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1.
The headspace volatile components of roots, stems, leaves, and flowers of Echinacea angustifolia,E. pallida, and E. purpurea were analyzed by capillary gas chromatography/mass spectrometry (GC/MS). Over 70 compounds were identified in the samples. All plant tissues, irrespective of the species, contain acetaldehyde, dimethyl sulfide, camphene, hexanal, beta-pinene, and limonene. The main headspace constituents of the aerial parts of the plant are beta-myrcene, alpha-pinene, limonene, camphene, beta-pinene, trans-ocimene, 3-hexen-1-ol, and 2-methyl-4-pentenal. The major headspace components of root tissue are alpha-phellandrene (present only in the roots of E. purpurea and E.angustifolia), dimethyl sulfide, 2-methylbutanal, 3-methylbutanal, 2-methylpropanal, acetaldehyde, camphene, 2-propanal, and limonene. Aldehydes, particularly butanals and propanals, make up 41-57% of the headspace of root tissue, 19-29% of the headspace of the leaf tissue, and only 6-14% of the headspace of flower and stem tissues. Terpenoids including alpha- and beta-pinene, beta-myrcene, ocimene, limonene, camphene, and terpinene make up 81-91% of the headspace of flowers and stems, 46-58% of the headspace of the leaf tissue, and only 6-21% of the roots. Of the 70 compounds identified, >50 are reported in Echinacea for the first time.  相似文献   

2.
The aroma compounds of rocket salad (Eruca sativa) SPME headspace samples of fresh leaves were analyzed using GC, GC-MS, and olfactometry. More than 50 constituents of the Eruca headspace could be identified to be essential volatiles, responsible for the characteristic intense green; herbal; nutty and almond-like; Brassicaceae-like (direction of cabbage, broccoli, and mustard); and horseradish-like aroma of these salad leaves. As aroma impact compounds, especially isothiocyanates, and derivatives of butane, hexane, octane, and nonane were identified. 4-Methylthiobutyl isothiocyanate (14.2%), cis-3-hexen-1-ol (11.0%), cis-3-hexenyl butanoate (10.8%), 5-methylthiopentyl isothiocyanate (9.3%), cis-3-hexenyl 2-methylbutanoate (5.4%), and 5-methylthiopentanenitrile (5.0%) were found in concentrations higher than 5.0% (calculated as % peak area of GC analysis using a nonpolar column).  相似文献   

3.
The aroma impact compound, 2-acetyl-1-pyrroline (2AP), has been identified for the first time in headspace of fresh bread flowers (Vallaris glabra Ktze) in which volatile components were extracted by solid-phase microextraction (SPME) at room temperature prior to analysis by gas chromatography-mass spectrometry. A total of 50 volatiles were detected. Among these, 23 volatiles were identified, predominantly in a group of terpenes. More volatiles were found in the extract of fresh bread flowers obtained by continuous steam distillation and solvent extraction (SDS). Of the 40 volatiles identified, the additional components were mainly straight-chain saturated hydrocarbons. 2AP was found in the extracts obtained by both SPME (0.37%) and SDS (2.71% relative proportion). Quantitative analyses of 2AP in bread flowers and other plant materials were performed by solvent extraction employing acidic solutions and capillary GC with flame ionization detection. The highest concentration of 2AP was found in dried flowers of V. glabra at 26.1 mg/kg. By comparison with other plant sources, fresh leaves of Pandanus amaryllifolius Roxb contain 2AP at 10.3 mg/kg and Thai fragrant rice, Khao Dawk Mali 105, at 3.0 mg/kg.  相似文献   

4.
The flavor volatiles in three Japanese rice cultivars, Nihonbare, Koshihikari, and Akitakomachi, during cooking were directly extracted by using a modified headspace solid‐phase microextraction (SPME) method and analyzed by gas chromatography‐mass spectrometry (GC‐MS). A total of 46 components were identified, including aldehydes, ketones, alcohols, and heterocyclic compounds, as well as fatty acids and esters, phenolic compounds, hydrocarbons, etc. The amount of key odorant compounds increased with cooking, while the amount of low‐boiling volatiles decreased. The similarities and differences of the three rice cultivars were determined through a comparison of their volatile components. Nihonbare was characterized by a higher amount of indole but an absence of the chemical class of fatty acid esters. In contrast, both Koshihikari and Akitakomachi had a higher amount of 4‐vinylphenol and an abundance of those esters. Koshihikari and Akitakomachi were quite similar in regard to those flavor volatiles. Furthermore, the observations in the research may suggest that the volatile components at cooking stage (I) were the representatives of the flavor volatiles of uncooked rice, while the volatile constituents at cooking stage (IV) were the representatives of the flavor volatiles of cooked rice.  相似文献   

