Effect of Composition of Gluthnin Subfractions on Rheological Properties of Wheat

Abstract

Gluten extracted from defatted flours of cv. Aubaine (extra‐strong), Hereward (strong) and Riband (weak) was separated into five different fractions (R2 to R6) by sequential centrifugation and addition of sodium chloride. A seven‐minute mixing time was used to carry out fractionation on the basis of depolymerization of glutenin macropolymers (GMP). Depolymerization of GMP occurred at much higher rates in dough of the weak cultivar compared to the strong and extra‐strong cultivars. Polypeptide compositions of different ghttenin fractions were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reduced and non‐reduced conditions, followed by densitometric scanning of stained patterns. The amount of HMW‐glutenin subunits decreased and LMW‐glutenin subunits increased correspondingly in each cultivar with the fractionation from R2 to R6. The rheological behavior of the fractions was analyzed by small deformation rheological tests (strain sweep and frequency tests). The high molecular weight fraction (R2) from extra‐strong wheat had a higher vahte of G' and a lower tan δ value as compared to strong and weak bread‐making wheats. The moduli of HMW glutenin fractions (R2 and R3) were frequency independent and promoted the network properties, whereas moduli of LMW glutenin fractions were frequency dependent and gave rise to a plasticizing effect. Therefore, it was concluded from the present studies that HMW‐glutenin subunits are not the only factors governing good bread‐making quality but their proportions in relation to low molecular weight glutenin subunits is equally important in sinking a balance between viscous and elastic properties essential for bread making performance.

Guava seed storage protein: Fractionation and characterization

“…2B) were similar among them, but differed from those obtained in the absence of reducing agent. These findings agree with those of Jood, Schofield, Tsiami, and Bollecker (2000), who found that glutelins are formed by high MW polymers stabilized through disulfide bridges. The pattern of the reduced samples includes three bands between 40 and 50 kD, other three polypeptides at 29, 27 and 25 kD, and two bands at 16 and 14 kD.…”

Viscoelastic characterization of glutenins in wheat kernels measured by creep tests

“…The correlation between sedimentation test, a gluten qualityrelated-parameter, and E 0 and compliances D 0 , D 1 and D 2 suggests that kernel elasticity is more related to genetic factors (i.e., glutenin composition). This data also agrees with studies of dough that suggest that fractions rich in HMW-GS provide elastic properties, whereas fractions rich in LMW-GS impart viscous properties (Jood et al, 2000). However, more research and larger sample sets representing different genotypes are necessary to provide sufficient evidence of the participation of LMW, with regards to the viscous behavior and its function as a plasticizer.…”

“…The high molecular weight glutenin subunits (HMW-GS) encoding genes occur at the Glu-1 loci (Payne et al, 1987), while the genes encoding low molecular weight glutenin subunits (LMW-GS) are mostly located at the Glu-3 loci (Singh and Shepherd, 1988;Luo et al, 2001). The LMW-GS represent about 30% of the total protein and about 60% of the total glutenins, and they seem to have a great effect on dough viscoelastic properties in both bread wheat and durum wheat (Luo et al, 2001;Jood et al, 2000). It appears that not only the total amount of protein is important but also the amount and type of the individual glutenin subunits.…”

Influence of Low Molecular Weight Glutenins on Viscoelastic Properties of Intact Wheat Kernels and Their Relation to Functional Properties of Wheat Dough

“…Studies of dough suggested that fractions rich in HMW-GS provided elastic properties, whereas fractions rich in LMW-GS imparted viscous properties (Jood 2000). At kernel level, the plastic area of samples with locus Glu-A3 showed 18.9% and 15.4% in alleles e and d respectively, compared with 12.4% for c and 10.8% for allele b maintaining constant HMW-GS (2*, 7+8, and 5+10).…”