Differences in solubilities of tannins after six treatments for removal ofastringency in persimmon fruit

The solubility of persimmon tannins during six treatments for removing astr ingency was compared using HCL in methanol at different concentrations and temperatures. We also examined the relationships between the solubilities a nd the concentration of acetaldehyde in the flesh. The six treatments were: a) acetaldehyde vapor, b) carbon dioxide gas, c) ethanol vapor on intact f ruit, d) ethanol vapor on postharvest fruit, e) peeled fruit for sun drying , and f) freezing and thawing. Treatments of fruits with acetaldehyde vapor , postharvest treatment with ethanol vapor, and freezing and thawing gave t annins with low, intermediate, and high solubility, respectively. The solub ility of tannins decreased with time after the removal of astringency; the residual tannins was highest in fruits with high acetaldehyde concentration s.