Buğdaydaki Gluten Proteinleri: Gliadin

Gluten kompleksinin 2 temel bileşeninden biri olan, sadece tahıl tohumlarında bulunan, kimyasal olarak basit proteinler sınıfına giren gliadin, heterojen bileşime sahip olup, birbirine benzer peptid zincirlerinden oluşmuştur. Glutenine göre daha simetrik, daha küçük yapıya, dolayısıyla daha düşük molekül ağırlığına sahip olan gliadin, hidrojen bağlı çözgenlerde ve %70-90'lık etil alkolde çözünebilir. Diğer tüm proteinlerden konsantre alkol çözeltilerinde çözünebilme özelliğiyle ayrılan, ancak suda ve saf alkolde çözünmeyen gliadin, uzayabilme yeteneğine sahip olup yekpare hamur kitlesi oluşumundan sorumlu olan başlıca bileşendir. Ekmek hacmini kontrol eden, şekil olarak küresel bir yapıya sahip olan gliadin, gluten oluşumunda pozitif yüke sahiptir. Gliadinler, elektroforez cihazında düşük pH'da fraksiyonlarına ayrıldıklarında alfa (?), beta (?), gama (?) ve omega (?) gliadin olmak üzere 4 gruba ayrılırlar. ?, ? ve ? gliadinler ekmekçilik açısından daha önemli işlev üstlenirler. Buna karşılık, zayıf emülgatör özelliği gösteren ve kükürt içermediği için S-S bağı oluşturamayan ?-gliadin, gluten oluşumunda ve ekmekçilikte en az öneme sahiptir. Bu derlemede, gliadin başta olmak üzere buğdaydaki gluten proteinleri ve ekmekçilikteki önemleri derlenmiştir.

Wheat Gluten Proteins: Gliadin

Gliadin, one of the two basic components of gluten complex, has been found only in cereal seeds, and chemically classified as basic proteins. It consists of homologous peptide chains and has more symmetrical, smaller structure thus lower moleculer weight than glutenin. It can be solubilized in solvents of hydrogen bond and 70-90% ethyl alcohol. Its solubilization property at concentrated alcohol solutions is a distinctive characteristic in comparison to other proteins; however, it cannot be solubilized in water and pure alcohol. Having the ability of extension, gliadin is the main component responsible from the uniform dough structure. Gliadin, which controls bread volume and has a spherical structure, becomes positively charged during gluten formation. At low pH, gliadins are electrophoretically separated into four groups as alpha (?), beta (?), gamma (?) and omega (?) gliadins. ?, ? and ? Gliadins have an important function in bread making. However, ?-gliadin has a less important role in gluten formation and bread making because it shows poor emulgator property and does not include sulfur in its structure, thus unable to form S-S linkages. Wheat gluten proteins, especially gliadin, and their role in bread making were reviewed in this review.

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