Odor significance of undesirable degradation compounds in heated triolein and trilinolein

To better understand production of undesirable or negative odors such as fruity, plastic, and waxy that are characteristic of higher oleic acid-containing oils, model heated oil systems of triolein and trilinolein were studied. Identification of the odor significance of volatile compounds produced by fractionated and nonfractionated triolein and trilinolein was done by purge and trap-gas chromatography-ion trap mass spectrometry-olfactometry. The predominant odors of the triolein heated 1, 3, and 6 h at 190°C were fruity and plastic, with other negative odors of acrid and grassy. Some of the volatile compounds that produced negative odors in heated triolein, in order of increasing concentration, were hexanal (grassy), octanal (fruity), (E)-2-decenal (plastic), nonanal (fruity), and (E)-2-undecenal (plastic). Some of the negative odor compounds in trilinolein heated for 1, 3 and 6 h, in order of increasing concentration, included (E)-2-nonenal (plastic), pentanal (grassy), and hexanal (grassy). However, the amount of volatile compounds produced and the intensity levels of the odors were lower in trilinolein than in triolein. Formation of many of the volatiles was explained after identification of the volatile precursors, including epoxy, keto, and dimer oxidation products that were produced during heating. Presented at the American Oil Chemists’ Society 90th Annual Meeting & Expo, Orlando, FL, May 9–12, 1999.     

Volatile components from triolein heated in air

In a continuing study to identify volatile odor constituents and their precursors from heated soybean oil, the following model triglycerides were heated to 192 C in air for 10 min: (a) pure triolein, (b) a mixture of triolein (25%)-tristearin, and (c) a randomly esterified triglyceride composed of oleic (25%) and stearic acids. Each model system produced the same major compounds which were identified as heptane, octane, heptanal, octanal, nonanal, 2-decenal, and 2-undecenal. These seven compounds apparently are unique to the oxidation of the oleate fattyy acid in each triglyceride sample. Minor volatile compounds from oxidized triolein included saturated and unsaturated aldehydes andn-hydrocarbons and saturated primary alcohols, methyl ketones, gamma lactones, and monobasic acids. Incorporation of stearic acid in the triglycerides noticeably increased the amounts of saturated minor compounds and the range of their carbon chain lengths. Decomposition products characteristic of the oxidation of stearate were apparent among decomposition products associated with the oxidation of oleate.     

Influence of the position of unsaturated fatty acid esterified glycerol on the oxidation rate of triglyceride

The influence of the position of unsaturated fatty acid esterified glycerol on the oxidation rate of triglyceride was investigated at 50 C. Randomized triglycerides used were prepared by random interesterification between saturated and unsaturated monoacid triglycerides using sodium methoxide as catalyst. The monoacid triglycerides used were tripalmitin, tristearin, triolein and trilinolein. The molecular species of the randomized triglycerides were analyzed by high performance liquid chromatography (HPLC) in combination with gas liquid chromatography (GLC) and enzymatic hydrolysis. From the results of oxygen absorption measurement by GLC, the randomized triglycerides were more stable towards oxidation than the triglyceride mixtures which were prepared by mixing the equivalent quantities of the same monoacid triglycerides as used in the random interesterification. This may be due to the decrease in the contents of most unstable unsaturated monoacid triglycerides by random interesterification with saturated monoacid triglycerides. Furthermore, from the results obtained with the detailed analysis of the randomized triglycerides at different stages of oxidation, it became clear that the triglycerides having unsaturated fatty acids linked at the 2-position of glycerol are more stable towards oxidation than those linked at the 1(or 3)-position. The carbon chain length of saturated fatty acids has essentially no influence on the oxidation rates of unsaturated fatty acids esterified in the same glycerol.     

