SUGAR AND TANNIN CONTENT CHANGES IN PERSIMMON FRUIT DURING ARTIFICIAL RIPENING WITH DRY ICE

Abstract

The aim of this study was to remove astringency from 'Morali' persimmon fruit by dry ice (solid CO 2 ) application. Fruit were collected at optimum harvest quality and 5 kg of fruit were placed into 30 L chamber, and treated for 24 and 48 h at three different CO 2 concentrations of 90%, 80% and 60%, based on free volume and then the chambers were closed. All treatments were carried out at 20°C. Effects of artificial de-astringency process on soluble sugar content using high performance liquid chromatography (HPLC) and fruit firmness (N), soluble solids content (%), soluble tannin content (mg/L) were studied. Application of both 80% and 90% CO 2 by dry ice for 24 h was found to be equally effective in maintaining firmness, total soluble solids, tannin and soluble sugar contents. These treatments also dramatically reduced soluble tannins to insoluble tannin forms without loss of sweetness resulting in a 'non-astringent' fruit. Fruit treated with dry ice remained firm and kept its quality after removal of astringency. Sugar and tannin might have interacted during treatment with dry ice (solid CO 2 ) application to form non-astringent fruit.