The Impact of Grain Protein Content on the Bread-Making Properties of Domestic Extra Strong Wheat Cultivar ‘Yumechikara’

‘Yumechikara’ is a domestic hard red winter wheat cultivar whose grain characteristics and processing properties vary with the growth condition. This paper describes the effects of the protein content of wheat on the grain quality and processing suitability of ‘Yumechikara’. Field studies showed that the grain protein content of ‘Yumechikara’ varied from 10.9 to 16.7% and the average value was 14.5%. In more than half the grain samples examined, the grain protein content was higher than the quality-evaluation standard value (11.5–14.0%). However, there was no variation in the other quality items, such as bulk density, ash content and falling number. To evaluate bread-making suitability, the grains with different protein contents were milled and mixed with the flour of soft wheat cultivar ‘Kitahonami’ at the ratio of 20–80%. At a protein content of less than 13.0%, ‘Yumechikara' showed lower quality in the evaluation, that is, lower quality of bread and increased dough mixing time. On the other hand, ‘Yumechikara' with a protein content of over 14.0% did not show lower quality in the evaluation. It is thus concluded that ‘Yumechikara’ with a grain protein content exceeding 13.0% is suitable for blending with ‘Kitahonami’. The blended wheat of ‘Yumechikara’ with a protein content of roughly 14.0% had good grain properties and processing suitability values equivalent to or exceeding those of conventional bread flour.