Influence of micro- and nano-bubble treatment on morphological characteristics and flow properties of spray-dried milk protein concentrate powders

This study investigated the morphological and bulk handling properties of milk protein concentrate (MPC) powders manufactured from incorporating micro- and nano-bubbles (MNB) before spray drying. Control MPC powders (C-MPC; no MNB treatment) and MNB-treated MPC powders (MNB-MPC; MPC dispersions passed through the MNB system and subsequently spray dried) were characterized in terms of particle size, shape factors, stability, variable flow rate, shear cell tests, compressibility, and wall friction. The MPC powders produced after the MNB injection process had better flowability and lower basic flow energy. Shear tests showed that C-MPC powders were more cohesive than MNB-MPC powders. The MNB-MPC powders had lower flow rate index values, lower wall friction angles, more rounded shape, and significant differences in powder compressibility compared with C-MPC powders. Overall, the results demonstrated that MNB incorporation during spray drying can produce ingredients with comparable morphological characteristics while improving the bulk powder properties.