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PubMed2005

Analytical determination of the suitability of different processes for the treatment of odorous waste gas.

In order to determine the efficiency of different treatment systems for the reduction of odorous emissions, a gas chromatographic method followed by simultaneous mass spectrometry and olfactometry (GC-MS/O) was developed. Samples from a coffee bean roasting and a fat and oil processing plant were analyzed, respectively. The results were compared with the data obtained by olfactometric measurements. At a coffee bean roasting plant, cooling gases were analyzed prior to and after treatment in a full scale bioscrubber. The GC-MS/O analysis showed that the amounts of aldehydes and ketones decreased after treatment of cooling gases of coffee bean roasting in the bioscrubber, whereas the contents of the heterocyclic compounds, like pyridine and the pyrazines, and acetophenone and guaiacol remained almost unchanged. The amounts of dimethyl disulfide, 3-hydroxy-2-butanone, and the carboxylic acids increased after bioscrubber treatment. Furthermore, the performance of each stage of a combined experimental plant for the treatment of exhaust air of fat and oil processing was investigated. This treatment plant consisted of a bioscrubber, a biofilter, and an activated carbon adsorber. The important odor-active compounds of the exhaust air of fat and oil processing were the typical fat oxidation products (aldehydes, ketones) and with lower importance 2-pentylfuran, a few terpenes and aromates. Again, the key odor-active compounds, aldehydes and ketones, were degraded in the bioscrubber. Further degradation of aliphatic, unsaturated, methylated, and cyclic alkanes, as well as aromates, terpenes, and furans by the biofilter was observed. After the last treatment stage, the activated carbon filter, only small amounts of aliphatic, unsaturated, methylated, and cyclic alkanes and aromates remained in the waste gas. For both applications, the results of the developed GC-MS/O method correlated very well with olfactometric measurements.

Air Pollution↗
PubMed1997

Supercritical fluids: an interesting medium for chemical and biochemical processes.

Interactions between solute and solvent in supercritical fluids (SCFs) are of fundamental importance because small changes in pressure or temperature near the critical point may alter reactivity in chemical and biochemical processes, and were examined such as those for ester synthesis catalyzed by a lipase in supercritical carbon dioxide and for a FT-IR study on the structures of reverse microemulsions in supercritical ethane. We previously conducted ester synthesis from acyl donors and terpene alcohols catalyzed by Candida cylindracea (CCL) lipase in supercritical carbon dioxide. In the near-critical region, (S)-(-)-terpene esters were stereoselectively synthesized from acyl donors and a primary alcohol such as (+/-)-citronellol. In a very limited pressure range near the critical point, interactions between carbon dioxide and enzyme molecules greatly increased with consequent drastic conformational changes in the enzyme, causing active sites to emerge to catalyze stereoselective synthesis. Therefore, supercritical carbon dioxide medium in the near-critical region should trigger the activation of the enzyme by causing movement of its surface groups and creating active sites. Two molecular aggregates, an enzyme and micelle, in supercritical fluids were studied with respect to their microstructure and activity for chemical reactions. High-pressure FT-IR spectroscopy has thus been used to clarify (i) the rotational isomerism of AOT molecules, (ii) characteristics of water and the water-head group, and (iii) RSO3-Na+ interactions in AOT reverse micellar aggregates in supercritical ethane. At 35.0 MPa, the proportion of trans-like to gauche-like conformers greatly increased as W0 was increased. A system of water/AOT/supercritical ethane was in a one-phase microemulsion state at W0 values less than 15 at 35.0 MPa and 306.1 K. At higher W'0 the system was in a two-phase state. The addition of lithium chloride makes the system become motionless in a one-phase microemulsion state at W0 above 30. This work demonstrates interesting pressure-, temperature, and salt effects on an enzyme-catalyzed esterification and/or maintenance of a one-phase microemulsion in supercritical fluids from practical and theoretical points of view.

Carbon Dioxide↗
PubMed2002

Chemical analysis of Ginkgo biloba leaves and extracts.

