The Formation of Calcium Lactate Crystals is Responsible for Concentrated Acid Whey Thickening

Schematic description of the various steps of the preparation of deproteinized concentrated acid whey supernatant (DCAWS) and the separation of insoluble fraction of thickened DCAWS for cations and anions analysis.

Evolution of torque (10⁻⁴ N·m) at 120 rad/s as a function of time (min) during stirring of lactic acid whey concentrate (——; a) and deproteinized concentrated acid whey supernatant (DCAWS) (-----; b) at 30°C. Evolution of refractive index (RI, °Brix) of the soluble phase of lactic acid whey concentrate during stirring at 30°C is shown (—■—) as a function of time (square = experimental data; line = exponential decay best fit).

Phase contrast optical micrographs of deproteinized concentrated acid whey supernatant (DCAWS) sampled at t = 0 (A), t = 260min (B), t = 275min (C), and t = 290min (D) during stirring run at 120 rad/s and 30°C.

Cationic and anionic mass concentrations in deproteinized concentrated acid whey supernatant (DCAWS) 60min after induction time, and in the filtrate and retentate of centrifugal filtration of DCAWS. Concentrations are expressed as percentage of the respective cationic and anionic mass concentrations in DCAWS.

Induction time (min, solid symbols) and respective torque amplitude (ΔF, 10⁻⁴ N·m, open symbols), as a function of calcium concentration (g/100g of H₂O) at constant calcium:lactate mass ratio of 1:10.3 during stirring runs (120 rad/s, 20°C) of pure systems (■,□) and deproteinized concentrated acid whey supernatant (DCAWS) (▴,▵). The dotted lines indicate the linear fit.

Induction time (min,■) and respective torque amplitude (ΔF, 10⁻⁴ N·m, □), as a function of pH during stirring of deproteinized concentrated acid whey supernatant (DCAWS) at 120 rad/s and 20°C.