Optimization and effect of pulsed electric field processing parameters on insolubility index of reconstituted milk protein concentrate 85 (MPC85)

Milk protein concentrates (MPC85) having 85% protein consist of both casein and whey proteins in their native state. They are manufactured from skim milk through ultrafiltration and diafiltration with the removal of lactose and minerals, followed by spray drying. One of the well-known issues and challenges associated with MPC are its solubility and formation of insoluble aggregates leading to issues with caking and reduced re-hydration abilities during storage. Hence modifying and customizing insolubility index of milk proteins will create a wide range of product specific applications in this ever-growing market of protein-rich foods. The current study investigated the effect of PEF processing on insolubility index of MPC85 using a response surface methodology (RSM) model and to optimize process conditions for minimum insolubility index. Experimental conditions such as temperature (25°C, 45°C, 65°C), electric field strength (EFS) (4kV/cm, 12kV/cm, 20kV/cm), and frequency (30 Hz, 165 Hz, 300 Hz) of PEF treatment were considered. The data obtained from the experimental design was fitted to second order polynomial equation. The results showed that, 25°C Temperature, EFS at 9.98 kV/cm and frequency at 165.43 Hz resulted in a minimum insolubility index, thereby minimizing the insolubility from 19.83 ml for a commercial sample to 11.99 ml, essentially causing a percentage decrease of 39.5% from commercial sample control and 20% percentage decrease in comparison to respray dried control in the study. The current data shows that the RSM could be a useful mathematical tool to optimize and customize insolubility of MPC85.