Nutritional Profiling of Underutilised Citrullus lanatus mucosospermus Seed Flour

Abstract

The seed of Citrullus lanatus mucosospermus, known as egusi, is versatile and explored for its oil and flour functionality. Raw flour can be used as a raw material in a nutritional program due to its oil-rich, remarkably high protein content, and richness in omega-6 fatty acids. There is a need to explore eco-friendly defatting methods using the supercritical CO2 extraction method (SFECO2) to preserve this seed’s generic richness and to control the flour–oil ratio in processing formulations. The supercritical fluid extraction method uses temperature, pressure, and CO2 flow rate to determine the best yield and extraction parameters. Defatted egusi flour (DEF) was extracted using three runs. Firstly, at 60 °C, 30 g/h, and 450 bar (DEF1); secondly, at 55 °C, 30 g/h, and 600 bar (DEF2); and thirdly, extraction was performed at 75 °C, 30 g/h and 600 bar (DEF3). Trace and major elements were analysed using Agilent 7700 quadruple ICP-MS (Agilent Technologies Network, Palo Alto, CA, USA) and Thermo Cap 6200 ICP-AES (Thermo Scientific, Waltham, MA, USA), respectively. The sugar was separated on a gas chromatograph coupled to a Mass Selective Detector (MSD). The fundamental pasting property measurements were performed using a Rapid Visco Analyser RVA 4500 Perten instrument Sin 214 31208-45 Australia. Data analysis was conducted using IBM SPSS version 29 software (v. 2022). The protein content of defatted egusi flour ranged from 48.4 for DEF2 to 60.4% w/w for DEF1 and differed significantly, with a rich amino acid high in glutamine ranging from 9.8 to 12.9 g/100 g). DEF2 (512.0 cP) showed the highest peak viscosity and was the most viscous among the samples. Defatted flour with lower temperature and lower pressure (60 °C and 450 bar) offered the best nutritional properties, proffering defatted egusi flour from SFECO2, a novel flour for dietary programs.