This section is from the book "A Treatise On Flour, Yeast, Fermentation And Baking Together With RecipesFor Bread And Cakes", by Julius Emil Wihlfahrt. Also available from Amazon: A treatise on flour, yeast, fermentation and baking, together with recipes for bread and cakes.
The "gluten" may be approximately determined as follows: Scale accurately twenty-five grams of flour, and in a suitable porcelain dish, mix with 13 to 15 cc of water, of about 80° Fahrenheit. The exact amount of water used should be 5% less than given for the absorption test. (See absorbing power.) Mix until the dough is clear, then cover the little ball of dough with water of the same temperature, and allow to stand for one hour exactly.
Next, over a fine hair sieve, wash out the starch and soluble matters, using a large excess of water, by kneading the little dough ball carefully between the fingers, taking care not to separate the dough. When the washings no longer become milky, and no visible particles of dough are left in the remaining gluten, it may then be considered washed clean. Allow this fresh gluten to lie in water of same temperature for half hour; next take from water and press out the surplus water, by working the gluten gently between the fingers, and drying the hands occasionally on a towel, and continue this operation until all surplus water has been worked off. Care must be taken that no particles of dough or gluten remain in the sieve, over which the dough was washed. Next bring this gluten, which is now in its wet stage, on to a piece of counterpoised paper, and weigh it carefully. The amount of dry gluten can be readily calculated by multiplying the weight of the wet gluten by 4, and dividing the product by 3, which will give approximately correct results. The wet gluten may be dried at a temperature, ranging from 210° to 220° F., until the weight is constant, and figures thus obtained will agree very closely with those of the calculated dry gluten.
The general condition of a gluten, its color, tenacity, elasticity, stickiness and other points, must be carefully noted before the gluten is dried and the quality of the gluten judged by general results.
The gluten may be dissolved into its two original constituents, namely, glutenin and gliadin, by placing the wet gluten into a flask containing about 100 cc solution of 70% alcohol and 1% of salt; allow this to digest over a water bath, then filter.
The residue, after being rewashed with strong alcohol, represents the glutenin. The filtrate is distilled, the rest, containing the gliadin, is further evaporated until the weight becomes constant, and the gliadin is therefrom calculated.
(cc stands for cubic centimeter, which corresponds to one gram in weight.)