Main Odor Research Articles

The contribution of biowaste disposal to odor emission from landfills

The biowaste fractions in municipal solid waste (MSW) are the main odor sources in landfill and cause widespread complaints from residents. The ammonia (NH3) and hydrogen sulfide (H2S) generation processes were simulated and compared between four typical biowaste fractions individually and combined in the mixed MSW. Food waste was found to be the main contributor to odor emission in mixed MSW, with H2S generation potential of 48.4 μg kg−1 and NH3 generation potential of 4742 μg kg−1. Fruit waste was another source for NH3 generation, with 3933 μg kg−1 NH3 generation potential. Meanwhile, nitrogen (N) was released in a faster way than sulfur (S) in waste, since 31% and 46% of total NH3 and H2S were generated in the first 90 days after disposal, with 1811 and 72 μg kg−1, and more emphasis should be placed in this initial period.Implications: Monitoring of odor generation from biowastes in MSW on a laboratory scale showed that food waste is the main source for NH3 and H2S generation, whereas waste fruit is another main contributor for NH3 released. Generally, N was released in a faster way than S from mixed-waste landfilling.

Effects of sediment capping to eliminate simulated alage-caused black bloom in eutrophic lakes

湖泛的发生与湖泊底部氧化还原条件和致黑致臭物充足供给直接相关.利用黄土和细沙对太湖湖泛易发区(月亮湾)底泥进行覆盖,模拟在湖泛可形成条件下,底泥-水体系及其界面主要物化性质与感官变化过程.结果表明:0.5cm黄土和1.0cm细沙的覆盖,从水色和嗅味半定量角度达到了对湖泛黑臭的控制,与对照组相比,覆盖组底泥间隙水中主要致黑物Fe²⁺浓度仅为对照组的1/3,主要致臭物甲硫醇和二甲基三硫醚等浓度则不到50%.进一步分析底部水体和底泥性质发现:经覆盖处理底部水体的溶解氧浓度提高近1倍,氧化还原电位基本处于250 mV以上水平,覆盖层1cm左右表层氧化还原电位和pH均远高于对照底泥.以黄土为主的底泥覆盖,主要因阻隔了下层底泥中物质迁移供给和对厌氧微生物参与的控制,以及黄土本身性质对湖底物化环境的影响等,在藻体大量聚集和死亡的水柱环境中,较好地阻止了致黑致臭物的形成,从而较有效控制湖泛的发生.;The occurrence of black bloom is directly related to adequate supply of odor and black substance and redox conditions at the bottom of lakes. Capping with losses and sand was conducted with the sediment from Yueliang Bay, which was heavily polluted and suffered from black blooms in the past years, to investigate the efficiency of black bloom control. The main characteristics of sediment-water system and sensory change process were analyzed. The results shows that capping with losses (0.5cm) and sand (1cm) control the formation of black bloom, from the perspective of visual and olfactory results (semi-quantitative). The main black substance (Fe²⁺) and odor substance (methanethiol and dimethyl trisulfide), in the pore-water of capping sediments was only 1/3 and 1/2 of the control cores, DO concentration and Eh of the bottom water was enhanced up to 100% and to 250 mV, respectively. Eh and pH of the surface capping sediment was also higher than uncapping control cores. Overall, the integrated capping system could eliminate the diffusion of nutrients from sediment and anaerobic microorganisms in the water, block the formation of taste and odors in the water, and prevent the occurrence of black bloom.

Volatile constituents of vetiver: a review

ABSTRACTA comprehensive and critical compilation of the volatile constituents of vetiver root (Chrysopogon zizanioides L.) is presented, including those present in its essential oil. This extremely complex material has stimulated analytical research for many decades in the hope of unravelling the secrets of its composition. Up to now, more than 300 molecules have been reported, mostly sesquiterpenoids possessing a large variety of skeletons, together with their norterpenic counterparts. This review attempts to clarify some of the discrepancies related to the characterization of these constituents, which were often due to the misuses of analytical methods without enough critical consideration of the literature. The identification of the main odour impact components of vetiver is also discussed, because much contradictory information appears in the literature on this subject. Copyright © 2014 John Wiley & Sons, Ltd.

