Effect of adding salt during the diafiltration step of milk protein concentrate powder manufacture on mineral and soluble protein composition

Abstract

Milk protein concentrate (MPC) powders offer a great potential for use in an array of food applications because of their nutritional and functional values. However, MPC powders with protein content ≥80% (MPC80) exhibit poor solubility and hence restrict their potential use. The objective of this study was to determine the impact of adding salt during the diafiltration stage of MPC80 manufacture on solubility, turbidity, and to compare minerals and protein content of supernatants of ultracentrifuged samples with control sample. Three types of samples were produced: MPC80-C (control) with or without salt treatment, MPC80-Na (150 mM NaCl), and MPC80-K (150 mM KCl). Lower solubility was observed in MPC80-C (53%) as compared to MPC80-Na or MPC80-K (100%). Higher turbidity was observed in MPC80-C (530 NTU) and lower turbidity was observed in samples of MPC80-Na (128 NTU) and MPC80-K (131 NTU). Furthermore, lower protein and calcium contents were observed in supernatants of ultracentrifuged samples of MPC80-C (2.3%; 0.35 mg.mL−1) as compared to MPC80-Na (3.8%; 0.63mg.mL−1) and MPC80-K (3.7%; 0.67 mg.mL−1). The opposite trend was found in reconstituted samples (5% TS). Our results showed that the addition of salt impacted the distribution of minerals and proteins in colloidal and soluble phases of MPC80-Na and MPC80-K. The results from this work will contribute to our understanding of the role that mineral-induced changes (depletion or addition) play in the functionality of MPC80.