The fatty oils from the seeds of Hyptis spicigera and Ocimum viride from Nigeria, and of O. kilimandscharicum, Euphorbia calycina, E. erythracac, and Charozophora plicata from the Sudan, have been examined with reference to their component fatty acids and their suitability as drying oils. The oils of H. spicigera, O. kilimandscharicum and Euphorbia calycina closely resemble conophor oil in their fatty acids and their high content of linolenic acid; that of E. erythracae is very similar to linseed oil in composition, and C. plicata seed oil resembles cottonseed oil in its proportions of linolcic, oleic and saturated acids, Features in the distribution, cultivation, or harvesting of the seeds under discussion would appear to present certain difficulties in their commercial exploitation as compared with Tetracarpidium (conophor), but it is clear seeds which yield oils equal or superior to linseed oil in drying properties, as indicated by their respective contents of linolenic glycerides.
The fatty oils from ten specimens of African sunflower seed from widely different areas, and an Argentine sunflower seed oil have been studied. The iodine values of the oils raged from 113–136, their linoleic acid contents from 44% to 72% and their oleic acid contents from 43% to 14%. Sunflower seed oils in which linoleic acid forms about 70% or more of the total fatty acids are excellent non‐yellowing drying oils. Although the results reported in this paper are insufficient to define whether the wide variations in the proportions of linoleic and oleic acids arc due to environmental or varietal causes, there is reason to consider that the environment of the sunflower plant exerts a much greater influence on the composition of the oil than differences in the variety of seed grown.
Sunflowers grown from named varieties of seed in Southern Rhodesia, Kenya and Tanganyika give seed oils of somewhat varying composition, but the seed oils from all varieties grown in any one location are practically identical in composition. Similarly, sunflower seed oils grown in three different parts of Zanzibar from two sorts of seeds (black and cream) are widely different in composition; here the oils from black seeds were somewhat more unsaturated than those from the cream seeds, but the main difference again is connected with the place of growth and, more specifically, seems to be connected with the rate of development of the seed. Seed harvested only two months after planting gave oils of extremely low unsaturation which, indeed, were not dissimilar from groundnut oils in linoleic acid content. The component glycerides of the least unsaturated oil (iodine value 94.7) have been determined.
Five specimens of sunflower seeds from Africa, the oils in which varied widely in composition (44-72% linoleic acid), were grown in three English gardens in West and East Cheshire and Kent. The composition of the resulting English-grown seed oils was broadly the same in all cases, irrespective of the seed sown. Most of the oils contained, on an average, 68-70% of linoleic acid, but the extreme range of linoleic acid varied from about 60 t o 7j7,. The apparent rxplanation of these subordinate differences may lie in the cffect of direct sunlight on the ripening seed heads, since flower-heads that became completely inverted and faced downwards gave the oils with highest linoleic acid content ; others, in which the stems turned more or less through go" so that the lieads were more freely exposed to direct light, gave oils with somewhat reduced linoleic acid content. It is concluded that varietal factors play little part in determining the composition of sunflower seed oils. The main effect is that high linoleic content is conditioned by slow development and ripening of the seed, and rice z w s a ; climatic (temperature) conditions and also, probably, the degree of incidence of light on the ripening seed heads are tlie factors which control the rate of development of the sect1 and also the relative unsaturation of the seed oil.
Like Niger seed oils (Part II) and sunflower seed oils (Part IV), safflower seed oils may vary somewhat widely in their content of Iinoleic acid; oils from Asiatic and some other sources contain 60%, or less, but other seeds grown in America or Australia furnish oils in which linoleic acid forms up to about 77% of the total fatty acids. Such oils contain negligible proportions of linolenic acid, and are excellent non‐yellowing drying oils. Safflower seed grown in Kenya has been examined and found to give oil practically identical with a recently described Australian oil, its component acids being palmitic 6·4, stearic 3·1, arachidic 0·2, oleic 13·4, and linoleic 76·9% by wt.
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