Hydrolysis of triglycerides in the isolated perfused rat lung

The purpose of this study was to investigate the hydrolysis of saturated and unsaturated triglycerides by lung lipoprotein lipase and to measure the incorporation of triglyceride fatty acids into lung tissue lipids. Lipolytic activity was studied in the isolated ventilated rat lung, perfused for 100 min in a recycling system with Krebs Ringer bicarbonate containing bovine serum albumin, 5.6 mM glucose, and 1.5 or 10 mM triglyceride. Saturated triglycerides were hydrolyzed at significantly (p<0.05) lower rates than unsaturated triglycerides; tricaprylin, trimyristin and tripalmitin were hydrolyzed at 8.1+1.8, 5.4+1.5 and 9.5+1.8 μmol free fatty acids/g dry wt/100 min, respectively, whereas triolein and trilinolein were hydrolyzed at 20.2+1.8 and 20.6+0.3 μmol free fatty acids/g dry wt/100 min, respectively. The polyunsaturated triglycerides, trilinolein and triarachidonin were hydrolyzed at even higher rates (44.3+3.0 and 50.9+5.4 μmol free fatty acids/g dry wt/100 min, respectively). Intralipid infused at a concentration of 10 mM triglyceride was hydrolyzed at a significantly higher rate than at 1.5 mM triglyceride (58+6.3 μmol free fatty acids/g dry wt/100 min vs 16.6+1.7 μmol free fatty acids/g dry wt/100 min, respectively). Labeled unsaturated triglycerides were broken down at significantly higher rates than labeled saturated triglycerides. Incorporation of triglyceride-fatty acid into lung lipid was greater into neutral lipids than into phospholipids. The data suggest that (a) the factors that appear to affect lung lipoprotein lipase activity are composition and concentration of circulating triglyceride, (b) uptake of fatty acids into the tissue was proportional to the rate of hydrolysis of the emulsion, and (c) triglyceride-fatty acids could therefore be used by the lung for metabolic needs. The data presented in part at the Annual Meetings of the American Physiological Society, Atlanta, GA, April 1981, and the American Thoracic Society, Detroit, MI, May 1981, and published in abstract form-Fed. Proc. 40, 621 (1981), andAm. Rev. Respir. Dis. 123, 219 (1981).     

Female-Produced Sex Pheromone of the Predatory Bug Geocoris punctipes

A compound identified from air-entrained volatiles produced by adult female Geocoris punctipes attracted male bugs and stimulated males to investigate nearby moving objects of the appropriate size in their search for females. The compound was identified as (E)-2-octenyl acetate, a relatively common component of the volatile semiochemicals produced by a number of heteropteran species. This compound comprised a significant proportion of the female volatiles, whereas it was detected in only trace amounts in volatiles collected from live males. Other components in the extracts from adults of both sexes included (E)-2-hexenyl acetate, (E)-2-octenal, and several saturated hydrocarbons, but these components were not part of the attractant. These compounds plus (E)-2-hexenal, (E)-4-oxo-2-hexenal, and (E)-2-decenal were found in extracts of homogenized adults, whereas the cast skins from late instar nymphs contained (E)-2-octenal, (E)-4-oxo-2-octenal, (E)-2-octenoic acid, and several saturated hydrocarbons.     

Volatile components from trilinolenin heated in air1

Headspace volatiles derived from trilinolenin heated to 192 C in air were collected, separated and identified using a microroom/GC-MS/ computer system. Data from four analyses indicated more than 80 volatiles were present. Of these volatiles, 38 have been identified, and their combined GC peak areas represent 90% of the total integrated Chromatographic area. Dominant volatiles identified included: ethanal (2%), 2-pentene (3%), ethanol (0.5%), 2-propenal (20%), propanal (7%), ethyl furan (13%), 2-butenal (4%), 2-pentenal (4%), 2,4-heptadienal (21%), 4,5-epoxy-2-heptenal (3%) and 2,4,7-decatrienal (2%). Most of the dominant and some of the minor volatiles are the predicted decomposition products of the four linolenin monohydroperoxides. However, the ratios of the predicted volatiles do not correspond to the monohydroperoxide ratios observed from autoxidized linolenate. Other primary and minor volatiles are present that are not predicted from the classical hydroperoxide decomposition hypothesis, which suggests that trilinolenin and some of the volatile compounds undergo further oxidation. Presented at the 73rd annual AOCS meeting, Toronto, 1982.     

The binding of model shortenings during mixing of mechanically developed bread doughs from fresh and stored flours

Model fats were prepared from defined binary mixtures of saturated and unsaturated triglycerides. Their effect on the volume of loaves prepared by the Chorleywood Bread Process (CBP), from fresh and storage-deteriorated flour, was similar to that given by a good bakery shortening. The use of radioactively-labeled glyceryl tripalmitate in fresh flour doughs enabled its distribution between ‘free’ and ‘bound’ lipid fractions of dough to be determined. Further studies which were made with the triglyceride of margaric acid, present only in trace amounts in wheat, showed that as the amount of saturated triglyceride added was increased, the amount entering the ‘bound’ fraction remained small and constant, whereas levels in the ‘free'lipid rose at similar rates in doughs made from fresh and stored flour. Evidence is given that ‘free’ rather than ‘bound’ saturated triglyceride is responsible for increasing the volume of CBP bread made from fresh flour. Unsaturated saturated triglyceride was ‘bound’ by stored flour doughs to a greater extent than by fresh flour doughs. A liquid saturated triglyceride could be used to replace the unsaturated triglyceride in a model fat. The poor effect of shortening on the baking properties of storage-deteriorated flour could be overcome by adding more fat, either as such, or by increasing the level of its liquid constituent. Results are discussed in relation to the apparent requirement for hard fat in making bread by the CBP from fresh flour.     

