DEVELOPMENT AND EVALUATION OF POWER OPERATED CLEANER CUM PEARLER FOR FINGER MILLET
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Date
2015
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
Finger Millet (Eleusine coracona), popularly known as Ragi, has high yield potential of greater than 10 t/ha under optimum irrigated conditions. Usually millet seeds have four layers namely hull, bran, germ and endosperm. Among these, endosperm is only the edible part of millet. Bran and germ are rich in oil and hence affect the storage quality of millets. So dehulling / pearling of finger millet is necessary to remove the hull, bran and germ to increase the shelf life of the pearled grain and flour. In traditional dehulling, the grain is mixed with water, allowed to stand for 5 minutes and pounded with a wooden pestle for 10-15 minutes. Then grains are subjected to drying and then winnowing operation to remove the bran and other fine material. The pounding and winnowing processes are repeated several times till the good quality millet is obtained. The most rustic equipment for cleaning is the winnower fan, air blowers etc., This operation is time consuming, laborious and uneconomical to the farmers. Therefore, there is a need to develop a suitable small scale cleaner cum pearling unit for finger millet so that the pearling losses can be reduced and it can be useful for farmers with small land holdings.
The effect of moisture content of 10, 13 and 16 % (w.b) on physical properties has been evaluated for finger millet of saptagiri variety. The average values of physical properties observed were length : 1.63 to 1.7 mm, width : 1.58 to1.65 mm, thickness : 1.43 to 1.54, geometric mean diameter : 1.54 to1.622mm, sphericity : 0.942 to 0.955, surface area : 7.4 to 8.2 mm2, volume : 1.74 to 2.26 mm3,thousand grain weight : 2.56 to 3.51g, porosity : 40.1 to 45.2, angle of repose : 25.5˚ to 30.5˚, static coefficient of friction for galvanized iron : 0.39 to 0.423, mild steel : 0.43 to 0.456, stainless steel 0.35 to 0.356 and terminal velocity : 2.56 to 3.4 m/s were increased as moisture content increased from 10 to 16 % w.b. Bulk density and true density were decreased from 740.6 to 671.4 kg/m3 and 1289 to 1232 kg/m3 respectively with the increase in moisture content from 10 to 16% w.b.
Name of the Author : V. VENKATA TEJASWINI
Title of the thesis : “DEVELOPMENT AND EVALUATION OF POWER OPERATED CLEANER CUM PEARLER FOR FINGER MILLET”
Degree to which it is submitted : Master of Technology
Faculty : Agricultural Engineering
Major field of study : PROCESSING AND FOOD ENGINEERING
Major Advisor : Dr. D.BHASKARA RAO
University : Acharya N.G Ranga Agricultural University
Year of Submission : 2016
The developed cleaner cum pearler for finger millet machine consisted of cleaning unit, hopper, and outer cylinder, inner cylinder with 12 cotton felts (10 x 10 x 1 cm) with one end of them bolted on its surface, main frame, aspirator (0.5hp) and electric motor (2.5hp). The cleaning unit consisted of stainless steel plate with circular perforations of 2 mm diameter which works on the principle of vibration through which the cleaned grains goes into pearling unit which consists of inner and outer cylinders. The clearance between cylinders was 2 cm and 1 cm at cotton felts for maximum compression and shearing of grains so that the grains get pearled. Pearled grain enter into closed outlet at the middle of which a pipe from the aspirator was fixed so that the husk and other lighter particles were collected by suction and cleaned, pearled grains were collected at the other end of the outlet. The cleaning efficiency of the machine was 88.2%. The performance of the machine was tested for its pearling efficiency, percentage of broken grain at speeds 1400, 900,500, 300 rpm; moisture contents 10, 13, 16 % (w.b) and at feed rates 90, 120, 150 kg/h for two passes. The optimum value of pearling efficiency was 80.1 % , 4.3 % of broken grain at 10% w.b moisture content, 900 rpm at 150 kg/h feed rate (II pass). The pearling efficiency decreased with increase in moisture content and increased with the increase of cylinder speed and feed rate. The percentage of broken grain decreased with the increase in moisture content and feed rate and increased with increase in cylinder speed. The highest percentage of broken grain was found to be 9.5 % at 10 % w.b moisture content, 1400 rpm at 90kg/h (II pass). The operating cost of the machine per kg was Rs 0.326/-.
Key words: Finger millet, physical properties, small scale cleaner cum pearler, moisture content, Screen effectiveness, pearling efficiency, percentage of broken grain.
Description
D5220
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