Now it has been known for a considerable period that bran contains an unorganised ferment called cerealin,[171] which is capable of changing starch into dextrin and other carbohydrates; but the information to be obtained about it was very meagre, and as it appeared that this body might play an important part in the fermentation, we proceeded to prepare some pure cerealin and to ascertain its action on pure starch. The cerealin was prepared by taking a kilo of bran and extracting it with 2 litres of distilled water at 30° C; the extract was filtered clear and 2 litres of strong spirits of wine containing 90 per cent. alcohol was added, when a flocculent precipitate separated, which was washed on a filter with alcohol, dehydrated with absolute alcohol, and dried over H2SO4. The cerealin thus prepared is an amorphous substance not quite white, difficultly soluble in water, though we think this is due to its having been coagulated, and that it might be prepared in some other way which would show it to be more soluble than that which you now see.
To show its action on starch we took 10 grm. of pure starch in 200 c.c. water at 40° C., and placed equal quantities in two flasks; to No. 1 about 0·1 grm. of the cerealin was added; No. 2 was left blank. These were kept at 40° C. for 10 hours, the clear liquid filtered off, and examined with Fehling’s solution. No. 1 reduced it strongly, showing that glucoses were present in considerable quantity. No. 2 had no effect whatever.
Addition of alcohol to No. 1 gave a white precipitate; this was thrown on to a filter, washed with alcohol, and dried at 100°, again dissolved in water, and inverted by boiling the solution with 1/20 part of strong sulphuric acid and then neutralising with sodium hydrate. The resulting solution reduced Fehling’s solution, showing that the body was dextrin. Strong bran infusion (which of course contains cerealin) acting on a thick starch mucilage, liquefies it, and forms glucoses and dextrin.
We have thus shown that the cerealin produces glucoses as well as dextrin, both from solid starch and from starch mucilage. This is most important, as it has been previously shown by one of us that the ferment attacks glucose very easily.
The drenches were now examined in order to ascertain the presence of glucose and dextrin; in the former communication it was stated that these were absent. We find, however, that by concentrating the liquid, that both are present in the early stages. Samples were taken one hour after mashing, and at 3, 6, 12, and 18 hours, while the drench was working.
These were evaporated to 1/5 bulk, filtered, and divided into two portions, one of which was examined with Fehling’s solution; to the other alcohol was added; the white precipitate after addition of alcohol was filtered off, washed with alcohol, dried at 100° C., redissolved in water, and boiled with sulphuric acid to invert it, then examined with Fehling’s solution.
The following results were obtained:—
| Hours | 1 | 3 | 6 | 12 | 18 |
| Glucoses or sugars reducing Fehling’s solution directly | Present in considerable quantity | Present in small quantity | Absent | Absent | Absent |
| Dextrins, Fehling’s solution reduced after inversion | Present in considerable quantity | Present | Traces | Faint traces | Absent |
| Soluble starch | Absent | Absent | Absent | Absent | Absent |
In a bran infusion kept from fermenting by a little ether or chloroform, the formation of glucose and dextrin goes on continuously, the glucose increasing in quantity; the action is, however, much slower than in the case of diastase; at the end of 12 hours, at a temperature of 40° C., about half the starch is transformed.