Nonvolatile Decomposition Products Research Articles

Effect of various postmortem processing times and blanching methods on quality of rainbow trout (Oncorhynchus mykiss) waste oil.

Oil extracted from fish waste is considered as a value‐added product. The effect of postmortem processing times (0, 3, 6, and 9 hr) and blanching methods (sodium chloride, pH shift, and high temperature) on the extracted oil from rainbow trout viscera was studied. Blanching was applied six hours prior to oil extraction to counteract the effects of delayed processing time and increasing the oil stability. Autolysis by digestive enzymes is main culprit of higher contents of free fatty acids, lipid oxidation, saponified compound, and saturation degrees in case of postponed oil extraction. Results showed that PV was increased after pH shift and high temperature blanching, while there were no significant differences by using salt blanching. The lowest amount of TBA, AV, Totox, and saponification index was observed in salt blanched treatment. The colorimetric values including L*, b*, and whiteness index were decreased after pH shift, whereas redness was increased. Unfavorable coloration could be attributed to the lipid oxidation process that giving rise nonvolatile decomposition products with carbonyl groups. Our results indicated that salt blanching could reduce the effects of delayed processing time and lead to higher quality value‐added product from rainbow trout viscera.

Pyrolysis study of a phosphorus-containing aliphatic–aromatic polyester and its nanocomposites with layered silicates

This paper deals with the thermal decomposition behaviour of a new fire retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-containing aliphatic–aromatic polyester and its nanocomposites with natural layered silicate (montmorillonite) under inert atmosphere studied by TGA–FTIR, Pyrolysis–GC/MS of volatile products and ATR–FTIR of non-volatile decomposition products. The phosphorus-containing polyester undergoes decomposition in two steps between 340 and 516 °C. The first step is associated with the release of carbon dioxide, acetaldehyde, ethene, acid-containing products (mainly benzoic acid) resulting in the formation of polyarylates followed by their decomposition in the second step with the evolution of carbon dioxide. DOPO-containing products, esters (mainly diethenyl terephthalate), carbon monoxide, acids and water are released through both stages. At the end of decomposition polyaromatic structures, diarylketones and organophosphorus esters built into the chemical structure of the char develop in the solid residue. The modification of the polyester with a layered silicate does not change the composition of the pyrolysis products, only their yield, and tended to diminish the charring of the polymer. A thermal decomposition scheme of the P-polyester is proposed and the mass spectra of some DOPO-containing products are discussed.

Thermal degradation of sulforaphane in aqueous solution.

Sulforaphane, a cancer chemopreventive agent identified from broccoli, was degraded in an aqueous solution at 50 and 100 degrees C. The reaction mixtures were extracted with methylene chloride and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Dimethyl disulfide, S-methyl methylthiosulfinate, S-methyl methylthiosulfonate, methyl (methylthio)methyl disulfide, 1,2,4-trithiolane, 4-isothiocyanato-1-(methylthio)-1-butene, and 3-butenyl isothiocyanate were identified as volatile decomposition products. After methylene chloride extraction, the aqueous layer was dried and silica gel column chromatography was used to separate and purify the nonvolatile decomposition products. The major thermal degradation compound was determined by (1)H NMR, (13)C NMR, and FAB-MS as N, N'-di(4-methylsulfinyl)butyl thiourea. A possible mechanism for the formation of these products is proposed.

Degradation and Stabilization of E8,E10-Dodecadienol, the Major Component of the Sex Pheromone of the Codling Moth (Lepidoptera: Tortricidae)

Exposure of E8,E10-dodecadienol, the major component of codling moth pheromone, to sunlight and air resulted in extensive degradation, primarily to nonvolatile oligomers and polymers. Contents and surface residues of new and field-aged pheromone dispensers used in codling moth mating disruption were also analyzed. The tacky film on the surface of field-aged dispensers was primarily nonvolatile decomposition products, and the pheromone remaining in the reservoir of field-aged dispensers degraded significantly. Carbon black, which physically blocks light, and 2 phenylenediamine antioxidants were effective stabilizers that hindered pheromone degradation.

Review of stability measurements for frying oils and fried food flavor

AbstractMeasurements of degradation in frying oils based on oil physical properties and volatile and nonvolatile decomposition products were reviewed. Rapid methods by means of test kits were also considered. Factors that affect the analysis of total polar components (TPC) in frying oils were examined. Relationships between TPC, free fatty acid (FFA) content, Food Oil Sensor readings (FOS), color change (ΔE), oil fry life and fried‐food flavor were evaluated. Flavor scores for codfish, fried in fresh and discarded commercial frying oil blends, were dependent upon individuals in the consumer panel (n=77). Part (n=29) of the panel preferred the flavor of fresh fat; others (n=24) didn't; the rest (n=24) had no preference. FFA, FOS and TPC were analyzed in two soybean oils and in palm olein during a four‐day period in which french fries were fried. Flavor score and volatiles of potatoes fried on days 1 and 4 in each oil were also determined. TPC, FFA and FOS significantly increased (P<0.05) in all oils during the frying period. TPC and FFA were highest in the used palm olein, and flavor of potatoes fried in palm olein on day 1 was less desirable than those fried in the soybean oils. Potatoes fried in day‐1 oils had significantly higher concentrations (P<0.10) of several pyrazines and aldehydes than those fried in day‐4 oils.

