A novel process of cyclodextrin production by the use of specific adsorbents: Part II. A new reactor system for selective production of α-cyclodextrin with specific adsorbent

Abstract We have developed a novel process of α-cyclodextrin (α-CD) production by using a new adsorbent that is characterized by its exceedingly powerful selectivity for α-CD compared with other CDs. α-CD production was carried out in a closed reactor system that was composed of a main reactor, wherein liquefied starch was converted to CDs by cyclodextrin glucosyltransferase (CGTase: EC 2.4.1.19), and a column packed with the adsorbent. While the reaction mixture was circulated in the system, α-CD was selectively adsorbed in the column and its concentration in the mixture of the main reactor was kept at a low level. This low concentration of α-CD stimulated the conversion of starch to CDs and as a result, enhanced its yield based on added starch. When 8.3 % (w/v) of liquefied starch was used in the reactor system, the yield of α-CD was 22.2% and α-CD occupied 58.7 % of the reaction mixture of total CDs synthesized. Meanwhile, in a batch system without the adsorbent, the yield of α-CD and its fraction were 10.8% and 45.0%, respectively. After the conversion reaction, and following the preliminary washing with water through the column. α-CD was easily eluted with hot water, resulting in a high purity of about 95%.