UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 557 



Joint Contribution from the Bureau of Plant Industry, WM. A. *\k*A 

 TAYLOR, Chief, and the Office of Markets and Rural %^ 



j£!& K &3'u Organization, CHARLES J. BRAND, Chief J^^^ji, 



Washington, D. C. 



A 



May 18, 1917 



A COMPARISON OF SEVERAL CLASSES OF AMERI- 

 CAN WHEATS AND A CONSIDERATION OF SOME 

 FACTORS INFLUENCING QUALITY. 1 



By L. M. Thomas, 

 Grain Supervisor, in Charge of Milling and Baking Investigations. 



CONTENTS. 



Page. 



Introduction 1 



Factors of importance in determining the 



quality of wheat 2 



Milling yield and flour color 2 



Flours of high and of low strength 3 



Loaf volume and texture 3 



Water absorption 5 



Classes of wheat studied 5 



Milling yield and related factors 6 



Yield of flour 6 



Yield of bran and shorts 7 



Moisture content and flour yields 7 



Flour yield and weight per thousand kernels. . 9 



Flour yield and weight per bushel '. . . 10 



Color of flour and bread 14 



Relation of yield and color to test weight and 



soundness 15 



Inseparable foreign material, flour yield, and 



color of bread 17 



Flour strength 18 



Comparisons of loaf volume 18 



Comparisons of texture 21 



Relation between crude protein in wheat and 



the strength of flour 22 



Protein content of wheat and flour 24 



Water absorption of flour 25 



Summary 25 



INTRODUCTION. 



The task of placing wheat classification and grading on a scientific 

 basis involves a consideration of two important problems, the first of 

 which is the investigation of the fitness of the several types of wheat 

 for the manufacture of white flour and the adaptation of the flour 

 from these several types to the manufacture of different kinds of 

 bread products. This primarily concerns the division of wheats of 

 distinctly different character into general classes. 



1 The investigations reported herein were made in the Office of Grain Standardization 

 of the Bureau of Plant Industry, under the direction of Dr. J. W. T. Duvel, Crop Tech- 

 nologist in Charge, in cooperation with the chemical department of the North Dakota 

 Agricultural Experiment Station. Since August 18, 1916, the grain-standardization 

 investigations of the Department of Agriculture have been administered jointly by the 

 Bureau of Plant Industry and the Office of Markets and Rural Organization in connection 

 with the enforcement of the United States Grain Standards Act. 



91418°— Bull. 557—17- 



