Abstract
Bitter leaf (Vernonia amygdalina) is one of the leafy vegetables that can be used to alleviate the problem of micronutrient malnutrition, prominent in tropical Africa. To ensure availability in non-growing areas or seasons, the vegetable needs to be preserved. Processing and preservation methods influence the nutrient content of vegetables. This research work is focused on the design and fabrication of an improved bitter leaf juice washing and extraction machine.
The machine consists of two basic compartments: the rotary beater unit compartment and the juice storage compartment. Other components include feeding hoppers, juice sieve, juice collector, transmission belt, main frame, pulleys and bearings. The frame is made of mild carbon steel of angle cross-section. It was built to a trapezoidal shape with dimension of 480 mm (longer length), 405 mm (shorter length) and 550 mm (height). The machine is an electrical powered bitter leaf juice extractor that washes bitter leaves fed into it and at the same time squeezes out the juice. It uses stainless steel beaters inclined to angle of 0o to wash and squeeze the leaves against the cylindrical hopper incorporated with a perforated plate that drained juice while pulp is expelled. The beater is designed to work with the principle of oscillatory motion. The designed and fabricated bitter leaf juice washing and extraction machine was evaluated to determine the power, torque, force, etc., that are required to wash and extract the juice.
The results obtained showed that the volume of the cylindrical hopper, speed reduction, angular velocity, centrifugal force, torque, power were 0.0127m3, 480 rpm, 50.285rad/sec, 303.430N, 3.03Nm, 0.75 hp. The percentage moisture content present in bitter leaf was determined as 59.66%. Besides, a minimum average bitter leaf washing juice time of 398.28seconds was required by the machine in comparison to manual extraction time of 724.13seconds. Also, the results of volume of bitter leaf juice extracted manually and mechanically from average mass (407.54g) of bitter leaves were 3.60 litre and 3.63 litre respectively. The bitter leaf juice extraction efficiency of the machine and the machine throughput capacity were obtained as 88.72 % and 1.032 g/sec. With this high value of machine efficiency and good value of machine throughput capacity, the machine performance is satisfactory.
