The lipid composition of margarines from stores in selected locations in the U.S. is reported. The lipids determined include the fatty acids, tocopherols and major plant sterols. Data are included for isomeric octadecenoic fatty acids (14 isomers or groups of isomers) and four isomeric octadecadienoic fatty acids common in partially hydrogenated vegetable fats, insofar as these are separable by capillary gas chromatography. Amounts of individual lipids found in vegetable oil margarines, spreads, imitation and diet margarines were: palmitate, 8.49 to 13.17% (normalized weight percent, calculated as triglyceride); stearate, 4.78 to 9.53%; linoleate, 6.06 to 46.39%; linolenate, 0.18 to 3.57%; α‐tocopherol, 0.3 to 24.3 mg/100g; γ‐tocopherol, 3.0 to 55.0 mg/100g; δ‐tocopherol, 0.5 to 18.9 mg/100g; campesterol, 10.6 to 106.3 mg/100g; stigmasterol, 13.1 to 60.9 mg/100g; sitosterol, 42.3 to 412.9 mg/100g. Amounts oftrans‐unsaturated octadecenoic fatty acids in these margarines varied from 10.74 to 30.06%. Small amounts of thetrans,trans, trans,cis andcis,trans isomers of linoleate also are reported.

A method is described for simultaneously determining tocopherols and sterols in fats and oils by quantitative capillary gas chromatography. Samples containing ca. 100 mg of lipid were saponified in capped tubes with aqueous KOH by heating for 8 min at 80 C; the unsaponifiable fraction was extracted with cyclohexane, freed of solvent, derivatized to form the trimethylsilyl ethers of both tocopherols and sterols, and ehromatographed on a 50 m X 0.25 mm glass capillary column coated with Dexsil 400. Most of the individual tocopherols and common sterols were well separated, although interfering peaks were seen in some samples, which for better specificity should ~be subjected to an initial purification. For most samples, however, the simplified sample preparation, without preliminary purification, was adequate when combined with capillary gas chromatography. Recovery, method and gas liquid chromatographic precision, and applications are discussed.

No abstract

A quantitative technique has been developed in which a weighed sample of cotton fiber is swollen in sodium hydroxide, centrifuged to remove liquid from between the fibers, and re weighed to determine its percentage increase in weight, the latter quantity being designated here as the fiber's "alkali-centrifuge value." The results obtained have been found to be related to two types of causal factors—namely, (1) the prior action of deteriorative agencies on the fiber, apparently especially on the outer wall of the fiber, and (2) the wall thickness of the fiber (as reflected in arealometer air-flow measurements). The fiber-deteriorative agencies which have been shown to bring about changes in the alkali-centrifuge value of cotton fiber include micro-organisms, certain enzymatically active filtrates from microbial growth media, sodium hypochlorite, hydrochloric acid, heat, and weathering. The microbial and enzymatic effects have been studied in more detail than the others. The new test is simple, rapid, inexpensive, quite highly reproducible, involves only standard laboratory equipment, and is essentially free from safety hazards to the operator. Several aspects of the methodology of the test are reported.