Effect of High-Intensity Ultrasound and Calcium Chelation on Functional Properties of Casein Micelles

Functional properties of caseins play a crucial role in the dairy industry, so it is important to develop methods to improve their functionality. The aim of this study is to investigate the combined effect of high-intensity ultrasound (HIUS) treatment and calcium chelation on functional properties of casein micelles. For this purpose, micellar casein concentrate (MCC) was prepared with a concentration of 3% (w/w) casein. Then, 0 and 10 mM of Disodium hydrogen phosphate was added. HIUS was performed at a frequency of 20 kHz, power intensity of 550 W/cm², and an amplitude of 100% for 0, 5, 10, 15, and 20 min at 25 °C. Factorial design was employed to investigate the effect of ultrasound time (UST) and disodium phosphate (DSP) on foam capacity (FC), emulsion activity index (EAI), gelation time (GT), G' at 480 min of oscillation time (G'₄₈₀), slope of complex viscosity, and linear viscoelastic region (LVR). At 0 mM of DSP, increasing UST from 0 to 15 min decreased GT from 114.39 ± 3.20 to 83.52 ± 1.61 min, and it extended LVR from 40.36 ± 0.12 to 41.27 ± 0.27% of the applied strain. In addition, applying HIUS for 15 min increased the elasticity and firmness of MCC gel networks at 0 mM of DSP. G'₄₈₀ was not influenced by UST, but it was reduced by DSP from 108.40 ± 3.29 to 15.78 ± 1.58 Pa. Increasing both UST and DSP significantly increased FC from 110.00 ± 13.23 to 163.33 ± 11.55% and foam stability (FS) in all treatments. FS reached its maximum (doubled) after 10 min of UST at 0 mM of DSP. However, EAI and emulsion stability index (ESI) decreased with increasing both UST and DSP. HIUS treatment combined with calcium chelation might highlight a new approach to improve foaming properties. However, regardless of calcium chelation, HIUS treatment is a promising technology to improve the gelling properties of casein micelles.