Biorefinery Valorisation of Shea (Vitellaria paradoxa) Processing Waste for High-Value Lipid and Protein Products in the Nigerian Middle Belt

Shea nut processing generates significant quantities of by-products including shea cake, defatted meal, and press effluent in the Middle Belt of Nigeria, where shea butter production is a major livelihood activity for rural women. These by-products contain valuable lipid fractions, proteins with emulsification and foaming properties, and polyphenols with antioxidant activity that remain largely unutilised. This study develops an integrated biorefinery framework for the valorisation of shea processing waste, targeting the sequential recovery of residual lipid, protein concentrate, and polyphenol extract for food and cosmetic applications. The theoretical contribution is a mass integration model for the shea biorefinery that optimises the allocation of raw material streams across multiple co-products to maximise total economic value recovery while minimising environmental impact. The biorefinery framework was evaluated using shea nut waste collected from cooperatives in Nasarawa, Kwara, and Kogi States (North Central zone). Residual lipid was recovered by solvent extraction and characterised for fatty acid composition by gas chromatography-mass spectrometry and triglyceride profile by high-performance liquid chromatography. Protein concentrate was prepared by isoelectric precipitation and characterised for amino acid profile, solubility, emulsification capacity, foaming stability, and oil absorption capacity. Polyphenols were extracted by ethanol-water and characterised by high-performance liquid chromatography with mass spectrometry. All recovered fractions were evaluated for application in food product matrices. An economic analysis showed a potential value recovery of 2.4 times the cost of by-product processing. The study represents an original integrated biorefinery framework for shea waste valorisation. Keywords: biorefinery, shea nut waste, lipid recovery, protein concentrate, Middle Belt Nigeria