Volatile compounds from the triacylglycerol ofcis,cis 9,15-linoleic acid

cis,cis 9,15-Linoleic acid, one of the isomers produced by partial hydrogenation of linolenic acid, may be a precursor of the hydrogenation odor observed during heating of partially hydrogenated soybean oil in air. Odors of hydrogenation, for example the melon odor, are associated with foods cooked in partially hydrogenated soybean oil that has undergone oxidative deterioration during heating. To better understand this oxidation mechanism, the volatiles from decomposition of the oxidation products of a synthesized model compound, tricis,cis 9,15-linoleoylglycerol, heated in air at 192°C were collected, separated, quantitated by gas chromatography with flame ionization detection and identified by mass spectrometry. Major volatiles observed indicated that each of the isolated double bonds at carbons 9,10 and 15,16 isomerized to form an allylic radical. The allylic radical derived from the isolated double bond at carbons 9,10 reacted with oxygen to form the 8,9,10 and 11 monohydroperoxides. The allylic radical derived from the isolated double bond at carbons 15,16 produced the 14,15,16 and 17 monohydroperoxides. The 8,9,10 and 11 monohydroperoxides are the expected precursors of the following volatiles identified by mass spectrometry: 2,8-undecadienal (5.9%), 2,7-decadienal (7.8%), 6-nonenal (8.4%) and 5-octenal (1.5% of total volatiles), respectively. These four aldehydes are analogous to major volatiles obtained from thermal decomposition of autoxidized trioleoylglycerol. The 14,15,16 and 17 monohydroperoxides are the expected precursors of 2-pentenal (9.0%), 2-butenal (8.0%), propanal (12.1%) and ethanal (2.0% of total volatiles), respectively. Among the above volatiles, 6-nonenal (cucumber-melon) is reported to have the most intense odor associated with deteriorated partially hydrogenated soybean oil.     

A Versatile and Quantitative Volatile-Delivery System for Laboratory Bioassays

A versatile moving-air system is described for delivering volatiles into a wind tunnel or other bioassay device. The system controls up to four volatile sources at one time. There is a calibrated, adjustable splitter for each source so that any percentage of a source's airstream, or none of it, can be directed to the system outlet at any moment. Thus, the system allows the sample volatiles to be bioassayed in any order and at any level or in mixtures of any desired proportions. Volatile sources of many types can be used, including single chemicals in slow-release formulations, mixtures of chemicals, or volatiles from living organisms. The volatile stream can be sampled by solid-phase microextraction (SPME) just before it enters the wind tunnel. Analysis of the SPME sample by gas chromatography allows absolute delivery rates of volatile components to be calculated. System performance was characterized with physical measurements and with bioassay experiments involving Carpophilus humeralis (F.) (Coleoptera: Nitidulidae). One bioassay experiment demonstrated how volatiles from a microbial culture (fermenting bread dough) and a synthetic counterpart (an aqueous solution of acetaldehyde, ethanol, 1-propanol, isobutanol, 3-methyl-1-butanol, 2-methyl-1-butanol, and ethyl acetate) could be compared at a range of dose levels, with just one sample of each type. These natural and synthetic volatile sources delivered very similar amounts of the above compounds and produced nearly identical dose–response curves. In another experiment, three bread dough volatiles (ethanol, acetaldehyde, and ethyl acetate) were tested in mixtures. Each component was used at four different levels (giving a total of 64 experimental treatments), but just one physical sample was needed for each chemical. The experiment provided clear information about response thresholds and interactions among these host volatiles. The volatile delivery system is versatile, easy to operate, and can be constructed from inexpensive materials.     

