Abstract: Date fruits are considered one of the greatest sources to provide a concentrated energy food. It’s also used in producing many industrials products. The flesh dates are utilized for many purpose of making sweets, preserves, condiments, breakfast foods, desserts, derived date products, confectionery, baking products, institutional feeding and health foods. To produce these products with date paste, the date pits should be manually or mechanically removed.
For the sake of industrial requirements to produce date paste (AGWA) from semi dried date fruits especially the Egyptian common variety (siwi variety) in maturity mode (tamr), a roller date pitting machine has been designed, constructed and experimented to evaluate it’s performance under the designed operating conditions. The tested operating parameters were five levels of rotating speed (40, 60, 80, 100, and 120 rpm), five levels of (P/D) pitch/diameter ratio (1, 1.3, 1.6, 1.9, and 2.2), and three levels of clearances between the two drums (0, 1, and 2 mm). It was evaluated based on the machine productivity, machine efficiency, energy requirement and operating cost.
Some physical and mechanical properties for the investigated fruits and their pits (Siwi variety) were studied such as; (dimensions, mass, density, friction angle between date and stainless steel sheet, and force required for strip the date pit.).
The obtained results indicated that the average values of the physical and mechanical properties of the fruit were 34.12mm, 20.96mm, 19.61mm, 10.98g, 9.40g, 1.59g, 0.6545g/cm3, 24.65cm, 10.94mm, 9.56mm. for fruit length, width, thickness, mass, flesh mass, seed mass, bulk density, pit length, width, and thickness. The pit take-off force was found to be 48.90 N, and the friction coefficient between dates and stainless steel surfaces was 0.67 .
The most important results can be concluded as: The highest machine productivity (423 kg/h) with the optimum machine efficiency (86.6 %) by using the pitting machine with drum speed of 80 rpm, with 1.6 P/D ratio, and drums clearance of 1 mm. The energy consumed to pit one ton of date with manual pitting is about 10.69 kW.h/ton. While, the energy required for the designed pitting machine was recorded as 3.47 kW.h/ton. The operating costs for the designed date pitting machine was 29.50 LE/ton, whereas the manual date pitting cost is about 178.57 LE/ton.
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