Woojeong Kim
Research Officer
University of New South Wales
Ms. Woojeong Kim is a PhD candidate in the School of Chemical Engineering at UNSW Sydney under the supervision of Prof. Cordelia Selomulya. Her research primarily focuses on processing strategies, exploring new food materials, and particle engineering in the food and beverage sector. She aims for eco-friendly and sustainable food processing and novel product development with functional and nutritional benefits.
Her PhD project is on encapsulating bioactive compounds using food ingredients such as protein, polysaccharide, and their combinations. Particularly, she investigates plant protein functionality using dairy/plant protein blends, focusing on protein interaction, structural modification, and food application including spray dried powder. She has successfully proposed the strategies to demonstrate the enhanced functionality of dairy/plant protein blends for emulsion stabilisation and encapsulation, and the newly designed systems will be applied in powder production using a microfluidic spray dryer to be used as novel food ingredients.
Plant/dairy protein complexes have emerged as promising natural emulsifiers to mitigate sustainability and health issues. Improving the functionality of plant/dairy protein complexes enables their uses as emulsifiers and carriers for bioactive compounds. This PhD project aimed to design plant/dairy protein complexes for encapsulating lipophilic bioactive compounds. Pea and whey proteins were selected as representative plant and dairy proteins.
Firstly, sodium alginate addition was found to enhance the stability of pea/whey protein-stabilised emulsions by preventing pea proteins from being displaced by whey proteins. As a second step, cross-linked pea/whey protein complexes by microbial transglutaminase with modified structure formed more stable emulsions and retarded the chemical degradation of β-carotene. Following this work, microfluidic modulation spectroscopy for characterizing secondary structure of pea/whey protein complexes revealed the increase of β-sheet content with cross-linking led to forming more stable emulsions due to amphiphilicity. Lastly, the surface composition of β-carotene microcapsules using pea/whey protein complexes was investigated using synchrotron infrared microspectroscopy, showing that the cross-linking and maltodextrin addition protected β-carotene from degradation by reducing the amount of surface oil.
Overall, polysaccharide addition and enzymatic cross-linking enhanced the emulsifying and encapsulation properties of the pea/whey protein complexes. The proposed processing techniques altered protein structures with the increase of β-sheet content and the exposure of buried hydrophobic sites of the proteins due to the formation of disulphide linkage, isopeptide interaction, and hydrogen bonding between heteroproteins. The thesis demonstrates the potential usefulness of pea/whey protein complexes to encapsulate lipophilic bioactive compounds in the emulsion-based food products and powder production.
