Encapsulation of Folic Acid in Sodium Alginate-Pectin-Poly(Ethylene Oxide) Electrospun Fibers to Increase Its Stability
This thesis explored the use of sodium alginate-pectin-poly(ethylene oxide) electrospun fibers as a carrier to stabilize folic acid - an essential micronutrient that is susceptible to degradation when exposed to light and acidic conditions. In the first phase of this research, electrospinning behaviour of aqueous alginate-pectin solutions was investigated. Aqueous polysaccharide solutions could not be electrospun unless poly(ethylene oxide) (PEO) was added (≥20% w/w), resulting in electrospun alginate-pectin fibers that varied from fiber to fiber-bead, depending on the polymer blend ratio, and concentration of the polymer solutions. Polymer solutions properties (surface tension, viscosity, conductivity) were determined to study their effects on the electrospinning behaviour of the polymer solutions. In the second phase of this research, folic acid was incorporated into the polymer solutions and electrospun. The efficacy of these fibers in improving the stability of folic acid under different pH conditions was investigated. FTIR and NMR spectroscopies were employed to elucidate the nature of polymer-polymer and folic acid-polymer interaction. In phase three, the release behaviour of folic acid under simulated gastrointestinal conditions was evaluated. Overall, this research showed that electrospun fibers with different morphologies could be produced by manipulating the polymer concentration, polysaccharide/PEO blend ratio, extent of sonication treatment during sample preparation, and electrospinning process parameters. The positive effect of PEO on the electrospining of alginate-pectin fibers was attributed to its electrical conductivity and surface tension lowering effects on the polymer solutions. Electrospun fibers produced from the combination of alginate-pectin resulted in higher retention of folic acid compared to that of alginate alone. Folic acid encapsulated in crosslinked electrospun fibers achieved close to 100% retention when stored in the dark at pH 3 after 41 days of storage. Minimal release of folic acid from the electrospun fibers was observed at pH 3, although the release was significantly higher at pH 1.2. On the other hand, the release of folic acid was nearly 97% at pH 7.8, a condition that simulated the pH condition in the intestine. From NMR and FTIR data, the stabilization effect of electrospun fibers on folic acid was attributed to physical entrapment and not specific chemical interaction. The research suggests that ethanol-treated crosslinked alginate-pectin electrospun fibers can potentially be used as a folic acid carrier to protect the micronutrient in food products, especially acidic food products such as fruit juices and acidified beverages.