Change in Wheat Quality with Ripening : II. Flour traits that affect quality

This study examined the change in flour quality with wheat grain development. Two winter wheat cultivars and two spring cultivars were harvested at 3-day intervals after anthesis in 1992 and 1993 in the Tokachi district of Hokkaido, Japan. Flour that extracted 60% of the grain weight was used for measurements. Whiteness and brightness, which were measured as the reflectance of flour paste at 455 and 554nm, respectively, increased with grain dry weight until the time of maximum grain dry matter accumulation (Tmax). For specific surface area and sedimentation value, which are connected to protein quality, the changes depended on the cultivars. For spring cultivars, Haru-yutaka and Haru-hikari, the specific surface area changed little, while sedimentation value increased until Tmax. For the winter cultivars, Chihoku-komugi and Takune-komugi, on the other hand, both the specific surface area and sedimentation value decreased with grain development. The change in maximum viscosity, which was attributed partly to climatic conditions, depended on both the year and cultivar. These results show that many flour qualities improve with grain development until Tmax, at which time the grain water percentage is about 40%, but quality does not improve thereafter. Therefore, it is believed that wheat can be harvested after the grain water percentage decreases less than 40%, at least in the Tokachi district of Japan.