A process for the preparation of large-ring cyclodextrins (LR-CD) with a degree of polymerisation (DP) of 9 - 21 from starch is described. LR-CD are obtained in a biocatalytic process in high yields by controlling the temperature and reaction time. The LR-CD mixtures obtained arc separated from glucose and others reaction products in a precipitation process. After removal of smaller CD by complexation reactions enhanced by an ultrasonication treatment, CD 9 to CD 21 can then be obtained in high purity following separation by preparative liquid chromatography on a combination of reversed (ODS, octadecyl silicate) and amino phases. Smaller CD, in particular CD 6 , CD 7 and CD 8 , (±-, (²-, and ³-cyclodextrin) and their derivatives are already produced commercially in large scale. In contrast, owing to the low yields in previously described production processes and the difficulties in their isolation, it has been not possible to obtain LR-CD in any larger amounts. The invention allows the preparation of single LR-CD in pure form obtained in high yields in a biocatalytic process.
