Identification of adduct radiolysis products from ethyl palmitate and ethyl oleate

Radiolysis induced adduct products have been separated and identi-fied from irradiated ethyl palmitate, ethyl α-d₂-palmitate and ethyl oleate. In the saturated compounds, adduct formation was observed mainly at the position α to the carbonyl group. The three major adduct products identified in irradiated ethyl palmitate were ethyl α-tetradecylpalmitate, ethyl α-pentadecylpalmitate and the α,α′- dimer of ethyl palmitate. Corresponding compounds were identified from the irradiated ethyl α-deuteropalmitate. Adduct radiolysis products formed in ethyl oleate were identified as the monoene and diene dimers.     

Recombination products from the radiolysis of tricaproin

A low molecular weight triglyceride, tricaproin, has been selected to study the higher molecular weight products produced by irradiation. In a previous publication the identification of the primary radiolytic products in tricaproin was reported. In the present work, 28 compounds considered to have been produced by the combination of free radicals have been identified. Among these are hydrocarbons, ketones, esters, alkanediol diesters and glyceryl ether diesters. Reaction mechanisms for the production of these compounds are discussed.     

Melting-point determination of fat products

A variety of methods exist for the determination of the melting point (mp) of fats. These include the Wiley mp (AOCS Method Cc 2–38), open capillary slip point, softening point and Mettler dropping point. The conditions under which the tests are performed influence the values obtained. Several of these methods were compared using a variety of fats, including margarine and soft margarine oils, lard, butter and hydrogenated Canola oils. The Mettler dropping-point values were found to coincide with the extrapolated solid fat curves obtained using wide-line NMR for all fats except butterfat. The reproducibilities of the Mettler dropping point and softening point were excellent; that of the slip point was poor. Presented at the 73rd AOCS annual meeting, Toronto, 1982.     

Nature of the side chain branches in low density polyethylene: volatile products from gamma radiolysis

Measurements of the yields of low molecular weight hydrocarbons after γ-irradiation of low density polyethylene (LDPE) in the solid and liquid phases have confirmed that the main products are ethane and butane. Alkene yields were small, contrary to some previous reports. Irradiation at 150°C doubled the total yield of hydrocarbons, but the relative proportions of different hydrocarbons did not change markedly. The compatibility of these results with ¹³C n.m.r. determinations of the distributions of short chain branches in the same samples of LDPE is considered.     

Viscoelastic properties of plastic fat products

An instrument is described for the creep analysis of plastic fat products. The instrument records the deformation of a sample under constant force. Deformation is sensed by a displacement transducer. Instantaneous elasticity, retarded elasticity and plastic flow can be calculated. The extent of instantaneous elasticity of plastic fat products was found to be dependent on loading time. At longer loading times, the instantaneous elasticity as a percentage of total deformation decreased, with a corresponding increase in permanent deformation. The effects of temperature, magnitude of force and work softening were investigated. The results are discussed in relation to the nature of the crystal network structure in plastic fat products.     

Ethylene adduct of conjugated octadecadienoic acids: II. Ozonization products

Methyl 8-(4-n-hexylcyclohex-2-enyl) octanoate obtained by esterifying the adduct of ethylene andtrans,trans-9,11-octadecadienoic acid was ozonized in methanol as a participating solvent. The resultant cyclic methoxyhemiperacetal was reduced with powdered zinc to the dialdehyde, methyl 9,12-diformylstearate, which was isolated as the tetramethyldiacetal. This dialdehyde readily air-oxidizes to give methyl 9,12-dicarboxystearate. Heating the cyclic methoxyhemiperacetal slowly from 25 to 100 C in vacuo results in an unusual decomposition reaction which gives hydrogen and methyl 9 (12)-carbomethoxy-12(9)-carboxystearate as the primary products and methyl 9 (12)-carbomethoxystearate as the major by-product. Treatment of the cyclic hemiperacetal with hydrogen peroxide in formic acid gave unexpectedly dihydroxystearic acid as one of the products. Presented in part at the AOCS-AACC Meeting, Washington, D. C., April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Effects of various parameters on the formation of radiolysis products in model systems

