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Physicochemical Aspects of Ultrathin Electrospun Zein Fibres for Encapsulation of Fish Oil

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Title: Physicochemical Aspects of Ultrathin Electrospun Zein Fibres for Encapsulation of Fish Oil
Author: Moomand, Khalid
Department: Department of Food Science
Program: Food Science
Advisor: Lim, Loong-Tak
Abstract: The ω-3 polyunsaturated fatty acids are beneficial to humans. The principal hurdle remains delivery of these fatty acids via foods or as nutraceuticals as they oxidize readily. In this study, an electrospinning method was developed to encapsulate fish oil, up to 30% (w/w), in zein fibres. The effects of aqueous ethanol and isopropanol solvents on the solubility of zein, viscosity, conductivity, and surface tension of the polymer solutions, were investigated and correlated with the morphology of the particles. Polymer solutions from both solvents exhibited shear-thinning behaviour, where ethanolic solutions had higher apparent viscosity values irrespective of the fish oil loading in comparison to isopropanolic solutions. Smooth and fibrous materials were generated from ethanol-based solutions, with increased diameter of 300 to 500 nm as the fish oil loading increased from 0 to 30% (w/w). Thinner fibres (190 ± 62 nm) with beads of an average size of 1 µm were produced from isopropanol zein solutions. Fish oil tends to migrate towards the core of the materials and concentrate in the beaded areas as a result of phase separation during the electrospinning process. This behaviour impacted encapsulation efficiency, loading capacity, as well as the stability of the fish oil when stored at 4, 25 and 60 °C for 14 days. The encapsulation efficiency of the electrospun zein fibres was 91% for ethanol-based and 96% for isopropanol-based fibres, at 30% (w/w) loading level. In addition to monitoring the formation of lipid peroxide, changes in covalent bond vibrations in fish oil and zein were studied using attenuated total reflection Fourier transform infrared (ATR-FTIR). Electrospun zein fibres provided a greater protection against oxidative degradation compared to the nonencapsulated fish oil. Aqueous ethanol solvent, in the presence of the added fish oil, promoted the formation of α-helix protein secondary structure, while isopropanol solvent promoted the formation of inter- and intramolecular β-sheet secondary structure. Under simulated gastrointestinal conditions, these electrospun materials exhibited gradual swelling and degradation rates while significantly higher when enzymes were introduced. The secondary structure of zein was impacted by the concentration of the polymer, solvent type, and exposure to SGI fluids.
Date: 2014-06
Rights: Attribution-NoDerivs 2.5 Canada
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Attribution-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NoDerivs 2.5 Canada