Tagatose: properties, applications, and biotechnological processes

d-Tagatose has attracted a great deal of attention in recent years due to its health benefits and similar properties to sucrose. d-Tagatose can be used as a low-calorie sweetener, as an intermediate for synthesis of other optically active compounds, and as an additive in detergent, cosmetic, and pharmaceutical formulation. Biotransformation of d-tagatose has been produced using several biocatalyst sources. Among the biocatalysts, l-arabinose isomerase has been mostly applied for d-tagatose production because of the industrial feasibility for the use of d-galactose as a substrate. In this article, the characterization of many l-arabinose isomerases and their d-tagatose production is compared. Protein engineering and immobilization of the enzyme for increasing the conversion rate of d-galactose to d-tagatose are also reviewed.