Odour emission characteristics of 22 recreational rivers in Nanjing

The odour emission characteristics of 22 recreational rivers in Nanjing were investigated and analysed. Eight odorous compounds (ammonia (NH₃), hydrogen sulphide (H₂S), sulphur dioxide (SO₂), carbon disulphide (CS₂), nitrobenzene (C₆H₅NO₂), aniline (C₆H₅NH₂), dimethylamine (C₂H₇N), and formaldehyde (HCHO)) were measured in odour emission samples collected using a custom-made emission flux hood chamber. The results showed that all odorants were detected in all monitoring rivers. NH₃ was the main odorant, with emission rates ranging from 4.86 to 15.13 μg/min m(2). The total odour emission rate of the Nan River, at 1 427.07 OU/s, was the highest of the all investigated rivers. H₂S, NH₃ and nitrobenzene were three key odour emission contributors according to their contributions to the total odour emission. A correlation analysis of the pollutants showed there was a significant positive correlation between the emission rate of NH₃ and the concentration of ammonia nitrogen (NH₄ (+)-N) and total nitrogen (TN). The H₂S and SO₂ emission rates had a significant positive correlation with sulphides (S(2-)) and available sulphur (AS) in the water and sediment. The content of TN, NH₄(+)-N, S(2-) and AS in the water and sediment affected the concentration of H₂S, SO₂ and NH₃ in the emission gases. NH₄(+)-N, S(2-) and AS are suggested as the key odour control indexes for reducing odours emitted from these recreational rivers. The study provides useful information for effective pollution control, especially for odour emission control for the recreational rivers of the city. It also provides a demonstrate example to show how to monitor and assess a contaminated river when odour emission and its control need to be focused on.

삶은 달걀의 부패에 따른 부위별 냄새물질의 발생특성 연구

In this study, the concentration of odorants released from albumin (EA) and yolk (EY) portions of boiled egg samples were determined as a function of storage time. The concentrations were measured at storage days of 0, 1, 3, 6, and 9 under room temperature. As such, odorants produced during both fresh and decay conditions were measured through time. A total of 19 compounds were selected as the main target odorants along with 12 reference compounds. GC-MS (for VOC) and GC-PFPD system (for sulfur gases) equipped with thermal desorption (TD) system were employed for odorant analysis in this work. The initial concentrations measured from the chamber system were converted into flux terms (ng∙g∙min). The EA showed the highest concentration of H2S (234 ng∙g ∙min) at EA-0, and the concentrations of AT (Acetone) was also seen clearly in the range of 11.7 (EA-0) to 58.6 ng∙g∙ min (EA-9). The EY showed similar patterns. EtAl (Ethyl alcohol) increased 9.47 (EA-1) to 96.7 ng∙g∙min (EA-9) in EA samples. Ketone, alcohol, sulfur groups generally exhibited high concentrations compared to other odorants. These data were also compared in relation to olfactometry related dilution-to-threshold (D/T) ratio by air dilution sensory (ADS) test and sum of odor intensity (SOI).

Odorous gaseous emissions as influence by process condition for the forced aeration composting of pig slaughterhouse sludge

