Determination of soluble persimmon tannin by high performance gel permeation chromatography

Condensed tannins present in persimmon fruits are responsible for the astringent taste. This paper describes an assay method for the determination of soluble persimmon tannin by high-performance gel permeation chromatography (HPGPC) which could be linked to a post column reaction system for the on line identification of phenolic compounds. The 80% acetone extract of crude persimmon tannin was purified using a Microcong centrifugal filter device to remove small molecules. The purified extracts were analyzed by HPGPC, using a TSK G4000 PWXL column and eluted with 10% methanol at a flow rate of 0.3 ml/min at 40degreesC. The recovery of 21.7 mg added soluble persimmon tannin standard from 2 g of persimmon paste was 80%. This assay method was used to determine the soluble tannin content during persimmon dehydration. The persimmon tannin content was decreased during dehydration and became undetectable before completion of the process. An on-line post column reaction system was developed with Folin-Ciocalteu's reagent for the confirmation of the presence of phenolic compounds. (C) 2002 Elsevier Science Ltd. All rights reserved.