Headspace Trapping Research Articles

Electroantennographic and Behavioral Responses of the Melon fly, Zeugodacus cucurbitae (Coquillett), to Volatile Compounds of Ridge Gourd, Luffa acutangular L.

The melon fly, Zeugodacus cucurbitae (Coquillett), is a major invasive pest, widely distributed in the Asia-Pacific region and some parts of Africa. Melon fly attractants could improve the effectiveness of current pest management measures. Previous studies have shown that some host fruits are attractive to melon flies but few have investigated the chemical compounds responsible for their attraction. In this study, we aimed to identify the volatile compounds from Luffa acutangula L that attract Z. cucurbitae. In headspace trapping, chemical profiling identified 19 compounds from ridge gourds, with 1-pentadecene being the major component. EAG results revealed that seven compounds elicited antennal responses in Z. cucurbitae, and significant differences in antennal responses between male and female Z. cucurbitae adults were recorded to p-xylene, alpha-pinene, and 1-octadecene. Behavioral experiments demonstrated that the EAG-active compounds methyl isovalerate and methyl myristate had either attractive or repellent effects on Z. cucurbitae at different concentrations, and 1-octadecene attracted Z. cucurbitae. Our findings provide a theoretical basis producing repellents or attractants for effective Integrated Pest Management of Z. cucurbitae.

Comparison of Dynamic Headspace Trapping on Tenax TA and Headspace Stir Bar Sorptive Extraction for Analysis of Grilled Chicken (Yakitori) Volatiles

Comparison of Dynamic Headspace Trapping on Tenax TA and Headspace Stir Bar Sorptive Extraction for Analysis of Grilled Chicken (Yakitori) Volatiles

Rapid Monitoring of Pharmacological Volatiles of Night-Flowering Evening-Primrose According to Flower Opening or Closing by Fast Gas Chromatography/Surface Acoustic Wave Sensor (Electronic zNose).

Aroma is important in night-flowering species, as visually they can not be observed well. Thus, the analysis of the volatiles of evening-primrose is of great interest in biological fields and therapy. Furthermore, the analysis of volatiles demands rapid and simple procedure, because volatiles decompose. The aim of this study is to show the rapid monitoring of the volatiles of evening-primrose according to the flowering or closing by fast gas chromatography/surface acoustic wave GC/SAW. Moreover, calibration according to the sensor temperature of the GC/SAW was performed, achieving a high reproducibility and excellent sensitivity. GC/SAW is an effective analytical method that provides on-line measurements without pretreatment of sample. Headspace solid-phase micro-extraction coupled to gas chromatography mass spectrometry (HS-SPME-GC-MS) and dynamic headspace trapping and extraction with GC-MS were employed to confirm the identification of the volatiles of evening-primrose compared to GC/SAW. Linalool was found to be the dominant component, comprising 96.4-25.2% of the total amount, according to the opening or closing. Interestingly, the amount of indole also varied according to the opening or closing (3.0-0.0%) such as linalool. Also, while the sensitivity increased with the reduction in the sensor temperature of the GC/SAW, the reproducibility showed a tendency to decrease. The results showed that flower opening is related to the volatiles emission, which is pharmacological and plant defensive. GC/SAW can be a useful analytical method for the rapid monitoring of volatiles of evening-primrose according to the opening or closing as it provides second unit analysis, as well as simple, and aroma pattern recognition. Copyright © 2017 John Wiley & Sons, Ltd.

Headspace trapping of the hydrides on a Pd(II)-coated graphite adsorptive bar as a microextraction method for ETV–ICP-MS determination of Se, Te and Bi in seawater and human hair samples

A new, simple and sensitive method by combining headspace Pd(II)-coated graphite bar microextraction (GBME) with electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS) was developed for the determination of trace Se, Te and Bi in seawater and human hair. In this method, the graphite bar was coated with Pd(II) and then used for headspace trapping of the hydrides of Se(IV), Te(IV) and Bi(III). The graphite bar with enriched hydrides of analytes was inserted directly into the graphite tube and subsequently determined by ETV-ICP-MS according to the established temperature program. The experimental parameters, which may affect the extraction and vaporization of target analytes, were systematically investigated and the optimal experimental conditions were established. Under the optimal conditions, the detection limits of the method were 8.6, 2.6 and 0.2 ng l(-1) and the relative standard deviations (RSDs) were 7.0%, 6.2% and 8.0% (C=0.20 microg l(-1), n=7) for Se, Te and Bi, respectively. Linearity was obtained over the range of 0.05-20.00, 0.01-5.00 and 0.01-20.00 microg l(-1) with the correlation coefficients of 0.9942, 0.9997 and 0.9976 for Se, Te and Bi, respectively. The proposed method was successfully applied for the determination of trace Se, Te and Bi in seawater and human hair samples. In order to validate the method, the proposed method has also been applied for the determination of trace Se, Te and Bi in the certified material of GBW07601 human hair, and the determined values were in good agreement with the certified values.

