Effect of Hot Water Treatment on Inducing Chilling Tolerance in Persimmon (Diospyros kaki Thunb.) Fruit cv. Karaj

The aim of this study was to determine the effects of hot water dips on chilling injury of karaj persimmons. Fruits were subjected to hot water dips at 20, 45, 50 or 55°C for 10 or 20 min. Treated and untreated fruits were then kept at 1°C and 85 - 90% relative humidity for 4 months. Fruit weight loss, firmness, total soluble solids (TSS), titratable acidity (TA), total phenolic content (TPC), soluble tannin content, chilling injury, antioxidant activity, electrolyte leakage (EL) and Malondialdehyde (MDA) content were measured 0, 15, 30, 45, 60, 75, 90, 105 and 120 days after storage. Peroxidase (POD) and catalase (CAT) activities were also determined at the end of storage. Hot water treatments had significant effects on firmness, TSS, TPC, soluble tannin content, chilling injury, EL and MDA content. Although the best results obtained in fruits that treated by 55°C for 20 min but this treatment had unpleasant effect on appearance and taste of fruits. So 50°C for 10 or 20 min and 55°C for 10 min were recognized the best treatment for maintaining fruit quality and reduce chilling injuries in Karaj persimmons.