A hypothesis for the structure and rheology of glutenin

Abstract

It is suggested that because of the rapid lowering of the viscosity of its solutions by reducing agents the major, important fraction of glutenin consists of linear molecules made up of polypeptide chains linked to one another difunctionally by S.S bonds. When dough is stretched the natural tendency of the polypeptide chains to return to a contracted state of low free energy accounts for the elasticity. The interchain S.S bonds are essential for elasticity because inter-chain adhesion between individual polypeptide chains will not overcome the stronger intra-chain forces unless reinforced by the S.S bond. If extension exceeds the elastic limit, viscous flow occurs because steric hindrance and molecular slip will prevent a return to the original conformation. Disulphide interchange is believed to play an important part in stress relaxation. Mechanical scission of S.S probably occurs when molecules at their elastic limit are subjected to too much stress; this may explain the work maximum in the Chorleywood Bread Process. Explanations are advanced for mechanical and activated dough development and evidence in favour of the hypothesis is discussed. IntroductionGlutenin molecules show a wide variation in size, but their weight-average molecular weight is high, exceeding 1 million according to Jones et aZ.I.2 They are assemblages of polypeptide chains of mol. wt. 20,000, which are joined to one another by S.S bonds from evidence provided by Nielsen et aZ.3 It was concluded by these last workers that the elastic and cohesive properties of glutenin depended on the integrity of the S.S crosslinked structure. The polypeptide chains, referred to throughout this paper as 'chains', though of similar mol. wt., do not appear to be identical because after reductive scission of S.S bonds they show a range of mobilities

Changes in conformation and sulfhydryl groups of tilapia actomyosin by thermal treatment

“…Up to 75 1C, the content of T-SH and R-SH decrease and the molecules larger than myosin heavy chain were discovered in SDS-PAGE, so we surmised that the disulfide bonds were formed in inter-and intra-molecules. Exclusive of temperature, the disulfide bond contents were also changed under different circumstances such as pH value, buffer, pressure and additive inhibitors (Ewart, 1968;Ikeuchi, Tanji, Kim, & Suzuki, 1992;Taguchi et al, 1987).…”

“…Therefore, an increase in R-SH contents detected probably shows the protein unfolding; a decrease in T-SH contents shows that disulfide bonds are formed. The polymerization of protein attributes to disulfide bonds formation, which occurs between wheat glutenins (Ewart, 1968), soy protein (Saio, Kajikawa, & Watanabe, 1971), whey protein (Ewart, 1968) and fish protein (Gilleland, Lanier, & Hamann, 1997). Moreover, disulfide bonds formation is significantly affected by variously heating conditions (Li-Chan, 1983).…”

Calculated molecular weight distribution for glutenin

“…The results of the research are the property of the MAFF and are Crown Copyright. The author thanks Dr R. A. Bailey for showing how eqn (1) can be more easily solved by a generating function than by induction, and Dr T. Fearn for calculating distribution curves by computer.…”

Correlating dough elastic recovery during sheeting with flour analyses and rheological properties

“…The 'Linear glutenin hypotheses' of Ewart (1968Ewart ( , 1972Ewart ( , 1978, proposed that glutenin contained molecules joined by disulfide bonds into linear polymers, with only a limited amount of branching. These molecules were responsible for elasticity.…”