DETERMINATION OF SUGARS IN GRAIN AND CATTLE FOODS. 



a method was devised which in the case of certain grains gave figures 

 that checked with those obtained by the alcohol digestion. The 

 procedure is as follows : 



Place 8 grams 1 of the finely ground grain in a 250-cc flask and add 

 190 cc of a 0.2 per cent solution of sodium carbonate. Allow to 

 stand at room temperature for two and one-half hours, shaking inter- 

 mittently. At the expiration of the time add 10 cc of a hot saturated 

 potassium alum solution; shake and filter. Use 25 cc of the solution, 

 the equivalent of 1 gram of material, for reduction by Allihn's 

 method, 2 calculating the cuprous oxid obtained (see page 7) to 

 dextrose by Allihn's table. To 50 cc of the solution in a 50 to 55 cc 

 flask, add 5 cc of concentrated hydrochloric acid and allow to stand 

 overnight for inversion. Then neutralize the whole solution with 

 sodium carbonate, make up to 100 cc, and in 25 cc of this (equivalent 

 to half a gram of material) again determine the total reducing sugar 

 by Allihn's method. Sucrose (see page 13) is obtained by multi- 

 plying the percentages of dextrose before and after inversion by the 

 factor 1.044, 3 then subtracting and multiplying the figure thus ob- 

 tained by 0.95. No correction of the percentages obtained is neces- 

 sary for the volume of the material, but when working with very wet 

 material the results should be corrected for the dilution caused by the 

 moisture content of the sample. 



COMPARISON OF THE TWO METHODS. 



The sodium carbonate digestion method having given good results 

 on grains, the authors decided to test it in comparison with the alco- 

 hol method on various classes of material and to determine its limi- 

 tations or the chance of error from differences in procedure. A num- 

 ber of representative samples were selected and comparative deter- 

 minations made. The results obtained on samples of corn, wheat, 

 and milo are given in the following table. These, and all subsequent 

 results, are expressed as invert sugar. 



Results on feeding stuffs by both methods. 



i Where only total sugars after inversion are to be determined and the quantity of total sugars is small 

 8.8 grams are used and extracted in the usual way. Fifty cc of the solution and 5 cc pf acid are inverted 

 overnight. The 55 cc are neutralized with dry sodium carbonate and 25 cc used for reduction. The figures 

 obtained for dextrose represent the amount from 1 gram of material. 



U. S. Dept. Agr., Bureau of Chemistry Bui. 107, Revised, p. 49. 



U. S. Dept. Agr., Bureau of Chemistry Bui. 107, Revised, p. 58. 



