A Handbook of Sugar Analysis; A Practical and Descriptive Treatise for Use in Research, Technical and Control Laboratories
(This historic book may have numerous typos and missing te...)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...of Sugars with Dilute Alcohol.--Bryan, Given and Straughn have recently made experiments upon the extraction of sugars from grains and similar products, using as solvents 50 per cent alcohol and 0.2 per cent sodium-carbonate solution. Both of these solvents inhibit the action of enzymes and were found to give concordant results upon certain classes of products. In many cases, however, the sodium-carbonate extraction gave much higher amounts of reducing sugar after inversion--a result, perhaps, of the solvent action of the alkali upon pentosans and other hemicelluloses. Bryan, Given and Straughn believe that extraction with 50 per cent alcohol, all points considered, is the most reliable method for general sugar work. The method outlined by them is as follows: Method of Bryan, Given and Straughn.--Place 12 gms. of the finely ground substance in a 300-c.c. graduated flask, adding, in case the material is acid, from 1 to 3 gms. of precipitated calcium carbonate. Add 150 c.c. of neutral alcohol of 50 per cent volume strength; mix thoroughly and boil on a hot-water bath for 1 hour, placing a small funnel in the neck of the flask to condense the vapor. Cool and make up to 300 c.c. with neutral 95 per cent alcohol. After mixing and settling transfer 200 c.c. of the clear solution to a distilling flask and distil off the excess of alcohol, which is thus recovered for future use. The liquid residue is evaporated to a volume of 20 to 30 c.c. (but not to dryness), and then washed with water into a 100-c.c. graduated flask. The solution is clarified with the necessary amount of neutral leadacetate solution, and, after standing 15 minutes, made up to 100 c.c. Pass through a folded filter, carefully saving all of the filtrate, to which add enough anhydrous sodium carbona...
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