Moisture – Influenced friction properties of ackee apple (Blighia sapida) seeds

The friction properties of ackee apple (Blighia sapida) seeds at an 11.9, 17, 22, 27, and 32% (w.b.) seed moisture were determined, which are vital for designing their processing techniques and equipment to replace the present manual methods. The ackee apple grows in many West African countries, especially Nigeria. The ackee seeds were harvested at Lanlate, Oyo State, Nigeria, where ackee trees are predominant. Standard experimental methods were adopted to determine the properties. The data were analysed using an ANOVA and the least significant difference (LSD) at P ≤ 0.05. As the moisture increased, the static coefficient of friction on glass (27.6–36.40), aluminium (27.0–30.2), polyvinyl chloride (PVC; 27.9–32.8) surfaces and normal stress at 200 g (8.73–8.93 g⋅cm–2), 300 g (11.65–11.79 g⋅cm–2) and 400 g (14.37–14.65) loads increased significantly and linearly. The shear stress linearly decreased at a 200 g load (1.62–1.25 g⋅cm–2), but was non-significant at the 300 and 400 g loads. The coefficient of internal friction linearly decreased (0.744–0.588) implying that the wet seeds flow more easily than the dry ones, which should be considered in designing conveyors. The relationships between the ackee seeds' moisture and friction properties were expressed with regression models. Data for designing the handling techniques and machines for the ackee seeds were obtained.