THE OIL CONTEXT OF FLAXSEED 
19 
The average oil content of the seeds designated as nonoil bear- 
ing was 5.74 per cent. The maximum amount was 9.56 per cent 
found in a sample of pigweed, and the lowest 2.27 per cent found 
in a sample of wild buckwheat. 
Green foxtail, the most common and most persistent weed seed 
4 found in dockage-free flaxseed, averaged 6.17 per cent of oil. One 
per cent of this weed when present in flaxseed reduces the oil 
content of the lot approximately 0.6 per cent. Not only are such 
types of weed seed deficient in oil but they have the further dis- 
advantage of reducing the oil yields from a crushing standpoint, 
inasmuch as they absorb approximately their own weight or vol- 
ume of linseed oil. 
It has been shown that the average oil content of clean flaxseed 
is 40.3 per cent. The inclusion of weed seeds in commercial flax- 
seed will reduce the oil content of the lot, the amount of reduction 
depending upon the percentage of weed seeds present, and whether 
these weed seeds are rich or poor in oil. Illustrative of this are 
the data in Table 13, showing the decrease in oil content with an 
increase in the foreign material present. 
Table 13. — Influence of the foreign material remaining in. flaxseed after dockage 
has been removed upon the oil content of flaxseed 
Percentage of foreign material 
to 0.99 
1 to 2.99 3 to 6.99 
7 to 9.99 10 to 14.99 
I 
Number of samples... . ..... ... 
4 
0.70 
.35 
11 15 
1. 13 3. 6 
.82 .91 
I 
14 10 
Average per cent foreign material 
7.7 
1.44 
12.1 
Average decrease in oil content due to foreign ma- 
terial.. . . _ ... . . 
3.09 
Even though certain weed seeds are rich in oil content, the quality 
of the oil is not so desirable as that from flaxseed. This is partic- 
ularly true with reference to the absorptive qualities of the oil, and 
the percentage of free fatty acids which are present. The absorptive 
or drying qualities of the oil from these weed seeds average only 
68 per cent as good as the absorptive qualities of the oil in flaxseed. 
It is evident, therefore, that the oil content of any given lot of 
flaxseed which contains appreciable quantities of inseparable foreign 
material can not be determined by observation but must be tested 
in order to determine accurately its oil content. 
RELATION BETWEEN COLOR OF FLAXSEED AND QUANTITY OF OIL 
Color of the seed does not appear to be an important index to 
the quantity of oil in flaxseed. During the last six years many 
samples of northwestern-grown flaxseed were analyzed that varied 
in color from a light tan to a deep mahogany brown. A comparison 
of the color of the seed with the oil content of the sample revealed 
no definite relationship between depth of color and content of oil. 
Samples of flaxseed of a rich mahogany brown color contained no 
more oil than did samples of a much lighter tint. 
These findings are contrary to those of Synder (8) whose data 
show that one would expect appreciable differences in the oil content 
