Prevention of low-temperature gelation in milk protein concentrates by calcium-binding salts

The objective of this study was to determine the effect of adding low concentrations of calcium-binding salts on the prevention of low-temperature gelation in milk protein concentrates (MPC). The MPC were created by a combination of ultrafiltration and diafiltration, standardized from 14 to 17% (wt/vol) protein content and mixed with one of 5 calcium-binding salts (sodium citrate, sodium hexametaphosphate, sodium polyphos-phate, sodium pyrophosphate, and sodium monophos-phate) adjusted to a pH of 6.75. The flow properties, apparent viscosity, and gel strength were determined for MPC containing a wide range of calcium-binding salt concentrations. Low-temperature gelation occurred in MPC with 16.0% and higher protein content. Low-temperature gelation at 16.0% protein content was prevented by the addition of any of the 5 salts tested at low concentrations (0.30 mM or less; sodium citrate, so-dium hexametaphosphate, sodium polyphosphate, so-dium pyrophosphate or sodium monophosphate), with sodium polyphosphate and sodium monophosphate be -ing the most consistent in preventing low-temperature gels. All MPC samples exhibited shear-thinning behav-ior (n = 0.52-0.72), which increased (lower n values) as the protein content increased and decreased by ad-dition of salt. At concentrations of salt above 1.00 mM, thermally irreversible gels were observed with relative strength dependent on the salt and protein content.

Automated summary

The study showed that adding low concentrations of calcium-binding salts can effectively prevent low-temperature gelation in milk protein concentrates (MPC), with sodium polyphosphate and sodium monophosphate being the most effective. All MPC samples exhibited shear-thinning behavior, with salt addition reducing viscosity and impacting gel formation.