determination of starch content in the 
PRESENCE OF INTERFERING POLYSACCHARIDS 1 
By George Pelham Waeton, Assistant Chemist, and Mayne R. Coe, Junior Chemist, 
Cattle Food Laboratory , Miscellaneous Division, Bureau of Chemistry , United States 
Department of Agriculture 
INTRODUCTION 
No method of analysis by which it is possible to determine accurately 
the quantity of starch present in materials containing plant mucilages, 
pectins, or similar interfering polysaccharids has yet come to the atten¬ 
tion of the authors. Such a method, if reasonably practicable, should 
be of direct aid to feed-control officials confronted with the problem erf 
detecting adulteration in linseed meal and cake. It is an open secret 
that from time to time unscrupulous millers or dealers handling linseed 
by-products (cake, meal, and flaxseed screenings) have resorted to the 
following practices: The so-called “fine screenings” from flaxseed are 
run in with clean seed on the way to the crushers, in sufficient quantity 
to bring the total content of “dockage” up to about 5 per cent; flax 
screenings are crushed and pressed for low-grade oil, and the resulting 
screenings cake is ground and mixed with ground linseed cake in vary¬ 
ing proportions; chaff, fine screenings, etc., removed from flaxseed, are 
pulverized and used to adulterate linseed meal. 
It is impossible to determine the quantity of the adulterant, or even 
to prove sophistication, unless it is excessive, by making the chemical 
analysis usually applied to feedingstuffs (8) 2 because of the variations 
in composition of pure flaxseeds from different sources and the diverse 
character of the “dockage” or impurities associated with the seed. 
The seed of the flax plant, however, contains no starch. Therefore any 
starch found in a linseed cake or meal is an impurity derived from foreign 
or nonflax tissues present in the product examined. A small quantity 
of such nonflax material, however, does not necessarily constitute an 
adulteration. The Association of Feed Control Officials of the United 
States holds that the maximum quantity of weed seeds and other foreign 
materials legitimately permissible in linseed cake or meal is 6 per cent, 3 
equivalent to 4 per cent of foreign matter in the seed before crushing. 
From data collected by the Bureau of Chemistry (8), it follows that 
linseed cake or meal containing less than 38 per cent of crude protein, 
more than 11 per cent of crude fiber, or more than 2 per cent of starch, 
when calculated to a moisture-free and ether-extract-free basis, is open 
to the suspicion of having been adulterated. As the starch content of 
the nonflax material normally associated with flaxseed would rarely, 
if ever, be greater than 50 per cent, 4 any linseed cake or meal contain¬ 
ing more than 3 per cent of starch should be considered to be adulterated. 
1 Accepted tor publication Eeb. ao , 1923. 
1 Reference is made by number (italic) to ‘‘ literature Cited." p. 1006. 
* In the definitions of the association there is the further provision that no portion of the stated 6 per 
cent of weed seeds and other foreign materials shall be deliberately added. 
* This opinion is based on the nature of the flaxseed “dockage" examined for a large number of samples 
of country, terminal, and mill seed ( 3 ). 
Journal of Agricultural Research* 
Washington, D. C. 
adr 
(995) 
Vol. XJOII, No. V 
Mar. 24, 1923 
Key No. E-20 
