2 DETERMINATION OF SUGARS IN GRAIN AND CATTLE FOODS. 



sugars in the water extract of the material. In the early methods * 

 of the Association of Official Agricultural Chemists, the procedure 

 was to "stir 3 grams of the sample in a beaker with 50 cc of water 

 for an hour/' filter, and make up to volume. This procedure gave 

 varying results, depending upon the temperature of the water during 

 extraction and the fineness of the material. Later this procedure 

 was modified by using ice water for extraction and submerging the 

 beaker during extraction in a bath of broken ice. 2 In a majority of 

 cases this does not wholly accomplish its purpose, namely, to stop 

 enzymic action and thereby insure concordant results. It is a rather 

 cumbersome procedure, and, while enzyms may be inhibited during 

 extraction, they become active again when the filtration is carried 

 on at room temperature. However, many now use this method of 

 procedure for preparing the extract for sugar determination. The 

 official methods offer as an alternate for the water method an extrac- 

 tion with 40 or 50 per cent alcohol, but no definite procedure is 

 outlined. 



O'Sullivan, as early as 1886, was using alcohol to extract barley for 

 the determination of the quantity and kind of sugars present. He 

 states this to be the usual method of determining sugars at that time. 

 Stone, 3 in 1897, published a method for "The Quantitative Deter- 

 mination of Carbohydrates in Foodstuffs," in which he extracted 

 successively with boiling alcohol, cold water, diastase or malt infusion, 

 dilute hydrochloric acid, and finally 1.25 per cent sodium hydroxid. 

 The alcohol treatment was for the removal of the true sugars, the 

 cold water for the removal of dextrin and soluble forms of starch. 

 Browne 4 published results obtained on a distillery waste by this 

 method, but beyond this little mention of it could be found. 



M. N. Straughn, when working with C. G. Church on the sugar con- 

 tent of dried sweet corn at the Maryland Experiment Station in 

 1902, tried many modifications of the water extraction and alcohol 

 extraction methods. In this product sugars were present in small 

 quantities together with a large percentage of starch, and the enzyms 

 were active, as the drying had been carried on at a low temperature. 

 On extracting this material with cold water great difficulties were 

 experienced in obtaining clear extracts and a rapid filtration. It was 

 soon found that the percentage of total sugars obtained by this 

 method increased with the length of time of extraction, or, if the time 

 of extraction was fixed, the results varied with the time consumed in 

 filtering. This increase was no doubt due to enzymic action. Ex- 

 traction with hot water could not be practiced, as the material gela- 

 tinized, some becoming soluble, and filtration was almost impossible. 



U. S. Dept. Agr., Bureau of Chemistry Bui. 46, p. 24. 

 *U. S. Dept. Agr., Bureau of Chemistry Bui. 107, Revised, p. 57. 

 J. Amer. Chem. Soc., 1897, 29: 183. 

 J. Amer. Chem. Soc., 1901, 23: 229. 



