Physico-chemical, functional and rheological properties of milk protein concentrate 60 as affected by disodium phosphate addition, diafiltration and homogenization.

Abstract

Ultrafiltration and diafiltration of skim milk altered delicate salt equilibrium and composition of 59 UF retentate (59 UFR), and thus adversely affected the reconstitutional and functional properties of milk protein concentrate (MPC) powders. It might be due to interaction and aggregation of proteins during spray drying. Therefore, this study was envisaged to investigate the effect of dis odium phosphate (DSP) addition, diafiltration and homog enization of retentates on physico-chemical, functional and rheological properties of MPC60 powders. Solubility of fresh control powder was significantly lower than MPC60- H powder; at par with that of MPC60-DSP and MPC60-Na– K, but remained minimum after 60 days of storage at 25 ± 1 C. The pH (6.6) adjustment of 59 UFR with DSP, significantly enhanced the dispersability, wettability, specific surface area (SSA), heat coagulation time (HCT), emulsification capacity and stability; buffer index of MPC60-DSP powder over control. Diafiltration of 59 UFR with NaCl and KCl, significantly (P \ 0.05) decreased calcium content, but enhanced pH and mineral content of MPC60-Na–K powder. This treatment led to significant improvement in dispersability, SSA, emulsification capac ity and stability, HCT and oil binding properties. Flowa bility, wettability, dispersability, HCT, foaming capacity, emulsification capacity and stability were also improved significantly in MPC60-H powder made from homogenized 59 UFR. Rheological behavior of reconstituted powder samples exhibited pseudoplastic behavior, best explained by Hershel Bulkley model. These MPC60 powders with improved functional properties can be used for the improvement of quality attributes of various food formulations