Is all lactose-free milk sweet? I recently decided to try lactose-free milk to see if I might have a problem with lactose.  I was happy to see Organic Valley has a lactose-free milk.  I bought the 2% and it has a sweet taste to it.  It tastes like cereal milk - that slightly sweet milk left in the bottom of the cereal bowl.  I didn't buy vanilla flavored milk and the ingredients don't have any sweetener that I can see.  Is the chemical or process they use to remove the lactose from the milk sweet?  The sweetness of the milk doesn't make the tea sweet, but it does give the tea a different taste (I can't place it, but maybe nuttier).  Do other lactose-free milks have a similar slightly sweet taste?
When making lactose free milk, the lactose isn't actually removed. Instead, lactase is added to the milk. This breaks down the lactose into its component sugars, glucose and galactose. Lactose is one of the least sweet sugars, relative to sucrose (table sugar). Both glucose and galactose are significantly sweeter than the original lactose, hence why lactose free milk tastes much sweeter.

Here is a chart showing the sweetness of different sugars.
Video and description of process of making lactose-free milk.