Artificial Ripening of ‘Shiraz’ Persimmon (Diospyros kaki Thunb. cv. ‘Shiraz’) Prior to Marketing

Abstract

Although it is one of the traditional fruits, persimmon production in Iran is only about 7,320 tons annually and there has been a decrease in cultivated acreage. The decrease in persimmon consumption can be attributed to the unpleasant astringency of the local Iranian cultivars. The producers' and handlers' lack of knowledge of techniques for removing astringency before sending the fruit to market has greatly influenced this issue. This study was conducted in order to develop recommendations for a simple and economical method for removing the fruit astringency of local cultivars. Fruits of a commercial cultivar (cv. ‘Shiraz’) in Fars province, Iran were harvested at the local commercial maturity stage (breaker stage). The fruits were dipped in ethanol (20, 35 and 50%), acetic acid (3, 6 and 10%), commercial vinegar, hot water (60°C) and tap water as control for 30 min. Some qualitative characteristics such as total soluble solids (TSS), vitamin C, total acids, pH and tannic acid of the treated fruits besides fresh weight changes were measured at 4-day intervals after storage at room temperature. Results indicate that vitamin C and TSS were highest in the 20% ethanol, hot water and 35% ethanol treatments. Total acid was highest in 10 and 6% acetic acid treatments. Tannins were highest in the control treatment and lowest in the 20% ethanol, hot water followed by 35% ethanol. Fruit juice pH was also highest in the 20 and 35% ethanol and hot water. Although tannic acid and total acid declined after treatment, fruit juice pH and TSS increased. Weight loss was lowest in the ethanol 20, 35 and 50%, and hot water treatments, respectively. Results suggest the use of 20% ethanol treatment with ‘Shiraz’ persimmon before short storage and supply to markets would be beneficial in improving consumer acceptance besides being commercially economical and practical.