5.
Volatile compounds were isolated from strawberry guava fruit by simultaneous steam distillation-solvent extraction according to Likens-Nickerson. Compounds were identified by capillary GC-MS and sensorially characterized by sniffing GC. Two hundred and four compounds were identified in the aroma concentrate, of which ethanol, alpha-pinene, (Z)-3-hexenol, (E)-beta-caryophyllene, and hexadecanoic acid were found to be the major constituents. The presence of many aliphatic esters and terpenic compounds is thought to contribute to the unique flavor of the strawberry guava fruit.  相似文献   

6.
The present study investigates the composition of volatile constituents and sensory characteristics of catnip (Nepeta cataria L.) grown in Lithuania. Hydrodistillation, simultaneous distillation-solvent extraction, static headspace, and solid phase microextraction methods were used for the isolation of aroma volatiles. Geranyl acetate, citronellyl acetate, citronellol, and geraniol were the major constituents in catnip. Differences in the quantitative compositions of volatile compounds isolated by the different techniques were considerable. A sensory panel performed sensory analysis of the ground herb, pure essential oil, and extract; aroma profiles of the products were expressed graphically, and some effects of odor qualities of individual compounds present in catnip on the overall aroma of this herb were observed.  相似文献   

7.
A quick headspace GC method for quantification of volatiles was developed, involving only minor sample preparation. Yogurt flavor compounds could be quantified in the micrograms per kilogram to milligrams per kilogram range without any difficulty, despite the complex matrix. Volatiles of traditional acidic and mild, less acidic yogurts were compared, and important differences were found for acetaldehyde, 2,3-butanedione, and 2,3-pentanedione. Concentrations of 2,3-butanedione and 2,3-pentanedione increased 2-3-fold in mild, less acidic yogurts compared to traditional acidic ones. This is due to accumulation of the precursors of the diketones, 2-acetolactate and 2-acetohydroxybutyrate, during fermentation in mild, less acidic yogurt. These precursors are subsequently converted to the corresponding diketones during storage. On the contrary, acetaldehyde formation was reduced in the mild yogurt, due to growth differences between the lactic acid bacteria used for fermentation of the milk. The quantitative results presented in this study validate previous GC sniffing conclusions (Ott et al. J. Agric. Food Chem. 1997, 45, 850-858), showing that yogurt aroma is the superposition of impact flavor compounds generated by fermentation on milk compounds.  相似文献   

8.
The essential oil of long-time stored seeds of dill (Anethum graveolens L.) from Bulgaria was analyzed by physicochemical methods, gas chromatography (GC), GC-mass spectrometry (MS) (achiral and chiral phases), and olfactometry, and its antimicrobial activity was tested by using different strains of microorganisms. More than 40 constituents of the essential dill oil, obtained from seeds stored for more than 35 years, could be identified as essential volatiles, responsible for the pleasant fresh (D-limonene) and spicy (D-carvone) odor of a high quality. As aroma impact compounds, D-carvone (50.1%) and D-limonene (44.1%) were found. Antimicrobial testings showed high activity of the essential A. graveolens oil against the mold Aspergillus niger and the yeasts Saccharomyces cerevisiae and Candida albicans.  相似文献   

9.
Coffee has been an important and heavily used beverage in many cultures over a long period of time. Although sulfur species have been found to be abundant constituents, no work to date has explored the presence of selenium analogues. Investigation of volatile selenium species from green coffee beans, roasted beans, and brewed coffee drink was performed using solid phase microextraction (SPME) sample preconcentration in conjunction with GC/ICP-MS. Several volatile selenium species at trace levels were detected from roasted coffee beans as well as in the steam from brewed coffee drinks. No detectable selenium (and sulfur) species, however, were found in the headspace of green beans, indicating that selenium-containing volatiles are formed during roasting, as is the case for the sulfur volatiles. Matching standards were prepared and used to identify the compounds found in coffee. Artificial supplementation of the green coffee beans with selenium before roasting was performed to further characterize the selenium-containing volatiles formed during the coffee-roasting process.  相似文献   

10.
Headspace volatiles of Yihchuan aromatic rice, a japonica rice cultivar, were extracted by a solid‐phase microextraction (SPME) method and analyzed by GC and GC‐MS. Effects of fiber types and an industrial milling process on the change of headspace volatiles were studied. Of the fiber types, divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), and carboxen/polydimethylsiloxane (CAR/PDMS) were suggested for use in the analysis headspace volatiles in terms of absorption or adsorption ability. Regarding the milling effect, the amount of total headspace volatiles from brown rice to white rice decreased ≈30%, and that of aldehydes and alcohols, the two largest groups of volatiles, decreased ≈20 and 15%, respectively. Comparatively, rice bran contained higher amounts of total headspace volatiles than milled rice grains.  相似文献   

