Physico-chemical characteristics and sensory quality of two date varieties under commercial and industrial storage conditions

The physicochemical characteristics of two date palm varieties, "Khalas" and "Barhee", commonly grown in the United Arab Emirates, were studied under commercial and industrial storage conditions. Storage conditions chosen were 2 months and 1 year at -3 °C and at room temperature (∼25 °C). Stored samples were analyzed for sugar, moisture, protein, ash and mineral element contents. Physical measurements on the date fruit, pit and flesh, measurements of the fruit's pitting pressure, shear pressure and modulus of elasticity, as well as sensory evaluation, were carried out on freshly harvested and stored samples. Significant variations in measured attributes were observed with storage treatments, but the two varieties did not behave similarly under matching storage conditions. Quality was best maintained after storage of 2 months at -3 °C for Khalas, and 1 year at -3 °C for Barhee. Overall, storage time and temperature as independent factors alone did not account for all of the observed variation in the studied attributes of Khalas and Barhee. Principal component analysis revealed that most of the variation of the stored dates comes from "size", followed by "texture" variables. The work pointed to some probable chemical and physiological systems responsible for deterioration of dates, the understanding of which can prove extremely helpful in developing methods of short- and long-term preservation of the fruit.