Java apple fruit features attractive skin, sweet and crispy flesh, and a high susceptibility to
mechanical damage. The java apple produced in Thailand has gained popularity in local
and foreign markets, is available almost all year round and is sold at good prices. Fruit
export drives postharvest mechanisation, of which fundamentally important machines
such as a mechanical sizer for java apple are still not available. This research was aimed at
designing, constructing, testing, and evaluating an efficient sizing machine for java apple.
Design concepts featured a) a sizing parameters which were determined by the diameter of
the fruit and b) a sizing mechanism which causes minimum damage. The sizing machine
comprised a feeding unit and a diverging belt sizing unit that are powered by two 187 W
220 V 50 Hz electric motors, gear reducer and pulleys. Performance tests indicated that
velocity and inclination angle of the sizing belt; feeding belt velocity and the fruit orientation
significantly affects the sizing performance at p < 0.05. The optimum conditions for
continuous mechanical sizing depended on the variety. The optimum sizing performance
was characterised by a contamination or error ratio of 10.8e16.5%, and a throughput
capacity of 149.7e195.1 kg h1 with no significantly noticeable damage to the sized fruits.
Manual sizing of the exported java apple featured an error ratio of 27.9%, a damage
percentage of 13.3%, and a capacity of 107.2 kg h1
. Therefore, the java apple sizing
machine can be operated without adding more mechanical damages to the sized fruit.