Effects of various parameters on the formation of radiolysis products in triplamitin, palmitic acid, oleic acid, caprylic acid and capric acid were investigated. A greater yeild of primary and recombination products was observed in palmitic acid compared to that of oleic acid. In general, higher amounts of recombination products are formed in both acids when irradiated at room temperature than at −45 C. In the short chain acids, the yield of the hydrocarbon recombination product was enhanced in the liquid state. In contrast, the ketone recombination product was formed in greater amounts from solid capric acid than from liquid caprylic acid. In the absence of oxygen, a linear relationship was obtained between the dose and the yield of radiolysis products in tripalmitin. In the presence of oxygen, a considerable increase in the formation of γ-palmitolactone, n-3 and n-2 alkanes was observed at room temperature.     

2-Alkylcyclobutanones from the radiolysis of triglycerides

A cyclic compound was isolated from the radiolytic products of each of the simple triglycerides containing C₆, C₈, C₁₀, C₁₂, C₁₄, C₁₆ and C₁₈ fatty acids. In each case the compound was identified as the 2-alkylcyclobutanone of the same carbon number as the precursor fatty acid. A mechanism is proposed for the production of these compounds which involves the formation of a six-membered ring intermediate, cyclization and cleavage at the acyl-oxy bond.     

Permeability of some fat products to moisture

Summary Films of cocoa butter, highly hydrogenated cottonseed oil, mixtures of highly hydrogenated cottonseed oil and cottonseed oil, chocolate liquor, and sweet milk chocolate were prepared; and their permeability to water vapor was determined by the cup method. The permeability constant was calculated in terms of grams of water diffusing through a centimeter cube in one second under a vapor pressure gradient of one millimeter of mercury across the cube. Under the test conditions employed, the permeability constant for cocoa butter at room temperature was found to vary from 5.8×10⁻¹² to 81.6×10⁻¹². The permeability constants for the highly hydrogenated cottonseed oil and the cocoa butter, under comparable conditions at room temperature, was found to be approximately 1.3×10⁻¹² and 33×10⁻¹², respectively. From data obtained with cocoa butter it was concluded that the permeability constant increased with moderate increases in film thickness. Polymorphism was found to have a large effect on permeability, an approximately 15-fold difference was found between quickly chilled and tempered films of cocoa butter at 3°C. (37.4°F.). The percentage of liquid component in the fat was found to have a large effect on permeability. The increasing of the percentage of liquid cottonseed oil in highly hydrogenated cottonseed oil from 0 to 40% increased the permeability constant from 1.3×10⁻¹² to about 420×10⁻¹². The permeability of chocolate liquor and sweet milk chocolate at room temperature was increased greatly when the relative humidity on the wet side of the films was increased to 100%. The nonfat components absorbed enough moisture to impair the structure of the film. Presented at the 32nd Fall Meeting of the American Oil Chemists' Society, Chicago, Ill., October 20–22, 1958. Fellow, National Confectioners' Association. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Identification of decomposition products from autoxidation of methyl 4,7,10,13,16,19-docosahexaenoate

This is a continuation of a previous publication in which a number of aldehydes, aldehyde esters, hydrocarbons, and methyl esters was identified among the oxidation products of methyl docosahexaenoate. In the present paper, the identification of certain keto-esters, unsaturated ketones, cyclic esters, and furan derivatives also is reported. Mechanisms for the formation of these compounds are proposed.     

Safety of oleochemical products derived from beef tallow or bone fat regarding prions

Bovine bone fat and beef tallow are widely used as raw material for oleochemical processes. Due to high temperature and pressure these processes are supposed to have an excellent inactivation potential for prions, i.e. the agent of BSE and other transmissible spongiform encephalopathies. To experimentally prove the destruction of the pathogenic prion protein aggregates under technically relevant conditions, oleochemical processes were emulated in the laboratory in reduced scale. Fat samples were spiked with highly infectious ex vivo prion rods and aliquots were taken before and after the processes. From these aliquots, undegraded prion protein was precipitated and determined by a sensitive Western blot assay. Degradation factors of 2 ?10³ ‐ 10⁴ for catalytic fat hydrogenation and 10⁷ for fat hydrolysis represent acceptable safety limits. With these experimental prion protein degradation factors the risk of human exposure to oleochemical products of bovine origin can be assessed. Assuming worst‐case scenarios, the annual risk for human consumption of hydrogenated beef tallow is less than 6.8 x 10^‐7 and for skin application of fatty acid derivatives is less than 7.0 x 10^‐10. Both values are smaller than the background risk of contracting sporadic Creutzfeldt‐Jakob disease (1 x 10^‐6 per annum).     