Volatile Release from Liquids: A Comparison of In Vivo APCI-MS, In-mouth Headspace Trapping and In vitro Mouth Model Data

In-mouth volatile release from flavoured water was followed using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) or using a hand-held, computer-controlled device based on sequential trapping of flavours on Tenax traps. The present results verify recent in vitro data obtained with a sophisticated, fully computerized mouth model apparatus and confirm its validity for the simulation of in-mouth dynamic volatile release. In-nose APCI-MS measurements showed considerable person-to-person variability in non-trained individuals during drinking due to subconscious control of muscles during swallowing and subsequent breathing. Data showed a 'swallow breath' volume reaching the nasal cavity from the throat, not from the mouth cavity. Flavour enriched air from the mouth was shown to be transported to the nose (via exhalation) immediately after the swallowing event, but the dynamic process of volatile equilibration between residuals of the swallowed liquid and the exhaled air predominantly determined volatile in-nose concentration. Owing to its dynamic character, the process of volatile equilibration and release in the throat upon exhalation should be similar to the in-mouth process studied in the present work. A full mechanical simulation of retronasal volatile transport, however, will remain difficult.

Studies on Turkish Rose Concrete, Absolute, and Hydrosol

The production of rose absolute from fresh flowers of the cultivated Rosa damascena Miller was realized using traditional and modern techniques, such as molecular distillation, extraction with liquified gases, etc. Headspace trapping and SPME techniques were employed in the sampling of volatile constituents in the concrete, absolute, and hydrosol, for analysis by GC/MS.

Comparison of the Volatile Components of Eight Cultivars of Potato after Microwave Baking

Eight cultivars of potato were baked in a microwave oven. The flavour components of the flesh were isolated by headspace trapping onto Tenax and analysed by gas chromatography–mass spectrometry. Lipid degradation and the Maillard reaction and/or sugar degradation were the main sources of the 80 flavour components identified. It is suggested that total levels of compounds and variations among their profiles may be attributed to differences in activities of lipid enzymes and levels of flavour precursors in the range of cultivars investigated.

Effect of pH and temperature on the formation of volatile compounds in cysteine/reducing sugar/starch mixtures during extrusion cooking.

Mixtures of cysteine, reducing sugar (xylose or glucose), and starch were extrusion cooked using feed pH values of 5.5, 6.5, and 7.5 and target die temperatures of 120, 150, and 180 degrees C. Volatile compounds were isolated by headspace trapping onto Tenax and analyzed by gas chromatography--mass spectrometry. Eighty and 38 compounds, respectively, were identified from extrudates prepared using glucose and xylose. Amounts of most compounds increased with temperature and pH. Aliphatic sulfur compounds, thiophenes, pyrazines, and thiazoles were the most abundant chemical classes for the glucose samples, whereas for xylose extrudates highest levels were obtained for non-sulfur-containing furans, thiophenes, sulfur-containing furans, and pyrazines. 2-Furanmethanethiol and 2-methyl-3-furanthiol were present in extrudates prepared using both sugars, but levels were higher in xylose samples. The profiles of reaction products were different from those obtained from aqueous or reduced-moisture systems based on cysteine and either glucose or ribose.

Choice and use of standards for dynamic headspace trapping and application to the analysis of the volatiles of baked potato.

When attempting to quantify the volatile components of a food isolated by dynamic headspace trapping onto an adsorbent, the analyst has to select the most appropriate compounds to use as standards and at which stage of the analysis to add them. Factors to be borne in mind include the volatility of the standard, the response of the GC detector, and whether to add the standard to the sample or to the adsorbent trap. This chapter considers the issues and describes the application of one chosen method to the quantitation of the volatile components of baked potato.