The chemical analysis and quality control of Ginkgo leaves and extracts is reviewed. Important constituents present in the medicinally used leaves are the terpene trilactones, i.e., ginkgolides A, B, C, J and bilobalide, many flavonol glycosides, biflavones, proanthocyanidins, alkylphenols, simple phenolic acids, 6-hydroxykynurenic acid, 4-O-methylpyridoxine and polyprenols. In the commercially important Ginkgo extracts some of these compound classes are no longer present. Many publications deal with the analysis of the unique terpene trilactones. They can be extracted with aqueous acetone or aqueous methanol but also supercritical fluid extraction is possible. Still somewhat problematic is their sample clean-up. Various procedures, not all of them validated, employing partitioning or SPE have been proposed. Some further development in this area can be foreseen. Separation and detection can be routinely carried out by HPLC with RI, ELSD or MS, or with GC-FID after silylation. TLC is another possibility. No quantitative procedure for flavonol glycosides has been published so far due their difficult separation and commercial unavailability. Fingerprint analysis by gradient RP-HPLC is possible. After acidic hydrolysis to the aglycones quercetin, kaempferol and isorhamnetin and separation by HPLC, quantitation is straightforward and yields by recalculation an estimation of the original total flavonol glycoside content. For biflavones, simple phenols, 6-hydroxykynurenic acid, 4-O-methylpyridoxine and polyprenols analytical procedures have been published but not all assays are yet ideal. Lately a there is a lot of interest in the analysis of the undesired alkylphenols and a few validated procedures have been published. The analysis of Ginkgo proanthocyanidins is still in its infancy and no reliable assays exist.

Anthocyanins↗
PubMed2002

C6-Green leaf volatiles trigger local and systemic VOC emissions in tomato.

In response to insect feeding, tomato plants (Lycopersicon esculentum) release elevated levels of volatile organic compounds; that is, monoterpenes and sesquiterpenes are released both locally and systemically with wounding while C(6) green leaf volatiles are released only from damaged leaves. With the exogenous application (100 nmol) of the C(6)-tomato-volatile (E)-2-hexenal, an increase in the release of local and systemic terpenes was observed, while an equimolar amount of methyl jasmonate triggered only local emissions of terpenes. Labeling studies with 13CO(2) showed that de novo synthesis was not required for monoterpene or sesquiterpene release immediately following chemical treatment or insect feeding. Comparative measurements were made between aldehyde doses applied to the plant and levels naturally released from leaves with insect damage.

Animals↗
PubMed2001

Transdermal delivery of ketoprofen using microemulsions.

A transdermal preparation containing ketoprofen was developed using O/W microemulsion system. Of the oils tested, oleic acid was chosen as the oil phase of the microemulsion, as it showed a good solubilizing capacity and excellent skin permeation rate of the drug. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant and cosurfactant for microemulsion formation, and the effect of these additives on skin permeation of ketoprofen was evaluated with excised rat skins. The optimum formulation of the microemulsion consisted of 3% ketoprofen, 6% oleic acid, 30% Labrasol/Cremophor RH 40 (1:1) and water. Terpenes were added to the microemulsion at the level of 5% and their effect on the skin permeation of ketoprofen from the microemulsion was evaluated. Of the four terpenes used, only limonene resulted in a powerful enhancing activity (3-fold increase over control).

Administration, Cutaneous↗
PubMed2003

Photoactive extracts from Thevetia peruviana with antifungal properties against Cladosporium cucumerinum.

Seeds of Thevetia peruviana were screened for their antifungal photoactivity. Extracts obtained either with n-hexane or dichloromethane were fractionated by column chromatography and further analysed by thin-layer chromatography. All seed extracts and fractions were tested for inhibition of the fungus Cladosporium cucumerinum for the evaluation of photoactive inhibitory effects. Antifungal light-dependent activity was observed for some of the fractions and both crude extracts. The most photoactive fraction was analysed by capillary gas chromatography with mass spectrometry in order to identify its constituents. Two major groups of compounds were identified, terpenes and fatty acids and derivatives. Pulegone, linoleic acid and palmitic acid were the major compounds. Terpenes seem to be the major substances with antifungal photoactivity.

