Raymond Reiser

Quantitative gas-liquid chromatography of triglycerides

To determine optimum operating conditions, an extensive study was made of the variables affecting quantitative recovery and resolution of model triglyceride mixtures. Parameters investigated included: flash heater temperature, carrier gas flow rate, type of carrier gas, column length, glass and metal columns, temperature program rate, linearity of detector response, physical design of gas chromatograph, and molecular species of triglyceride.Results indicate that with optimum operating conditions, triglyceride molecular weights through trierucin can be quantitatively analyzed. Accurate calibration is essential, since quantitative response factors vary somewhat with operating conditions, triglyceride carbon number, and the chromatograph used. Cocoa butter and rat adipose tissue triglycerides have been quantitatively analyzed by this technique.

Cis-Trans isomerization of oleic acid by nitrous acid

Oleic acid wascis-trans isomerized by HNO2 generatedin situ by reacting NaNO2 with a mineral acid. The influence on the reaction of time, temp, agitation, solvent, amt of catalyst and type of mineral acid was investigated. Optimum reaction conditions were defined for achieving equilibrium isomerization in 30 min with minimum by-product formation. After isomerization, nitrogenous by-products were efficiently removed using silicic acid. The active species causingcis-trans isomerization was tentatively identified as free radical nitrogen dioxide.

The influence of dietary fatty acids and environmental temperature on the fatty acid composition of teleost fish.

Marine and fresh water fish were depleted of tissue unsaturated fatty acids to various degrees and subsequently presented with linoleic and linolenic acids at different dietary levels, at different temperatures, with and without other dietary fat.Examination of the tissue fatty acids demonstrated that marine and fresh water fish do not differ between themselves or from other classes of animals in the following basic mechanisms of deposition and interconversions of dietary fatty acids:1)The fish are readily depleted of tissue polyunsaturated fatty acids.2)Dietary linoleic and linolenic acids are deposited, the former to a greater degree than the latter.3)At high levels of linoleic or linolenic acids in the diet there is no significant degree of their conversion to the longer chain more highly unsaturated acids typical of marine oils.4)At low levels of linoleic or linolenic acids in the tissues there is a significant, but slight, conversion to the longer chain acids at low environmental temperatures.5)The increase in the level of linoleic acid in tissue lipids which accompanies increases in the dietary levels, quickly tapers off above dietary levels of 5%.6)Temperature differences between 13 and 23C had little or no influence on the deposition or interconversion of polyunsaturated acids.7)Dietary cottonseed oil, which contains cyclopropene fatty acids, produces an increase in tissue stearic acid in the fundulus.

Influence of High Levels of Dietary Fats and Cholesterol on Atherosclerosis and Lipid Distribution in Swine

The degree of incorporation of injected 1-C14-acetate into tissue cholesterol on cholesterol free diets was much higher in the liver and plasma of swine ingesting saturated than unsaturated fat. The levels of cholesterol in all tissues increased with the presence of fat or cholesterol in the diet. In most cases, especially in the presence of cholesterol, cholesterol levels were highest in the presence of unsaturated fat. The combination of unsaturated fat with cholesterol in the diet produced the greatest degree of typical atheromatosis and the highest levels of cholesterol in the tissues, while saturated fat with cholesterol produced diffuse atypical lesions.

Analysis of triglycerides by consecutive chromatographic techniques. i.cuphea llavia seed fat

The triglycerides ofCuphea llavia var.miniata seed fat were separated according to the number of double bonds/molecule using preparative thin layer chromatography (TLC) on silicic acid impregnated with silver ion. The recovered frac-tions were quantitated by the chromotropic acid technique. Each fraction was then separated ac-cording to mol wt using gas-liquid chromatog-raphy (GLC). This multiple chromatography procedure resolvedC. llavia triglycerides into 17 different components. The triglyceride composition ofC. llavia seed fat was calculated from the above results. Since the fat contains 91.2 mole % decanoic acid, it was expected that each triglyceride molecule would contain at least two molecules of decanoic acid. Results showed this to be generally true, but sev-eral minor component triglycerides not conform-ing to this pattern were found.

The analysis ofCis-trans fatty acid isomers using gas-liquid chromatography

The geometric isomers of many unsaturated fatty acid methyl esters can be separated using high-resolution gas-liquid chromatography on polyester or Apiezon columns. Separations reported for the geometric isomers of monounsaturated, ricinoleic, linoleic, conjugated, and epoxy fatty acids are reviewed here. New data is presented on the resolution of linolenate geometric isomers on both polyester and Apiezon columns. The separation of methyl oleate and methyl elaidate on a polyester column has also been accomplished. Techniques for preparing and using the high-resolution columns necessary for these separations are reviewed.

The hydrogenation of dietary unsaturated fatty acids by the ruminant

SummaryGoats were fed alfalfa meal containing 10% cottonseed or linseed oil. After 11 weeks the fatty acids of rumen, stomach, and caecum contents were compared to those of the feed.It was found that the high levels of linoleic and linolenic acis of the feed were reduced to very low levels in the rumen, with comparable increases in the saturated acids. Monoethenoid acids were increased after linseed oil ingestion and in one animal after cottonseed oil ingestion.The ratio of monoethenoid to saturated acids in the rumen fat was lower than in the endogenous fat of nonruminant animals. This explains the paradox of the low ratio in the depot fat of ruminants even after the ingestion of highly unsaturated fats.

The effect of diet on the fatty acid composition of several species of fresh water fish

SummaryFour kinds of fresh water fish were captured in the young stage, maintained on a low-fat diet for about two months, and either continued on that diet or transferred to test diets containing 10% cottonseed or menhaden oil for about five weeks. The fish were then sacrificed, and their total body fatty acids were examined for relative amounts of 2, 3, 4, 5 and 6 double bonds. It was found that no significant change from the natural diet occurred in the fatty acids on the low-fat or cottonseed oil diets while on the menhaden oil diet the fatty acid composition changed to resemble the composition of that oil.These changes differed from those of the marine mullet in that the body fat of the latter lost much of its naturally occurring polyunsaturated acids, when placed on the low-fat regimen, and regained it on the menhaden oil diet.

Gas-liquid chromatography of triglyceride mixtures containing both odd and even carbon number fatty acids

Quantitative GLC of triglycerides has been extended to natural fats containing both odd and even carbon number fatty acids. A 1.83-m glass column containing 3.0% JXR silicone on 100/120 mesh Gas-Chrom Q resolved triglycerides differing by only one carbon number. Peak resolution was significantly improved by hydrogenating each triglyceride sample prior to GLC analysis.The triglycerides of four fish oils (mullet, tuna, menhaden, and pilchard) and one seed fat (Acanthosyris spinescens) containing odd carbon number fatty acids were analyzed by this technique. The method was also useful for determining the triglyceride composition of the cyclopentene fatty acid oil fromHydnocarpus wightiana seeds.

Gas‐liquid chromatography of triglycerides from erucic acid oils and fish oils

By critically selecting optimum operating conditions, quantitative gas-liquid chromatography of triglycerides has been extended to molecules containing substantial amounts of C20, C22, and C24 fatty acids. The triglycerides of four erucic acid oils (water cress, rapessed, nasturtium, andLunaria annua) and two fully hydrogenated fish oils (menhaden and tuna) have been quantitatively analyzed by this technique. The average fatty acid chain length calculated from the triglyceride composition of each oil agreed closely with that determined by GLC of its respective methyl esters. Several conclusions about the triglyceride composition of the fats analyzed are discussed.