Proximate, Elemental, and Functional Properties of Novel Solid Dispersions of Moringa oleifera Leaf Powder

Abstract

Moringa oleifera leaf powder (MOLP) is a rich source of antioxidants, protein, minerals, vitamins, and various phytochemicals and has been used to combat malnutrition in many countries. However, despite its many benefits, MOLP has low a solubility in water, necessitating the development of ways to address this issue. To improve the solubility of MOLP, solid-dispersed Moringa oleifera leaf powders (SDMOLPs) have been developed through freeze-drying, melting, microwave irradiation, and solvent evaporation methods using polyethylene glycols (PEG4000 and PEG6000) (1:1) as hydrophilic carriers. The solid dispersions were evaluated for their proximate composition using standard analytical procedures. Elemental composition was characterized using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). Water absorption capacity (WAC) and water-solubility were further evaluated as functional properties. Proximate composition revealed that MOLP and SDMOLPs were rich in protein, energy, carbohydrate, ash, and fat contents. MOLP solid dispersions are a major source of minerals (Ca, Mg, Cu, and Zn), and can be used to alleviate many mineral deficiencies. All solid dispersions had significantly higher (p < 0.05) solubilities (ranging from 54 to 64%) and WAC (ranging from 468.86 to 686.37%), relative to that of pure MOLP. The increased solubility of SDMOLPs may be attributed to the hydrogen bonds and intermolecular interactions between MOLP and the hydrophilic carriers. The results indicate that the solid dispersion technique can be successfully employed to improve the solubility of MOLP. And the solid-dispersed MOLPs with enhanced functional properties may be useful as functional ingredients in foods and beverages, dietary supplements, or nutraceutical formulations.

Keywords: EDS; Moringa oleifera leaf powder; elemental composition; functional foods; functional properties; nutritional properties; solid dispersions; solubility.

Figure 1

The SEM-EDS spectra of (a) MOLP and (b) SDMOLP.

Figure 2

The water absorption capacity of MOLP and solid-dispersed MOLP prepared by melting, freeze-drying, solvent evaporation, and microwave methods using PEG4000 and PEG600 carriers. Bars with different superscripts in the same category (PEG) were significantly different (p < 0.05).

Figure 3

The solubility of the MOLP and solid-dispersed MOLPs prepared through melting, solvent evaporation, freeze-drying, and microwave irradiation using the PEG4000 and PEG6000 carriers. Bars with different superscripts in the same category (PEG) were significantly different (p < 0.05).