Effect of some Natural Substances on Fruit Quality of Washington Navel Orange under Cold Storage

Aims: To study the response of Washington navel orange fruits to some natural post harvest treatments under cold storage.
Study Design: A randomized complete block design with three replicates was used.
Place and Duration of Study: This study was carried out during two successive seasons 2013 and 2014 in the post harvest laboratory of Agricultural Development System project in Faculty of Agriculture, Cairo University, Egypt.
Methodology: Harvested fruits were directly transferred to the laboratory. Experimental fruits were divided into six similar groups. Each group was subjected to one of the following treatments: Control tap water plus tween (80), Black cumin oil at 2%, Black cumin oil at 3%, Ginger oil at 2%, Ginger oil at 3% and Wax. Fruits were stored at 5°C and 85-90% relative humidity for 63 days. Changes in some physical and chemical fruit properties were determined at seven days intervals.
Results: The results showed that, fruit weight loss (%), decay (%), total soluble solids (TSS) percentage and respiration rate (ml/kg/h) of Washington navel orange fruits were increased in most cases with advancing the storage period. Meanwhile, total acidity (%) and ascorbic acid (V.C) as (mg/100 ml juice) were decreased with prolonging the storage period. Furthermore, the lowest values of weight loss (%), decay (%), ascorbic acid, respiration rate and fruit shelf life (days) were scored by wax treatment, as well as, the best results of total soluble solids with the same bare with control especially in the first season. Meanwhile the lowest total acidity content was gained by the control.
Conclusion: Treatment of Washington navel orange fruits with wax proved to be the most efficient treatment in enhances fruit quality and storability under cold storage.