Effect of storage duration on some physical properties of date palm (cv. Stamaran)

Most of the date fruits are processed traditionally in Iran. It becomes imperative to characterize the fruits with a view of understanding the properties that may affect the design of machines to handle their processing. The objectives of this study were to find the basic physical properties of date fruit at different storage time. Some physical properties of the Iranian Stamaran date variety were measured at the tamr stage of maturity for pitted dates during 6 months storage (25 °C of temperature and 75% of humidity). The results showed that length of the samples decreased by 8.31% from 39.21 to 35.95 mm, and no significant change for width and thickness. Mean mass and volume of the fruit did not change significantly. The projected area along length (PL) did not change significantly, but projected areas along width (PW) and along thickness (PT) decreased by 4.26% from 647.41 to 619.8, and 8.32% from 666.89 to 611.43 mm2, respectively. The fruit density, bulk density, porosity and sphericity did not change significantly. The geometric mean diameter and surface area decreased by 5.01%, from 25.53 to 24.25 mm, and 9.57%, from 2049.3 to 1853.1 mm2, respectively. The mean coefficients of static friction increased significantly from 0.36 to 0.38, 0.33 to 0.35 and 0.42 to 0.45 on steel, galvanized iron, and plywood, respectively.