Compost sustainability requires a better control of its gaseous emissions responsible for several impacts including odours. Indeed, composting odours have stopped the operation of many platforms and prevented the installation of others. Accordingly, present technologies collecting and treating gases emitted from composting are not satisfactory and alternative solutions must be found. Thus, the aim of this paper was to study the influence of composting process conditions on gaseous emissions. Pig slaughterhouse sludge mixed with wood chips was composted under forcedaerationin 300L laboratory reactors. The process conditions studied were: aeration rate of 1.68, 4.03, 6.22, 9.80 and 13.44L/h/kg of wet sludge; incorporation ratio of 0.55, 0.83 and 1.1 (kg of wet wood chips/kg of wet sludge), and; bulking agent particles size of <10, 10<20 and 20<30mm. Out-going gases were sampled every 2days and their composition was analysed using gas chromatography coupled with mass spectrometry (GC–MS). Fifty-nine compounds were identified and quantified. Dividing the cumulated mass production over 30days of composting, by odour threshold, 9 compounds were identified as main potential odour contributors: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone, 1-propanol-2-methyl, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and acetophenone. Five gaseous compounds were correlated with both aeration rate and bulking agent to waste ratio: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone and 1-propanol-2-methyl. However, dropping the aeration rate and increasing the bulking agent to waste ratio reduced gaseous odour emissions by a factor of 5–10, when the required threshold dilution factor ranged from 105 to 106, to avoid nuisance at peak emission rates. Process influence on emissions of dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide were poorly correlated with both aeration rate and bulking agent to waste ratio as a reaction with hydrogen sulphide was suspected. Acetophenone emissions originated from the wood chips. Olfactory measurements need to be correlated to gaseous emissions for a more accurate odour emission evaluation.

Sensory Experiences and Expectations of Italian and German Organic Consumers

We explore sensory experiences and expectations of Italian and German organic consumers when purchasing and eating organic food. Ten focus group interviews were performed and the results were analyzed using qualitative content analysis. Outcomes indicated that although sensory attributes are not the main purchase drivers, flavor and odor are the most important in driving consumers' choice. Findings also suggested that training consumers' sensory abilities offers new market opportunities to organic marketers. From a marketing perspective, Italian consumers seem to equally appreciate nonsubjective as well as subjective marketing information about organic products, whereas in Germany non subjective aspects appear to be predominant.

Chemosignaling diversity in songbirds: Chromatographic profiling of preen oil volatiles in different species

Large foraging seabirds are known to navigate to food sources using their excellent sense of smell, but much less is known about the use of olfaction by the songbirds (passerine birds). Some evidence of individual recognition based on the bird preen oil volatile organic compound (VOC) compositions, which is the main odor source in birds, have been reported for dark-eyed junco and house finch. In this study we have investigated preen oil VOCs in 16 different songbird species and two other small bird species in order to determine whether the VOC compositions follow phylogenetic and evolutionary relatedness. We have used the stir bar sorptive extraction (SBSE) methodology followed by gas chromatography–mass spectrometry (GC–MS) to determine preen oil VOCs during the long light summer conditions for mostly wild caught birds. Large diversity among the VOC compositions was observed, while some compound classes were found in almost all species. The divergent VOC profiles did not follow the phylogenetic family lines among the bird species. This suggests that songbirds may use VOC odors as a mate recognition cue.

Aroma of Decontaminated Leaf and Fruit Spices

Selected leaf and fruit spices were steam decontaminated by original continuous process. Aroma compounds of spices were analyzed before and after decontamination. A total of identified 24 volatiles were identified in marjoram, 21 volatiles in thyme, 8 volatiles in caraway and 14 in coriander, as it was also mentioned by other authors. The GC/O analysis showed that the primary compounds responsible for aroma in analyzed spices were linalool and cis-sabinene hydrate in marjoram, thymol in thyme, carvone in caraway and linalool in coriander, which received the highest dilution factor values (FD) both before and after decontamination. It was determined that the content of the main odorants may be estimated by a SPME/GC method. On the basis of these compounds it was found that steam decontamination caused considerable losses in leaf spices. No significant changes were found in the content of volatile compounds in fruit spices as a result of decontamination. Also, chiral analysis of key odorants in spices did not show changes in the enantiomeric distributions (linalool in marjoram, carvone in caraway and limonene in coriander) as a result of decontamination.

