Journal Of The Federated Institutes Of Brewing PDF Download

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ...higher the apparent diastatic power. In order that the test may be carried out at a constant temperature in winter and summer, and since it is easier to heat water than to cool it, these chemists suggest that the 10 test-tubes containing the starch conversions should be placed in a water bath for an hour at a constant temperature of 70 F. (21 C). After the 10 test-tubes containing the malt extract and soluble starch have remained for exactly an hour 5 c.c. of Fehling's solution are added to each, the tubes again shaken, and the whole series placed in a boiling-water bath for 10 minutes. On examination, some of the tubes will be found to be over-reduced, as shown by their yellow colonr, and others under-reduced, as shown by their blue colour. The two consecutive tubes--one of which is slightly over-reduced and the other slightly under-reduced--are selected, the point of exact reduction will lie somewhere between these two, and to arrive at it more accurately, a second series of tubes are started to which quantities of malt extract, between the limits found in the preliminary experiment and differing by 0'02 c.c., are added. The diastatic capacity of a malt is taken as 100 when 0'1 c.c. of malt extract produces sufficient reducing sugar to completely reduce 5 c.c. of Fehling's solution. If, therefore, the 5 c.c. of Fehling's solution were exactly reduced in the first tube of the above series, the diastatic capacity of the malt would be 100; if exact reduction occurred in the second tube, the diastatic capacity would be 50, and so on. It is, therefore, seen that a wide range is covered between tubes 1 and 2, hence the necessity for carrying out a second series of tests in which the difference in the volumes of malt extract added to the...