Chemical reactions involved in deep fat frying of foods: VI. Characterization of nonvolatile decomposition products of trilinolein

A laboratory apparatus that could be used to treat pure triglycerides under simulated deep fat frying conditions was designed and built. By the use of this apparatus, the volatile decomposition products produced during frying could be quantitatively collected at the same time. Pure trilinolein was treated in this apparatus at 185 C for 74 hr. The volatile decomposition products were collected quantitatively. Their fractionation and identification will be reported in a subsequent paper. The nonvolatile decomposition products were isolated from the treated trilinolein as the non-urea-adduct-forming methyl esters. They constituted 26.3% of the treated trilinolein and were separated into seven fractions by repeated liquid column chromatography. Chemical and physical analyses of these fractions indicated that the chemical reactions taking place under simulated deep fat frying conditions were not entirely the same as those during simple heating under air. One of the seven fractions was further purified by thin layer chromatography and then identified as a cyclic carbon to carbon linked dimer which amounted to 4.9% of the treated trilinolein. Another fraction was further purified by thin layer chromatography, followed by gas chromatography, and then identified as noncyclic hydroxy dimers formed through carbon to carbon linkages. The noncyclic dimers constituted 2.8% of the treated trilinolein. The other four fractions were depolymerized by hydroiodic acid. The depolymerization products were fractionated by thin layer chromatography and then analyzed. It was estimated that the treated trilinolein contained 8.4% of trimers formed through carbon to carbon linkages, and 4.9% of dimers and trimers joined through carbon to carbon or carbon to oxygen linkages in the same molecule and also trimers, in which all the three monomeric units were joined through carbon to oxygen linkages. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers, The State University.     

Analysis of lipoxygenase kinetics by high-performance liquid chromatography with a polymer column

Soybean lipoxygenase (LOX; EC 1.12.11.12) catalyzes the oxygenation of polyunsaturated fatty acids, acylglycerols and phosphoglycerols, producing a regio-and enantiospecific hydroperoxide product. The goal of this work was to measure the relative rate of LOX-catalyzed oxidation of mixtures of lipids containing linoleate, using high-performance liquid chromatography (HPLC) and a light-scattering detector (LSD). Previous literature sugested that reversed-phase HPLC with silicabased columns could be used for the separation of individual fatty acids, acylglycerols, phosphoglycerides and their oxidation products. However, these columns produced ineffective separations of phosphoglycerides unless choline chloride and a strong base, such as KOH, are present in the mobile phase. Such modifiers precluded the use of the LSD. It was found that a reversed-phase column based upon an organic polymer support, rather than on silica, was able to separate these mixtures with a ternary solvent gradient of methanol/water/acetonitrile without the need for the addition of modifiers. The oxidation time course of a mixture of linoleic acid, trilinolein and 1-linoleoyl-2-stearoyl-sn-glycero-3-phosphocholine was followed using the developed HPLC method. The results showed that trilinolein and phosphatidylcholine reacted at one-tenth the rate of linoleic acid. The diacylglycerol, 1,3-dilinolein, was oxidized at a rate that was approximately 40% that of linoleic acid, with the formation of mono-and dihydroperoxides as well as other unidentified products.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry: VIII. Volatile thermal decomposition products of hydroperoxy cyclic peroxides

Secondary oxidation products are important sources of volatiles because of their susceptibility to further decomposition. Volatiles from the thermal decomposition of hydroperoxy cyclic peroxides have been identified by capillary gas chromatography followed by mass spectrometry (GC-MS). By using a saturated hydroperoxy cyclic peroxide as a synthetic model, the thermal decomposition pathways have been elucidated. Main cleavage occurs between the peroxide ring and the carbon-bearing hydroperoxide group. Volatiles produced were generally similar to those from corresponding monohydroperoxides. New volatiles identified included methyl furan octanoate, methyl ketones, and conjugated diunsaturated aldehyde esters. The general fragmentation observed between the peroxide ring and the hydroperoxide-bearing carbons is sufficiently predictable that it can be used as a tool for the structural characterization of hydroperoxy cyclic peroxides. Hydroperoxy cyclic peroxides from autoxidized and photosensitized oxidized methyl linolenate are suggested as important precursors of volatiles that may affect flavor quality of lipid-containing foods.     

