INFLUENCE OF INCORPORATION OF SOYA LECITHIN INTO SKIM MILK POWDER ON THE HEAT-STABILITY OF RECOMBINED EVAPORATED MILK

The effects of incorporation of soya lecithin into skim milk powder on the heat stability of recombined evaporated milk (REM) were investigated on six occasions during the dairying season. Soya lecithin was either added to skim milk prior to preheating or added to the concentrate before drying. In some cases, lecithin was added to the control skim milk powders at the recombining stage. Incorporation of lecithin markedly increased the heat stability of REM, irrespective of the time in the season. The extent of stabilisation was dependent on the order in which lecithin was added to the powders. Lecithin addition had no effect on the heat stability of reconstituted concentrated skim milks. Lecithin addition had little effect on the amount of protein adsorbed at the fat-serum interface during homogenisation, suggesting that stabilising action of lecithin does not simply involve the displacement of protein from the fat-serum interface.