386 BEVERAGES.
the malt, and in this way the starch is converted into a kind of starch paste ; when returned to the tun, this paste meets with the diastase remaining unconverted, and then very rapidly undergoes change into dexttine and sugar. From the nature of the German process, the wort is rich in dextrine and poor in sugar ; consequently when fermented it yields less alcohol.
Graham has experimented, for the purpose of answering the question, in what way can the practical brewer alter the ratio of dextrine to gluc,ose ; to ascertain if it can be altered to any extent, and whether there is a limit to the action of the diastase on the starch. The experiments were confined to one malt, analysis of which gave Water .. 7.51 Albuminous bodies (insoluble) .. 10.71 Glucose .. 5-48 A sh 2.50 Dextrine 8.82 Woody fibre, empyreumatic products, Sta'reh 48.77 and the like .. 14.37 Albuminous bodies, soluble .. 1.48 Cold Aqueous Extract.
15 minutes. 30 minutes.
Glucose .. 5.48 7.14 Dextrine .. 8.82 9.65 Alcoholic Extract.
80 per cent. 50 per cent.
Glucose 1.00 • • 5.68 When this malt was treated with water there was obtained, after a period of fifteen minutes, 5.48 per cent. of sugar, and 8.82 per cent. of dextrine, or in an additional fifteen minutes, 17.14 of sugar and 9.65 of dextrine. An almost identical solution was obtained with 50 per cent. of alcohol, and from this fact it was concluded that the particular sample of malt contained an amount of sugar equal to 5i per cent. The next point ascertained was the amount of action taking place at different temperatures in a given time ; and starting with cold water at 15° to 21° (60 to 70° F.) the liquor was raised to the temperature indicated in the following table, and continued for two hours These results show that there is a gradual increase in the amount of sugar formed, and that at 60° (140° F.) the process instead of being gradual, suddenly increases in intensity, yielding a much greater amount of extract.
Graham also has tested the validity of the assertion as to the German process, varying in the range of temperature of 74° to 75° (165° to 167° F.), being the most favourable for the conversion of starch and dextrine into sugar. The mashing heat was started on the principle of a low initial
temperature, raised up in the first hour to 38° (100° F.). It was then kept for two hours at a tem perature of 60° to 63° (140° to 145° F.), and was finally raised to 71° or 75° (165° or 167° F.). The following table shows the results : Two hours at Six hours at 74° to 75° (165° to 167° F) 74° to 75° (165° to 167° F.) Weight of extract per cent. .. 70.25 70.55 Draff 77 .. 21.58 20.71 Glucose 39.06 41.671 = Starch 62-52 Starch 62.51 Dextrine .. 27 • 36 .. 25.00 These results show a considerably larger amount of extract than with cold water, very much higher even than in the English infusion process. By prolonging the period for the temperatures at a higher stage, the German brewer is correct in his idea of getting a larger amount of sugar, and it remained to he seen, as an interesting experiment, what an extreme temperature of 79° (175° F.) would affect. A sample of malt was taken, and heated gradually, during sixty minutes, from the cold up to 77° (170° F.). It was then kept at that exceedingly high temperature for two hours, and the amount of sugar formed and extract obtained, are as in the following table : (1) (2) Weight of extract, per cent. .. 69.70 69.10 Draff .. 23.51 .. 23.35 Glucose .. 32.10 32.05 Dextrine SI 30.29 30.60 Graham considers that these experiments aro conclueive as to the advantage of low initial tem perature, and a high final temperature, and therefore experimented as to the best way to arrango tho mashing tomperaturee. Malt was healed from the cold up to 29° (85° F.) for one hour, then from 29° to 60° (140° F.) for one hour, when it was kept for three hours at 60°, and then boiled. In the second series of experiments the malt was raised during the first hour from the cold to 60°, when it was allowed to remain for two hours, and then raised very rapidly to 79°, when it was boiled. In the third experiment it wae raised in the first hour to 60°, maintained during the second at that temperature, and in the third hour ralsed to 79°.