STUDIES ON THE DIGESTIBILITY AND NUTRITIVE 



VALUE OP BREAD. 



INTRODUCTION. 



The investigations reported in this bulletin, which were carried on at 

 the University of Minnesota in 1900-1902, are a continuation of the 

 experiments on the digestibility and comparative nutritive value of 

 bread made from different grades of fiour reported in previous bulle- 

 tins of this Office," and include two series of digestion and nitrogen 

 metabolism experiments with healthy men on a diet of milk and bread 

 made from different grades of wheat ffour, namely, straight patent, 

 entire wheat, and graham. In the first series, which included 9 

 experiments carried on in 1900-1901 (pp. 20-31), the different grades of 

 flour used were all ground from the same lot of hard Scotch Fife spring 

 wheat. In the second series, which included 15 experiments, carried 

 on in 1901-2 (pp. 32-50), the flours were ground from soft winter wheat. 



The standard graders of flour produced by the modern process of 

 milliup- are discussed in detail in a former bulletin^' and also in later 

 pages of this bulletin. Briefly stated, by graham flour is meant the 

 product o})tained by grinding the entire wheat kernel. Entire-wheat 

 flour is the product obtained by removing about one-half of the coarse 

 bran before o-rindino-. This flour is flner than graham, but not as fine 

 as the patent grades of flour. In milling the patent flour all of the 

 bran is removed. Several grades of patent flour are produced, but 

 the one most commonly found on the market, known as "standard 

 patent," "straight patent," or "straight grade" consists of the first 

 and second patent and first clear grades combined. By ordinary proc- 

 esses of milling a little over 72 per cent of the total wheat is recovered 

 as straight or standard patent flour and about 2.5 per cent as low grade 

 and "red dog" flours, the remaining 25 percent being returned in the 

 form of bran, shorts, and other offal. 



During late years the relative food value and merits of these differ- 

 ent kinds of flour have been the subject of extensive discussion; but 

 an examination of the literature on bread and flour shows that but few 

 digestion experiments v/hich are really directly comparable have been 



«U. S. Dept. Agr., Office of P^xperiment Stations Buls. 67 and 101. 

 t>\J. S. Dept. Agr., Office of Experiment Stations Bui. 101, pp. 7,8. 



