Search

Gluten proteins, representing the major protein fraction of the starchy endosperm, are predominantly responsible for the unique position of wheat amongst cereals. These form a continuous proteinaceous matrix in the cells of the mature dry grain and form a continuous viscoelastic network during the mixing process of dough development. These viscoelastic properties underline the utilization of wheat to prepare bread and other wheat flour based foodstuffs. One group of gluten proteins is glutenin, which consists of high molecular weight (HMW) and low molecular weight (LMW) subunits. The HMW glutenin subunits (HMW-GS) are particularly important for determining dough elasticity. The common wheat possesses 3 to 5 HMW subunits encoded at the Glu-1 loci on the long arms of group 1 chromosomes (1A, 1B, and 1D). The presence of certain HMW subunits is positively correlated with good bread-making quality. Glutamine-rich repetitive sequences that comprise the central part of the HMW subunits are actually responsible for the elastic properties due to extensive arrays of interchain hydrogen bonds. Genetic engineering can be used to manipulate the amount and composition of the HMW subunits, leading to either increased dough strength or more drastic changes in gluten structure and properties.

In the current research, arabinoxylans (AX) and arabinogalactans (AG) were extracted from different wheat varieties and utilized in bread at different levels (0.5 and 1%). Texture analysis (hardness, fracturability, gumminess, cohesiveness) of dough and bread was performed using texture analyzer. Results showed that the AX content in whole wheat flours ranged from 2.93 to 4.68% while AG ranged from 0.47 to 0.93%. Hardness of bread decreased significantly because of the increase in the levels of AX and AG while it improved during storage study. Moreover, bread fracturability improved as the AX and AG levels increased. Highest gumminess was assigned to Shafaq-06 with increasing trend from control to 0.5% AX level. After the addition of AG, highest bread gumminess (155.74 ± 6.1, 156.32 ± 7.9) was observed in Shafaq-06. Both fracturability and gumminess have been increased with the addition of these nonstarch polysaccharides but decreased with the storage intervals. [ABSTRACT FROM AUTHOR]