Profiling the effects of microwave-assisted and soxhlet extraction techniques on the physicochemical attributes of Moringa oleifera seed oil and proteins

Abstract

There is a constant search for biomaterials from natural products like plants for food and industrial applications. The work embodied in this report aimed at investigating the effects of microwave-assisted and soxhlet extraction (MAE and SE) techniques on the functional physicochemical quality characteristics of Moringa oleifera seed oil and proteins extracts. M. oleifera ​seeds were ground to fine powders and oil was extracted by microwave-assisted and soxhlet extraction techniques using petroleum ether. Quality attributes including yield percent, moisture content, iodine, saponification, specific gravity, viscosity, pH, thiobarbituric acid, acid and peroxide values were measured. Mineral and vitamin contents, chemical/functional groups, fatty acid (FA) composition, and reducing power of the oil were evaluated. Metabolomics of protein extracted from the defatted powders were analyzed by nuclear magnetic resonance (NMR). M. oleifera ​oil from MAE and SE methods had good yield (34.25 ​± ​0.0%, 28.75 ​± ​0.0%), low moisture content (0.008 ​± ​0.0%, 0.011 ​± ​0.0%), non-drying and unsaturated, moderately saponified, less dense (0.91 ​± ​0.01, 0.92 ​± ​0.02 g mL⁻¹), had Newtonian flow, were weakly acidic, showed good content of FAs, recorded strong potential for long shelf-life, showed stability against oxidative rancidity and enzymatic hydrolysis, had very rich deposits of micro- and macro-nutrients as well as water-soluble and lipid-soluble vitamins, and functional groups in the oil were reflective of its content of long- and medium-chain triglycerides (LCT and MCT). Monounsaturated and saturated fatty acids (MUFA and SFA) were detected and the oil has excellent ferric ion reducing power. NMR metabolomic assay revealed the presence of nine essential amino acids (EAAs) in the protein extract. MAE technique is a feasible and acceptable alternative for high throughput extraction of ​M. oleifera ​oil with high yield and excellent quality attributes. The study revealed that MAE did not impart any remarkable advantage(s) on the physicochemical properties of ​M. oleifera ​seed oil and protein compared to SE technique.