Re‐examination of the linear glutenin hypothesis

The hypothesis that glutenin molecules consist of polypeptide chains joined by SS bonds into linear concatenations, instead of into branching giant molecules, is further examined. The concept that secondary forces can build up sequentially to produce appreciable tension in the molecules appears to fit the facts better than the idea that entangled molecules behave like a knot, which predicts a relation between tenacity and mol.wt. not observed for other high polymers. Work hardening arises because orientation makes the most effective use of secondary forces, the molecules being aligned so that they overlap by substantial fractions of their lengths. SS interchange in dough not only relieves stress but controls the average length of concatenations. Viscous flow depends predominantly on molecular slip, but is assisted by mechanical fission and SS interchange. In a resting dough mechanical scission is absent and SS interchange makes a relatively greater contribution to stress relaxation. Mechanical scission will not occur in terminal segments of concatenations. In an overworked dough, the length of many concatenations is at least halved by mechanical scission, greatly reducing the resistance. The predicted level of SH groups produced by mechanical fission is of a similar order to an experimental value quoted in the literature.