Biodiesel potential of Cucumeropsis mannii (white melon) seed oil: A neglected and underutilized resource in Nigeria

A major challenge in the biodiesel industry is the availability of high-quality vegetable oil feedstocks. Thus, there is a continuous search for quality biodiesel feedstock whose production will trigger economic impact on the agricultural sector, minimize land degradation and without significant disruption to the food chain. In this work, we extracted and analysed oil from neglected and underutilized Cucumeropsis mannii seeds for their potential in biodiesel production. The oil content of C. mannii seed was 40.8 ± 0.56%. GC-MS analysis of the oil revealed the presence of 47.0% saturated fatty (predominantly palmitic acid, stearic acid) and 53.0% of unsaturated fatty acids (predominantly oleic, linoleic and erucic acids). The physicochemical properties were determined and values were as follows: iodine value (111.07 ± 0.15 g/100 g), saponification value (192.03 ± 0.37 mg/kg of oil), peroxide value (2.60 ± 0.10 meq/kg), acid value (4.20 ± 0.02 mgKOH/g) free fatty acid (2.51 ± 0.02%), relative density (0.93 ± 0.02), the refractive index at 28 °C (1.46 ± 0.04) and viscosity at 30 °C (3.00 ± 0.10 mm²/s). The fuel properties namely, cloud point, pour point, flash point and caloric value were determined and the values were 3.03 ± 0.11 °C, 1.00 ± 0.10 °C, 279.04 ± 0.99 °C and 31.10 ± 0.11 MJ/kg, respectively. In addition, the protein content of the defatted seed was found to be 47.4 ± 0.61 g/100 g. The defatted protein-rich cakes can be upgraded as a food additive; thus the C. mannii seed oil can serve as biodiesel feedstock without altering the food chain. These characteristics demonstrate the potential of C. mannii oil as a high-quality feedstock for biodiesel production. We envisage that its utilization as biodiesel feedstock will improve the market value of these seeds, thus supporting the economic development of local farmers in rural areas.