UNITED STATES DEPARTMENT OF AGRICULTURE 



&MM BULLETIN No. 328 



^SYt~'x2^' Contribution from the Bureau of Plant Industry 



4Usr&Ju 



WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



December 30, 1915 



MILLING AND BAKING TESTS OF WHEAT CON- 

 TAINING ADMIXTURES OF RYE, CORN COCKLE, 

 KINGHEAD, AND VETCH. 



By R. C. Miller, Assistant in Charge of Dockage Investigations, Office of Grain 



Standardization . 



CONTENTS. 



Introduction 1 



Frequency of occurrence of impurities in 



wheat 2 



Comparison of the specific gravity of wheat 



and of its impurities 2 



Methods of preparation and milling 3 



Descriptions of the different impurities 5 



Comparative milling yields of wheat and of 



its impurities 10 



Milling and baking tests of wheat contain- 

 ing impurities 10 



Tests with flour blends 17 



Tests with wheat containing kinghead seed. . 18 

 Tests with wheat containing wild- vetch seed, 



as grown 19 



Analyses of wheat, of the impurities, and of 



flour containing admixtures 20 



Special cleaning devices 22 



Mechanical analyses of corn-cockle screenings . 22 



Summary 23 



INTRODUCTION. 



Wheat as grown and as marketed frequently contains various kinds 

 of so-called inseparable impurities, such as rye (Secale cereale), corn 

 cockle (Agrostemma giihago), kinghead, or great ragweed (Ambrosia 

 trifida), and wild vetch (Vicia angustifolia) . These impurities are 

 considered inseparable, inasmuch as they are not readily removed 

 from wheat by the grain-cleaning machinery in general use in grain 

 elevators and flour mills, because of their similarity in size, shape, 

 and specific gravity to the wheat in which they occur. 



Millers claim that the presence of these impurities in wheat in 

 appreciable amounts injures the milling and baking qualities of the 

 flour. The result is that wheat which cpntains a noticeable amount 

 of these ingredients when marketed is generally penalized by being 



Note.— The data presented in this bulletin are applicable to the wheat-producing sections of the 

 United States and are ol interest to farmers, grain dealers, flour millers, and bakers. 

 10373°— Bull. 32S— 15 1 



