摘要
Mango fruit （Mangifera indica） is very rich in fibre and vitamin C which are the required nutrients for good health and easy digestion of food in human body system. However, the fruit is highly perishable in its natural state after harvest due to the chemical deterioration and environmental effects. Due to the perishable nature, abundant wastage during the production season and relative scarcity during the off season were recorded by farmers. Processing the fruit into the form that can easily be stored, preserved, packaged, transported or consumed is crucial to having the product all the year round. Besides, mango juice can be consumed freshly, processed into dry powder, mixed or blended with other juice to make fruit jams, or evaporated to concentrates. These products have a lot of potential in food and beverage industries for export and foreign exchange earnings. Therefore, a small scale machine to process mango fruits to high quality juice is highly essential to reduce the postharvest loss and then add value to the commodity. To achieve this purpose, an abrasion-macerating device （AMD） was designed, fabricated and tested for small scale mango juice extraction. Design considerations focused on the techno-economic status of the micro and small scale fruit juice processors who are the intended users of the machine. The major components of the machine included hopper, perforated drum, screw conveyor, juice outlet, waste outlet, frame, electric motor and motor stand. Other components included screw shaft, the juice collector, top cover and the transmission system. In operation, the screw conveyor conveys and presses the mango fruits against the perforated roughened drum. The abrasion/tearing process of the screw on the flesh of the fruit and further pressing against the drum squeeze enough juice out of the fruit. The juice extracted is drained through the perforated mesh of the juice channel into the juice outlet from where it is collected while the residual waste is collected at the waste outlet. The machine was tested using freshly harvested mango fruits and results obtained showed an average juice yield, extraction efficiency and extraction loss of 34,56%, 55.14% and 10.15%, respectively. These values of juice yield, extraction efficiency and low level of extraction loss indicate satisfactory performance of the machine. Powered by a 2.5 hp single-phase electric motor, the machine has a production cost of USD565 with the construction materials being locally available at affordable costs. A cottage mango juice extraction plant based on this technology can provide employment for at least two persons at the same time providing fresh juice at low costs and residual waste as an ingredient for livestock feed manufacturing.
