UHT processed milk concentrates

Ultrafiltration and reverse osmosis concentrates made from milk with differ ing fat and protein contents were sheared in defined flow conditions to est ablish the critical concentration of the constituents beyond which flow pro perties and heat stability change. The viscosity of the concentrates at 20 degrees C was calculated for volume concentrations below 0.5. Non-Newtonian flow occurred above this concentration, and heat coagulation tests at 140 degrees C revealed a dramatic drop in heat stability. The: dense packing of the constituents above a volume concentration of 0.5 led to altered flow p roperties and decreased heat stability. The heat stability at 140 degrees C and storage stability correlated with the ash content and these increase a s the ash contents decrease. Milk may be treated by applying ultrafiltratio n and nanofiltration to reduce ash content and enable high quality milk con centrates with a long-life stability to be produced by means of ultra-high temperature heating.