Effect of grinding temperatures on particle and physicochemical characteristics of black pepper powder

The cryogenic grinding method is extensively used to get the best quality of spice powders. The particle and physical-chemical characteristics of the ground black pepper powders produced at the grinding temperatures of -120, -80, -40, 0 and 40 degrees C were investigated. The flowability and particle size demonstrated a positive relationship with the increasing grinding temperature for the powders, whereas, specific surface area and surface roughness of the particles showed a negative correlation. SEM analysis revealed the surface morphology and shape of the particles. The availability of mineral composition of the powder significantly increased with the reduction in the grinding temperature. Interestingly, the highest value was noticed for K followed by Ca and Cl at all the temperatures. Furthermore, a significant increase in the moisture content (10.5%), water activity (19.1%) and volatile oil content (20.1%) of the powder was noticed with the decrease in the grinding temperature. While the pH value and specific energy consumption for conveying and grinding were significantly decreased by 3.7 and 87.2%, respectively. Also, the total color difference of the powder was minimal at a grinding temperature of -40 degrees C. However, no monotonous trend was observed for the gross calorific value of the powders. (C) 2016 Elsevier B.V. All rights reserved.