The primary aim of this study was to determine whether size-exclusion
high performance liquid chromatography (SE-HPLC) could be used for
quality prediction of South African wheat cultivars.
· A bread cultivar, a cracker cultivar and two soft wheat cultivars were
used in this two-year experiment.
· Protein extracts of wheat flour were analysed by SE-HPLC.
· SDS was used for the first protein extraction step, and the rest of the
proteins were extracted by sonication.
· The SE-HPLC method fractionated the storage proteins (both SDS-soluble
and SDS-insoluble) into four distinct peaks of decreasing
molecular size range, representing mainly larger polymeric proteins
(mainly HMW-glutenins), smaller polymeric proteins (mainly LMW-glutenins),
larger monomeric proteins (mainly gliadins), and smaller
monomeric proteins (mainly albumins and globulins).
· The wheat samples were also analysed for a total of 11 important
quality characteristics.
· Relationships between the amount and size-distribution of polymeric
and monomeric proteins and flour quality properties were established.
· The influence of different nitrogen (N) treatments on protein fractions
and quality characteristics was also determined by SE-HPLC.The results showed that both the genotype and N-treatments had a
significant influence on quality characteristics.
· However, the genotype (cultivar effect) had a more significant
influence on the protein fractions and quality characteristics than the
N-treatments.
· The total amounts of N applied during the treatments had a more
significant eff ect on protein fractions and quality characteristics than
later N-applications (N applied during the flag leave stage).
· The SDS-soluble and SDS-insoluble polymeric proteins were found to
be equally important in quality prediction.
· The hard wheat cultivars were characterised by an increase of
polymeric protein as opposed to monomeric protein.
· The polymeric proteins (glutenins) were strongly positively correlated
with dough strength properties, such as alveograph P/L ratio and
alveograph strength.
· The large monomeric proteins, which are mainly gliadins, were
positively associated with the soft wheat cultivars, and had a
consistently significant negative effect on quality characteristics, such
as falling number (FLN), vitreous kernels (VK), alveograph P/L ratio
and alveograph strength.
· The large monomeric proteins showed positive correlations with single
kernel weight (SK weight), single kernel diameter (SK diameter) and
breakflour yield (BFLY).
· SE-HPLC provided a simple and an objective test for measuring the
relative size-distributions of wheat storage proteins.
· SE-HPLC also proved to be very usefull in predicting quality.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08232005-103805 |
| Date | 23 August 2005 |
| Creators | Meintjes, Gisela Diana |
| Contributors | Prof MT Labuschagne |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08232005-103805/restricted/ |
| 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 Free State 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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