The presence or absence of specific proteins, the quantities of gluten proteins and the ratios of gliadins to glutenins or of gluten protein types determine the dough properties and baking performance of flours [1] and these characteristics can be very different, in terms of quality and quantity, according to the accessions.
Highlights from scientific literature:
Einkorn lines may have strongly different contents of protein even under the same growing conditions [2]
Einkorn flours have a relatively high contents of total gliadins when compared to the contents of glutenins. The content of gliadins or glutenins can also doubles between different accessions.
The ratio of gliadins to glutenins it can also triples between different accessions.
The α-gliadins were more abundant than γ-gliadins: they can also be double that of γ-gliadins.
The contents of ω5-gliadins is very hgh for einkorn compared to common wheat. The quantity of ω5-gliadins can also triples between different accessions. In accession ID331 the ω5-gliadins are absent.
In einkorn flours HMW-GS present a very low contents compared to common wheat. HMW-GS proteins can also double between different accessions.
LMW-GS are the protein type most present in the glutenin fractions. LMW-GS proteins can also double down between different accessions.
The influence of the genotype on the proportions of gliadins, glutenins and the different gluten protein types with respect to total protein can be very strong. Gliadins represent the 80-94% of total gluten proteins, glutenins represent the 6-20% of total gluten proteins.
HMWGS, essential for creating the network of gluten polymers [21], are far lower in quantity than common wheat. Their quantity can also be about 4% lower.
These characteristics (strongly affected by the genotype [4]) are decisively reflected on the rheological characteristics, clearly influencing:
• the formation of the dough which has very low stability (dough development time was negatively correlated with the ratio of gliadins to glutenins and positively with the content of glutenins) and a poor ability to rise (due to the weakness of the glutinic network which has a generally very limited ability to expand).
• The final result: loaf form, crumb structure, and bread volume (mainly dependent on the content of HMW glutenins; and not very sensitive to the ratio gliadins to glutenins)
- However, there are also genotypes with an excellent aptitude for baking (Saponaro et al., 1995; Borghi et al., 1996)
More:
• Einkorn gluten has a high gas retention capacity and a low water retention capacity (D’Egidio et al. 1993)
• Doughs prepared from einkorn flour also exhibit lower mixograph characteristics and are sticky and difficult to handle mechanically (Yamashita et al. 1957)
• Einkorn grain has a very soft texture (Pogna et al. 2002)
• In contrast to common wheat, the bread quality of einkorn flour is not influenced by the content of total gluten proteins, whereas other parameters such as glutenin content and the ratio of gliadins to glutenins are as important as for common wheat [5].
Note:
From the “Studies on the protein composition and baking quality of einkorn lines Herbert Wieser · Karl-Josef Mueller · Peter Koehler”
“The absence of a group of γ-gliadins at the beginning of the γ-gliadin elution region was unique for einkorn compared to all other wheat species. “
Questa caratteristica ne permette la classificazione in quattro gruppi, ulteriore sottodivisione è possibile analizzando il numero di ω5-gliadine presenti e le subunità delle glutenine a basso peso molecolare.
References
1. Kieffer R, Wieser H, Henderson MH, Graveland A (1998) J Cereal Sci 27:53–60
2. Brandolini A, Hidalgo A, Moscaritolo S (2008) J Cereal Sci 47:599–609
3. Wieser H, Bushuk W, MacRitchie F (2006) In: Wrigley C, Bekes F, Bushuk W (eds) Gliadin and glutenin—the unique balance of wheat quality. AACC International, St. Paul, pp 213–240
4. Borghi B, Castagna R, Corbellini M, Heun M, Salamini F (1996) Cereal Chem 73:208–214
5. Abdel-Aal E-SM, Hucl P, Sosulski FW, Bhirud PR (1997) J Cereal Sci 26:363–370
Keywords: einkorn dough properties; einkorn baking performance; gliadins; glutenins; ratio of gliadins to glutenins; α-gliadins; γ-gliadins; ω5-gliadins; einkorn dough development time; einkorn loaf form; einkorn crumb structure, einkorn bread volumes and HMW glutenins; high einkorn gas retention capacity; einkorn low water retention capacity; einkorn handle mechanically difficult; sticky einkorn doughs; einkorn low mixograph characteristics