Abstract

This study elucidated the reactive role of the supercritical fluid extrusion (SCFX) process along with calcium chelation by added sodium hexametaphosphate (SHMP) in altering the physicochemical properties of milk protein concentrate (MPC) with added sucrose (MPC-S) to make expanded extrudates of defined microstructure that self-disintegrate in the mouth. Calcium chelation by SHMP and temporarily induced acidity (pH 4.75) due to the formation of carbonic acid via SC-CO₂ incorporation during SCFX prevented protein–protein interactions involving calcium bridging and disulfide bonding in MPC-S extrudates. The electrophoretic patterns demonstrated increased solubility of caseins in MPC-S-SHMP extrudates when compared to MPC-S-control. MPC-S-SHMP extrudates absorbed three times more water than MPC-S-control extrudates after 30 s of hydration. Textural analysis demonstrated that the compression strength of MPC-S-SHMP extrudates reduced by 93% on hydration as compared to 31% for MPC-S-control samples. During hydration, increased water absorption by MPC-S-SHMP extrudates resulted in weakened extrudate structure and decreased mechanical strength contributing to self-disintegration in less than 30 s in the mouth which was confirmed by sensory evaluation.

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