Using the free comments method for sensory characterisation of Cabernet Franc wines: Comparison with classical profiling in a professional context

In this study, we adapt the free comments method to a professional wine panel and compare it with the classical profiling method. Indeed, the methods classically used for sensory analysis appear to be poorly suited to a professional wine panel, which is less time available than other panel types.The odour properties of thirty-one Cabernet Franc wines from the Loire Valley region were described by two distinct panels performing, respectively, a classical profiling and a free comments method. Both methods were performed by wine professionals without prior common training. The classical profiling data were analysed using analysis of variance (ANOVA), the Student Newman-Keuls (SNK) test and principal component analysis (PCA). The free comments data were analysed with a global Chi-square, a Chi-square per cell test and a correspondence analysis (CA). The data analysis was followed by a multiple factor analysis (MFA) allowing assessment of the correspondence between the sensory maps obtained using the two methods. As expected, a large number of descriptors were generated via the free comments method, providing rich information on the set of products. In general, the two methods underlined similar main odour characteristics of the Cabernet Franc wines. The free comments method was advantageous for highlighting the specific characteristics of a number of products. This method is less time consuming and allows easy characterisation of wines. In conclusion, the free comments method may represent a convenient alternative to conventional descriptive analysis in a wine professional context or a convenient sensory mapping tool for conducting the preliminary phases of sensory studies, such as the generation of attributes.

Volatile constituents of blue‐coloured hybrid tea rose flowers

ABSTRACTThe volatile constituents of ‘Blue Moon’ and ‘Blue Perfume’ rose flowers, which, on an olfactory basis, are classified as a ‘blue type’ were analysed using Aromascope® technology (modified headspace technology) and solvent extraction methods followed by gas chromatography–mass spectrometry analysis. One hundred and eighty components were identified in the headspace volatile components of ‘Blue Moon’ flower and 188 components were identified in solvent extracts. Among them, geraniol, nerol, citronellol, 1,3‐dimethoxy‐5‐methylbenzene and dihydro‐β‐ionol were identified as the main odour components. On the other hand, in ‘Blue Perfume’, 165 components were identified in the headspace volatile components and 150 components were identified in solvent extracts. Among them, geraniol, nerol, citronellol, neral, and geranial were identified as the major odour compounds. From both rose flowers, three components were newly identified: 2‐isopropyl‐4‐methylthiazole, (Z)‐cyclododec‐9‐enolide (yuzu lactone), and methyl cis‐(Z)‐jasmonate. 2‐Isopropyl‐4‐methylthiazole and methyl cis‐(Z)‐jasmonate were identified in both of the headspace components and solvent extracts of the two types of rose flower, and then yuzu lactone was identified only in solvent extracts as the one of the minor components. Several components identified in both flowers have asymmetric carbon atoms in their molecules, leading us to analyse their chirality. For the first time, the enantiomer ratios of linalool, (E)‐nerolidol, theaspiranes and dihydro‐β‐ionol could be assigned by multi‐dimensional gas chromatography–mass spectrometry. The results were as follows in both rose flowers. The ratio of the (S)‐enantiomer vs. the (R)‐enantiomer of linalool was 8:92. Only the (S)‐enantiomer was detected for (E)‐nerolidol and dihydro‐β‐ionol. The ratios of the (2R,5R)‐enantiomer vs. the (2S,5S)‐enantiomer in theaspirane A and the (2R,5S)‐enantiomer vs. the (2S,5R)‐enantiomer in theaspirane B were about 4:96. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Determination of compounds responsible for tempeh aroma

Tempeh is a fermented food, popular mainly in south-east Asia, but also among vegetarians worldwide. It is produced by fermenting soybean or other beans with Rhizopus strains and usually eaten deep-fried, steamed or roasted. The flavour of tempeh depends upon the fermentation time, beans used and the (eventual) frying process. Our goal was to identify compounds responsible for the unique aroma of fermented and fried soy tempeh. Gas chromatography–olfactometry (GC–O) with the aroma extract dilution analysis (AEDA) approach, was used to determine key odorants after 1 and 5days of fermentation and subsequent frying. Comprehensive gas chromatography–mass spectrometry (GC×GC–ToF-MS) was used for their quantitation using stable isotope dilution analysis (SIDA) or standard addition (SA) methods. Odour activity values (OAV) were calculated for 19 out of 21 key odorants. Tempeh was fermented for 5days and fried, and the main aroma compounds were found to be the following: 2-acetyl-1-pyrroline, (FD=1024, OAV 1380), 2-ethyl-3,5-dimethylpyrazine (FD=512, OAV 338), dimethyl trisulfide, (FD=512, OAV 900), methional (FD=512, OAV 930), 2-methylpropanal (FD=512, OAV 311) and (E,E)-2,4-decadienal (FD=512, OAV 455). The frying process induced the increase or appearance of the main key odorants in tempeh.

