Assessment of the flowability of spray-dried milk powders for chocolate manufacture

Abstract

This work reports on the flowability of novel milk powders that have potential for application in the manufacture of chocolate. Many milk powders are cohesive which can give rise to powder flow problems. Shear cell techniques were used to measure the following powder flow properties: powder flowfunction, effective angle of internal friction and angle of wall friction. These measurements were used in assessing cohesion developed within the powders under compaction and adhesion to a stainless steel surface. The work investigated how fat content, free-fat content, particle size, moisture content, lactose content, amorphous lactose content and storage conditions influenced the flowability of the milk powders. Increased fat content reduced powder flowability especially when comparing 1% and 26% fat powders. Varying free-fat content showed no effect on flowability. Particle size had a major influence on flowability, as increasing the particle size significantly improved the flowability of powders with 1% and 26% fat content. The concentration of amorphous lactose present increased the susceptibility of powders for sorbing moisture, resulting in reduced flowability and caking. Finally, powder flow property measurements can be applied in the design of hoppers and silos that give consistent reliable flow, which is essential in powder handling and processing operations. © INRA, EDP Sciences, 2005.