Regularities in the Carbohydrate Composition of Barley Grain

In the course ofinvestigations on the proteins indications were obtained that there exist in the carbohydrate composition of barley grain regularities which are similar to those demonstrated among the proteins. (L. R. Bishop, this Joutn., 1930, 3E6.) It therefore became desirable to ascertain whether the indications were correct; for, if these regularities could be established in carbohydrate composition, the results would be of considerable importance both in their practical application and in the study of barley metabolism. The obvious method of attack on this problem was to estimate the quantities of the individual carbohydrates in a number of samples of barley, and in part this has been done. However, this would give results of biochemical interest only, but this work sought to obtain at the same time results of direct practical application by considering, in addition, empirical divisions of the carbo hydrates of barley. The empirical estima tions included are those for " brewers' extract," crude fibre and a new estimation designated the " insoluble carbohydrate " which aims, as far as possible in a single rapid estimation, to measure the carbo hydrate fraction complementary to extract— that of " spent grains." Objections may be raised to the use of such empirical estimations, but experience suggests that, under their appropriate standardised condi tions, they give definite, reproducible frac tions of the carbohydrates present. While it may be pointed out that the "scientific estimations " of starch, cellulose, lignin and hemicelluloses* are open to similar objections; for a consideration of these estimations shows that in every case they, too, depend on the use of standardised conditions and an empirical factor. In