Recovery of cholesterol from the β-cyclodextrin-cholesterol complex using immobilized cyclomaltodextrinase of alkalophilic Bacillus sp. KJ 133

A new combined method including the enzymatic hydrolysis of β-cyclodextrin (β-CD) and solvent extraction of cholesterol from the hydrolyzed mixture was developed to recover cholesterol from a β-CD-cholesterol complex prepared from dairy products, such as cream, milk, and cheese. Cyclomaltodextrinase (cyclomaltodextrin dextrin hydrolase, EC 3.2.1.54, CDase) prepared from alkalophilic Bacillus sp. KJ 133 hydrolyzed the β-CD of the β-CD-cholesterol complex, and then, free cholesterol was efficiently extracted from the hydrolyzed mixture by a nonpolar solvent such as ethyl acetate. To increase the stability of free CDase, immobilized CDase was developed using sodium alginate as a carrier. The immobilized CDase showed a high recovery yield of cholesterol in a time-dependent manner compared to the free CDase. A gas chromatography analysis showed that more than 70% of cholesterol was recovered from the β-CD-cholesterol complex of cream by the immobilized CDase, whereas only 3% and 29% of cholesterol were recovered when the solvent extraction and free CDase treatment were used, respectively. The cholesterol recovered can be used as a raw material for steroid synthesis. Furthermore, this method can be an efficient way to recover cholesterol or other organic compounds that are bound in a β-CD-cholesterol or -organic compound complex.