In people with lactose intolerance, some of the unhydrolyzed lactose passes into the colon, where it tends to draw water from the interstitial fluid into the intestinal lumen by osmosis. Up to 20% of the US population suffers some degree of lactose intolerance. For some people the inability to synthesize sufficient enzyme increases with age. As a result, many adults experience a reduction in the ability to hydrolyze lactose to galactose and glucose in their small intestine. Infants and small children have one form of the enzyme lactase in their small intestines and can digest the sugar easily however, adults usually have a less active form of the enzyme, and about 70% of the world’s adult population has some deficiency in its production. Lactose makes up about 40% of an infant’s diet during the first year of life. To Your Health: Lactose Intolerance and Galactosemia Whether it occurs in the body or a glass beaker, the hydrolysis of maltose produces two molecules of D-glucose. The same reactions can be carried out in the laboratory with dilute acid as a catalyst, although in that case the rate is much slower, and high temperatures are required. In the body, such hydrolysis reactions are catalyzed by enzymes such as maltase. Therefore, an ingested disaccharide must first be broken down by hydrolysis into its two constituent monosaccharide units. The human body is unable to metabolize maltose or any other disaccharide directly from the diet because the molecules are too large to pass through the cell membranes of the intestinal wall. Maltose is about 30% as sweet as sucrose. In the manufacture of beer, maltose is liberated by the action of malt (germinating barley) on starch for this reason, it is often referred to as malt sugar. It is formed most often by the partial hydrolysis of starch and glycogen. Maltose occurs to a limited extent in sprouting grain.

Galactose anomeric carbon