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sur le développement des zones arides et semi-arides

Titre : Characterisation and encapsulation of Moringa oleifera extracts

Auteur : George, Toyosi Timilehin

Université de soutenance : Cape Peninsula University of Technology

Grade : Master of Science and Technology : Food Science and Technology 2021

Résumé partiel
Moringa oleifera Lam. (Family : Moringaceae) has been well-documented for the high presence of bioactive and phytochemical compounds with health-promoting potentials. However, these phytochemicals are susceptible to damage during processing and storage. The use of encapsulation to improve the functionality and stability of phytochemicals has been established as a viable way of protecting them. Here, microcapsules containing Moringa oleifera extracts were developed using maltodextrin (MD) and gum Arabic (GA) coating materials, individually and as a combination (MDGA). Bioactive compounds in Moringa oleifera leaf powder (MoLP) and seed powder (MoSP) were extracted using 60% ethanol (EtOH), acidified methanol (Ac. MeOH) and water (H2O) and their phytochemical compositions were characterized by spectrophotometry and liquid chromatography-mass spectrometry (LC-MS). The antioxidant capacities were evaluated using the oxygen radical antioxidant capacity (ORAC), ferric reducing antioxidant power (FRAP) and 2-diphenyl-1-picrylhydrazyl (DPPH) assays. Furthermore, to determine the optimum microcapsule preparation conditions for maximum encapsulation efficiency, the coating material, core/coating ratio, as well as ultrasonication time, were varied and their efficiencies were determined by response surface methodology (RSM). The newly developed microcapsules from MD, GA and MDGA were analysed using scanning electron microscopy for morphological properties ; thermogravimetric analysis (TGA) for thermal properties ; X-ray diffraction studies for crystallinity patterns ; and Fourier transform infrared (FTIR) spectroscopy for the structural composition of the microcapsules. Additionally, the physical and functional properties of the microcapsules were measured to determine the effects the coating materials had on production. The EtOH MoLP extract had the most phenolic (24.0 ± 0.4 mg GAE/g) and flavonoid (14.1 ± 0.2 mg QE/g) contents with the former showing a strong positive correlation with the antioxidant (ORAC) value. The LC-MS profiling of extracts also revealed the presence of many bioactive compounds such as neochlorogenic acid, 3-p-coumarylquinic acid, rutin, quercetin 3-galactoside, kaempferol O-rutinoside, malic acid, citric acid, etc. and these were more abundant in the EtOH MoLP, hence, was chosen for encapsulation

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