Investigating the Factors Affecting on The Amount of Date Pit Powder in a Model Mill

Date palm is one of the most important export products of Iran. The date pit is about 10% of the total weight of the date, and can be used in livestock feeding after being ground, and also in many processing factories. The purpose of this study was to find the effects of rotational speed, type of blades, feeding rate and temperature on the amount of powder produced in a model mill. The device consists of chassis, electrical motor, feed unit, mill unit with two types of blades and grading unit. The effects of rotational speed, blade type, feeding rate and temperature on physical properties (amount of pits that is cracked, half-broken, full crushed, powdered) and chemical properties (amount of oil, protein, fiber, ash) were investigated. Experiments were grouped into two independent parts. The first one was conducted to determine the effects of rotational speed (2400, 2600 and 2800 rpm), two types of blades (vertical and diagonal) and three temperature levels (50, 100 and 150 C˚) on amount of powder produced in the constant feed rate. After determining the speed, blade type and optimum temperature, the second group of experiments were conducted to determine the effects of feeding rate (700, 1200 and 1700 gr/min.) on the amount of powder produced. The experimental design was factorial based on completely randomized design with three replications. The results from the first group of experiments showed that the effects of temperature, speed and type of blade and their interaction on all physical properties were significant at 1% level. Maximum amount of pit powder was obtained at 2800 (rpm) blades speed, 700 (gr/min.) of feeding, 150 C˚ temperature using diagonal blades. Among the chemical properties, only temperature at 1% level was significant on the protein content of the date palm kernel powder.