DIASTASE

This curious substance, extracted by water from crushed malt, and precipitated from that infusion by alcohol, as is described under Fermentation , has been made the subject of new researches by M. Guerin Varry. The conclusions deducible from his interesting experiments are the following :— 1. One part of diastase, di olved in 30 parts of cold water, put with 408 parts of potato starch out of contact of air, did not exercise the slightest action upon this substance in the course of 63 days, under a temperature varying from 68° to 79° Fahr. 2. Two parts of diastase do not in the course of an hour, cause the globules of three parts of starch to burst, at a temperature approaching very nearly to that of the hot water which bursts them into a paste. It follows that diastase acts no part in the proce of germination, towards eliminating the teguments of the starch, or transforming its interior portion into sugar, and a gummy matter a imilated by plants. 3. Diastase liquefies and saccharifies the paste of starch without absorption or disengagement of gas; a reaction which takes place equally in vacuo, as in the open air. 4. 100 parts of starch made into a paste with 39 times their weight of water, mixed with 6·13 parts of diastase di olved in 40 parts of water, and kept for an hour between 140° and 149° Fahr., afforded 86·91 parts of sugar. 5. A paste containing 100 parts of starch, and 1393 parts of water, put in contact with 12·25 parts of diastase di olved in 367 parts of cold water, having been maintained at 68° Fahr. during 24 hours, produced 77·64 parts of sugar. 6. The preceding experiment, repeated at the temperature of melting ice, afforded at the end of 2 hours, 11·82 parts of sugar. 7. The most favourable proportions and circumstances for the production of a great quantity of sugar, are a slight exce of diastase or barley malt, (at least 25 per cent. of the latter), about 50 parts of water to one of starch, and a temperature between 140° and 149° Fahr. It is of the greatest consequence for the saccharification to take place as speedily as po ible, so that the sugar produced may not be left in contact with much gummy matter ( dextrine ), in which case, the diastase will not convert the latter into sugar. In fact, the liquefaction and saccharification should proceed simultaneously. 8. The sugar of starch, prepared either with diastase, or sulphuric acid, crystallizes in cauliflowers, or in prisms with rhomboidal facets. It has the same composition as sugar of grapes. 9. Diastase even in exce does not saccharify the gummy matter di olved in the water along with the starch sugar, but when the gum is insulated, it is convertible almost entirely into sugar. 10. Gum arabic, cane sugar, and beer yeast, suffer no change from diastase. 11. A watery solution of diastase readily decomposes on keeping, either in contact or out of contact of air. 12. When starch-sugar, whether obtained by means of diastase or sulphuric acid, is submitted to the spirituous fermentation, the sum of the weights of the alcohol, carbonic acid, and water of crystallization of the sugar, is le than the weight of the sugar by about 3 1 ⁄ 2 per cent. This difference proceeds in a great measure from the formation of some acetic acid, lactic acid, volatile oil, and probably some other unknown products in the act of fermentation.