Bazı Ekmeklik Buğday Çeşitlerinin Fonksiyonel ve Tam Buğday Ekmeği Özelliklerinin Karşılaştırılması, Kalite ve Fonksiyonel Özellikler Bakımından İyileştirilme Olanaklarının Araştırılması
Özet
Six bread wheat varieties (modern cultivars) widely grown in Turkey, nine different bread wheat varieties registered in former years prior to 1970 (old cultivars) and three different local wheats grown in Anatolia in the past (landraces) were used in the present study. The production of the landraces significantly decreased after the introduction of modern varieties. The main aim of this thesis was to determine and compare the quality characteristics, functional properties and nutritional properties of the modern and old bread wheat varieties and landraces. Physical properties (hectoliter weight, thousand kernel weight and SKCS hardness index), Zeleny sedimentation value, protein, water extractable/total arabinoxylan, soluble and total dietary fiber, phytic acid, phenolic and mineral contents, bile acid binding capacities of wheats were determined. The second aim was to determine and compare the quality, functional and nutritional properties of whole wheat breads (WWB) produced using modern and old bread wheat genotypes. The third aim was to investigate the effect of enzyme (xylanase) on quality and functional properties of WWB. The fourth aim was to determine and compare the glycemic index (GI) of WWB produced using modern and old bread wheat varieties.
The results indicated that there were no extreme differences between the old and new wheats in terms of physical properties. However, endosperms of the old cultivars were softer than those of the modern cultivars. Landraces had the highest average protein content among all samples. Average sedimentation and modified sedimentation values, Farinograph development time, stability, quality number of modern wheats were higher than those of the old cultivars.
Modern wheats had the highest average total dietary fiber and total arabinoxylan content. Landraces had the highest average soluble dietary fiber, phenolic content and phytic acid contents, Ca, K, Mg, Mn, P and Zn levels but the lowest bile acid binding capacity among all genotypes.
WWB of modern varieties had higher average volume and lower firmness values as compared to those of WWB produced from old varieties. WWB of old wheat varieties had higher average soluble dietary fiber content as compared to that of modern wheat varieties. Enzyme added WWBs (WWB-E) had higher volume and lower firmness values (1.day) compared to control WWBs. WWB-Es had higher WEAX content as compared to those of control WWBs.
WWBs produced from modern wheat varieties had the highest average Ca, Cu and Zn contents and the lowest P content as compared to old wheat varieties (p<0.05). WWBs produced from modern wheat varieties had the highest average bioavailability of Cu and S and the lowest bioavailability of Ca, Fe and Mn as compared to those of old wheat varieties (p<0.05). The differences between average estimated (in vitro) glycemic index values of the WWBs produced from modern and old varieties were not significant.
The results in the present study indicated that while modern varieties had better results in some of the quality/functional/nutritional parameters investigated, old varieties or landraces had better results in others. Breeding programs should be adopted to select wheat lines with higher AX, especially higher in WEAX, mineral and phenolic contents, mineral bioavailability and bile acid binding capacity, lower phytic acid content. The results of the present study indicated that the old cultivars and landraces can be a good genetic resource for the characteristics which they had better results and they might be used in wheat breeding programs to develop new cultivars.
