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Creators/Authors contains: "Kim, Jin-Woo"

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  1. Abstract

    Biologically extracted cellulose nanocrystals (CNCs) are rod-like and amphiphilic materials with surface-exposed (hydrophilic sites) and hidden (hydrophobic sites) hydroxyl groups. These physicochemical characteristics make CNCs suitable for use as emulsifying agents to stabilize emulsions. Stable oil-in-water emulsions, using sulfated (i.e., –$${{\text{SO}}}_{3}^{-}$$SO3-) CNCs that were ionically crosslinked with alkaline-earth (i.e.,$${{\text{Mg}}}^{2+}$$Mg2+) or transition-d-block (i.e.,$${{\text{Zn}}}^{2+}$$Zn2+) metal cations, were developed without the use of any synthetic surfactants or prior functionalization of pure CNCs with hydrophobic molecules. Various emulsion surface properties such as interfacial tension, surface charge, surface chemistry, as well as rheology were characterized. Ionically crosslinked CNCs (iCNCs) adsorbed at the interface of an oil and water and fortified the emulsion droplets (5–30 µm) against coalescence by lowering the interfacial tension from 65 mN/m (i.e., pure CNC mixture with oil) to 25 mN/m (i.e., iCNC mixture with oil) and reducing zeta potential with surface charge values (–30 mV to –10 mV), ideal to maintain droplet layer assembly at the water–oil interface. This study provided an alternative approach to achieve particle-stabilized and surfactant-free emulsions by using divalent metal nitrates to develop “clean” emulsion-based technologies for applications in many industries from agriculture to food to pharmaceuticals.

     
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  2. Abstract

    Bioactive food compounds, such as lycopene, curcumin, phytosterols, and resveratrol, have received great attention due to their potential health benefits. However, these bioactive compounds (BCs) have poor chemical stability during processing and low bioavailability after consumption. Several delivery systems have been proposed for enhancing their stability and bioavailability. Among these methods, porous biopolymers have emerged as alternative encapsulation materials, as they have superior properties like high surface area, porosity, and tunable surface chemistry to entrap BCs. This reduces the crystallinity (especially for the lipophilic ones) and particle size, and in turn, increases solubilization and bioavailability. Also, loading BCs into the porous matrix can protect them against environmental stresses such as light, heat, oxygen, and pH. This review introduces polysaccharide‐based porous biopolymers for improving the bioaccessibility/bioavailability of bioactive food compounds and discusses their recent applications in the food industry. First, bioaccessibility and bioavailability are described with a special emphasis on the factors affecting them. Then, porous biopolymer fabrication methods, including supercritical carbon dioxide (SC‐CO2) drying, freeze‐drying, and electrospinning and electrospraying, are thoroughly discussed. Finally, common polysaccharide‐based biopolymers (i.e., starch, nanocellulose, alginate, and pectin) used for generating porous materials are reviewed, and their current and potential future food applications are critically discussed.

     
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  3. Abstract

    An efficient and rapid method is established for micron cellulose (1, 20 microns) oxidation utilizing Oxone (KHSO5) in combination with 2,2,6,6‐tetramethylpiperidinyl‐1‐oxyl (TEMPO) and NaOCl in aqueous NaHCO3solution (pH 7.5 to 8.5) under microwave irradiation. This method affords two different forms of nano TEMPO‐cellulose, that is, a water‐insoluble form (Form‐I, 14 nm) and a water‐soluble form (Form‐II, 8 nm). Cellulose oxidation utilizing this Oxone methodology has advantages over other methodologies, which include low cost and formation of two nano TEMPO‐cellulose forms over a rapid reaction time utilizing microwave irradiation conditions. TEMPO‐cellulose forms are characterized by FT‐IR, NMR, solid state13C‐NMR, and by elemental analysis. The TEMPO‐cellulose forms morphology is studied by scanning electron microscopy analysis. The average fiber width and length of TEMPO‐cellulose materials are determined in nanometer range by transmission electron microscopy analysis and the surface charge is identified by zeta potential.

     
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