4 Maine Agricultural Experiment Station. 1920 



As the baking quality or strength of wheat has been com- 

 monly regarded as being determined by the chemical composi- 

 tion, the problem of strength in wheat has long been studied 

 from the chemical point of view. Two aspects of this problem 

 were especially subjected to a frequent study, viz., the relation 

 between the chemical composition and the bread-making value, 

 and the influence of the environment upon the chemical com- 

 position of wheat. In the first stage of the study of the relation 

 between the chemical composition and strength the quantity of 

 protein and gluten was regarded as the determining factor of 

 strength. As the accumulating evidence on this point was not 

 concordant the investigators in this field turned to the study of 

 the quality of gluten, notably its chemical quality. Various 

 theories have been suggested in explanation of the strength of 

 wheat, such as the gliadin number i. e. the ratio of gliadin to 

 glutenin, the absolute amount of gliadin in the flour, the ratio 

 of nitrogen to available potassium, the nitrogen in amino form, 

 the ratio of total nitrogen to soluble nitrogen in flour, enzymic 

 activity, etc. The study of the physical properties of the gluten 

 gained an impetus since the work of T. B. Wood 2 , who after 

 establishing that the gliadin and glutenin of strong and weak 

 flours were identical, found that the strength of wheat flour "is 

 associated with a high ratio of proteid to salt and that the size 

 of the loaf depends in the first instance on the amount of sugar 

 contained in the flour together with that formed in the dough 

 by diastatic action." 



In studying the extensive literature on the chemistry of the 

 strength in wheat one must be impressed with the marked diver- 

 gence of views on this problem despite the careful work and 

 standard analytical methods. In view of this the plant breeder 

 is naturally inclined to suspect the heterogeneous nature of the 

 material as being responsible for the conflicting results. For in 

 the study of the chemistry of strength the individuality of the 

 wheat variety that furnished the flour, its inherent specific in- 

 fluence upon the baking value, has been generally neglected. 

 And yet it would seem more reassuring to the plant breeder if 

 in the investigation of such a subtile problem as strength in 

 wheat an inductive rather than deductive procedure be adopted 



Wood, T. B. The Chemistry of Strength of Wheat Flour. Jour, 

 Agric. Sci. 1907 Pt. I., pp. 139-160 and II pp. 267-277. 



