Summary
· Ethiopian cultivars and advanced lines of bread and durum wheat were
studied for their grain quality characteristics under different
environmental conditions. The influence of different protein fractions,
ratios and subunits on bread making quality were determined by means
of HPLC. Significant correlations across diverse genotypes and
environments might indicate the potential use of these techniques in
breeding programmes.
SE-HPLC
Bread wheat
· The genotypes studied expressed genetic variability in most of the
important quality traits. Protein levels across the two environments
were relatively low. A decrease in protein content led to an increase in
mixing time. Genotypes at the lowest protein site had the longest
mixing times.
· The higher protein site had higher average concentrations for all
fractions extracted, except for SDS soluble and insoluble LMP.
· Across the two environments, the SDS soluble and insoluble polymeric
proteins had a highly significant influence on quality.
· The number of correlations observed increased across environments
compared to individual environments.
· Higher significant correlations were observed between ratios of
proteins compared to that found between individual proteins. SE-HPLC
Durum
· Similar results to bread wheat were seen for durum genotypes
tested. The lower protein environment resulted in a lower protein
content and increased mixing time.
· The average concentrations for SDS soluble LPP and SMP and
insoluble LMP, SMP, TUPP and LUPP were higher at the high
protein potential site.
· The number of correlations increased across environments, than
when environments were considered individually.
· The magnitude of the correlations increased across environments.
· Higher significant correlations were observed between ratios of
protein fractions and quality traits, notably the correlations between
the ratio of SDS insoluble LPP:LMP and SPP:LMP with mixograph
development time (0.545*** and 0.518***, respectively).
· Durum has the potential of improvement for bread making quality.
Bread and durum wheat
· The average flour protein content was slightly higher for durum
wheat, at the higher protein site, but similar at Motta.
· The mixograph development time for both wheat types was longer
at Motta, than at Adet, with the mixing time for durum slightly longer
than that of bread wheat at Motta.
· The durum genotypes had higher average SDS soluble and
insoluble LPP and SMP fractions, at both environments, compared
to bread wheat.
· The opposite was true for LUPP and TUPP fractions, where the
bread wheat genotypes had a higher average.
· The LUPP fraction and the SDS insoluble SPP displayed a direct
relationship with SDS sedimentation, continuously across
environments.
· The averages of baking quality traits for bread and durum wheat,
with the exception of SDS sedimentation, did not differ extensively. This indicated the potential application of durum wheat for
comparable breadmaking utility.
RP-HPLC
Due to the large amount of data generated by RP-HPLC, emphasis was
placed on the general trends across entries and differences between
entries were not discussed.
Bread wheat
· A total of 38 glutenin subunits (including minor peaks and
unresolved shouders) were resolved.
· Forty two bread wheat gliadin peaks were differentiated.
· The environmental effect was visible in entries in both variation in
quantity observed and as presence or absence of subunits.
· Peaks/subunits correlating with baking parameters differed across
different environments. This indicated sensitivity to environmental
influences.
· Some correlations occurred consistently, regardless of the
differences in environment.
· Significant polymeric-polymeric and monomeric-monomeric as well
as polymeric-monomeric correlations were observed. These
interactions need to be considered when determining functionality.
Correlations might be due to indirect effects.
· Stepwise multiple regression can assist in determining direct
relationships. It also gives an indication of the interactions
excisting between protein components.
· The regression models indicated the individual proteins contributing
to the quality trait. Some proteins were major contibutors,
explaining 59% of the variation occurring in the parameter. The
most important contributors to quality remained the glutenin
subunits. Durum wheat
· A total of 42 glutenin subunits (including minor peaks and
unresolved shouders) were resolved.
· Fifty one durum wheat gliadin peaks were differentiated.
· Similar results to bread wheat were obtained for durum wheat
entries.
· Unlike the bread wheat results, specific durum subunits influenced
more than one baking parameter simultaneously.
· More interactions between the different protein subunits influencing
specific traits were visible. No distinct patterns were visible
between the subunit type and functional property.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08102007-140403 |
| Date | 10 August 2007 |
| Creators | Koen, Elizma |
| Contributors | Prof CD Viljoen, 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-08102007-140403/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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