In order to throw some light upon this question I undertook a series of experiments, the result of which I give below.
Preliminary experiments were made with five different commercial brands of malt extract. Their reducing-sugar content and diastatic activity were determined. The percentage of reducing sugar showed no great variation and needs no further comment. The diastatic activity, however, varied considerably. By the diastatic activity is meant the number of times its (own) weight of maltose a given quantity of extract will produce when allowed to act upon acid-free soluble starch for one hour at a temperature of 40 degrees C. (104 degrees F.).
The activities of the five extracts mentioned above are as follows: No. 1—8.56, No. 2—15.71, No. 3—8.60, No. 4—9.69, No. 5—20.13. These results were obtained under similar conditions, and are, therefore, strictly comparable. It is quite evident that these extracts have different sugar-producing values. No. 5, for example, will produce 2.35 times as much sugar as No. 1.
Malt Extract vs. Sugar.
Having determined the relative diastatic values of the malt extracts, it was desirable to determine their values as sugar producers in bread-making; and to see if the saccharine material in bread could not be supplied cheaper by means of malt extract than by the use of granulated sugar, as is commonly done. Five different breads were made, all conditions and ingredients being kept as nearly similar as possible, except the kind and quantity of saccharine material used. After the breads were made and dried the percentages of reducing sugars were determined. The tabulated results follow:
| Grams Flour. | Saccharine Material. | P’c’t’ge Sugar Pound. | |
| No. 1 | 800 | 20 gm. cane sugar | 5.37 |
| No. 2 | 800 | None | 3.64 |
| No. 3 | 800 | 8 gm. malt extract No. 5 | 6.00 |
| No. 4 | 800 | 8 gm. malt extract No. 1 | 5.68 |
| No. 5 | 800 | 1 gm. malt extract No. 5 and 30 gm. cooked flour | 5.27 |
The percentages found are calculated on the dry bread. The results reveal several interesting and significant facts. The eight grams of the lowest diastatic extract (activity 8.56) produced more sugar in the bread than the twenty grams of cane sugar. It is also evident that the lowest diastatic extract produced nearly as much sugar as the highest. The ratio of their activities is 8.56 to 20.13, while the ratio of the percentages of sugar produced is only 5.68 to 6.00. We might expect that the extract with an activity of 20.13 would produce more sugar than the one having an activity of only 8.56, but the results show that it did not. The explanation seems to be that both have an activity sufficiently high to convert into sugar and dextrin all the starch that is freed from the cellulose by having the cell walls broken, and neither attacks the starch granules that are still enclosed by cellulose.
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.