Sucrose is a disaccharide. It has the chemical formula C12H22O11. Its structure is composed of one glucose and one fructose joined at the glucosyl C1 to the fructosyl C2 by an ether bridge.
Erlose is a trisaccharide, composed of two glucosyls and one fructosyl subunit. Erlose can be formed from sucrose and glucose by joining the glucose C1 to the C4 of the glucosyl subunit of glucose by an ether bridge.