386 Volatiles of E. coli O157:H7 and Foodborne Pathogen Detection on Strawberry Fruit

Strawberry fruit were inoculated with the human pathogen E. coli O157:H7, and the bacteria were recovered from the fruit over a 3-day period of storage at room temperature. The bacterial population was maintained on fruit when the inoculation level was relatively high and increased when the inoculation level was low. The volatile metabolites of E. coli O157:H7 growing on plate count agar (PCA) and on inoculated strawberry fruit were collected by a headspace trapping system and analyzed by gas chromatography and GC-mass spectrometry. E. coli O157:H7 grown on PCA produced a variety of volatile compounds including indole as a major component and a series of methyl ketones. A nonpathogenic E. coli also produced these compounds. However, there was not an appreciable amount of indole collected from E. coli O157:H7 inoculated strawberry fruit as compared to the large amount of volatiles produced by the fruit. Strawberry fruit were able to capture over 95% of the vapor phase indole fed to them from a neat source.

Composition of the Essential Oil and the Headspace Sample of Mandragora autumnalis Bertol. Fruits

Fresh ripe fruits of Mandragora autumnalis were subjected to water distillation and headspace trapping. Both products were analyzed by GC/MS. In the essential oil, 100 compounds were characterized representing 92% of the oil with ethyl decanoate (14.2%), ethyl dodecanoate (13–1%) and decyl acetate (10.7%). Forty nine headspace constituents were identified making up of 99–2% of the total components detected. The main components were ethyl hexanoate (34.6%) and ethyl butyrate (25.5%).

Aroma Changes during Black Currant (Ribes nigrum L.) Nectar Processing

Aroma changes during processing of black currant nectar were examined both by the dynamic headspace trapping technique and by sensory evaluation. Pasteurized and enzyme-treated nectars were compared with control nectar. Significant differences were found for 13 aroma compounds, of which 10 were subsequently identified. Nine of the identified compounds were esters, and eight of these decreased in quantity during enzyme treatment. Additionally, a total of 14 terpenes or terpenols were identified, and only one of these changed significantly in concentration during enzyme treatment. Pasteurization caused only minor changes in the concentration levels of the volatile compounds. GC-sniffing was used to estimate the potency of individual aroma compounds; the fruit esters as well as the terpenoids were apparently significant contributors to the aroma of black currant nectar. Keywords: Aroma; juice; enzymation; pasteurization; black currant

ブドウ‘マスカット・オブ・アレキサンドリア’果汁の成熟中におけるモノテルペンの変化

Seasonal changes in monoterpene concentrations in the juice of Muscat of Alexandria grape were investigated. Volatile monoterpenes were analyzed by trapping them in the headspace with Tenax-TA. Reproductive results were obtained when headspace gas was trapped at 40°C for 180 min. In the headspace trapping method, the concentration of each monoterpene was slightly lower compared to those extracted with n-pentane directly from juice. Clear peak separations were obtained by gas chtomatography. Linalool increased rapidly from 30 days after veraison and reached a maximum in late September, it then declined. Geraniol increased slowly from the stone hardening stage to the overripe stage. Percentages of linalool and geraniol to total monoterpene at harvest were 66.3 and 27.0, respectively.

Warning Odor of the North American Porcupine(Erethizon dorsatum)

Volatile compounds in the lipid coating of the lower-back quills of the North American porcupine,Erethizon dorsatum, were collected using headspace trapping on Tenax and analyzed by gas chromatography–mass spectrometry (GC-MS), GC with organoleptic detection, and GC with a chiral stationary phase. Over 50 components were isolated, primarily oxygenated aliphatics, lactones, and isoprenoids. The most abundant constituent was tetradecyl acetate, which does not contribute significantly to the odor of the quill lipids. GC with a wide-bore capillary column and a human nose as detector was used to determine the retention time of the peak with the characteristic porcupine odor. Comparison of this organoleptic chromatogram with those obtained with a flame ionization detector and GC-MS showed the compound to be a δ-decalactone. The racemic mixture of this optically active substance does not possess the unique odor. Resolution of the enantiomers of δ-decalactone by GC with a chiral cyclodextrin phase shows that the isomer possessing the characteristic porcupine odor is the(R)-δ-decalactone. We suggest the biological function of this compound is to serve as a warning odor, which, in conjunction with an initial quill strike, produces a conditioned aversion in potential predators.

