David Firestone

Heated fats. I. Studies of the effects of heating on the chemical nature of cottonseed oil

When cottonseed oil was heated at 225°C. in the presence of air for long periods of time, nonurea adduct-forming monomers and dimers were formed which were toxic to rats. Analyses showed that the toxic fractions contained moderate amounts of carbonyl and hydroxyl and that they contained unsaturation difficult to remove by hydrogenation. Cyclic structures appeared to be present in the dimer fraction. The production of nonurea adducting monomers and dimers is associated with polymerization and other reactions of linoleic acid.

The determination of polymers in fats and oils

Fats and fatty acids are polymerized by oxidative or thermal processes. Structures have been deduced by using a number of chemical and physical techniques. General methods applicable to the analysis of polymerized oils include determinations of acetone number, iodine value (I.V.), molecular weight, dielectric constant, viscosity, and refractive index. Monomers, dimers, and trimers are separated generally by molecular distillation. In addition, urea fractionation and a number of chromatographic techniques are useful for the detection of monomers, dimers, and polymers.

Update on control of olive oil adulteration and misbranding in the United States

The Food and Drug Administration has carried out a regulatory program since 1982 to control olive oil adulteration and mislabeling in the U.S. Analysis of imported and domestically packaged olive oil products and inspection of domestic packers have significantly reduced the presence of undeclared esterified olive oil in olive oil products. Undeclared esterified olive oil was present in 13% of olive oils examined in a 1985–86 survey, compared to 65% in a 1983–84 survey. Undeclared olive pomace oil and seed oils continue to require surveillance in a continuing effort to eliminate olive oil adulteration.

Detection of adulterated and misbranded olive oil products

The Food and Drug Administration has been examining bulk and packaged olive oil products in a continuing program to detect adulteration of olive oil products. Thirteen of 20 products collected in 1983–84 labeled as olive oil contained undeclared esterified (synthetic) olive oil and four contained undeclared olive-residue oil (derived from olive pomace and pits). Seven of 13 brands of imported olive oil contained undeclared esterified oil, suggesting that considerable quantities of esterified oil have been shipped to the United States identified as olive oil.

Detection of trace fatty acids in fats and oils by urea fractionation and gas-liquid chromatography.

The detection of trace fatty acids (<0.1%) in a fat or oil by gas-liquid chromatography is possible when the methyl esters are fractionated with urea to provide a number of less complex fractions. Identification and estimation of trace fatty acids is simplified by quantitative removal of other fatty acids having similar gas chromatographic retention times. A detailed knowledge of the order in which inclusion compounds are formed was obtained by fractionating a complex mixture of marine and vegetable fatty acids. In addition, lanolin was fractionated to determine the preferential order in which saturated, branched chain (iso-, anteiso-) and hydroxy acids form inclusion compounds. Using urea fractionation and gas chromatography, 52 trace fatty acids were tentatively identified in butter, 30 in lard, and 26 in walnut oil.

The examination of fats and fatty acids for toxic substances.

The chick edema disease factor was found to be present in a number of distillates and residues that were obtained during the production of commercial fatty acids. The raw materials from which the toxic samples were produced included inedible animal tallows, acidulated vegetable oil foots, and oils recovered from tin plate manufacture. The chick edema factor was found to be present in several oleic acids and in a triolein. Twenty stearic acid samples which were examined were nontoxic.The nonurea adduct-forming fatty acids that were isolated from commercial oleic acids and various distillates and residues from the manufacture of commercial fatty acids were found to be toxic to weanling rats even after hydrogenation. Analysis of the nonurea-adducting monomers that were isolated from a fatty acid by-product distillate indicated the presence of cyclic structures.

Studies of the chick edema factor. II. Isolation of a toxic substance

A crystalline halogen containing material producing chick edema symptoms at 0.1 part per million in the diet has been isolated from a sample of triolein which was toxic to monkeys. This material is similar to that reported by Harmanet al. (4) but differs somewhat in ultraviolet speetral properties.

A review of methods for determining pesticide residues, contaminants and adulterants in fats and oils

Sensitive chromatographic methods are available for determining chlorinated pesticide residues and chick edema factor contaminants in fats and oils. Determination of chlorinated pesticide residues in fats and oils generally involves acetonitrile extraction, Florisil column cleanup, and analysis by electron capture gasliquid chromatography (ECGLC). However, other procedures are available including dimethyl sulfoxide extraction and sweep codistillation. Sensitive screening tests for chick edema factor involve alumina column fractionation of isolated unsaponifiable matter, sulfuric acid cleanup, and examination by ECGLC. Admixtures of animal and vegetable fats are detected by the gasliquid chromatography (GLC) of isolated sterols, and individual vegetable oils can be characterized by GLC analysis of the sterols as well as of the other unsaponiflable constituents.

Low temperature separation of trace amounts of dimethylpolysiloxanes from food

Dimethylpolysiloxanes, which are difficult to determine in fatty foods, can be separated at low temperatures by special freeze-out apparatus. Final determination is made by atomic absorption, visible or ultraviolet spectrometry. Recoveries from cottonseed oil and cake mix ranged from 95% to 110%.