Starch-based Films Incorporated with Different Bioactive Compounds for Food Packaging Using Pressurized Hot Water Technology

  • Author / Creator
    Zhao, Yujia
  • In recent years, biodegradable polymers, like starch, have been studied as potential packaging materials to deal with the increasing concern on plastic disposal/degradation and to extend food products shelf-life. This objective of this thesis was to develop bioactive starch-based films using pressurized hot water technology, with the incorporation of various bioactive compounds (e.g. gallic acid, chitosan and carvacrol essential oil), to investigate the potential application of such films on ready-to-eat (RTE) ham. All films produced were characterized by mechanical, physico-chemical, structural, optical and functional properties. First, cassava starch and chitosan behaviors in pressurized hot water media were studied at 75-150 oC and 50-155 bar to understand depolymerization and interactions between them. Then, bioactive films composed of chitosan, gallic acid and cassava starch were developed in pressurized hot water media. The tensile strength and hydrophobicity of films improved as chitosan ratio increased up to 0.15 g/g starch, due to the cross-linking of electrostatic interaction, ester bonds and hydrogen bonds. Further addition of cellulose nanofibers (63.1% purity) improved tensile strength from 0.83 to 10.51 MPa. Also, films prepared from potato by-products showed high tensile strength (0.9-7.8 MPa) with the increasing ratio of potato peel. Furthermore, carvacrol essential oil was incorporated to chitosan-cassava starch films to improve antimicrobial activity. Antimicrobial tests performed on RTE ham showed that chitosan and carvacrol added cassava starch films inactivated L. monocytogenes (log cfu/cm2 <2) and extended ham shelf-life up to 25 days. In addition, the biodegradability tests demonstrated the complete degradation of such films in compost (< 85 days). Finally, essential oil nanogels and film grafting opens new alternatives in packaging. All these results suggested that pressurized hot water technology is a promising green method to develop bioactive starch-based films with enhanced mechanical and water barrier properties. The incorporation of various bioactive compounds provided starch-based films with unique antioxidant/antimicrobial activities that were applied on ham, suggesting potential use on a wide variety of food products.

  • Subjects / Keywords
  • Graduation date
    Spring 2019
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.