Casein micelle dissociation in skim milk during high-pressure treatment: Effects of pressure, pH, and temperature

The in situ turbidity (τ) of reconstituted skim milk powder under pressure (P) at temperatures from 5 to 40°C and pH from 5.5 to 7.5. The pressure was increased manually from 0.1 up to 500MPa, and for every 50MPa, an intensity spectrum of the milk was measured. The in situ turbidity was calculated using the intensity at 600nm. For the improvement of visual comparison, the lines connecting turbidity values of milk at natural pH are in bold. Error bars represent the SD of 3 to 5 individual milk samples.

The logistical curve fitting based on Equation 2 of the measured in situ turbidity (τ) under pressure (P) of reconstituted skim milk powder at pH 7.0 and 30°C with the threshold pressure (P_t) marked.

The barostability diagram of casein micelles in reconstituted skim milk powder. The threshold pressure (P_t) for disruption of the casein micelle integrity in skim milk at temperatures (T) 5, 10, 20, 30, or 40°C and pH 5.5, 6.0, 6.7, 7.0, or 7.5 is presented. Data are means of 3 to 5 experiments on individual milk samples; the coefficient of variation was <5% for each threshold level.