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 preparation made for bakers and sold to them as Malt Extract should be prepared at a comparatively low temperature in mashing, in order to conserve the diastase. The diastase and proteids in such an extract exist in a more concentrated form, than in higher temperature extracts. Of course the grade of Malt used in itself is of importance; pure barley malt extract is by far the most desirable and should be given preference over extracts made from blend of malt and other extracts.
Diastase in malt extract, is the active agent by which the saccharification of starch is caused, producing maltose sugar from the starch of the flour of other gelatinized starch products that may be added to the dough or developed in baking.
The formation of maltose sugar with small quantities of dextrine is productive of good flavor and unmistakably increases the moisture-retaining power in the finished loaf of bread. It indirectly improves the size and color by reason of the stimulating action which Maltose sugar has on yeast, by being directly fermentable, and thereby the work of the yeast is hastened and fermentation accomplished quicker and more thoroughly.
During the stages of fermentation yeast feeds on the maltose for the purpose of supplying alcohol and carbon dioxide gas. Diastase has by itself a slow action on the wheat starch, but when the starch is submitted to the joint action of Malt Extract and Yeast, the quantity of starch affected by the joint action is greatly increased. If gelatinized starch products, say two percent to the weight of flour used, are added this action is accelerated and the dough thereby considerably benefited. The diastase, however, remains continuously active during the entire process of baking, producing maltose sugar all the while, until during baking a temperature of about 170° F. is reached, at which point the diastase itself is killed. But the rise in temperature in the interior of the loaf is more gradual, and so also is the action of the diastase greater, reaching its maximum near the center of the loaf. The yeast itself is destroyed at a much lower temperature and as the diastase remains longer active, it is evident that none of the maltose produced by this latter action can be fermented by the yeast, but remains in the bread as maltose and dextrine.
These substances account for the sweetness, improved flavor and moisture in the bread.
I can recommend everyone interested in the manufacture of the best bread to the use of malt extract. Malt extract improves the bulk of bread by its influence on fermentation. It improves the texture, bloom, moisture, whiteness, flavor and keeping qualities of the bread by its sugar producing qualities.
Other things being equal, the market value of a loaf of bread is in direct proportion to the amount of sugar left therein after baking.
The longer the fermentation is continued, the more of the sugar contained in the dough will be consumed by fermentation. Thus we develop "sour bread."
As malt extract continues to make maltose sugar, even during part of the time the bread is in the oven, its value to the baker becomes at once very pronounced.