Large-scale preparation of 6-O-caffeoylsophorose from acylated anthocyanins in purple sweet potato

6-O-caffeoylsophorose(CS) is a functional component of vinegar produced by the acetic fermentation of storage roots of purple sweet potato (cultivar Ayamurasaki). Large-scale preparation of CS was examined using a synthetic absorbent resin, Diaion HP20. The CS-rich preparation produced by heat cleavage in acidic conditions from purple sweet potato pigment (PSP) was purified by the HP20 open column method. However, a high purity of CS was not achieved due to the co-elution of chlorogenic acid. To remove the interfering chlorogenic acid, PSP was applied to the column and eluted with 15% ethanol, resulting in the elution of chlorogenic acid while the anthocyanins were absorbed to the resin. We were thus able to obtain chlorogenic acid-free PSP (CF-PSP) with a recovery ratio of approximately 66%. As a result of the purification of CS from heat-treated CF-PSP, we obtained CS with a purity of 80% at a recovery ratio of approximately 12%.