ABSTRACT
Fresh dates contain high moisture (about 60%), thus limiting the shelf life; therefore, drying is necessary. Matured date fruits are allowed to partially dry on the trees before they are harvested and further sun dried to enhance their keeping quality and storage. However, problems associated with sun drying are well documented (Guine and Castro 2002; Doymaz 2004, 2005). The quality of sundried products under dusty conditions becomes very poor and nonuniform with a low yield. Due to persistent rain and stormy conditions, a large amount of the harvested dates becomes moldy, fermented, dusty, and damaged by birds and insects. The growers become disheartened and consequently the rate of further cultivation and propagation of the variety is impaired badly. To minimize the postharvest damages, streamline the production, and improve the quality of the produce, the adaptation of appropriate scientiŸc measures becomes imperative (Saleem et al. 2005). Dehydration
Introduction .................................................................................................................................... 175 Materials and Methods ................................................................................................................... 176 Determination of the Equivalent Radius and the Shape Factor of Date Palm Fruit ....................... 176 Determination of Drying Characteristics of Date Palm Fruit ........................................................ 177 Determination of Rehydration Characteristics and Capacity of Dehydrated Date Palm Fruit ...... 178 Evaluation of Color Changes in Untreated and SulŸted Dried Date Palm Fruit Varieties during Storage ................................................................................................................................ 178 Results and Discussion .................................................................................................................. 179
Effect of Variety on Moisture Content, Moisture Ratio, and Drying Rates of Date Palm Fruits ............................................................................................. 179 Effect of Drying Temperature on Moisture Ratio and Drying Rates of Date Palm Fruits ........ 181 Effect of Variety on Moisture Diffusivity and Activation Energy of Date Palm Fruit during Drying ....................................................................................................................................... 181 Effect of Variety on Moisture Diffusivity and Activation Energy during Rehydration of Date Palm Fruits ............................................................................................... 182
Rehydration Capacity of Date Palm Fruits .................................................................................... 183 Effect of SulŸte Pretreatment on Color Stability of Dried Date Palm Fruits ............................ 185
Conclusion ..................................................................................................................................... 187 References ...................................................................................................................................... 187
in low-cost oven driers at controlled temperatures and ¨ow of air will ensure an appropriate level of moisture in dates and better preservation of the product quality.
