Correlation of Loaf Volume with Peptizing Action of Salts on Wheat Flour Proteins. ∗

Abstract

We have recently completed in this laboratory an extensive study of the peptizing action of certain salt solutions on a series of wheat flours.† The 12 wheat flours used were selected with the object of including flours from the various types of wheat grown extensively in the United States and Canada. The experimental procedure was to weigh out 6 grams of flour into a 100 cc. centrifuge tube, and to add 50 cc. of a salt solution of given concentration. This mixture was then shaken for 30 minutes in a mechanical shaker, and the flour residue tightly packed in the bottom of the tube by an electric centrifuge. The clear supernatant liquid was decanted into a Kjeldahl flask and the extraction repeated on the flour residue with 50 cc. of fresh salt solution, repeating the shaking, centrifuging and decanting, and following this with a third extraction of the residue, with a fresh portion of 50 cc. of the salt solution. Sulfuric acid was then added to these combined extracts, and the nitrogen dissolved by the salt solution determined by the usual Kjeldahl-Gunning procedure. From the values thus obtained, the percentage of the wheat flour proteins soluble in the salt solution was calculated.

In all, 21 different inorganic salts were used, nearly all in four different concentrations, so that we have data as to the percentage of protein dissolved by the different salts, and the effect of concentration of the salt on protein peptization. Obviously such data are too extensive for summarization here. Great variations in the peptizing action of the various salts were observed. For example, normal solutions of KF dispersed an average of 13.07 per cent of the total protein, whereas a similar concentration of KC1 extracted an average of 22.77 per cent.