Identification of a deoxyguanosine-malondialdehyde adduct in rat and human urine

In an ongoing study, rat and human urine have been examined for the presence of malondialdehyde (MDA) derivatives as indicators of the nature of lipid peroxidative damage caused by this compoundin vivo. MDA in urine was found to be present mainly in the form of two lysine adducts, one acetylated and the other unacetylated, reflectingin vivo reactions with tissue proteins. Two minor metabolites were identified as adducts with the phospholipid bases serine and ethanolamine and a third one as an adduct with the nucleic acid base guanine. The identification of an MDA adduct with deoxyguanosine (dG-MDA) among the products of hydrolysis of rat liver DNA suggested the possible occurrence of this compound in urine. In the present study dG-MDA was identified in rat and in human urine, and a high-performance liquid chromatographic method utilizing fluorescence detection was developed for its estimation. The method is sensitive to 1 pmol of dG-MDA and requires a minimum of 1 mL of rat urine or 5 mL of human urine. Its rate of excretion by five-week-old rats (28.54±2.28 nmol/kg/24 h) (mean±SEM) was higher than that for nine-week-old rats (6.29±1.02) and much higher than that for adult humans (0.40±0.05). The results indicate that, as reported for 8-hydroxy-deoxyguanosine, dG-MDA excretion is related to metabolic rate. Excretion of dG-MDA by the rat, like the excretion of total MDA, declines during growth on a body weight basis at a rate similar to the decrease in resting energy metabolism. In contrast to other MDA derivatives excreted in rat urine, vitamin E deficiency had no effect on the excretion of dG-MDA. Together with evidence that the dG-MDA content of rat liver DNA likewise is unaffected by vitamin E depletion or by administration of catalysts ofin vivo lipid peroxidation, these findings indicate that DNA is protected from lipid peroxidative damage, possibly through conservation of the vitamin E associated with the lipids of the nuclear membrane.     

Ethylene adduct of conjugated octadecadienoic acids: I. Peracid oxidation products

8-(4-n-Hexylcyclohex-2-enyl)octanoic acid obtained by the addition of ethylene totrans,trans-9,11-octadecadienoic acid was treated with 28% hydrogen peroxide in acetic or formic acid to give the hydroxyacetoxy or-formoxy derivative. Saponification of the hydroxyacetoxy derivative yielded two crystalline glycols. The hydroxyformoxy fatty acid was converted in one step either to the glycol ester, methyl 8-(4-n-hexyl-2,3-dihydroxycyclohexyl)octanoate, by reaction with anhydrous hydrochloric acid in methanol or to the acetone derivative of the glycol ester by treatment with dimethoxypropane and anhydrous hydrochloric acid in methanol. Epoxidation of the C₂₀ cyclohexene fatty methyl ester gave the oxirane derivative. A ring opening reaction of the diol acid with periodic acid yielded 9,12-diformylstearic acid. Presented in part at the AOCS-AACC Meeting, Washington, D.C., April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Evidence for the mechanisms of formation of radiolysis products using a deutero labeled triglyceride

Several previous studies of the radiolysis of fats and related compounds such as pure triglycerides, fatty acid methyl esters, and free fatty acids, have led to the hypothesis that radiolytic products result from selective cleavages at specific locations. This hypothesis is confirmed by the results of mass spectrometric analysis of the compounds formed upon gamma irradiation of tributyrin labeled with deuterium in the glycerol moiety. Compounds derived from alkyl, acyl, and acyloxy cleavages are characterized by the absence of deuterium whereas those involving the glyceryl moiety are found to carry the deuterium labels.     