Attraction of a Flying Nitidulid (Carpophilus humeralis) to Volatiles Produced by Yeasts Grown on Sweet Corn and a Corn-Based Medium

Attraction to microbial volatiles was examined for the sap beetle, Carpophilus humeralis, which is a pest of maize. Using 54 pure yeast and bacterial cultures, we evaluated differences in volatile emissions among species of microorganisms and whether these differences were associated with insect attraction. On a sterile corn-based medium, both yeasts and bacteria generally multiplied well and produced detectable volatile metabolites. The yeasts ranged from inactive to highly attractive, but no bacterial cultures attracted beetles above control levels. A variety of alcohols, esters, ketones, acids, and phenolic compounds were identified from the headspace above yeast cultures. Growth, volatile production, and, ultimately, attractiveness to beetles depend strongly on the ability of the yeasts to assimilate and/or ferment the carbohydrates present. Abundant volatile production on sweet corn was observed only with yeasts that are able to ferment sucrose and/or maltrose. Saccharomyces cerevisiae (ferments glucose, sucrose, and maltose) and Candida shehatae (ferments glucose and maltose) produced considerably more attractive volatiles than Candida guilliermondii, which only ferments glucose. Yeast volatiles important for beetle attraction included typical fermentation-associated substances (ethanol, acetaldehyde, 2-methyl-1-propanol, 1-propanol, ethyl acetate, 3-methyl-1-butanol and 2-methyl-1-butanol), and also 3-hydroxy-2-butanone, whose presence was not correlated with the occurrence of fermentation. Using aqueous mixtures of synthetic components that produced headspace compositions simulating those of attractive yeasts, it was shown that the typical fermentation volatiles are attractive but not essential for attractiveness. 3-Hydroxyl-2-butanone is sufficient but not necessary, although its attractiveness is enhanced by the presence of fermentation volatiles such as ethanol and 2-methyl-1-proponol. In nature, the beetles could take advantage of a variety of different microbial metabolic processes to locate hosts. The laboratory bioaasays in this study involved flight and therefore were particularly relevant to host-finding behavior in the field.     

Effect of heat on triglycerides of corn oil

Results of a study on the effect of heating corn oil in air to a 200C temp are reported. Heated oil was separated on a silicic acid column into 8 fractions. The first four fractions, constituting about 62% original oil, were found to be unchanged triglycerides. The remaining 4 fractions constituted polymeric and degraded products of high molecular wt. Percentage losses from the respective positions in the oleo- and linoleoglyceride fractions suggest that fatty acids in primary positions are slightly more susceptible to heat than those in the 2-position. Assuming a 1,3-random 2-random distribution, triglyceride fraction in the heated oil contained 6.7% trilinolein as compared to 17.7% in fresh oil. Evidence is presented which shows presence of branching in short chain unsaturated acids and of hydroxy acids in the saponified polymeric fractions. Presented in part at the AOCS Meeting, New Orleans, 1962     

Viscosity prediction for fatty systems

Viscosity data have been measured as a function of temperature for two pure polyunsaturated fatty compounds (linoleic acid and trilinolein), for two multicomponent fatty systems, for a commercial-grade oleic acid (approximately 80% pure), and for canola oil. The measurements were performed in Cannon Fenske glass capillary kinematic viscometers. The contents of a large data bank, containing viscosity data for saturated, monousaturated, and polyunsaturated pure fatty substances, were correlated by an equation based on the number of carbon atoms and double bonds. By using this equation for pure compounds and the UNIMOD group contribution method for mixtures, the viscosity data for model fatty systems, commercial oleic acid, and canola oil were predicted. The good results obtained in the present work indicate that this approach can be a valuable tool for designing or evaluating chemical process equipment for the oil industry.     

Degradation of unsaturated triglycerides injected into a pressurized reactor

To evaluate the precombustion chemistry of vegetable oils under conditions that exist in a diesel engine, several pure unsaturated triglycerides (triolein, trilinolein, trilinolenin) were injected into a pressurized reactor where they were subjected to thermal and oxidative degradation under varying conditions of atmosphere (air or nitrogen), temperature and pressure. Vapor samples were collected and then analyzed by gas chromatography/mass spectrometry techniques. In general, the samples consisted of similar mixtures regardless of the reaction conditions or triglyceride used as starting material. The most prominent compounds identified in these samples were fatty acids of different chain lengths and a variety of aliphatic hydrocarbons. Smaller numbers of other classes of compounds, such as aldehydes, were also detected. Presented at the 81st AOCS Annual Meeting, Baltimore, MD, April 1990.     