11.
The headspace analyses of pollen, whole living female and male flowers, and staminoids have been performed on Laurus nobilis L. (Lauraceae) from Italy to determine whether there are differences in the volatiles emitted in order to give a contribution to the roles of the different flower parts in the pollination ecology of dioecious plants. Also, the essential oils obtained from male and female plants have been studied to evaluate a possible correlation between the spontaneously emitted volatiles and the constituents stored in the glandular tissues. Furthermore, the headspace sampling technique has been improved, with respect to previously employed methods, by means of solid-phase microextraction (SPME).  相似文献   

12.
Fresh elder flowers (Sambucus nigra L.) were extracted with an aqueous solution containing sucrose, peeled lemon slices, tartaric acid, and sodium benzoate to make elder flower syrup. Aroma compounds emitted from the elder flower syrup were collected by the dynamic headspace technique and analyzed by GC-FID and GC-MS. A total of 59 compounds were identified, 18 of which have not previously been detected in elder flower products. The concentrations of the identified volatiles were measured in five elder cultivars, Allesoe, Donau, Sambu, Sampo, and Samyl, and significant differences were detected among cultivars in the concentration levels of 48 compounds. The odor of the volatiles was evaluated by the GC-sniffing technique. cis-Rose oxide, nerol oxide, hotrienol, and nonanal contributed to the characteristic elder flower odor, whereas linalool, alpha-terpineol, 4-methyl-3-penten-2-one, and (Z)-beta-ocimene contributed with floral notes. Fruity odors were associated with pentanal, heptanal, and beta-damascenone. Fresh and grassy odors were primarily correlated with hexanal, hexanol, and (Z)-3-hexenol.  相似文献   

13.
Recent developments in methods for isolation and measurement of volatiles from cereals are reviewed. The main types of isolation methods, namely, direct extraction, distillation, and headspace, have recently been complemented by solid phase microextraction. Direct solvent extraction provides efficient recovery of compounds with a broad range of polarities and volatilities, whereas headspace techniques provide relatively clean extracts. Supercritical fluid and solid phase microextractions have not yet been fully evaluated for cereals. GC and GC/MS remain the dominant techniques for measurement of the extracted compounds, although new electronic noses show promise. Relating these results to human perception requires careful control to ensure valid comparisons and, in this respect, aroma extract dilution analysis is a useful procedure.  相似文献   

14.
A headspace (HS)-trap method in combination with gas chromatography (GC)-mass spectrometry (MS) was developed for the determination of volatile constituents in hops. The highly sensitive HS-trap system reduces the detection limit by using up to four trap enrichment cycles. Seventy hop samples of different varieties and cultivation regions, from the 2008 harvest, were examined using the HS-trap-GC-MS method and the established "European Brewery Convention" (EBC) method for hop essential oil analysis. Twenty-one different volatiles were quantified for each hop sample. For all compounds, except caryophyllene oxide, a strong correlation was found between the results of the HS-trap method and the EBC method. Experiments have revealed that the EBC method using steam distillation is not appropriate for thermolabile compounds, such as caryophyllene oxide, due to decomposition during boiling. The HS-trap method is fast and sensitive, requires small sample amounts and minimal sample preparation, and is easy to apply.  相似文献   

15.
Samples of an Australian oat cultivar, Echidna, were pilot-scale processed. At each stage of the processing (raw oats, groats, kiln dried dehulled oats (KDHO), and rolled (flaked)) samples were removed for later sensory and GC-MS analysis of the flavor components. Mean taste panel scores from a trained taste panel were calculated according to attributes (cereal, burnt, toasted, floury, and yeasty). Attributes were generally similar for both KDHO and flaked oats except in the yeasty attributes. Panelists were able to differentiate between groats, KDHO, and flaked oats (raw oats were not included). The largest effects of heat processing were found for the attributes toasted and yeasty aroma; toasted, cereal, and yeasty flavor; and toasted and yeasty aftertaste. A multi-organoleptic sensor analyzer was able to differentiate all samples when the output was subjected to discriminant function analysis. A reintroduced sample was recognized with a confidence level better than 96%. Solid-phase microextraction (SPME) of headspace followed by GC--MS was used to identify volatiles after either dry or slurry heating. Several SPME fiber types were evaluated as to their ability to sorb oat volatiles. A 100-microm poly(dimethylsiloxane) SPME fiber was found to provide the best adsorption profile as measured by number of compounds sorbed and peak area response. A range of alcohols, aldehydes, alkyl benzenes, dienes, and ketones was identified in the processed samples.  相似文献   

