Production and evaluation of water based powder-liquids and powder-liquid mixing

Mixing powders with a low amount of liquid is a frequently used process in industry. However, homogeneous mixtures are not easy to achieve due to agglomeration and lump formation. Our own new approach is to add the liquid to the dry powders in the solid state as so called powder-liquids (PL), produced in a spray chilling process. This favors the formation of uniformly blended product mixtures at standard conditions and facilitates the incorporation of functional components. From this we derive new ways for sustainable processing of powder based material systems, such have already been reported for fat based powder-liquids. The aim of this work was to produce and characterize water based powder-liquids and to evaluate their mixing with wheat flour, a relevant model powder. Our results showed that the flowability of water based powder-liquids was lower than for pure wheat flour or related PL/flour mixtures. Accordingly, the flowability of the mixtures decreased with increasing powder-liquid concentration, but without negative impact on the mixing quality. A comparison of wheat flour mixed with water based powder-liquid and sprayed liquid into the wheat flour in a powder mixer showed that the use of powder-liquids resulted in a better mixing homogeneity throughout the whole mixing process. In addition, the powder-liquids gave a more homogeneous state of the final mixture. This demonstrates that water based powder-liquid mixing is an advantageous process to achieve optimized liquid distributions, allowing for an efficient production of homogeneous products with low moisture content and reduced drying requirements downstream. This largely supports environmentally sustainable processing goals.