Effect of Rain during Ripening on the Quality of Wheat Grain and Its Flour. : I. Changes in some constituents and enzymes of grain by moist treatment of ears.

Abstract

Flours obtained from Japanese domestic wheat generally produces more sticky and weak doughs than those from wheat imported to Japan. Very humid climate at the ripening period of domestic wheat may be one of the causes of this unpreferable trend. So, the effect of a moist treatment was examined on the chemical characteristics of ripening wheat which was kept from rain after heading by covering with glass roof, and the results were compared with those obtained on wheat ripened without covering. Moist treatment of ears brought remarkable increase in free sulfhydril content and the activity of proteolytic, lipolytic, and catalytic enzymes in embryo. Smaller changes in these articles also occurred in both endosperm and bran. In endosperm the susceptibility to papain and the content of non-protein nitrogen increased to some extent. These results for grain were consistent with those obtained for flours from domestic wheat showing weak dough characteristics. The activity ratio of alpha-amylase to protease in the treated sample was influenced significantly by treating temperature. The extent of change by the moist treatment varied with ripening stage of the grain. More serious deteriorations occurred on the treatment at "hard dough" stage, or thereafter, than the earlier stages.