Value addition to underutilized oilseed crops through saponification of avocado and coconut oils in South-Kivu, Democratic Republic of Congo

Abstract Underutilized oilseed crops contribute significantly to food security and poverty alleviation in the Democratic Republic of Congo (DRC). However, their potential remains underexploited due to limited data on their oil quality and potential applications. This study investigated the physicochemical properties of avocado and coconut oils extracted using solvent-based (ethanol) and solvent-free methods, and assessed their suitability for soap production. Solvent extraction yielded 20 – 30% higher oil outputs compared to solvent-free extraction. Avocado oil obtained via solvent extraction exhibited higher acid and free fatty acid values of about 25% and more than double, respectively, than the solvent-free method. Its saponification value was also approximately 8% higher with solvent extraction than the solvent-free method. For coconut oil, acid and free fatty acid values were slightly higher with solvent extraction, while its saponification value was about 7% higher than that of the solvent-free method. Solvent-extracted oils exhibited higher ester values, suggesting more efficient extraction of lipid components. Soaps produced from these oils showed alkaline pH values within acceptable ranges (9.2 and 8.7 for avocado and coconut oil, respectively). Additionally, coconut oil-based soap demonstrated superior foaming capacity compared to avocado oil-based soap, indicating better performance in soap formulation. Despite slightly lower yields, solvent-free oil extraction offers a practical, low-cost solution for small-scale rural soap production, particularly empowering women and youth by integrating underutilized local resources with minimal input requirements. These results underscore the importance of enhancing local oil extraction technologies and promoting the industrial value-addition of underutilized oilseed crops.