Feasibility study of lecithin nanovesicles as spacers to improve the solubility of milk protein concentrate powder during storage

Progressive loss of solubility of high-protein dairy powders is an unsolved issue in the dairy industry. Recent research has found that the solubility loss of powders is mainly contributed by the loss of dissociability of casein micelles from the parent powder particles. One of the ways of maintaining solubility of powders is to reduce the rate of development of association between casein micelles, by introducing spacers between the micelles. In this work, feasibility of using lecithin nanovesicles (produced by microfluidization) as spacers to improve solubility of protein-rich dairy powders was investigated. Nanostructured high-protein dairy powders were manufactured by adding 1, 5 and 10% w/w (of the total solids) nanovesicle (similar to 82 nm) dispersions to MPC80 suspensions and spray drying at 160 A degrees C inlet and 75 A degrees C outlet air temperature. The powders obtained were stored at 25 or 4 A degrees C and 0.23 water activity and analysed for solubility loss during storage. The biggest effect of addition of lecithin nanovesicles on solubility was seen after 90 days of storage at 25 A degrees C. Addition of nanovesicles at a level as low as 1 and 5% w/w (of the total solids) could improve the solubility of MPC80 by 13 and 30%, respectively during storage at 25 A degrees C for 90 days. As expected, the solubility of all powders did not change much during 180 days of storage at 4 A degrees C and remained above 90%.