No abstract

This study was undertaken to develop appropriate and low cost grading device for a variety of economically important agricultural produce, in order to increase their market demand. This grader was tested for tomato with three grades which raise the value of the produce significantly due to that worked on the principle of rolling the produce around the axis of minimum mass inertia was evaluated. Two grades were separated based on the opening size and a third grade consisted of produce that overflowed the largest opening. The opening for grade I, II and III were 55mm to 65mm, 65 mm to 75 mm and >75mm respectively. The grader was tested for tomatoes at slope of 08 degrees, 10 degrees and 12 degrees and the 10 degree was the best slope. The rates for which the grader was tested were 192 kg/h, 288kg/h and 576kg/h and the percentage of tomato correctly graded were 90%, 89% and 72% at slope of ten degree respectively.

Sesame, (Sesamum indicum) is one of the oldest and important oil seed crop in the world. The sesame seed apart from providing edible oil is also rich in protein. A study was carried out to evaluate the performance of a medium scale screw type oil expeller for extracting sesame oil. In fact, the mechanized medium scale method has not been previously applied in the oil expelling industry for sesame seed in Sri Lanka. For this experiment, the popular screw type machine with 25 mm shaft pitch, 75x315 mm internal barrel and 4 kW three phase motor were used. The development was made in order to increase the oil expelling efficiency in terms of extract bar clearance, speed of the main spiral shaft and outer body closer to the exhaust out let. The optimum oil yield was 44% obtained under 0.2mm and 0.3mm barrel shaft clearance and the main spiral shaft speed of 75 rpm. The quality of refined oil at maximum oil yield was analysed out in terms of saponification value, free fatty acid and specific gravity. The results obtained for saponification value, free fatty acid and specific gravity were 182.33, 3.3.12 % and 0.917 gcm-3 .respectively. Color of the sesame oil was closer to the yellow which revealed by the lightness value (L*) of 26 and positive value b of 8.27. The capacity and energy consumption per kilograms of refined sesame oil were 39kg/hr and 0.103kWh/kg. This study reveals that sesame oil could be obtained using the screw type oil expeller and it can be recommended for medium scale entrepreneurs relative to the traditional Sekku method.

Abstract:Particle size affects many characteristics in the manufacturing process. Controlling the particle size helps to assure that the milled material will be consistent and repeatable with respect to firstly color, that is, uniform particles assure batch-to-batch color consistency, Secondly, flowability that is critical to packaging, tableting, weighing. Thirdly, uniformity, that is , consistent bulk density.Fourthly, density -helps control shipping costs and minimize dust. Fifthly, reconstitution, that assures the desired dissolution rate, Sixthly, chemical reaction that is vital for uniform, controlled chemical change. Finally, taste that allows precise portion control for consistent taste. The aim of this project is to design and develop a rasp bar mill for size reduction of maize seeds for different purposes. The fabricated rasp bar mill is capable of feeding maize around 60-180 kg/h, delivering of grits 60-90%, with sieve effectiveness 90-100% at a power requirement of 800-1400W,for different sieve perforation sizes of 5, 6, 7, 8 mm respectively. Key words:Size reduction, Rasp bar mill, Maize gritting IntroductionMaize ( Particle size affects many characteristics in the manufacturing process. Controlling the particle size helps to assure that the milled material will be consistent and repeatable with respect to firstly color, that is, uniform particles assure batch-to-batch color consistency, Secondly, flowability that is critical to packaging, tableting, weighing. Thirdly, uniformity, that is , consistent bulk density.