A gel is a cross-linked polymer network that spans an entire liquid medium; its properties depend strongly on the interaction of the polymer and the liquid medium. There are various ways to induce gelation in different systems such as altering temperature or pH. In this study, phenol extracted protein fractions from non-acclimated (NA) and cold-acclimated (CA) winter rye (Secale cereale L. cv Musketeer) leaf tissue were subjected to freeze-thaw treatment. Gelation was induced in the NA and CA extracts after repeated freeze-thaw treatments, accompanied by a change in sample rheological properties. Further experimentation revealed that gel formation only occurred at high pH (pH 12.0) and that a minimum of 3 to 4 freeze-thaw cycles were required. The viscosity of the protein gel increased 5.7- to 9.5-fold in the NA and CA extracts respectively upon freeze-thaw. Experiments optimizing the extraction conditions and protein concentration were also performed. The gel was stable and only a specific combination of chaotropic agent, anionic surfactant and reducing agent such as urea, sodium docecyl sulfate (SDS) and â-mercaptoethanol (â-ME) with heating could disrupt the gel network. The gel was composed of several proteins in the extracts as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Based on SDS-PAGE analysis, ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) was identified as the major protein component in the gel. Various experiments were performed to assess the role of Rubisco in gel formation; however, the results were inconclusive. It is suggested that these extracts may contain antifreeze proteins (AFPs) that have been demonstrated to form amyloid gels upon freeze-thaw. Further studies examining the composition and mechanism of gel formation may result in a future role for this material in the food industry.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-03312011-145414 |
| Date | 11 April 2011 |
| Creators | Lim, Ze Long |
| Contributors | Low, Nicholas H., Gray, Gordon R., Krol, Ed S., Khandelwal, Ramji, Sammynaiken, R., Moore, Stanley A. |
| 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-03312011-145414/ |
| Rights | unrestricted, 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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