ultrasonic analysis of heat induced coagulation in calcium fortified milk
C. Smyth, K Dawson and V. Buckin.
Progress in Colloid and Polymer Science, 112(39), pp. 37-43 (1999)
The key components determining the physical behaviour of milk are casein micelles. Heat-induced coagulation of casein micelles is a major problem in the design of new milk based products in the food industry. Many of food additives reduce the stability of casein micelles in milk, leading to coagulation during heat treatment. Up to now there was a lack of experimental methods allowing fast, non-expensive and technically non-complicated analysis of the heat stability of milk colloids. In the present work we used a new high resolution ultrasonic resonator technique to monitor the coagulation of calcium fortified low fat milks. The technique provides a relatively cheap, rapid and non-destructive analysis and requires small volumes of material. Two independent parameters, ultrasonic velocity and ultrasonic attenuation in milk, were measured as a function of temperature to analyse the effects of the addition of calcium and selected stabilisers on the coagulation temperature. Both parameters give the same value of coagulation temperature with a resolution better than 0.1 K. The results allowed us to evaluate the concentrations of stabilizers required to prevent the coagulation of calcium fortified milk at temperatures below 373.15 K.