Antifungal Agents↗
PubMed1999

Resin-based defenses in conifers.

Bark beetle infestation and associated fungal infection are a serious disease problem in conifer species. Conifers have evolved elaborate, constitutive and inducible, terpene-based defense mechanisms to deter insect pests and their symbiotic fungal pathogens. This process involves the secretion of oleoresin, a complex mixture of monoterpenes, sesquiterpenes and diterpenoid acids. Induced oleoresinosis in grand fir (Abies grandis) provides a model system for studying the regulation of defensive terpene biosynthesis and for identifying relevant genes. The ecological relationships between conifers, beetle pests, beetle predators and fungal pathogens present several possible avenues for manipulating oleoresin composition to improve tree resistance. Possible examples include chemically disguising the host, adding toxins and altering the levels of pheromone precursors, attractants for predators or hormone mimics to disrupt insect development. Strategies and prospects for generating transgenic conifers with increased defense capability are discussed.

Journal Article↗
PubMed2000

Odour-impact compounds of Gorgonzola cheese.

Volatile concentrates were obtained by vacuum distillation from both natural and creamy Gorgonzola cheese and isolated by continuous liquid-liquid extraction. Both were analysed by high resolution gas chromatography (HRGC), HRGC-mass spectrometry and HRGC-olfactometry. A total of 63 components were identified in the neutral extract of the natural type (21 esters, 13 ketones, 14 alcohols, 5 aldehydes, 1 sulphur compound, 7 aromatic compounds and 2 terpenes) and 52 in the creamy type (17 esters, 12 ketones, 10 alcohols, 5 aldehydes, 1 sulphur compound, 5 aromatic compounds and 2 terpenes). Ketones, whose major components were 2-nonanone and 2-heptanone, were the predominant constituents of the neutral fraction. By olfactometric analysis of the neutral extracts, 23 odour-impact compounds were found in the natural and 21 in the creamy Gorgonzola cheese. 1-Octen-3-ol, ethyl hexanoate, 2-nonanone, 2-heptanone, 2-heptanol, ethyl butanoate, 2-nonanol and 4-methylanisole were the key odorants of the natural cheese, whereas 2-heptanone, 2-heptanol, ethyl butanoate, 3-methyl thiopropanal and an unidentified constituent with a fruity odour were characteristic of the creamy Gorgonzola cheese. On the basis of high odour unity values, 2-nonanone, 1-octen-3-ol, 2-heptanol, ethyl hexanoate, methylanisole and 2-heptanone were the most important odorants of natural and creamy Gorgonzola cheese aroma.

Animals↗
PubMed2003

Bifunctional abietadiene synthase: mutual structural dependence of the active sites for protonation-initiated and ionization-initiated cyclizations.

Abietadiene synthase from grand fir catalyzes two sequential, mechanistically distinct cyclizations, of geranylgeranyl diphosphate and of copalyl diphosphate, in the formation of a mixture of abietadiene isomers as the committed step of diterpenoid resin acid biosynthesis. Each reaction is independently conducted at a separate active site residing in what were considered to be structurally distinct domains typical of terpene cyclases. Despite the presence of an unusual 250-residue N-terminal insertional element, a tandem pair of charged residues distal to the insertion was shown to form a functional part of the C-terminal active site. Because abietadiene synthase resembles the ancestral plant terpene cyclase, this observation suggests an early evolutionary origin of catalytically important positively charged residues at the N-terminus of enzymes of this general class. A series of N- and C-terminal truncations of this enzyme were constructed and characterized, both alone and as mixtures of adjacent polypeptide pairs, to assess the proposed domain architecture, the function of the insertional element, and the role of presumptive interdomain contacts. These studies indicated a requirement for the insertional element in functional folding and allowed definition of the minimum primary structure of N- and C-terminal active site peptides. Most importantly, the results showed that, although the two active sites of abietadiene synthase are catalytically independent, substantial contact between the two regions is essential for the functional competence of this enzyme. Thus, the two cyclization sites of abietadiene synthase cannot be dissected into catalytically distinct domains, and, therefore, abietadiene synthase is unlikely to have arisen by fusion of two previously independent genes.

