Efficiency of recrystallization methods for the purification of β-cyclodextrin

Abstract

Cyclodextrins are an important class of products made from starch, and have many applications in the food and other industries. Among the cyclodextrins, β-cyclodextrin (β-CD) is the most important and is produced in the largest amount. Some commercial preparations of β-CD contain contaminants which must be eliminated to enhance the purity of the product. The purity of β-CD was increased by four different methods, i.e. recrystallization in water, and purification with isopropanol, cyclohexane, or isopropanol and cyclohexane. Purity of β-CD following the isopropanol method was over 99%, but the yield was only 40%. After cyclohexane treatment or the combined treatment with isopropanol and cyclohexane, purity was also over 99%, but yield was over 60%. Contaminants in commercial β-CD may be soluble or insoluble. Some contaminants would be bound in the inclusion cavity, and elimination of such contaminants by recrystallization in water was not successful. The purity and endothermic energy changes of β-CD were also determined by differential scanning calorimetry.