Willard D. Hubbard

Comparison of various methods for the extraction of total lipids, fatty acids, cholesterol, and other sterols from food products

Abstract and SummarySeven methods were used to compare the efficiency of total lipid extraction from 13 samples of eight different food products. The methyl esters of fatty acids and the butyrate esters of sterols were prepared and analyzed by gas liquid chromatography. On the basis of total lipid recovered and amounts of fatty acids and sterols present, a chloroform: methanol procedure was selected as the most effective method.

Gas chromatography of the fat-soluble vitamins: A review

The application of gas liquid chromatography (GLC) as an analytical tool for the determination of the fat-soluble vitamins A, D, E and K has yet to be utilized to its full potential. A review of the published work of many researchers in this field is presented. GLC methods to measure the vitamin A isomers have not been developed to any appreciable practical extent. Liquid liquid chromatography might well be the technique of choice. In the field of vitamin D there are indications that a practical GLC analysis is feasible for pharmaceutical preparations. The GLC applications for vitamin E are diverse, well defined and generally widely accepted in research laboratory situations and for regulatory and quality control usage. Vitamins K1 and K2 have been measured with limited success in a few research laboratories, but the GLC methods have not developed on a practical basis. However GLC is used for measuring vitamin K3 (menadione and menadione sodium bisulfite) on a fairly routine basis in quality control laboratories.

Evaluation of eight extraction methods and their effects upon total fat and gas liquid chromatographic fatty acid composition analyses of food products

Samples of corn beef hash, frozen turkey pie, frozen beef pie, and beef stew were extracted by eight methods. Methyl esters of the fatty acids contained in the extracted fat residue were prepared with BF3-methanol reagent and measured quantitatively by gas liquid chromatography. A 4N HCl digest followed by ethyl ether extraction was the most effective extraction method. Total lipid extracted, fatty acid distribution, and triglyceride recovery were the primary evaluation criteria. Recovery studies were carried out on eight different foods ranging from high meat content to pure vegetable shortening.

Sample size influence on boron trifluoride-methanol procedure for preparing fatty acid methyl esters

Sample size influences the yields of methyl esters of fatty acids by the boron trifluoride-methanol method. A study of the method revealed that best recoveries are obtained by using a minimum of 350 mg of lipid extract to prepare the methyl esters.

Comparison of total fat fatty acids cholesterol and other sterols in mayonnaise and imitation mayonnaise

Nine brands of mayonnaise and five brands of imitation mayonnaise were purchased from supermarkets in the Washington, DC, area. The samples were analyzed for total fat, fatty acids, sterols, and moisture. Little variation in total fat and saturated fatty acid values was observed among the brands of mayonnaise. The polyunsaturated fatty acid content of mayonnaise ranged from 28.0 to 47.9 g/100 g product. The cholesterol levels were divided between two ranges, 50-55 and 75-79 mg/100 g product. In contrast, there was wide variation in the lipid composition of the different brands of imitation mayonnaise. The total fat values for these products varied from 14.3 to 50.4 g/100 g product. The cholesterol content varied between 0 and 72 mg/100 g product; the latter figure equals the cholesterol content of many of the mayonnaise samples.

Production of Copper Deficiency in the Rat by an Egg Albumin Diet

Summary Copper deficiency as judged by achromotrichia and lower levels of copper in blood, plasma, liver, kidney, brain, and hair was induced in black rats by feeding a copper-deficient diet containing egg albumin. Results obtained with this diet were comparable to those obtained with a skim milk copper-deficient diet. Ascorbic acid, at 1% of the diet, had no effect on the development of copper deficiency in rats fed the egg albumin diet. Soybean protein diets were ineffective in producing copper deficiency. Plasma protein patterns obtained by disc electrophoresis were not influenced by copper deficiency.