If you have a recipe that requires you to scald milk, you may wonder why it is necessary to engage in this step. Older recipes often had cooks scald milk in order to make the milk free from bacteria and other pathogens that could have infected it. However, the commercial milk that is now sold is pasteurized and is already free from any dangerous pathogens.
There are other ideas, however, about why it is necessary to scald milk for certain recipes. The recipes that call for scalded milk are often breads and other baked items, many of which require yeast. It is speculated by some that scalded milk makes the texture of bread softer and more pleasant. Others believe that milk that has been brought to a high temperature reacts better with yeast. Another theory is that when a cook scalds milk, it will react better with gluten. With a better reaction with gluten, baked items are thought to rise better.
Though there are many reasons given to scald milk, many cooks believe that it is never necessary to scald milk if you are using pasteurized milk. Many newer recipes don't add scalding milk into the preparation steps because pasteurization is so common. However, if you do use a older recipe book, you may see this step in many of the recipes. In most cases, when working with older recipes that call for you to scald milk, it is generally considered acceptable to skip the step and leave the milk as is.