*3.3.1 Hydrogenation*

Lactose is readily reduced to its corresponding alcohol, where the carbonyl group reacts with the hydrogen ion. This reaction is represented by scheme (1), and it is the main reaction occurring during the hydrogenation. Concomitantly, other reducing sugars (lactulose, galactose, and glucose) are also hydrogenated to form their respective alcohol (lactulitol, galactitol, and sorbitol). These reactions are exemplified in scheme (4), (10), and (9), respectively. Lactulose is formed through isomerization, while galactose and glucose are formed via hydrolysis of lactose.
