Physicochemical, nutritional and dissolution properties of solid-dispersed Moringa Oleifera leaf powder effervescent beverage granules

Abstract

The aim of this study was to establish the physicochemical, nutritional, and dissolution properties of the solid-dispersed Moringa oleifera leaf powder (SDMOLP) with the view to present it as an easy-to-drink functional beverage. Solid dispersions of Moringa oleifera leaf powder (MOLP) were successfully prepared using polyethylene glycols (PEG4000 and PEG6000) as hydrophilic carriers and various solid dispersion methods, including melting, freeze-drying, solvent evaporation, and microwave irradiation methods, respectively. The resulting SDMOLPs were evaluated for their nutritional composition, functional and dissolution properties. The mineral composition was characterised using the Scanning Electron Microscopy-Energy Dispersive X-Ray Spectrometry (SEM-EDX) technique. Moreover, the characterisation of pure MOLP and SDMOLPs was carried out by performing SEM, scanning transfer electron microscopy (STEM), powder X-ray diffraction (PXRD), diffraction scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier Transform Infrared spectroscopy (FTIR). A Vankel’s dissolution apparatus with the United States Pharmacopeia (USP) basket method was employed for the dissolution study of the dispersions. SDMOLPs effervescent beverage granules were produced using a wet granulation method. A 5-point Hedonic test scale [1 (dislike very much) to 5 (like very much)] was used to determine the sensory and consumer acceptability of the beverage granules. Proximate analysis revealed that pure MOLP is rich in protein content (28.52%) and metabolisable energy (344.46 Kcal/100 g), with appreciable levels of fat 5.13%, moisture 8.44%, and ash 11.81%. While SDMOLP had protein content ranging from 12.42-14.23%; moisture, 2.65-4.03%; fat, 2.51-3.21%; and ash, 4.03-6.16%. All the SDMOLPs showed significantly higher (p < 0.05) solubility and water absorption capacity (WAC) that ranged from 56.86 to 63.29% and 468.86 to 686.37%, respectively. Pure MOLP had a solubility and WAC of 25.45% and 345.09%, respectively. The mineral composition indicated that all SDMOLPs were high in calcium (38.28-65.05%), magnesium (4.24-17.97%), phosphorous (1.73-13.52%), copper (2.33-27.05%), sulphur (6.00-36.98%), iron (0.15-3.88%), zinc (0.00-8.49%) and sodium (0.00-2.93%). PXRD results revealed that SDMOLPs were partially amorphous with strong diffraction peaks at 2𝜃𝜃 values of 19° and 23°. The calorimetric and thermogravimetric curves showed that SDMOLPs were more thermally stable than pure MOLP. The FTIR spectrum of MOLP showed variable peaks at 3285 cm-1, 2981 cm-1, 2849.45 cm-1, 1630.36 cm-1, 1411.7 cm-1,1049.44 cm-1, and 536.03 cm-1 attributable to O-H- bending and N-H group, asymmetric C-H stretching, symmetric C-H group, C=O stretch, C-N stretch, C-O-C symmetrical and N-H stretching, respectively. Significant peak shift and intensity reduction of O-H, N-H, and C=O functional groups in SDMOLPs evidenced the existence of intermolecular interactions between MOLP and PEG carriers, indicating strong hydrogen bonding between the two components. The dissolution rate of SDMOLPs was significantly improved . The sensory evaluation results of the SDMOLP effervescent beverages showed that mean hedonic scores of sensory attributes ranged from neither like nor dislike to like moderately for appearance (3.19-3.92), colour (3.23-4.04), aroma (4.00-4.13), taste (3.08-3.77), texture (3.04-3.66) and overall acceptability (3.40-4.00). The novel MOLP solid dispersions could be used to produce functional easy-to-drink beverages.