The changes in fruit constituents and other characteristics of persimmon fruits treated with ethanol alone or ethanol plus ethylene were examined during de-astringency and ripening at various temperatures ranging from 5° to 40°C.
1. There was a rapid decrease in tannin concentration at high temperatures with a 1.9-fold decrease for each 10°C rise in temperature.
2. A gradual decrease in flesh firmness occurred during the early holding period at 15° to 40°C. At 10°C the firmness decreased slowly and at a very slow or almost undetectable rate at 5°C. Later, there was a rapid decrease in firmness, but no significant difference was found in the rate of decrease at temperatures of 5° to 25°C. At 10°C, however, this rapid decrease in firmness began earlier than at 15° to 30°C and the softening fruits appeared to become water-logged in theflesh region.
3. The decrease in peel chlorophyll concentration was rapid at 15°C and slow at both 5° and 30°C. The increase in peel carotenoid concentration was rapid as the temperature was increased from 5° to 30°C, and in this case no appreciable amount of lycopene was found in the peel.
4. The decrease in flesh firmness began earlier in ethylene-treated fruits than in untreated ones. The softening accelerated by ethylene treatment remained at a constant level during holding at any temperature thereafter.
5. The concentration of ethanol vapor within packed cartons rose quickly to a peak about 1 hour after the application of the ethanolic solution and then decreased rapidly. These changes were more apparent with higher temperatures. The penetration of applied ethanol into fruits was almost complete within less than 3 days even at a low temperature of 10°C.