First, what is aseptic milk?
Aseptic milk is milk with a confusing concept: milk that is shelf stable. You expect milk to be refrigerated so that it doesn’t spoil within the day. Because of this, it’s alarming the first time you see milk cartons set on a store shelf besides boxed and canned foods, but that’s the selling point of the drink. Aseptic milk helps extend trips to the grocery store by providing a product that can last months after its refrigerated counterpart. And once you drink it, you will discover it is the milk you love!
Second, how is aseptic milk produced?
Put simply, aseptic milk is called so because it is free from any bacterial contamination. The process to make it is more complicated, though. Sterilizing each step through heat treatment, the process ensures that both milk and packaging are free of harmful bacteria, keeping milk safe without the need for refrigeration or added preservatives.
Packaging is guided through diluted, heated hydrogen peroxide before the hydrogen peroxide is forced from the packaging using pressure rollers or hot air. Next, like pasteurization, the food itself must be heated. Liquid products with low acidity like milk are more prone to bacteria than high-acidic products. To stop this, milk is heated between 280°F to 302°F for one or two seconds. This UHT, or Ultra High Temperature, process minimizes unwanted changes in the milk. Lastly, both the package and its contents are exposed to high pressure and high temperature in a humid environment. Once complete, the milk is bacteria-free and shelf stable and this aseptic milk can also be known as ultra-pasteurized milk.
But this process of treating milk with high temperatures sounds familiar and it isn’t deemed ultra-pasteurized. The two have their similarities, though. Another heat-treated process is pasteurization, developed by Louis Pasteur in 1864. The heat kills harmful bacteria like e-Coli and bacteria responsible for diseases like typhoid fever and tuberculosis. In addition to making milk safe to drink, pasteurization is used to increase its shelf life and reduce spoilage. It sounds a lot like aseptic milk, but the refrigerated milk you find in your grocery store is pasteurized.
Third, how is aseptic milk shelf stable and pasteurized milk is not?
Pasteurized milk is heated at a higher temperature of 161°F for 15 seconds. While aseptic milk should be refrigerated and used within about a week once opened, the packaging and differing heating times mean pasteurized milk must be refrigerated whereas ultra-pasteurized aseptic milk allows for a longer shelf life.
Fourth, when consumed, what’s the difference?
Besides refrigeration, nothing! Pasteurized milk and aseptic milk have the same great taste and nutrients.