Accumulation of soluble and insoluble tannins during fruit development in nonastringent and astringent persimmon [Diospyros kaki]

We examined the accumulation of soluble and insoluble tannins during fruit development in "Jiro", a pollination-constant, nonastringent cultivar and "Hiratanenashi", a pollination-variant, astringent parthenocarpic cultivar of persimmon. Soluble tannins were synthesized and had accumulated in the fruits of both cultivars by the second growth stage but "Hiratanenashi" accumulated more tannins than "Jiro" did. In "Hiratanenashi" fruit, almost all of the tannins which accumulated during fruit development were in the soluble from; the total amount varied little after the second growth stage. In "Jiro" fruit the proportion of insoluble tannins to total tannins was about half in the early stages of growth. A portion of insoluble tannins in "Jiro" fruits could not be dissolved after the second growth stage. These results suggest that soluble tannins in "Jiro" fruit are more apt to polymerize into the insoluble form than those in "Hiratanenashi" fruit, but once they become insoluble, they