Identification of Aroma Active Compounds of Cereal Coffee Brew and Its Roasted Ingredients

Cereal coffee is a coffee substitute made mainly from roasted cereals such as barley and rye (60-70%), chicory (15-20%), and sugar beets (6-10%). It is perceived by consumers as a healthy, caffeine free, non-irritating beverage suitable for those who cannot drink regular coffee made from coffee beans. In presented studies, typical Polish cereal coffee brew has been subjected to the key odorants analysis with the application of gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). In the analyzed cereal coffee extract, 30 aroma-active volatiles have been identified with FD factors ranging from 16 to 4096. This approach was also used for characterization of key odorants in ingredients used for the cereal coffee production. Comparing the main odors detected in GC-O analysis of roasted cereals brew to the odor notes of cereal coffee brew, it was evident that the aroma of cereal coffee brew is mainly influenced by roasted barley. Flavor compound identification and quantitation has been performed with application of comprehensive multidimentional gas chromatography and time-of-flight mass spectrometry (GCxGC-ToFMS). The results of the quantitative measurements followed by calculation of the odor activity values (OAV) revealed 17 aroma active compounds of the cereal coffee brew with OAV ranging from 12.5 and 2000. The most potent odorant was 2-furfurylthiol followed by the 3-mercapto-3-methylbutyl formate, 3-isobutyl-2-methoxypyrazine and 2-ethyl-3,5-dimethylpyrazine, 2-thenylthiol, 2,3-butanedione, 2-methoxy phenol and 2-methoxy-4-vinyl phenol, 3(sec-butyl)-2-methoxypyrazine, 2-acetyl-1-pyrroline, 3-(methylthio)-propanal, 2,3-pentanedione, 4-hydroxy-2,5-dimethyl-3-(2H)-furanone, (E,E)-2,4-decadienal, (Z)-4-heptenal, phenylacetaldehyde, and 1-octen-3-one.

Method development for determining the malodor source and pollution in industrial park

Malodor pollution emitted from industrial park has become an important environmental issue. However, the difficulty in investigating malodor pollution is in determining the malodor source. The objective of this study was to develop a model for determining the malodor source and pollution in industrial park, via multiple time and site measurements of odor intensity and air pollutants, together with wind direction in different seasons, and the critical environmental factors could be also identified by correlating the odor intensities with meteorological conditions and the concentrations of air pollutants. A high-malodor-polluted industrial park involving metal and petrochemistry processing industries was selected as the study subject, and sampling was performed close to residential districts. Nine sites were selected as sampling points by a chessboard design, with each site measured for 5days in fall and spring, respectively. Odor intensity (ratings 0–5) and environmental factors, including meteorological condition, PM10, PM2.5, total volatile organic compounds (TVOCs), ammonia and reduced sulfides, were evaluated six times daily. The results indicated that the incidences of odor ratings 1–5 were 71.9% and 81.0% in two seasons in the sampling area, and an open ditch for collecting industrial wastewater for feeding to the wastewater treatment plant was identified as the main odor source. Multiple regression analysis showed that the odor rating significantly correlated with TVOC concentration and wind speed (P<0.05); odor intensity increased by 0.001 units on the rating scale for each 1ppb increase in TVOCs, and decreased by 0.154 units for each 1m/s increase in wind speed. This study developed a method to explore malodor pollution in industrial park, providing a novel thinking to understand and resolve malodor problems.