Analysis of neutral volatiles of mayonnaise by direct gas chromatography and mass spectrometry

Simple procedures have been developed for analyzing neutral volatiles from mayonnaise by direct gas chromatography and combined direct gas chromatography-mass spectrometry. For gas Chromatographic analysis, a glass liner containing glass wool coated with alkali in the lower quarter and plain glass wool in the remaining space is placed in the heated inlet of a gas Chromatograph, and mayonnaise and water are injected onto the plain packing. Neutral volatiles eluted from the mayonnaise by the combined action of water, carrier gas, and heat collect on the cool column of the gas Chromatograph, but acetic acid is trapped by the alkaline glass wool and thus does not interfere with the analysis. After removal of the liner with the spent sample, the temperature of the column oven is programmed to resolve the volatiles. For mass spectrometric analysis, neutral volatiles are passed directly from a Chromatograph inlet to a second inlet liner containing a porous polymer that traps most organic compounds but has low affinity for water. These neutral organic volatiles are desorbed from the porous polymer in the inlet of a Chromatograph interfaced with a mass spectrometer for analysis. This procedure allows components resolved by the gas Chromatograph to be identified by mass spectrometry without interference from either water or acetic acid. A total of 21 neutral volatile compounds was identified in mayonnaise. Presented at the AOCS Meeting, Chicago, September 1976.     

Predatory Mite Attraction to Herbivore-induced Plant Odors is not a Consequence of Attraction to Individual Herbivore-induced Plant Volatiles

Predatory mites locate herbivorous mites, their prey, by the aid of herbivore-induced plant volatiles (HIPV). These HIPV differ with plant and/or herbivore species, and it is not well understood how predators cope with this variation. We hypothesized that predators are attracted to specific compounds in HIPV, and that they can identify these compounds in odor mixtures not previously experienced. To test this, we assessed the olfactory response of Phytoseiulus persimilis, a predatory mite that preys on the highly polyphagous herbivore Tetranychus urticae. The responses of the predatory mite to a dilution series of each of 30 structurally different compounds were tested. They mites responded to most of these compounds, but usually in an aversive way. Individual HIPV were no more attractive (or less repellent) than out-group compounds, i.e., volatiles not induced in plants fed upon by spider-mites. Only three samples were significantly attractive to the mites: octan-1-ol, not involved in indirect defense, and cis-3-hexen-1-ol and methyl salicylate, which are both induced by herbivory, but not specific for the herbivore that infests the plant. Attraction to individual compounds was low compared to the full HIPV blend from Lima bean. These results indicate that individual HIPV have no a priori meaning to the mites. Hence, there is no reason why they could profit from an ability to identify individual compounds in odor mixtures. Subsequent experiments confirmed that naive predatory mites do not prefer tomato HIPV, which included the attractive compound methyl salicylate, over the odor of an uninfested bean. However, upon associating each of these odors with food over a period of 15 min, both are preferred. The memory to this association wanes within 24 hr. We conclude that P. persimilis possesses a limited ability to identify individual spider mite-induced plant volatiles in odor mixtures. We suggest that predatory mites instead learn to respond to prey-associated mixtures of volatiles and, thus, to odor blends as a whole.     

Properties of 2-oleodipalmitin, 2-elaidodipalmitin and some of their mixtures

The glycerides 2-oleodipalmitin (POP) and 2-elaidodipalmitin (PEP) were synthesized and their melting behavior and dilatometric properties were determined. Three mixtures of POP with PEP were examined. Five polymorphs of POP and four of PEP were identified by x-ray diffraction patterns. Rates of transformation of the lower melting polymorphs were, in general, quite rapid at temperatures just below their melting points. But transformation of unseeded POP to its highest melting form was slow and required several days at a temperature just below melting. Coefficients of expansion were determined for the highest melting polymorph and the liquid form of each triglyceride. Melting dilation was determined for the highest melting polymorph. Mixtures of POP with PEP exhibited different melting ranges depending on the tempering procedures and the composition, but even quickly-solidified mixtures tempered without melting to the highest melting range as they were slowly heated over a period of 2 hr. Slow cooling from the melt essentially segregated the components. Presented at the AOCS Meeting, Minneapolis, October 1969. So. Utiliz. Res. Dev. Div., ARS, USDA.     

Chemical reactions involved in the deep-fat frying of foods. VII. Identification of volatile decomposition products of trilinolein1

The acidic and nonacidic volatile decomposition products (VDP) produced by pure trilinolein maintained at 185 C with periodic injection of steam were collected, fractionated, and identified. One hundred thirty-three volatile compounds were positively or tentatively identified. The compounds identified included a number of new and interesting compounds, some with valuable organoleptic properties, such as the unsaturated lactones. 1 Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey