Keeping It Fresh: Learning About Non-fat Dry Milk
National Dairy Council has been receiving questions lately about non-fat dry milk powder and oxidized cholesterol, so we wanted to help clear up a few things about where food and nutrition science stand to address the topic more broadly.
Non-fat dry milk is made by removing water from pasteurized fat-free milk, using a heat treatment followed by evaporation and spray drying. Companies have learned that any cholesterol remaining in the milk, even just a small amount, can become oxidized when it’s exposed to conditions such as high heat, light or long storage times. Minimizing these changes improves the quality of the milk and maintains its fresh taste.
Oxidation — which simply means exposure to oxygen — can eventually change the original make-up of food. That’s why many foods have expiration dates on them, to help us know when they are past their prime. In the case of non-fat dry milk, it’s the cholesterol that can become oxidized when the milk is past its expiration date. Food scientists have determined that the oxidation of cholesterol can be minimized by using low processing temperatures, using oxygen-proof packaging and storing the finished product in a cool, dark place. Once it’s in our pantries, we also need to keep dry milk powder in a cool, dark place and pay attention to the expiration date. (The shelf life of regular non-fat dry milk powder is approximately 12 to 18 months; for instant, it’s six to 12 months.)
Some companies add non-fat dry milk powder to fat-free milk to give it a creamier texture. Since a low-heat process is used to make the dry milk powder, little if any cholesterol oxidation is expected. The addition of this ingredient will be listed on the milk label.
The 2015 Dietary Guidelines for Americans recommends three cups of low-fat and fat-free milk or equivalent milk products daily as part of a healthy dietary pattern to maintain health and help reduce the risk of chronic disease. That includes non-fat dry powdered milk, reconstituted with water or used as a recipe ingredient.