Why are we toasting it?
Milk powder contains lactose. Lactose is the natural sugar that occurs in most mammal milks. But with all forms of sugar you can caramelize it. This is known as the Maillard reaction. The Maillard reaction is a fascinating chemical process that occurs when natural sugars in the milk powder interact with pre-existing amino acids in the milk. This reaction is responsible for the development of complex flavors and appealing colors in various cooked foods. This reaction will yield a golden brown powder that has a caramelly aroma with nutty and sweeter undertones. Essentially a powdered brown butter.