Abies↗
PubMed2003

Ozone-initiated reactions with mixtures of volatile organic compounds under simulated indoor conditions.

This study examines the primary and secondary products resulting from reactions initiated by adding ozone to complex mixtures of volatile organic compounds (VOC). The mixtures were representative of organic species typically found indoors, but the concentrations tended to be higher than normal indoor levels. Each 4-h experiment was conducted in a controlled environmental facility (CEF, 25 m3) ventilated at approximately 1.8 h(-1). The mixture investigated included 23 VOC (no O3), O3/23 VOC, O3/21 VOC (no d-limonene or alpha-pinene), and O3/terpene only (d-limonene and alpha-pinene). The net O3 concentration was approximately 40 ppb in each experiment, and the total organic concentration was 26 mg/m3 for the 23 VOC mixture, 25 mg/m3 for the 21 VOC mixture, and 1.7 mg/m3 for the d-limonene and alpha-pinene mixture. When the 23 VOC were added to the CEF containing no O3, no compounds other than those deliberately introduced were observed. When O3 was added to the CEF containing the 23 VOC mixture, both gas and condensed phase products were found, including aldehydes, organic acids, and submicron particles (140 microg/m3). When O3 was added to the CEF containing the 21 VOC without the two terpenes (O3/21 VOC condition), most of the products that were observed in the O3/23 VOC experiments were no longer present or present at much lower concentrations. Furthermore, the particle mass concentration was 2-7 microg/m3, indistinguishable from the background particle concentration level. When O3 was added to the CEF containing only two terpenes, the results were similar to those in the O3/23 VOC experiments, but the particle mass concentration (190 microg/m3) was higher. The results indicate that (i) O3 reacts with unsaturated alkenes under indoor conditions to generate submicron particles and other potentially irritating species, such as aldehydes and organic acids; (ii) the major chemical transformations that occurred under our experimental conditions were driven by O3/d-limonene and O3/alpha-pinene reactions; and (iii) the hydroxyl radicals (OH) that were generated from the O3/terpene reactions played an important role in the chemical transformations and were responsible for approximately 56-70% of the formaldehyde, almost all of the p-tolualdehyde, and 19-29% of the particle mass generated in these experiments.

Air Pollution, Indoor↗
PubMed2006

Release of trace organic compounds during the decomposition of municipal solid waste components.

Landfill gas contains numerous speciated organic compounds (SOCs) including alkanes, aromatics, chlorinated aliphatic hydrocarbons, alcohols, ketones, terpenes, chlorofluoro compounds, and siloxanes. The source, rate and extent of release of these compounds are poorly understood. The objective of this study was to characterize the release of SOCs and the regulated parameter, non-methane organic compounds (NMOCs) during the decomposition of residential refuse and its major biodegradable components [paper (P), yard waste (YW), food waste (FW)]. Work was conducted under anaerobic conditions in 8-L reactors operated to maximize decomposition. Refuse and YW were also tested under aerobic conditions. NMOC release during anaerobic decomposition of refuse, P, YW, and FW was 0.151, 0.016, 0.038, and 0.221 mg-C dry g(-1), respectively, while release during aerobic decomposition of refuse and YW was 0.282 and 0.236 mg-C dry g(-1), respectively. The highest NMOC release was measured under abiotic conditions (3.01 mg-C dry g(-1)), suggesting the importance of gas stripping. NMOC release was faster than CH4 production in all treatments. Terpenes and ketones accounted for 32-96% of SOC release in each treatment, while volatile fatty acids were not a significant contributor. Release in aerobic systems points to the potential importance of composting plants as an emissions source.

