How Lactose-Free Milk Is Made

If you avoid regular dairy products because of lactose intolerance, you can turn to lactose-free milk and other dairy products. Have you ever wondered what being lactose intolerant means or how the chemical is removed from milk?

Lactose Intolerance Basics

Lactose intolerance isn't an allergy to milk. What it means is that the body lacks sufficient amounts of the digestive enzyme lactase, which is needed to break down lactose or milk sugar. So if you suffer from lactose intolerance and ingest regular milk, the lactose passes through your gastrointestinal tract unaltered. While your body can't digest lactose, gut bacteria can use it, which release lactic acid and gas as products of the reaction. This leads to bloating and uncomfortable cramping.

How Lactose Is Removed From Milk

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By Anne Marie Helmenstine, Ph.D.

There are a few ways to remove lactose from milk. As you'd guess, the more involved the process, the more the milk costs at the store. These methods include:

• Adding the enzyme lactase to milk, which essentially predigests the sugar into glucose and galactose. The resulting milk still contains the enzyme, so it is ultrapasteurized to deactivate the enzyme and extend the shelf life of the milk.
• Passing milk over lactase that is bound to a carrier. Using this procedure, the milk still contains the sugars glucose and galactose but not the enzyme.
• Membrane fractionation and other ultrafiltration techniques that mechanically separate lactose from milk. These methods completely remove the sugar, which better preserves milk's "normal" flavor.

Why Lactose-Free Milk Tastes Different

If lactase is added to milk, the lactose breaks down into glucose and galactose. The milk contains no more sugar than before, but it tastes a lot sweeter because your taste receptors perceive glucose and galactose as sweeter than lactose. In addition to tasting sweeter, milk that is ultrapasteurized tastes different because of the extra heat applied during its preparation.

How to Make Lactose-Free Milk at Home

Lactose-free milk costs more than regular milk because of the additional steps required to make it. However, you can save most of the expense if you turn regular milk into lactose-free milk yourself. The easiest way to do this is to add lactase to the milk. Lactase drops are available at many stores or from online retailers, such as Amazon.

The amount of lactose removed from the milk depends on how much lactase you add and how long you give the enzyme to react (usually 24 hours for full activity). If you are less sensitive to the effects of lactose, you don't need to wait as long, or you can save more money and add less lactase. Aside from saving money, one advantage to making your own lactose-free milk is that you won't get that "cooked" flavor of ultrapasteurized milk.

Additional References

• Morr, C V, and S C Brandon. “Membrane Fractionation Processes for Removing 90% to 95% of the Lactose and Sodium from Skim Milk and for Preparing Lactose and Sodium-Reduced Skim Milk.” Journal of Food Science, U.S. National Library of Medicine, Nov. 2008.