Put milk in a pan (preferably a thin-bottomed one) over very high heat and leave the room. Come back when the smell becomes unpleasant and throw the milk and the pan away.
Seriously, to scorch milk is to burn it. The proteins stick resolutely to the bottom of the pan. The sugar also burns onto the pan and imparts an unpleasant flavor and color to the milk. And it is the devil to clean the residue of scorched milk from a pan.
Many older recipes called for you to scald milk, that is, to bring it nearly to a boil (185°F, 85°C, or more), preferably in a thick-bottomed pan, and stirring actively, to keep a protein skin from forming on the surface and keep the proteins and sugar from sticking to the bottom. Scalding served two purposes, to kill potentially harmful bacteria in the milk, and to destroy enzymes that keep the milk from thickening in recipes. Pasteurization, however, accomplishes both of those goals, and since almost all store-bought milk in Western countries is pasteurized these days, scalding is essentially an unnecessary step.
Shirley Corriher, the noted food scientist, baker, and author of Cookwise (Canada, UK), says she does scald milk before using it in breads, however. She says there is a protein in the whey that marginally reduces the volume of a loaf of bread as it rises and bakes. This is especially noticeable with the use of nonfat dry milk, and it appears that the amount of milk used really matters. That is, in relatively small quantity, the use of unscalded milk seems to have no negative effect on the formation of the loaf. But for her “peace of mind,” Corriher says she continues to scald milk and reconstituted dry milk for her baking projects.
Another reason some recipes continue to call for scalded milk is that they simply want you to heat the milk first, as it will speed the cooking process, help melt butter, dissolve sugar more easily, etc.
To help keep a scalding project from turning into a scorching one, try some of these tips:
- Rinse your pan with cold water before adding and heating the milk, keep the heat to medium, and stir attentively.
- Heat the milk in a double boiler and stir occasionally.
- Heat the milk in a heat-proof glass container in a microwave oven.