CHEMICAL AND SENSORY QUALITY OF BROCCOLI (BRASSICA OLERACEA L. VAR ITALICA)

ABSTRACTFive cultivars of broccoli (Brassica oleracea L. var. italica) were analyzed for individual glucosinolates, S‐methylcysteine sulfoxide (SMCSO), aroma volatiles and sensory quality. Total glucosinolate content ranged from 47 to 93 μmol μmol·g dry weight1, and SMCSO ranged from 22 to 57 μmol μmol·g dry weight1. A total of 11 glucosinolates were identified in the broccoli cultivars. The major glucosinolates were: progoitrin, glucoiberin, glucoraphanin, glucobrassicin and neo‐glucobrassicin and they accounted for more than 95% of the total content. Glucoiberin was only found in appreciable amounts in purple‐headed broccoli. Pentanol, pentanal, hexanal, heptanal and nonanal were the most abundant higher boiling volatiles isolated from cooked broccoli using dynamic headspace trapping on Porapak and solvent desorption with diethyl ether. Sensory analysis by a trained panel showed that scores for cooked vegetable odor (‘hay’ and ‘green peapod’) were significantly different between cultivars. In contrast, scores related to Brassica odor (‘cauliflower’ and ‘mustard’) were not significantly different. The content of individual glucosinolates, SMCSO and higher boiling volatiles in the cultivars is discussed in relation to the sensory quality of the cooked product.

Comparison of Dynamic Headspace Concentration on Tenax with Solid Phase Microextraction for the Analysis of Aroma Volatiles

Two different headspace extraction methods for aroma volatiles were compared: headspace solid phase microextraction (SPME), using both poly(dimethylsiloxane) (PDMS) and polyacrylate (PAc) fibers, and dynamic headspace trapping using a glass-lined stainless steel trap, containing Tenax TA. The samples studied were a cola and a diet cola. Extraction time and temperature were the same for each analysis. The dynamic headspace method extracted more volatiles from both samples than did SPME with either filament. The profile obtained using the PDMS fiber was similar to that of the Tenax TA extract but was much less intense. The PAc extract contained fewer components than the PDMS extract but included two polar volatiles not present in the other two extracts. Reproducibilities were similar for both techniques. Qualitative differences between the two cola samples were small, although the total quantity of volatiles extracted from the cola was up to 4 times greater than for the diet cola. Keywords: Cola; gas chrom...

Chemical and Genetic Attributes of a Maize-Silk Olfactory Trait

A maize inbred extracted from an Iowa synthetic (BSBB) produces silks with an odor that is easily detectable by most humans. The inbred did not demonstrate greater field resistance to ear-feeding by insects than sister lines from the same synthetic. The odorous trait was determined to be inherited as a recessive trait but could not be positively associated with a single gene when the odorous line was crossed with unrelated normal lines. Failure to produce a single-gene Mendelian ratio for F2 and backcross generations was attributed to errors in classification for a subjectively evaluated trait and the seeming incomplete penetrance of the trait, possibly due to the presence of modifying genes. Eleven compounds that differed from those obtained from nonodorous sister lines were separated and identified by headspace trapping and analysis by gas chromatographic and mass spectrometric techniques. A five-member panel clearly identified the odorous compound as indole.

Floral scent in bat-pollinated plants: a case of convergent evolution

The chemical composition of floral scent in eight bat-pollinated species belonging to six different plant families was investigated. Floral scent was collected by headspace trapping using porous adsorbents and the chemical composition determined by coupled gas chromatography-mass spectrometry. In all species except one the floral scent was found to include sulphur-containing compounds, of which several are reported for the first time in floral scents. Three species contained mushroom-like smelling fatty acid derivatives with a C8-skeleton. Such flowers may be recognized by pollinators as humid environments in otherwise dry surroundings. The presence of similar or chemically closely related sulphur containing compounds in floral scent of bat-pollinated plant species from differing families may represent a case of convergent evolution in scent composition and an adaptation to attract this specific group of pollinators with similar sensory preferences.

Headspace analysis of hyacinth flowers

AbstractThe volatiles of white hyacinths were isolated by dynamic headspace trapping. More than 70 constituents could be identified by GC and GC‐MS. The principal constituents were benzyl acetate and (E, E)‐α‐farnesene. Beside these, sensorily important substances like indole, oct‐1‐en‐3‐ol and phenylacetaldehyde were identified. Minor traces of three substituted pyrazines could be detected by GC‐sniffing. The advantages of the simultaneous “closed‐loop stripping” technique using various adsorbing agents at the same time were demonstrated. By this means artefact formation and discrimination of individual components could be determined.

New Method for Analyzing the Volatiles in Beer

A new method is reported for analyzing the medium- and high- boiling-point volatiles in beer, using CCl3F for extracting the whole volatiles and then the headspace trapping method with Tenax TA. This method seems to be effective for analyzing the flavor not only of beer but also of other beverages, especially those containing a large amount of ethanol.