[1] At this temperature, bacteria are killed, enzymes in the milk are destroyed, and many of the proteins are denatured.
[4] Scalded milk is called for in the original recipes for Béchamel sauce, as adding hot liquid, including milk, to a roux was thought less likely to make a lumpy sauce or one tasting of raw flour.
In traditional yogurt making, as done in the Eastern Mediterranean and Near East, the milk is often heated in flat pans until reduced to about half.
Whatever the effect of scalding on milk protein may be, it is mainly this concentrating that reduces whey separation.
Modern commercial processors use dried or concentrated milk or vegetable gums and gelatins such as pectin, carrageenan, or agar ("vegetable gelatin") to prevent whey separation in yogurt.