Physical and chemical quality attributes of freeze-stored dates

Dates can be consumed at three stages: at the fully-ripe stage (khalal), when partially overripe (rutab), and at the fully overripe stage (tamar). Only the latter stage of dry dates i.e., tamar are traditionally stored for future consumption and processing. However, with the introduction of freeze-storage in rural date palm cultivation areas, prolonged storage in freezers has been gaining popularity as it allows for the consumption of all three stages at any time of the year. The effects of prolonged freezestorage on date physical and chemical quality attributes were assessed in this study. Dates were collected at three ripening stages (i.e., khalal, rutab & tamar) from 8-years old date palms (Phoenix dactylifera L.) grown in northern Oman and subjected to storage at -18°C in a conventional freezer. Fruit quality data were collected at harvest, after 6 months and 10 months of storage. The results showed that prolonged freezing affected fruit physical and chemical quality at different ripening stages. Physical attributes such as flesh and seed weights were reduced during freeze-storage, while percentage of flesh to seed and fruit volume was not affected by freezing. Moreover, storage up to 6 months produced the highest total soluble solids, titratable acidity, pH and biomass for all ripening stages. Rutab stage maintained high fruit volume, flesh and seed weights during storage. Whereas, tamar stage had the highest total soluble sugars, titratable acidity but the lowest pH, TSS: TA ratio, pectin and biomass. No interaction between ripening stages and storage duration was found in this study. Results suggest that prolonged freeze-storage is a viable alternative that allows for the consumption of dates at three stages of ripening compared to conventional storage of only dry dates.