Determination of Physical and Mechanical Properties of Onion (CV. Horand)

In order to design the processing machines for onion, it is necessary to have enough information about its size, density, shape index, angle of friction and penetration resistance (hardness). In this research, physical and mechanical properties of onion cultivar Horand were studied with a completely randomized design experiment with 20 replications. Three levels of, small, medium and large onion bulb size (small was less than 4 cm, medium between 4 to 7 cm and large greater than 7 cm) were evaluated. The results showed that with the increasing size of the bulbs there was an increase in the mass (18.16 to 151.85 gr), geometric mean diameter (34.49 to 68.51mm), arithmetic mean diameter (34.54 to 69.42 mm), surface area (5241.98 to 18827.18mm2), volume (31500 to171400 mm3), coefficient of static friction on the plastic and galvanized iron surfaces (0.34 to 0.57 and 0.37 to 0.53, respectively) and finally, the shape index of onion bulbs (1.02 to 1.22). Increasing bulb size increased Horand cv. true density (772.3 to 886.6 kgm-3), static friction coefficient on the wood surface (0.32 to 0.41) and requirement power for penetration (5.66 to 6.50 kgf). Big bulbs were more susceptible to frictional injuries than medium and small ones.