Electrospun composite pullulan-soy protein isolate nanofibers: impact of solution and process parameters on fiber morphology and physical properties

• Main Author: Koh, Hannah Zhu'er
• Other Authors: Hu Xiao
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/157087
• Institution: Nanyang Technological University

Natural composite fibers made from Soy Protein Isolate (SPI) and pullulan (PUL) in water were characterised after needleless electrospinning using wire electrode. Solution parameters such as SPI to PUL blend ratios, pH of solution, denaturation temperature and duration were varied to study their effects on fiber morphology and diameters. The addition of NaOH to increase pH yielded smaller fiber diameters with greater size uniformity. Differing amounts of pullulan added as the carrier polymer also affected solution viscosities and electrical conductivities, which were investigated in relation to fiber size. Process parameters such as applied voltage and carriage speed also served to adjust fiber diameter size, where consistent size patterns were observed with increasing voltage from 30 to 50kV. However, varying carriage speed did not result in any observable pattern. The composite fibers ranged between 60-250nm in diameter, and like other hydrocolloid blends, solution properties were more significant parameters on fiber morphology. Additionally, infrared spectroscopy confirmed intermolecular interactions between both components, and fiber thermal stability was analysed as well. These food-grade green nanofibers may potentially find applications in the food and smart packaging industries.