Attempts to develop dual-purpose durum wheat cultivars for both pasta and bread-making
have been unsuccessful. To better understand this limitation, thirty durum
genotypes, selected based on their diverse geographical origin, and five bread wheat
cultivars were compared as to their flour mixing properties, dough physical characteristics
and baking performance. The polymeric composition of gluten protein was determined
using SE-HPLC of unreduced flour protein extracts and the size-distribution of the gluten
polymer was estimated by determining the SDS-unextractable polymer (macro-polymer)
content. Durum genotypes were characterized by a lower bread-making quality compared
to bread wheats, in spite of higher total flour protein and gluten polymer contents. This
was due to a weaker gluten and lack of dough extensibility. The stronger gluten
characteristics of bread wheats were associated with a greater ability to form macro-polymers.
However, two durum cultivars had a higher macro-polymer content than many
of the bread wheats, suggesting that an additional property, unrelated to size-distribution
of the gluten, contributes to the greater loaf volumes observed for bread wheats.
Considerable variability for most quality attributes was observed among durum genotypes.
Gluten strength and dough extensibility were the most important factors associated with
superior baking performance. These two parameters were not inter-related. Durum
genotypes expressing LMWG-1 had the weakest gluten and the poorest baking
performance. This allele contributed less protein to the glutenin fraction and the sub-units
produced exhibited a reduced ability to form macro-polymers. Among the durum
genotypes expressing LMWG-2, those carrying HMWG-(6+8) were characterized by a
better baking quality than genotypes carrying HMWG-(7+8) or HMWG-20. Genotypes
carrying HMWG-20 were characterized by a comparatively weaker gluten and a lower
macro-polymer content. The better baking performance of genotypes expressing HMWG-(6+8) relative to that of genotypes carrying HMWG-(7+8) was attributed to the greater
dough extensibility characterizing the former group, but not to differences in gluten
strength-related parameters. There was no indication of differences in the gluten
polymer's size-distribution between the two groups. / Graduation date: 1997
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34213 |
| Date | 28 March 1997 |
| Creators | Ammar, Karim |
| Contributors | Kronstad, Warren E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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