Browsing by Author "Nakajima, Mitsutoshi"

Now showing 1 - 8 of 8
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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 characterization of water-in-oil nanoemulsions loaded with acai� berry anthocyanins: insights of degradation kinetics and stability evaluation of anthocyanins and nanoemulsions
    (Food Research International, 2018) A.S. Rabelo, Cezar; Taarji, Noamane; Nauman Khalid; Kobayashi, Isao; Nakajima, Mitsutoshi; A. Neves, Marcos
    Açaí berry is the fruit of an Amazonian palm tree and rich in anthocyanins (ACNs). Scientific studies have proven the health benefits of açaí berry and declared this fruit as “super fruit”. ACNs have high antioxidant activities, but they are unstable and can easily deteriorate during food processing. In order to protect ACNs and increase their applicability, food-grade water-in-oil (W/O) emulsions were successfully formulated with different concentrations of açaí berry extracts (AEs). The formulated W/O nanoemulsions were relatively stable, with no phase separation after 30 days of storage. The average droplet size varied between 146.8 to 814.8 nm, with higher values corresponding to samples without AEs. All W/O nanoemulsion samples exhibited antioxidant activity and high retention rates of polyphenols after 30 days of storage. ACN retention followed firstorder kinetics, with high protection of ACNs observed in emulsified samples. 2% AE encapsulated in a 30 wt% W/O nanoemulsion had an estimated half-life of 385 days. The results indicate that stable nanoemulsion systems with high ACN protection can be produced with possible applications in the food and pharmaceutical industries.
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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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    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.
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    In vitro bio accessibility of ergocalciferol in nanoemulsion-based delivery system: the influence of food-grade emulsifiers with different stabilising mechanisms
    (International Journal of Food Science and Technology, 2018) Shu, Gaofeng; Nauman Khalid; Boon Tan, Tai; Zhao, Yiguo; A. Neves, Marcos; Kobayashi, Isao; Nakajima, Mitsutoshi
    The effect of emulsifier type on thein vitrobioaccessibility of ergocalciferol-loaded nanoemulsions wasexamined (mouth, stomach and small intestinal phases). Oil-in-water nanoemulsions were prepared usingemulsifiers with different stabilising mechanisms: decaglycerol monooleate (MO7S; steric), modifiedlecithin (ML; electrostatic), sodium caseinate (SC; electrosteric) and ML-MO7S (combined electrostaticand steric). The droplet size, size distribution,f-potential and microstructure of nanoemulsions duringdigestion depended on the emulsifier type. The fate of lipid in the small intestinal phase also relied on theemulsifier type, with the free fatty acids release rate decreasing in the following order: MO7S>ML-MO7S>ML>SC. The ergocalciferol bioaccessibilities in nanoemulsions prepared using MO7S (62%),ML (64%) and ML-MO7S (65%) were similar and significantly higher than that stabilised by SC (12%).No significant loss of ergocalciferol was observed in all nanoemulsions after full digestion; they werechemically stable against digestion conditions, regardless of the emulsifier type.
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    Long-term stability of droplet production by microchannel (step) emulsification in microfluidic silicon chips with large number of terraced micro channels
    (Chemical Engineering Journal, 2018) T. Vladisavljevi, Goran; E. Ekanem, Ekanem; Zhang, Zilin; Nauman Khalid; Kobayashi, Isao; Nakajima, Mitsutoshi
    A long-term production stability of oil-in-water emulsions by microchannel (step) emulsification was investigated using two cross flow silicon chips consisting of 540 or 1850 microchannels fabricated on 10 parallel terraces. Each terrace was 9.54 mm long and consisted of 54 channels with a depth of 5 μm and a width of 18 μm (chip 1) or 185 channels with a depth of 4 μm and a width of 8 μm (chip 2). The dispersed phase was a mixture of 2 wt% polycaprolactone (PCL) and 1 wt% poly(d,l-lactic) acid (PLA) dissolved in dichloromethane and the continuous phase was 2 wt% poly(vinyl alcohol). After solvent evaporation, the droplets were transformed into highly uniform composite polymer particles with an average diameter of 8.8 or 4.9 μm. The percentages of active channels, droplet sizes and droplet generation frequencies at individual terraces were investigated in both chips to reveal any flow maldistribution. After 6 h of production in chip 1, overall 95% of the channels produced droplets and the percentage of active channels on each terrace was at least 91%. The percentage of active channels decreased by decreasing the size of the channels. The mean droplet size varied negligibly across individual terraces over 7 h. Slightly higher droplet generation frequencies and smaller percentages of active channels were observed at central terraces. The droplet generation frequencies at the channels located close to each other were similar, indicating that droplet formation dynamics was coupled. The droplet size was not affected by the dispersed phase flow rate.
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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.
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    Microencapsulation of betanin in monodisperse w/o/w emulsions
    (Food Research International, 2018) Eskildsen Pagano, Ana Paula; Nauman Khalid; Kobayashi, Isao; Nakajima, Mitsutoshi; Antonio Neves, Marcos; Leite Bastos, Erick
    Betanin is the main pigment of the food color beetroot red (E162). Due to the fair heat and light stability of E162, this pigment is mainly used in minimally processed packaged food products. Encapsulation increases the stability of betanin, but detailing on the effect of different sources of betanin on the properties and stability of multiple emulsions are scarce. Here we describe the encapsulation of E162, spray-dried beetroot juice and betanin in a monodisperse food-grade water-in-oil-in-water (W/O/W) emulsions by using microchannel emulsification. We compare the tinctorial strength of the encapsulated pigments and investigate the effect of temperature, storage period and pigment concentration on emulsion stability and color. Betanin increases the overall stability of the W/O/W emulsion, reduce the oil droplet size and improve size distribution when compared to the negative control without pigment and to emulsions containing betanin from other sources.