Flour can be used to form dough with very high viscoelasticity by kneading well and adding water. The higher protein content in wheat flour helps form good dough that is suitable for making bread. However, there is the wheat which bread characteristics have bad though a protein content is high. In addition to the amount of gluten, the quality of the gluten has also been determined to be important. An increased interest in gluten quality has led to elucidation of the relationship between the sub-unit structures of gliadin and glutenin, and the baking quality. These studies have clearly shown that wheat containing “5+10” high molecular weight glutenin subunit (HMWG) exhibits excellent bread-making properties. Much of the wheat grown in North America and Europe contained “5+10”, but in Japan this was only true for a few varieties.
In recent years, varieties with “5+10” have started to be made in Japan, introduced by breeding.
The details of the mechanism of disulfide-binding (S-S bond) formation have not yet been determined. Protein disulfide isomerase (PDI) is the enzyme that catalyzes S-S bond formation in proteins. We think that PDI involved in wheat seed storage protein synthesis remains present in the flour, becoming involved in S-S bond formation in the bread-making process. We consider this hypothesis. As a result of PDI activity comparison of in flour, they tends to exhibit high PDI activity in bread making highly wheat was observed. As a result of the production of bread is added to the medium flour and PDI obtained by the E. coli expression system, it was found that improves the specific volume.
In the future, by advancing the research on the relationship with the flour subunit structures and S-S bond formation by PDI, it is considered that meaningful information is obtained.