The focus of this research was to develop a plant-based microcapsule for flax oil by complex coacervation. Complex coacervation involves the electrostatic attraction between two polymers of opposing charges. Specifically, the research aimed to: a) identify the ideal biopolymer and solvent conditions required for complex coacervation involving pea protein isolate (PPI) and gum Arabic (GA); b) understand the functional behaviour of PPI-GA complexes as food and biomaterial ingredients; and c) develop methodologies for encapsulating flax oil within PPI-polysaccharide capsules. Complex coacervation between PPI-GA was found to be optimized at a biopolymer weight mixing ratio of 2:1 in the absence of salt. The functional behaviours of the optimized biopolymer mixture were then investigated as a function of pH (4.30-2.40) within a region dominated by complex coacervation. Emulsion stability was found to be greater for PPI-GA mixture systems relative to PPI alone at pH values between 3.10 and 4.00; emulsions produced under one-step emulsification exhibited higher stability compared to those of two-step emulsification at all pH values. Foam expansion was independent of both biopolymer content and pH, whereas foam stability improved for the mixed system between pH 3.10 and 4.00. The solubility minimum was broadened relative to PPI at more acidic pH values. These findings suggested that the admixture of PPI and GA under complexing conditions could represent a new food and/or biomaterial ingredient, and has potential as an encapsulating agent. Two encapsulation processes were employed in this research: high speed mixing (two-step emulsification) and low speed mixing (one-step emulsification). Flax oil capsules formed using the gelatin-GA mixture (as control) under high speed mixing exhibited low moisture content, water activity and surface oil, and afforded adequate protection against oxidation relative to free oil over a 25 d storage period. The PPI-GA mixture failed to produce acceptable capsules using either high or low speed mixing. In contrast, PPI-alginate capsules were produced and exhibited similar chemical properties as gelatin-GA capsules, except with lower
encapsulated flax oil content (30% vs. 50% w/w). However, oxidative stability may adversely affected by the low speed mixing condition during encapsulation.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-09142009-213047 |
| Date | 17 September 2009 |
| Creators | Liu, Shuanghui |
| Contributors | Nickerson, Michael, Low, Nicholas |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-09142009-213047/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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