HEAT-STABILITY OF HOMOGENIZED CONCENTRATED MILK .1. COMPARISON OF MICROFLUIDISER WITH A VALVE HOMOGENIZER

The effect of homogeniser type and processing sequence on the heat coa gulation of concentrated milk has been studied. The effect of homogeni sation on the heat stability of concentrated milk is complex. When hom ogenisation takes place after concentration, heat stability declines a s the severity of homogenisation increases. However, under the specifi c circumstances, where homogenisation is carried out before forewarmin g or concentration, heat stability recovers when the fat particle size is reduced below a threshold diameter (ca. 0.4 mu m). Further reducti ons in size enhance the recovery of heat stability. This conclusion ap pears to hold independently of the method of particle size reduction. Nevertheless, a Microfluidiser has been found to be a very effective m eans of particle size reduction and allows production of very stable c oncentrates. This study suggests that industrial application of severe pre-homogenisation treatments in the production of dairy products mer its further investigation.