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On the use of Taka-Diastase in estimating starch

Published online by Cambridge University Press:  27 March 2009

Edwakd Horton
Edwakd Horton
Affiliation:
Rothamsted Experimental Station, Harpenden, Herts.
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Extract

In an attempt to estimate starch in the grain of wheat grown under varying manurial conditions the writer has obtained results which it seems desirable to put on record for the information of others who may be using or propose fco use the Taka-diastase method.

Before devoting attention to wheat, experiments were made with pure potato starch under the conditions advocated by Davis and Daish. At first, owing to the use of insufficient enzyme, the results were low but immediately 0·1 gm. was taken the results were satisfactory (Table I).

Type
Research Article
Information
The Journal of Agricultural Science , Volume 11 , Issue 3 , July 1921 , pp. 240 - 257
Copyright
Copyright © Cambridge University Press 1921

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References

page 240 note 1 Davis, and Daish, , Journ. Agric. Sci. 1914, 6, p. 151.Google Scholar

page 242 note 1 Journ. Agric. Set. 1916, 7, p. 269, Fig. 2.Google Scholar

page 243 note 1 Chem. Soc. Trans. 1897, 71, 100.Google Scholar

page 243 note 2 Journ. Agric. Sci. 1914, 6, pp. 160–61.Google Scholar

page 248 note 1 English Patent No. 17, 277, a.d. 1894.

page 256 note 1 If it be supposed that in an experiment in which 2 grams of vacuum-dried starch were used, 10 per cent, of this was left in solution as dextrin whilst the remaining 1·8 grams were converted 0·8 gram into maltose and 1 gram into dextrose, then the final solution (500 c.cm.) will contain 0·2 gram of dextrin, 1·111 gram of dextrose and 0·844 gram of maltose. These three substances in the concentrations given would impart to the solution optical rotations of 0°·323, 0°·468 and 0°·929 respectively—totalling 1°721. Twenty-five c.cm. of the solution will reduce 0·2008 gram of copper oxide, 0·1431 gram due to the dextrose and 0·0577 gram due to the maltose. Then by using these two values (1°·721 and 0·2008) in the ordinary starch calculation (Journ. Agric. Sci. 1914, 6, 160–61)Google Scholar the amount of starch found as being originally present is 1·9730 or 98·65 per cent, of the weight taken.