This method called ultrahigh‐ temperature processing (UHT) results in a partial loss of some of the vitamins (riboflavin, vitamin C, folic acid, and a few others), and the higher temperatures denature and cook some of the proteins (Maillard reaction—see Chapter 6) and alter some of the fats producing what some consider a slightly off‐flavor. UHT milk is popular in regions without local dairy farms as it holds its usefulness longer. Many European countries use UHT milk for more than half of their milk needs due to space and reduced energy requirements, as the milk does not have to be refrigerated Milk can be whipped into a foam, which is a type of colloid.
To form a foam colloid, one substance (in this case air) is trapped in another. If low‐fat skim milk is foamed (<2% fat), as in the foaming of milk for a cappuccino, it is the denaturing proteins that trap the air bubbles much like egg white foam. But if heavy cream (>35% fat) is foamed, as in the preparation of whipped cream, it is the fat that traps the air bubbles.
The resulting creams and foams are unique for milk and different from other foams such as egg white foams. Both are types of colloids—where one substance (in this case air) is trapped in another (cages of fat—whipped cream or bubbles of protein and some phospholipids). Whipped Creams The directions for whipped cream are pretty simple. In a large chilled bowl, add one cup of cold heavy cream and whip until peaks are stiff. Add sugar or vanilla just as the peaks are almost stiff.