Isolation of rapeseed plants containing no erucie acid in their seed oil gave simultaneous selection for low eieosenoic acid. Genetic analysis of populations segregating for erueie acid content indicated that the synthesis of these fatty acids was controlled, in the developing embryo, by two genes which displayed no dominance and acted in an additive manner. As the genetic capacity for crucie acid synthesis decreased, there was an increase in percentage of oleic acid with no corresponding decrease in total oil content. The percentage of eicosenoic acid remained relatively constant with decreasing erucie acid except in the zero erucie acid genotype where only 1% eieosenoie was detected instead of approx 12%. These observations were interpreted to mean that eicosenoic and erueie acids were formed by a genetically controlled carbon chain lengthening system operating by the addition of acetate moleeules to the carboxyl end of oleic acid. This hypothesis was supported by data obtained from the injection of radioactive sodium acetate into immature rapeseed pods. In the monoene fraction of the oil, eieosenoate had three times the speeifie activity of oleate and erucate had twice the activity of eieosenoate. On oxidation, the monoearboxylie fragments of these three acids had low and similar specific activities while in the diearboxylic acids, where chain elongation has presumably taken place, activity increased in the ratio of 1:5:19.

Docosenoic acid from rapeseed oil or herring oil in the diet of the young rat promoted an accumulation of cardiac lipid. The triglyceride fraction accounted for most of the deposited fat and contained a high concentration of the docosenoic acid. Liquid rapeseed oil, partially hydrogenated rapeseed oil or partially hydrogenated herring oil increased the amount of cardiac fatty acids at 1 week and led to the development of degenerative lesions at 16 weeks. Whale or seal oils low in C22 fatty acids produced little effect on the amount of lipids in the heart of rats or gerbils. The latter species receiving 20% rapeseed oil in the diet showed a peak in cardiac lipid deposition at 4 days with similar levels of total fatty acids to that of rats, but with a lower concentration of erucic acid. Oil fromLimnanthes douglasii and hydrogenated herring oil also increased the amount of cardiac fatty acids in gerbils. A high intake of docosenoic acid was common to the animals displaying the cardiac alterations.

Summary The fatty acid composition of a number of vegetable oils and of two synthetic mixtures of methyl esters are compared by gas‐liquid chromatography and by standard methods. The calculated iodine values from G.L.P.C. results are in good agreement with measured iodine values and are indicative of the reliability of the G.L.P.C. values. Standard methods gave lower values for linoleic acid and higher values for linolenic acid than did G.L.P.C. This deviation was particularly evident in oils with a high proportion of linolenic acid,e.g., linseed oil. The results of G.L.P.C. are considered to be accurate to within one unit percentage. Thermal stability of the polyester polymers can be improved by using 1,4‐butanediol or ethylene glycol as the polyols instead of diethylene glycol.

Gas‐liquid chromatographic analysis of methyl esters of two samples of castor oil gave the following (as wt %): palmitate 1.2, 0.9; stearate 0.7, 1.2; arachidate 0.3, 0.2; hexadecenoate 0.2, 0.2; oleate 3.2, 3.3; linoleate 3.4, 3.7; linolenate 0.2, 0.2; ricinolE'ate 89.4, 89.0; and dihydroxystearate 1.4, 1.3. Oxidative cleavage of purified methyl ricinoleate indicated that the double bond was exclusively in the 9舑10 position.Castor oil glycerides were fractionated in a 100‐tube CCD apparatus using 90% ethanol and commercial hexane as solvents. Analysis of pooled fractions showed (as mole %) triricinolein 68.2, diricinoleins 28.0, mono‐ricinoleins 2.9 and nonricinoleins 0.9. These results coupled with lipase hydrolysis of the whole oil and of the fractions agree well with the distribution pattern proposed by Vander Wal.

The effects of increasing the saturated fatty acids in a dietary vegetable oil composed mostly of unsaturated fatty acids were studied in rats. A mixture of palm oil and Swedish rapeseed oil fed for 4 weeks as 20% of a purified diet promoted weight gains which exceeded those obtained with Polish rapeseed oil of a similar content of erucic acid, and altered the proportion of saturated fatty acids in the tissues to reflect that of the diet. When methyl esters of saturated fatty acids were added to Swedish rapeseed oil, similar effects on weight gain were not observed, but methyl esters of fatty acids from corn oil and rapeseed oil were shown to be of less nutritional value than the original glycerides. From fatty acids of olive oil, glycerides containing 3% palmitic acid were prepared, and produced weight gains which did not differ significantly from those of rats fed Polish rapeseed oil with a similar content of palmitic acid and 20% erucic acid. The characteristic effects of rapeseed oil are, therefore, attributed to its low content of saturated fatty acids as well as its high content of erucic acid.