Comparison of the Characteristics of Removal of Astringency in Two Japanese Persimmon Cultivars, ^|^prime;Denkuro^|^prime; and ^|^prime;Hiratanenashi^|^prime;

Abstract

SummaryThe characteristics of removal of astringency of two Japanese persimmon (Diospyros kaki Thunb.) cultivars, `Denkuro' and `Hiratanenashi', when treated with warm water, ethanol vapor and CO2 gas, were investigated.The patterns of the changes in peel color and flesh firmness were much the same for each treatment in both cultivars.The astringency of `Denkuro' and `Hiratanenashi' fruits was removed with both warm water and CO2 treatments. Decrease of soluble tannin occurred earlier in `Denkuro' than in `Hiratanenashi' in warm water treatment. In the ethanol treatment, astringency of `Hiratanenashi' was removed gradually and thoroughly, whereas there was almost no decrease of soluble tannin in `Denkuro' for 6 days.Ethanol and acetaldehyde accumulated in the flesh earlier and their levels were a little higher in `Denkuro' than in `Hiratanenashi' fruits when treated with warm water. The patterns of ethanol and acetaldehyde accumulation were almost the same in CO2 treatment in the two cultivars. In ethanol treatment, much more ethanol accumulated in `Denkuro' than in `Hiratanenashi' fruits, but only little acetaldehyde was detected in `Denkuro' , while a small but obvious amount accumulated in `Hiratanenashi'. The decrease of soluble tannin was, on the whole, closely related to the level of acetaldehyde accumulation in both cultivars.The responses of fresh juice to acetaldehyde vapor seemed almost the same between the two cultivars.From these results, the cultivar differences between `Denkuro' and `Hiratanenashi' and their regulative mechanisms in removing astringency were discussed.

Evaluation of Astringency and Tannin Content in ‘Xichu’ Persimmons Using Near Infrared Spectroscopy

“…Soluble tannin appeared in the form of an insoluble polymer when transformed to insoluble tannin by reaction with accumulated acetaldehyde under CO 2 gas treatment. [6,25] De-astringent persimmons contained tannin mostly in an insoluble form, and this probably resulted in more variation in the refractive indices of the interfaces in the flesh, leading to higher scattering characteristics. The flesh near the skin responded effectively to the de-astringent treatment and was full of insoluble tannin.…”

“…Soluble tannins are transformed to insoluble tannins when acetaldehyde accumulates in the flesh in an airless state. [5,6] By the time the astringency is low enough to be palatable to the consumer, the fruit texture has become too soft. Therefore, harvested fully mature fruit are subjected to de-astringent treatment using carbon dioxide to eliminate the soluble tannins responsible for astringency.…”

Effect of deastringency treatment of intact persimmon fruits on the quality of fresh-cut persimmons

“…We used effective treatment conditions for the deastringency treatments, as per those reported in previous studies (Kato, 1984;Seu & Sohn, 1976;Taira et al, 1989). Sets of 10 kg astringent persimmons were submitted to three different treatments: (a) 2 days at 20°C in 80% CO 2 atmosphere in a gas tight glass jar (15 L), (b) 2 days at 35°C in a water bath, and (c) 6 days at 20°C in an atmosphere of 35% ethanol in a gas-tight glass jar (15 L).…”

“…The physicochemical and physiological changes induced by deastringency treatment in intact persimmons vary according to the variety of the fruit and the deastringency methods, which include warm water treatment (Taira, Itamura, Abe, & Watanabe, 1989), ethanol treatment (Kato, 1984), high CO 2 treatment (Arnal & Del Rio, 2003;Seu & Sohn, 1976), and modified atmosphere packaging (Pesis, Levi, & Ben-Arie, 1986). The astringency removal resulting from the deastringency treatments is mainly because of a direct reaction between acetaldehyde, produced during anaerobic respiration developed by the deastringency treatment, and soluble tannins, which form an insoluble product devoid of astringency (Fukushima, Kitamura, Murayama, & Yoshida, 1991;Matsuo, Itoo, & Ben-Arie, 1991).…”

Temperature Affects Astringency Removal and Recurrence in Persimmon

“…THE REMOVAL of astringency from persimmon (Diospyros kaki L.) fruits has been achieved by several methods (Kitagawa and Glucina, 1984), based on exposing the fruit to anaerobic conditions or to products of anaerobic respiration. An efficient means of removing astringency has been treatment with 80% CO* for 1-3 days, the duration depending on cultivar, temperature and stage of maturity (Matsuo and Itoo, 1977;Taira et al, 1989). This involved a two-stage process, with only the initial induction stage requiring presence of CO, (Gazit and Adatq, 1972;Matsuo and Itoo, 1977).…”