Air Pollutants↗
PubMed2003

Comparison of natural and roasted Turkish tombul hazelnut (Corylus avellana L.) volatiles and flavor by DHA/GC/MS and descriptive sensory analysis.

Natural (raw) and roasted hazelnuts were compared for their differences in volatile components and sensory responses. A total of 79 compounds were detected in both hazelnuts, of which 39 (27 positive, 5 tentative, and 7 unknown) were detected in natural hazelnut and 71 (40 positive, 14 tentative, and 17 unknown) were detected in roasted hazelnut. These included ketones, aldehydes, pyrazines, alcohols, aromatic hydrocarbons, furans, pyrroles, terpenes, and acids. Pyrazines, pyrroles, terpenes, and acids were detected in roasted hazelnut only. Concentrations of several compounds increased as a result of roasting and these may play significant roles in the flavor of roasted hazelnut. Pyrazines together with ketones, aldehydes, furans, and pyrroles may contribute to the characteristic roasted aroma of hazelnut. Descriptive sensory analysis (DSA) showed that some flavor attributes such as "aftertaste", "burnt", "coffee/chocolate-like", "roasty", and "sweet" were rated significantly higher in roasted hazelnut compared to its natural counterpart. Natural and roasted hazelnuts can be distinguished using these attributes.

Aldehydes↗
PubMed2005

Comparison of volatiles of cultured and wild sea bream (Sparus aurata) during storage in ice by dynamic headspace analysis/gas chromatography-mass spectrometry.

Cultured and wild sea bream were compared for differences in their volatile components over a 23 day storage period in ice. A total of 60 compounds in cultured and 78 compounds in wild sea bream were tentatively identified (in addition to this, there were 23 unknowns in cultured and 29 unknowns in wild sea bream volatiles). These included aldehydes, ketones, alcohols, aromatics, terpenes, furans, sulfur-containing compounds, an acid, and miscellaneous compounds. Although selection of best fish is a subjective matter, more aldehydes, ketones, aromatics, and terpenes were found in wild sea bream as compared to that of its cultured counterpart. Both sea bream samples exhibited complex volatile profiles over the entire storage period. The combination of several classes of volatile compounds, dependent upon their concentrations and odor thresholds, is responsible for the distinctive and unique flavor of fresh cultured and wild sea bream. Relative concentrations of several compounds (trimethylamine, piperidine, methanethiol, dimethyl disulfide, dimethyl trisulfide, 1-penten-3-ol, 3-methyl-1-butanol, and acetic acid) increased continually throughout the storage period, and these may have the potential to be used as indicators of sea bream quality.

Alcohols↗
PubMed2006

Hydrolysis and transformation of grape glycosidically bound volatile compounds during fermentation with three Saccharomyces yeast strains.

The ability of three Saccharomyces wine yeasts (S. cerevisiae AWRI 838, S. cerevisiae AWRI 1537, and S. bayanus AWRI 1375) to liberate volatile compounds from sugar-bound aroma precursors was investigated using synthetic and grape glycosides under different experimental conditions. In model systems involving the incubation of yeast cells with either synthetic or grape-derived glycosides under conditions more favorable for glycosidase activities and less favorable for acid-catalyzed hydrolysis (pH 5.0 and 30 degrees C), all yeast strains studied proved to be capable of hydrolyzing glycosides, with S. bayanus AWRI 1375 displaying greater hydrolytic activity than S. cerevisiae AWRI 838 and AWRI 1537. During the fermentation of a chemically defined grape juice-like medium containing glycosidic precursors extracted from Vitis vinifera cv. White Frontignac (synonym Muscat à Petit Grains Blanc), all yeasts promoted a significant hydrolysis of different precursors, which varied according to the chemical structures of both the sugar and the aglycon moieties, as determined by GC-MS analysis of trifluoroacetylated derivatives. Hydrolysis of the White Frontignac derived glycosidic precursors during fermentation resulted in the release of monoterepene alcohols, terpene oxides, terpene diols, and 3-oxo-alpha-ionol, demonstrating the significant potential of these yeast strains to contribute to wine varietal volatile composition during alcoholic fermentation.

