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Abstract
This investigation was carried out during 2012, 2013, and 2014 seasons on ”costata”, ”tanenashi” and ”tamopan” persimmon fruits as an early, mid and late season varieties, respectively and usually astringent until fully ripe to study the effect of traditional ripening method (calcium carbide), ethrel treatment and CO₂ (using citric acid and sodium bicarbonate to generating CO₂) on fruit quality after determine the maturity stage. Besides, the effect of CO₂ de-astringency treatment for ”cotata” persimmon fruits on: Structural changes, acetaldehyde production, Tannins and Total phenolic content, organoleptic score, fruit firmness and Antioxidant enzymes activity[Superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)]. The obtained results indicated that, age of 169, 176 and 183 days from full blooming coincided with the maturity stage of ”costata”, ”tanenashi” and ”tamopan” cultivars, respectively. CO2 treatment was more effective and faster than ethrel or calcium carbide treatments in attaining a high taste score (i.e. De-astringency) as a response to its pronouncing effect in removing astringency than other treatments. The lowest value of fruits firmness was associated with ethrel and calcium carbide treatment. The different in fruit firmness values between CO₂ treatment and control were not significant. The control treatment recoded highest significant value of total tannins. While, the lowest value of total tannins was associated with CO₂ treatment followed by ethrel treatment and calcium carbide treatment. The parenchyma structure of the CO₂-treated fruit was very similar to that seen before CO₂ treatment and, once again, with an insoluble material filling the vacuoles of tannic cells. In this case, while some intercellular spaces remained air-filled, others were filled with a soluble material