STUDIES IN CARBOHYDRATES 



MATERIALS, APPARATUS, AND METHODS 



IX THE investigations herewith detailed, wheat bread, oyster, soda, and 

 Educator crackers, pretzels, matzoth, and taka-diastase, peas, beans, 



lentils, and a dozen starches were used. 



Acme, Freihofer, Kolb, Jones, and Sharpless breads were examined. All 

 loaves were weighed; physical properties texture, odor, flavor, and color- 

 noted for the crust and interior. 



The loaf and crust were crumbled separately and allowed to dry in the 

 air. Each sample was powdered by grinding in a coffee-mill and transferred 

 to a stoppered bottle. In the case of crackers, preliminary drying was omitted 

 as unnecessary. They were powdered and bottled as the bread. In the com- 

 position experiments the moisture was determined in the fresh bread, loaf 

 and crust, and in the crackers as purchased. 



Acidity is expressed as lactic acid, determined by shaking 10 gm. of the 

 material with 250 c.c. of distilled water for fifteen minutes, filtering and 

 titrating an ah'quot portion of the nitrate. A second portion was evaporated 

 to dryness in a platinum dish, the residue being the water-soluble material. 



Ash was determined by burning 2 gm. at a very low heat until white. 



Salt was determined by macerating 5 gm. with 20 c.c. of water and titrat- 

 ing with silver nitrate, using potassium chromate as indicator. 



Fat was determined by extracting 8 gm. with ether in the usual extraction 

 tube for ten hours. 



Nitrogen was determined by the Kjeldahl-Gunning method, using 3 gm., 

 and the protein was calculated by the factor 6.25. 



Total carbohydrate was determined by macerating 2.5 gm. in 10 c.c. of 

 water in a mortar, cooling to 10 C., adding 20 c.c. of concentrated hydro- 

 chloric acid, previously cooled to 10 C., and allowing the paste to steep for 

 thirty minutes at 20 C. The mixture was transferred to a 100 c.c. flask, 5 

 c.c. of a 4 per cent, solution of phosphotungstic acid were added, and made 

 up to the mark with hydrochloric acid (sp. gr., 1.125), a l so cooled to 10 C. 

 The mixture was well shaken and placed for thirty minutes in a water-bath 

 at 20 C. After filtering and allowing to stand for fifteen minutes the filtrate 



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