Evaluation of a portable watermelon juice extracting machine

Abstract

A small-scale machine for extracting watermelon juice was developed with locally available materials and evaluated to determine its best extracting operating factors. The machine slices a whole watermelon and extracts its juice content. This machine operates on the principle of compressive and shearing force exerted through an auger.  Component parts includes feeding hopper, conveyor shaft, auger conveyor housed in a cylindrical chamber, juice sieve, juice collector, seed - pulp outlet, gear and main frame. It was powered by a 1hp electric motor, coupled to a gear reduction speed to operate at 46.67 rm^-1. In operation, watermelon fruits introduced via the hopper is squeezed and transferred to the auger conveyor. The auger presses and squeezes the watermelon fruit to extract the juice. The juice extracted is filtered through the juice sieve into juice collector while the seeds and pulp are discharged through another outlet.  Performance evaluation was carried out using different sizes of watermelon fruit (2.3 kg, 2.6 kg, 2.8 kg, 3.1 kg and 3.3 kg) to determine juice yield, extraction efficiency and extraction loss. Results revealed maximum juice yield of 86 %, extraction efficiency of 92.6 % and extraction loss of 14 % respectively. The machine has a capacity of 49.04kg / hr. It is simple to operate and maintain; therefore, it is an attempt at enhancing production of watermelon juice by small scale farmers.