Fermentation↗
PubMed1999

Extractable components of the aerial parts of Salvia lavandulifolia and composition of the liquid smoke flavoring obtained from them.

The fraction extractable with dichloromethane of the aerial parts of sage (Salvia lavandulifolia) and the liquid smoke obtained from this plant are studied by means of gas chromatography/mass spectrometry and gas chromatography. The extract of the aerial parts of the sage plant contains not only terpene, sesquiterpene hydrocarbons, and their oxygenated derivatives, which are interesting compounds both for their organoleptic properties and for their antioxidant activity, but also a large group of phenolic compounds with abietatriene or related structure, the mass spectra of which are given, many of them having antioxidant, antiviral, and antibacterial properties. The liquid sage smoke obtained is slightly acidic and contains common smoke components in specific proportions, and a large group of aromatic nitrogenated derivatives such as pyrazine and pyridine derivatives in small proportions, together with the main oxygenated terpene derivatives present in the plant; some of the compounds detected in this liquid smoke have not been described as smoke components before.

Flavoring Agents↗
PubMed1999

Release of volatile odor compounds from full-fat and reduced-fat frankfurters.

The effect of fat content on the release of volatile aroma compounds from frankfurters has been investigated. Although the release of most n-alkanals, alcohols, ketones, and furans was little affected by changes in the fat content of frankfurters, that of monoterpene hydrocarbons, sesquiterpene hydrocarbons, terpenes containing oxygen, cyclopentenones, phenyl propanoids, and phenols was greatly increased when the fat content was decreased. Some odors were also detected more frequently in the low-fat than in the full-fat sausages. These included smoky odors, due to phenols, spicy, synthetic, and floral odors due to terpenes, and meaty, roasted odors caused by sulfur-containing heterocyclic compounds. The release of aroma compounds from frankfurters appears to be closely related to the solvation of these compounds in the lipid phase.

Animals↗
PubMed2000

Specificity of papaya lipase in esterification with respect to the chemical structure of substrates.

Esterification, catalyzed by papaya (Carica papaya) lipase (CPL), was studied with various alcohols and carboxylic acids under competitive conditions. Acids studied were straight-chain saturates of different chain lengths, with octanoic acid as the reference. Alcohols chosen were aliphatic straight-chain, branched, secondary, tertiary, terpene, and aromatic alcohols of different chain lengths, using 1-hexanol as the reference. The initial reaction rate increased with increasing chain length of the acid from C4:0 to C18:0, followed by a slight decrease with C20:0. In the case of alcohols, an optimum chain length of 8 carbon atoms was obtained for the straight-chain aliphatic group (C2 to C16). Ethanol, 1-propanol, and secondary and tertiary alcohols showed rather low reactivity. Branching of the alcohols was found not to affect the reactivity in esterification; among the terpenes, beta-citronellol [(2E)-3, 7-dimethyl-6-octenol] and geraniol [(2E)-3,7-dimethylocta-2, 6-dien-1-ol] were found to be more reactive than nerol [(2Z)-3, 7-dimethylocta-2,6-dien-1-ol]. The highest reaction rate was found for the aromatic benzyl alcohol (phenylmethanol).

Fruit↗
PubMed2003

New Lewis-basic N-oxides as chiral organocatalysts in asymmetric allylation of aldehydes.

Allylation of aromatic and heteroaromatic aldehydes 1a-k with allyltrichlorosilane 2 can be catalyzed by the new heterobidentate, terpene-derived bipyridine N-monoxides 4, 6a,b, and 8-11 (</=10 mol %) to afford (S)-(-)-3 with high enantioselectivities (</=99% ee). The stereochemical outcome has been found to be controlled by the axial chirality of the catalyst, which in turn is determined by the central chirality of the annulated terpene units. Solvent effects on the conversion and the level of asymmetric induction have been elucidated, and MeCN has been identified as the optimal solvent for these catalysts.

Journal Article↗