XV. CEREAL FOODS. 

 WHEAT FLOUR. 



1 MOISTURE.-OFFICIAL. 

 Determine moisture as directed in VIII, 2. 



2 ASH.-OFFICIAL. 



Determine ash as directed in VIII, 4, using 5 grams of the flour. 



3 CRUDE FAT OR ETHER EXTRACT.-OFFICIAL. 



Determine the ether extract as directed in VIII, 10. With fine flour the addition 

 of an equal weight of clean, dry sand is frequently necessary. 



4 CRUDE FIBER.-OFFICIAL. 

 Determine crude fiber as directed in VIII, 68. 



5 ACIDITY OF WATER EXTRACT.— TENTATIVE. 



Weigh 18 grams of the flour into a 500 cc. Erlenmeyer flask and add 200 cc. of 

 carbon dioxid-free water. Place the flask, loosely stoppered, for an hour in a water 

 bath kept at 40°C., shaking occasionally. Filter upon a dry, folded filter, return- 

 ing the first 10-15 cc. of the filtrate to the filter. Titrate 100 cc. of the clear filtrate 

 with N/20 sodium hydroxid, using phenolphthalein as an indicator. Each cc. of 

 N/20 sodium hydroxid is equivalent to 0.05% acidity as lactic acid. 



6 SUGARS.-TENTATIVE. 



Determine reducing sugars and sucrose as directed in VIH, 58 and 59. 



7 PROTEIN.-OFFICIAL. 



Determine nitrogen as directed in I, 18, 21 or 23. Multiply the percentage of 

 nitrogen by 5.7 to obtain the percentage of protein. 



ALCOHOL-SOLUBLE PROTEIN. 



8 Method I. {By nitrogen determination) — Tentative. 



Transfer 4 grams of the flour to a 15O-200 cc. bottle or Erlenmeyer flask and add 

 100 cc. of 70% alcohol by volume, taking care that none of the material sticks 

 to the bottom of the container. Shake thoroughly 10-12 times at intervals of 30 

 minutes at room temperature, or shake continuously in a shaking machine for 

 an hour, and then set aside overnight. Shake thoroughly once more, allow to settle 

 and filter through a drj^ folded filter, returning the first runnings to the filter until 

 a clear filtrate is obtained. 'Pipette 50 cc. of the filtrate, equivalent to 2 grams of 

 the sample, into a Kjeldahl flask, dilute with 100 cc. of water to prevent frothing 

 during digestion and determine nitrogen as directed in I, 18, 21 or 23. 



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