16.
Volatiles were obtained from commercially prepared and laboratory-prepared rice cakes using high-flow dynamic headspace isolation with Tenax trapping. Analysis was carried out by capillary GC/MS. More than 60 compounds were identified. Major volatiles included 1-hydroxy-2-propanone, furfuryl alcohol, 2, 5-dimethylpyrazine, 2-methylpyrazine, pyrazine, hexanal, furfural, pentanol, 3-hydroxy-2-butanone (acetoin), and ethyl-3, 6-dimethylpyrazine. Although not ideally applicable to a dry product, concentration/threshold ratios indicated that the compounds with a high probability of contributing to the aroma and flavor included 3-methylbutanal, dimethyl trisulfide, 2-ethyl-3,5-dimethylpyrazine, 4-vinylguaiacol, hexanal, (E,E)-2,4-decadienal, 2-methylbutanal, 2-acetyl-1-pyrroline, 1-octen-3-ol, and 1-octen-3-one.  相似文献   

17.
The release of volatile compounds from infused tea was monitored using on-line atmospheric pressure chemical ionization (APCI) mass spectrometry. Assignment of the APCI ions to particular compounds was achieved using gas chromatography of tea headspace with dual electron ionization and APCI-MS detectors. Six ions in the APCI spectrum could be assigned to individual compounds, five ions were associated with isobaric compounds (e.g., 2- and 3-methylbutanal and pentanal) or stereoisomers (e.g., heptenals or heptadienals), and a further four ions monitored were identified compounds but with some unknown impurities. Reproducibility of infusion preparation and the analytical system was good with percentage variation values generally below 5%. The analysis was used to study the effect of infusion and holding temperatures on the volatile profile of tea headspace samples, and this was found to be compound-dependent. Both the extraction of volatiles from leaf tea and the release of volatiles into the headspace play a role in creating the aroma profile that the consumer experiences.  相似文献   

18.
The volatile composition of the headspace from Citrus unshiu Marcov. forma Miyagawa-wase blossom was investigated. The volatile constituents were absorbed by a solid-phase microextraction (SPME) fiber and directly transferred to a GC-MS. Volatile compositional changes of C. unshiu blossom prepared via different drying methods (shade, microwave, and freeze-drying methods) were also determined. A total of 96 volatile constituents were confirmed in the headspace from these samples. Monoterpene hydrocarbons were prominent in the headspace volatiles of C. unshiu blossom: fresh, 84.1%; shade-dried, 60.0%; microwave-dried, 88.4%; and freeze-dried, 29.9%. p-Cymene (23.3%) was the most abundant component in the headspace of fresh C. unshiu blossom; gamma-terpinene was the most abundant in shade- and microwave-dried samples (26.8 and 31.2%, respectively) and beta-caryophyllene (10.5%) in freeze-dried sample. By using an electronic nose consisting of six metal oxide sensors, principal component analysis of the volatile compounds showed a clear aroma discrimination of the fresh and all dried blossom samples.  相似文献   

19.
Analysis of biogenic volatile organic compounds (BVOC) of 14 Eucalyptus clones has been performed using an automated headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography (GC)/ion trap mass spectrometry (ITMS) method. Correlations between pulp properties of Eucalyptus clones and the BVOC of their leaf headspaces were studied. The compounds alpha-terpineol and the sesquiterpene beta-eudesmol were positively correlated with S5, a property related to the hemicelluose content in the pulp. Qualitative results obtained with automated HS-SPME were sufficient to group together the same species and related hybrids through cluster analysis and were confirmed through principal component analysis. A preliminary separation of the essential oils of Eucalyptus dunnii through comprehensive two-dimensional gas chromatography (GC x GC) showed approximately 580 peaks compared to approximately 60 in a typical GC/ITMS first-dimension chromatogram. The potential of HS-SPME coupled to GC x GC to improve the separation of Eucalyptus volatiles and other plant essential oils looks extremely promising for new applications of unsupervised learning methods.  相似文献   

20.
Odors in the headspace of apple trees were characterized by in situ volatile collections in the orchard. Sixty-two compounds were quantitatively identified with thermal desorption-gas chromatography-mass spectrometry over the complete fruit-growing season. Overall quantities in the headspace of fruit-bearing twig were highest at petal fall and at the beginning of June and August. Interestingly, the latter two periods coincide with the flight maxima of the codling moth, Cydia pomonella, one of the principal pest insects of apple fruit worldwide. Dual-choice bioassays with mated adult female moths in a Y-tube olfactometer showed that the blend of plant-derived volatiles repelled this key pest of apple at petal fall and attracted it from July to mid-August. Single-component analysis indicated that benzaldehyde and butyl acetate might contribute to the observed repellent effect, but the constituents accounting for the attractant effect mid-season remain to be further elucidated. The attractant effect clearly originates from the apple fruit and not from the twig with leaves, as bioassays demonstrated conclusively.  相似文献   

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