It is a quite significant fact, too, that the one gram Of malt extract No. 5, together with thirty grams cooked flour, produced nearly as much sugar in the bread as the twenty grams of granulated sugar. This bread, No. 5, in addition to having the sugar supplied in the cheapest way, had its moisture and freshness retained longer than the other breads.
The bread having no saccharine material added showed on analysis to have 3.64 per cent. of reducing sugar. Some of this sugar was in the flour, but the larger part of it was formed by the enzymes in the flour during the fermentation period and the baking of the bread.
Knowing the percentage of sugar and the weight of dry bread produced from the 800 grams of flour, I calculated the amount of sugar in the total quantity of bread produced in each baking. Then by deducting the amount of sugar in bread No. 2, which had no sugar added, from the amount in the other breads, the total amount of sugar produced by the malt extract was obtained. In this way it was found that the malt extract No. 5 produced 2.65 times its weight of sugar when added directly to the dough as is commonly done, and that it yielded 14.67 times its own weight of sugar when a portion of the flour was cooked, as in experiment 5; or it produced 5.5 times as much sugar when added to flour, the starch of which had been gelatinized by cooking, as it did when added to the raw flour. The cooked flour was cooled to 120 degrees F. and then the malt extract added. The results show that while malt extract produces considerable sugar when added directly to the raw flour, it produces much more sugar when a portion of the flour is cooked.
Now, one might suppose that the heat of the oven would certainly gelatinize a portion of the starch, and thus aid the diastase in the conversion of the starch into sugar, and avoid the necessity of cooking a portion of the flour. But when we consider the fact that the starch does not begin to gelatinize until the temperature is raised to 152 degrees, which is already about 30 degrees above the most favorable temperature for the activity of the diastase, and the fact that the diastase is killed at a temperature of about 175 degrees F., we can readily see why the gelatinization of starch in the oven is of little assistance to the diastase in the conversion of starch into sugar.