Experiment No. 26
Acidity of Flour
Weigh into a flask 20 gms. of flour and add 200 cc. distilled water. Shake vigorously. After letting stand 30 minutes, filter and then titrate 50 cc. of the filtrate against standard KOH solution, using phenolphthalein as indicator, 1 cc. of the alkali equals 0.009 gms. lactic acid. Calculate the per cent of acid present.
1. How may the acidity of a flour be determined? 2. The acidity is expressed in percentage amounts of what acid? 3. What per cent of acidity is found in normal flours? 4. What does a high acidity of a flour indicate?
Experiment No. 27
Moist and Dry Gluten
Weigh 30 gms. of flour into a porcelain dish. Make the flour into a stiff dough. After 30 minutes obtain the gluten by washing, being careful to remove all the starch and prevent any losses. Squeeze the water from the gluten as thoroughly as possible. Weigh the moist gluten and calculate the per cent. Dry the gluten in the water oven and calculate the per cent of dry gluten.
Experiment No. 28
Gliadin from Flour
Place in a flask 10 gms. of flour, 30 cc. of alcohol, and 20 cc. of water. Cork the flask and shake, and after a few minutes shake again. Allow the alcohol to act on the flour for an hour, or until the next day. Then filter off the alcohol solution and evaporate the filtrate to dryness over the water bath. Examine the residue; to a portion add a little water; burn a small portion and observe odor.