Browsing by Author "J. Barrow, Colin"

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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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    Gypenosides as natural emulsifiers for oil-in-water nanoemulsions loaded with astaxanthin: insights of formulation, stability and release properties
    (Food Chemistry, 2018) Chen, Zhang; Shu, Gaofeng; Taarji, Noamane; J. Barrow, Colin; Nakajima, Mitsutoshi; Nauman Khalid; A. Neves, Marcos
    The formulation, physicochemical stability and bioaccessibility of astaxanthin (AST) loaded oil-in-water nanoemulsions fabricated using gypenosides (GPs) as natural emulsifiers was investigated and compared with a synthetic emulsifier (Tween 20) that is commonly applied in food industry. GPs were capable of producing nanoemulsions with a small volume mean diameter (d4,3 = 125 ± 2 nm), which was similar to those prepared using Tween 20 (d4,3 = 145 ± 6 nm) under the same high-pressure homogenization conditions. GPs-stabilized nanoemulsions were stable against droplet growth over a range of pH (6–8) and thermal treatments (60–120 °C). Conversely, instability occurred under acidic (pH 3–5) and high ionic strength (25–100 mM CaCl2) conditions. In comparison with Tween 20, GPs were more effective at inhibiting AST from degradation during 30 days of storage at both 5 and 25 °C. However, GPs led to lower lipid digestion and AST bioaccessibility from nanoemulsions than did Tween 20.