Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum

Abstract

Micellar casein and casein monomers in milk serum are in a dynamic equilibrium. At temperature below 15–20 °C a considerable amount of casein monomers, β-casein in particular, is released from the casein micelle into the aqueous serum phase. This study investigates the effects of added calcium and related variations of pH on this peculiar equilibrium in order to minimize the amount of caseins in the serum and to better understand the casein permeation during microfiltration. The pH was varied in the range of 6.3 to 7.3 and the content of calcium was increased up to 7.5 mM by adding CaCl2. Upon equilibration, the milk was separated by ultracentrifugation and the amounts of protein in the supernatant were analyzed. It was shown that the addition of low amounts of calcium shifts the equilibrium towards the micellar casein phase and can, thus, lower the serum casein content induced at low temperatures. Relative to that, the adjustment of pH separately from the CaCl2 addition had a minor effect on casein concentration and composition in the serum.

Rheological Properties of Goat Milk Coagulation as Affected by Rennet Concentration, pH and Temperature

“…Lowering the pH from 7.0 to 5.2 shortens the RCT, with the optimal pH for hydrolysis of κ-casein in the range of 5.1-5.3 [2,4]. The most important effects of lowering the pH of milk are the dissolving of micellar calcium phosphate, reduction in the net charge of the casein as well as dissociation of caseins from micelles [3,10]. Additionally, it has been reported that limited pH lowering leads to an increase in the gel firming rate [11].…”

Evaluation of the cytotoxic activity of sorafenib‐loaded camel milk casein nanoparticles against hepatocarcinoma cells

“…It provides stability to the system as calcium binds to casein phosphoprotein is pH‐dependent and generally binds at pH 7 or above. [ 30 ]…”

“…Sorafenib-loaded casein nanoparticles (SFN-CasNPs) were prepared according to our previously reported method [18] and further optimized to improve their drug encapsulation efficiency. Briefly, 200 µL of methanolic solution of sorafenib (1 mg mL (20,30,40,50) µL (Table 3) was added as a crosslinker and for the formation of casein nanoparticles. It was kept on a magnetic stirrer for evaporation of the organic solvent.…”

Variations in the biochemical and functional properties of commercial low-moisture part-skim mozzarella during 3 months of storage at 4 °C

“…The natural variation in milk pH was found to affect cheese composition, i.e., cheeses manufactured from milk with a relatively low pH at renneting had less protein (P < 0.05) (Fig. 1C), an effect that may ensue from a greater displacement of micellar casein to the whey (Schiffer, Scheidler, Kiefer & Kulozik, 2021). In addition, cheeses made from curd that was drained/milled at a relatively low pH, had lower DM (P < 0.05) (Figs.…”