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.

This research evaluated and determined some moisture-influenced physical and gravimetric properties of Blighia sapida seeds relevant to machine design at 11.9, 17.0, 22.0, 27.0 and 32.0% moisture levels (wet basis). These properties are vital in handling and seed process design. With increasing seed moisture (11.9 to 32.0%), there was no statistically significant effect on the seed axial dimensions, principal diameters, sphericity and surface area. This is because seed axial dimensions relatively determine other properties afore stated. However, there were significant and linear increases in thousand seed mass (189.3 – 230.3 g), bulk (377.0 - 418.3 kg m-3) and true (714.3 - 771.1 kg m-3) densities but decrease in porosity was not significant. Increase in bulk and true densities is due to the rate of increase in the seed mass being more rapid than the rate of increase in its volume, as the seed moisture increased. A non-linear decrease showed in seed volume (3.4-3.2 cm3). Behavioral patterns of ackee seeds and their investigated properties, under increasing moisture was expressed using regression models. Required primary data for the design of handling techniques and process machinery for ackee apple seeds were generated.