Diffuse reflection spectrophotometry (DRS) for recognition of products of radiolysis in polymers

The mechanism of radiolysis of polymers can be recognized by product analysis and identification of reaction intermediates, followed by their determination. Among product analysis methods, the most appropriate is spectrophotometry. Due to the poor transparency of polymers occurring mostly as powders from the polymerization line, and the opacity or poor transparency of most processed polymers, the best mode of measurement is diffuse reflected light spectrophotometry (DRS) in UV-VIS. Application of the DRS method to simple systems of low molecular weight and the comparison with the transparent system of the same chemical composition has shown a full veracity of the approach and the application to polymer systems is justified. The important feature of the DRS method is the measurement of absorption spectra against unirradiated polymer sample. Therefore only products of radiolysis are shown, because optical disturbance at the surface texture of the sample is compensated and does not interfere with the recorded spectrum. Optical spectra of irradiated polymers are compared with EPR spectra, leading to a more precise identification of products. Several polymeric systems investigated in our laboratory are listed and one of the systems is presented in the paper in detail: radiation chemistry of virgin polypropylene investigated by the DRS, EPR and gravimetry (chain reaction of oxidation, initiated by us pulse of radiation, but proceeding for several months, in the polymer exposed to air). The diffuse reflected light spectrophotometry is very often a key method among other methods of investigation and has proved its usefulness in the investigation of radiation chemistry of many classes of polymers.     

Kinetics of fat migration within chocolate products. Part III: fat bloom

Nougat filled milk chocolates were stored at different temperatures to registrate the changes of their qualities. As a consequence of fat migration, triglyceride composition, melting properties, and solid fat contents of coating and filling were changed. After long-term storage fat bloom was developed on the chocolate surfaces. In parts I and II of the publication the influences of storage temperature on kinetics of lipid migration have been reported. Now, part III demonstrates the influence of storage temperature on bloom formation. Fat bloom on filled chocolates is started by fat migration and influenced by the crystallization tendency within the chocolate coating. The results are useful to improve shelf-life of filled chocolates and chocolate-coated bakery.     

Hydrogen bromide titration for soaps in fat products

Since none of the existing methods for determining soaps in fat products have been found to be entirely satisfactory, a method has been devised for the determination of alkali metal soaps by direct titration with Durbetaki reagent (hydrogen bromide dissolved in glacial acetic acid). When the titration was conducted at room temperature in acetic acid-benzene solution with crystal violet as indicator, soaps of potassium, sodium and lithium could be determined accurately in anhydrous oils, monoglycerides, and sucrose esters. The presence of alcohols, glycerol and sucrose did not interfere in the direct titration. However, oxidized oils, epoxides, and cyclopropenoid acids, which are known to consume hydrogen bromide, did interfere. Products containing the interfering substances could be analyzed by a modified procedure in which the alkali metal cations were extracted from a mixture of amyl acetate andn-butanol (1:3) into an aqueous solution of acetic acid, and titrated as the acetates.     

New fat products: Glyceride esters of adipic acid

Summary Six new glyceride esters of adipic acid were prepared, and their properties were determined. By the Presented at the 49th Annual Meeting of the American Oil Chemists' Society, Memphis, Tenn., April 21–23, 1958. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Biomarkers for intake of dairy fat and dairy products

The aim of this study was to correlate the fatty acids characteristic of dairy fat (14:0, 14:1, 15:0, 17:0 and 17:1) in adipose tissue, serum lipid fractions and the estimated intake of dairy fat, and to investigate whether they can be used as biomarkers for dairy fat/product intake. The highest correlations were observed between 14:0 in adipose tissue and the estimated intakes of 14:0 (r = 0.60) and dairy fat (r = 0.50), and between 15:0 in adipose tissue and the estimated intakes of 15:0 (r = 0.55) and dairy fat (r = 0.55). Among the fatty acids in serum lipid fractions, 15:0 in cholesteryl esters (CE) and triacylglycerols showed the highest correlation to both 15:0 in adipose tissue, intakes of 15:0, dairy fat and dairy products. The results from our study suggest that the contents of fatty acids characteristic of dairy fat (14:0, 14:1, 15:0, 17:0, 17:1) in adipose tissue might be used as markers not only for the intake of dairy fat, but also of dairy products (times/day). When adipose tissue specimens are not available, 15:0 in serum CE appears to be the best marker for dairy fat intake. It was also observed that fatty acids from dairy fat are incorporated differently into serum lipid fractions and adipose tissue.