SUGAR CONTENT CHANGES IN PERSIMMON FRUITS (DIOSPYROS-KAKI L) DURING ARTIFICIAL RIPENING WITH CO2 - A POSSIBLE CONNECTION TO DEASTRINGENCY MECHANISMS

The existence of a very active invertase was demonstrated in persimmon fruits (Diospyros kaki L., var. Triumph). However, this high activity becomes manifest only after crushing the fruit. On analysis of the soluble sugars, under conditions causing protein denaturation, persimmon was shown to contain mainly sucrose and much less glucose and fructose, these two monosaccharides being at a ratio larger than 1 : 1. The soluble sugar content decreased significantly during the CO2 treatment of the fruits for deastringency, without, however, loss of sweetness. Also, the total soluble solids content remained as high as before the treatment. Upon acid treatment of the soluble fraction, its soluble sugar content increased, remaining constant during the deastringency process. A possible interaction between tannins and soluble sugars is proposed to explain the loss of astringency in persimmon fruits upon treatment with CO2.