How Lactase Changes Milk
Lactose is a two-part sugar: one glucose molecule joined to one galactose molecule. In ordinary digestion, the enzyme lactase splits that bond in the small intestine, allowing the resulting sugars to be absorbed. People who make too little lactase may have trouble digesting lactose, so dairies can do part of that work before the milk is consumed.
The added lactase acts on lactose throughout the milk, converting it into glucose and galactose. The process changes the sugar’s form, not the milk’s basic ingredients: the two simpler sugars remain in the carton rather than being removed.
Why the Milk Tastes Sweeter
Glucose and galactose register as sweeter to the tongue than lactose does. So even without extra sweetener, lactose-free milk can taste noticeably sweeter than its conventional counterpart. That sweetness is a sensory effect of the conversion, not evidence that sugar was added.
The practical difference is where the splitting happens. With regular milk, the body must supply enough lactase; with lactose-free milk, much of the lactose has already been broken down before the first sip. The carton, in effect, contains milk with the digestion step moved upstream.
