Enzymatic approaches for the synthesis of high fructose syrup

Abstract

Fructose is a monosaccharide widely used for food, pharmaceutical, and medical applications. Such ubiquity can be ascribed to its various superior technical properties over the conventional sugar, sucrose, and many beneficial roles in the human body. High fructose syrup (HFS) can be synthesized from starch or inulin using enzymatic/chemical methods. A well-known conventional approach is the hydrolysis of starch using amylolytic enzymes and subsequent isomerization of dextrose to fructose by glucose isomerase. The product yield by this method is only 42% and the product mixture also contains 50% dextrose and 8% other saccharides. HFS can also be produced from inulin by a single-step method using inulinases. In the single-step enzymatic method, inulinase acts sequentially on ß-(2, 1) linkages of inulin to release the fructose units. By this method approximately 95% fructose yield can be obtained. Acid hydrolysis of inulin/ starch is not recommended because it imparts color to the product and a few undesired products, like difructose anhydride, are also formed. In the present chapter, enzymatic approaches are described for the preparation of HFS from starch and inulin.