Glucose syrup is a kind of starch syrup produced by starch under the action of enzyme or acid. Its main components are glucose, maltose, maltotriose and maltotetraose. The solid is white crystal, slightly sweet in water, with optical rotation, and its aqueous solution rotates to the right.

Widely existing in organisms, it is a component of disaccharides (such as sucrose and maltose) and polysaccharides (such as starch and cellulose). Glucose syrup is hydrolyzed from starch, and glucose is produced by microbial enzymatic method in 1960s. This is a major innovation and has obvious advantages over acid hydrolysis. There is no need for refined raw materials and acid-resistant and pressure-resistant equipment in production, and the sugar solution has no bitterness and high sugar yield. In the food industry, glucose can be made into fructose by isomerase treatment, especially fructose syrup with 42% fructose content, which is as sweet as sucrose and has become an important product in the sugar industry.