The thermal decomposition of arbutin

The thermal decomposition of arbutin starts at the melting at 200°C and terminates at 288°C. Non-volatile decomposition products are mainly hydroquinone(Hq), 1,6-anhydro-β-D-glucopyranose(16AGP), 1,6-anhydro-β-D-glucofuranose(16AGF) and α- and β-D-glucose. In order to elucidate the kinetics, the methods of Friedman and Ozawa are applied for the thermal decomposition of arbutin. In Friedman's method, the activation energy is 26.27 kcal mol −1, the order of reaction is 0.985 and A = 6.94 × 10 8 sec −1. In Ozawa's method, the activation energy has an initial value of 27.87 kcal mole −1, a minimum value of 26.50 kcal mole −1 and a final average value of 27.61 kcal mole −1, the order of reaction is 1, and A = 1.55 × 10 8 sec −1.

Chemical reactions involved in the deep-fat frying of foods.

AbstractDeep‐fat frying is one of the most commonly used procedures for the preparation and manufacture of foods in the world. During deep‐fat frying, oxidative and thermal decompositions may take place with the formation of volatile and nonvolatile decomposition products, some of which in excessive amounts are harmful to human health. A limited survey of frying fats used in commercial operations indicated that some were maintained at good quality and others were overused or abused. The volatile decomposition products produced by corn oil, hydrogenated cotton‐seed oil, trilinolein, and triolein, under simulated commercial frying conditions, were collected, fractionated, and identified. A total of 211 compounds were identified. The nonvolatile decomposition products produced by trilinolein, triolein, and tristearin under simulated commercial frying conditions were collected and characterized. After being treated under deep‐fat frying conditions at 185 C for 74 hr, trilinolein yielded 26.3% non‐urea‐adduct‐forming esters, triolein yielded 10.8%, and tristearin also yielded 4.2%.

Chemical reactions involved in deep-fat frying of foods: VIII. Characterization of nonvolatile decomposition products of triolein.

AbstractTriolein was heated under simulated deep‐fat frying conditions at 185 C for 74 hr. The thermally oxidized triolein was converted into methyl esters and then fractionated by urea exclusion. The urea adduct‐forming ester (89.2%) was found to be methyl oleate unchanged by the frying treatment. The nonurea adduct‐forming esters (10.8%) were further fractionated by silicic acid column chromatography into nine fractions with molecular weights ranging from 304 to 742. Physical and chemical analyses of the fractions indicated that some of them contained oxygen atoms which could not be accounted for by ordinary functional group analyses. The polymers isolated were formed by both carbon‐to‐carbon and carbon‐to‐oxygen linkages. The nonpolar dimers were further purified by thin layer and gas chromatography. Structure elucidation revealed that they consisted of a noncyclic dimer and a noncyclic dimer containing a carbonyl group, each of which amounted to 1.36% of the triolein originally used. The polar polymers were studied by depolymerization and the analysis of the depolymerized products. It was estimated that the triolein used for simulated deep fat frying contained 1.1% trimers formed through carbon‐to‐carbon linkages, 1.9% dimers and trimers joined through carbon‐to‐carbon linkages, and 3.1% dimers and trimers joined through carbon‐to‐oxygen or carbon‐to‐carbon linkages in the same molecule and also dimers and trimers in which all the monomeric units were joined through carbon‐to‐oxygen linkages. The precise form of the oxygen linkages are not known. However, the fact that it is not cleavaged by HC1 and HI suggests ether linkages.

A thermal study of hydrated lanthanide heptafluorobutyrates

Several hydrated lanthanide salts of heptafluorobutyric acid have been prepared and characterized. Hydration studies have shown the compounds to exist in various hydration states across the series. Powder X-ray diffraction studies support the existence of variable hydration states in that three distinct crystalline forms exist. Infrared analysis revealed two types of structures to be present. Upon dehydration of the lighter rare earth hydrates to intermediate dihydrates, all of the compounds showed similar structures. Decomposition was found to be exothermic. The volatile decomposition products were identified by infrared analysis and found to consist of CO, CO 2, CF 3CF 2COF and CF 3CF 2CF 2COF. The amounts of each gas were found to be dependent on the decomposition temperature. The non-volatile decomposition products were identified by powder X-ray diffraction and found to consist of LnF 3, LnOF and Ln 2O 3.

Low-work-function surfaces produced by cesium carbonate decomposition

Cesium carbonate (Cs2CO3) was heated to the decomposition temperature of approximately 600 °C. The nonvolatile decomposition products were condensed on a nickel substrate while the carbon dioxide was removed by pumping. The deposited material is characterized by an effective work function of between 1.05 and 1.15 eV at 450 K and by photoemission in the visible and near-infrared region of the spectrum. It is suggested that the deposited material consists of Cs2O, possibly Cs2O2, and adsorbed cesium. Silver, evaporated from a heated silver bead, produced the typical photoemissive and thermionic properties of a silver-oxygen-cesium (S-1) photocathode. The material may be of interest for thermionic energy converters and for the formation of silver-oxygen-cesium photocathodes.

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

AbstractA 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.