Browsing by Author "A. Neves, Marcos"

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    Formulation and characterization of astaxanthin-enriched nanoemulsions stabilized using ginseng saponins as natural emulsifiers
    (Food Chemistry, 2018) Shu, Gaofeng; Nauman Khalid; Chen, Zhang; A. Neves, Marcos; J. Barrow, Colin; Nakajima, Mitsutoshi
    In this study ginseng saponins (GS) were used as natural emulsifiers to formulate and stabilize O/W nanoemulsions loaded with astaxanthin (AST). GS were found to be highly effective at reducing the interfacial tension at the soybean oil–water interfaces, and were capable of producing nano-scaled droplets (d4,3 ≈ 125 nm) using a high-pressure homogenizer. The droplet size of the nanoemulsions decreased with increasing emulsifier concentration and homogenization pressure. The nanoemulsions were stable without droplet coalescence against thermal treatment (30–90 °C, 30 min), and over a narrow range of pH values (7–9). GS-coated droplets were unstable in acidic conditions (pH 3–6) and in the presence of salt (>25 mM NaCl). The formulated nanoemulsions showed slight change in d4,3 during 15 days of storage at 5, 25 and 40 °C. However, the chemical stability strongly depended on the storage temperature, with the lowest level of AST retained in nanoemulsions stored at higher temperature.
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    Formulation and stabilization of oil-in-water nanoemulsions using a saponinsrich extract from argan oil press-cake
    (Food Chemistry, 2010) Taarji, Noamane; A. Rabelo da Silva, Cezar; Nauman Khalid; Gadhi, Chemseddoha; Hafidi, Abdellatif; Kobayashi, Isao; A. Neves, Marcos; Isoda, Hiroko; Nakajima, Mitsutoshi
    In this study, we formulated and stabilized oil-in-water nanoemulsions using a crude extract from argan press-cake as sole emulsifier. Various extracts from argan press-cake were prepared in order to select the most surface-active one(s) foreseeing emulsions preparation. Fifty percent (v/v) ethanolic extract reduced the interfacial tension to a minimum value at both MCT oil and soybean oil interfaces (12.7 and 10.5 mN m−1 respectively). This extract was also effective at producing fine emulsions with small droplet sizes (d3,2 < 115 nm) and good physical stability using different oils such as soybean oil, MCT oil and fish oil and at conventional homogenization conditions (100 MPa for 4 passes). On the other hand, the emulsions were very sensitive to NaCl addition (≥25 mM) and to acidic pH (<3) indicating that the main stabilization mechanism is electrostatic, likely due to the presence of surface-active compounds with ionizable groups such as saponins.
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    Microchannel emulsification: a promising technique towards encapsulation of functional compounds
    (Critical Reviews in Food Science and Nutrition, 2018) Nauman Khalid; Kobayashi, Isao; A. Neves, Marcos; Uemura, Kunihiko; Nakajima, Mitsutoshi
    This review provides an overview of microchannel emulsification (MCE) for production of functional monodispersed emulsion droplets. The main emphasis has been put on functional bioactives encapsulation using grooved-type and straight-through microchannel array plates. MCE successfully encapsulates the bioactives like β-carotene, oleuropein, γ-oryzanol, β-sitosterol, L-ascorbic acid and ascorbic acid derivatives, vitamin D and quercetin. These bioactives were encapsulated in a variety of delivery systems like simple and multiple emulsions, polymeric particles, microgels, solid lipid particles and functional vesicles. The droplet generation process in MCE is based upon spontaneous transformation of interfaces rather than high energy shear stress systems. The scale-up of MCE can increase the productivity of monodispersed droplets >100 L h−1 and makes it a promising tool at industrial level.