose and coefficient of friction were found to increase with increasing moisture range from 9.9-17.6 % (d.b). A comparative study was conducted to observe influence of single-and double-stage hammer grinding on average particle size, volume surface mean diameter, mass mean diameter and volume mean diameter of ground turmeric powder. The average temperature of turmeric powder was in the range of 38°C to 54°C and 35°C to 48°C for single-stage and double-stage hammer grinding, respectively. Comparatively finer powder was made by double-stage hammer grinding. Turmeric powder ground with double-stage grinding had volatile oil, curcumin and oleoresin retention ranging from 75-80%, 72-75% and 85-90%, respectively, at different moisture contents. Turmeric powder obtained from double-stage hammer grinding retained 15-25% more volatile oil, oleoresin and curcumin of active compounds as compared to single-stage hammer grinding. Browning index and yellowness index were superior in double-stage hammer grinding.