Differential scanning calorimetry study of pressure/temperature processed β-lactoglobulin:: The effect of dextran sulphate

beta-Lactoglobulin at pH 7 in the presence or absence of dextran sulphate (1:1 weight ratio) was subjected to a combined pressure and temperature treatment (pressures up to 280 MPa, temperature up to 60degreesC and time up to 30 min). The effect of the treatment was assessed post-processing using differential scanning calorimetry. The thermograms in absence of dextran sulphate were very broad with possibly a shoulder on the low temperature side and showed a decrease in calorimetric enthalpy as the intensity of treatment increased. In the presence of dextran sulphate the thermograms had a much sharper shape. The calorimetric enthalpy was reduced further than in the absence of dextran sulphate. This demonstrated that the polysaccharide sensitised the protein to the combined treatment. Treatment with pressure and temperature alone demonstrated that dextran sulphate sensitised the protein structure to pressure. The species created by the combined process could be in the molten globule state and possess improved functional properties. Also the operating parameters applied could potentially be conditions for improved functionality. (C) 2004 Elsevier Ltd. All rights reserved.