Evaluating the dispersion of toxic odour emissions from complex sources

This article describes an original approach for evaluating exposure to toxic odour emissions, based on methods commonly used for assessing the impact of odour, adopted in this specific case to examine the non-carcinogenic health effects of odours in the city of Terni, Italy. First the hazardous volatile organic compounds emitted from the main odour sources were identified and quantified by chemical analysis. The Hazard Index (HI) was used to assess the toxicity associated with the emissions. The HI is the sum of the concentrations of the hazardous compounds weighted with their Reference Concentration (RfC). A RfC is the estimated continuous inhalation concentration at which people are unlikely to risk any deleterious effects during their lifetime. Atmospheric dispersion modelling was based on the Toxicity Emission Rate (TER) which, like the Odour Emission Rate (OER) conventionally used to quantify odour emissions, relates the HI with the air flow of an emission source; it is as a simple but effective method for the general characterization of toxic odour emissions in complex scenarios. The results indicated that citizens’ exposure to the non-carcinogenic toxic compounds involved in odour emissions was below the level expected to have adverse effects on human health. Classical risk assessment techniques should now be employed to define the pollutants and their effects better and to validate this approach.

Volatile fingerprinting of chestnut flours from traditional Emilia Romagna (Italy) cultivars

The volatile profile of nine monocultivar chestnut flours, obtained from fruits grown in Italy (Parma province), was characterised by a head-space solid-phase microextraction (HS-SPME) coupled with GC-MS technique. The volatile fraction was composed of 44 main compounds belonging to different classes, mainly aldehydes, ketones, alcohols, furans and terpenes. Aldehydes, in particular hexanal, are the most abundant components. In order to better understand the origin of the different volatile compounds during the drying and milling processes, samples of fresh fruit were also analysed by the same technique and the data obtained were statistically and critically compared in order to get a picture of the volatile evolution in chestnut from fresh fruit to flour. Finally, the nine monocultivar flours were chemometrically classified on the basis of the main odour descriptors associated with the volatile fingerprinting.

Main Odorants in Jura Flor-Sherry Wines. Relative Contributions of Sotolon, Abhexon, and Theaspirane-Derived Compounds

The aromatic profile of Jura flor-sherry wines (also called "yellow wines") has been little studied. Only acetaldehyde, diethoxy-1,1-ethane, and sotolon have been described as key odorants. In the present work, three wines (vintages 2002 and 2003) were investigated by gas chromatography-mass spectrometry and gas chromatography-olfactometry (GC-O) aroma extract dilution analysis. The goal was to assess the relative impact of varietal, fermentation, and oak-barrel compounds by using two complementary extraction procedures. No grape terpenoids were found after the long barrel aging (6 years and 3 months). On the other hand, two candy/fruity esters issued from yeast exhibited high flavor dilution factor (FD) values: ethyl isobutyrate (64-1024) and ethyl isovalerate (128-1024). As expected, many oak-related odorants were found in the XAD 2 flavor extracts, mainly homofuraneol [2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone] (cotton candy, FD = 16-256) and cis-β-methyloctalactone (butter, woody, FD = 256). Most probably issued from oxidation of the grape constituent theaspirane, an exceptional grenadine odor was perceived by GC-O up to dilution 64-1024. Chemical oxidation experiments and GC-high-resolution mass spectrometry (HRMS) allowed us to identify it as 4-hydroxy-7,8-dihydro-β-ionone (RI(CPsil5CB) = 1373), a hydrolysis-derived product of dihydrodehydro-β-ionone. With an extraction dedicated to hydrophilic compounds, the key role of sotolon was confirmed (112-387 μg/kg; FD = 256-1024). This procedure enabled us to also evidence its ethyl analogue, abhexon (31-74 μg/kg; FD = 64-256).

Characterization and control of odorous gases at a landfill site: A case study in Hangzhou, China

Municipal solid waste (MSW) landfills are one of the major sources of offensive odors potentially creating annoyance in adjacent communities. At the end of May 2007, an odor pollution incident occurred at the Tianziling landfill site, Hangzhou, China, where the residents lodged complaints about the intense odor from the landfill, which drew a significant attention from the government. In this study, ambient air monitoring was conducted at the Tianziling landfill site. The main odor composition of the gas samples collected on June 1st 2007 and the reduction of various odorous gases from the samples collected on June 1st 2009 due to the applied odor control techniques were determined using gas chromatography-mass spectrometry (GC-MS). In addition, variations of primary odorous gaseous (NH 3 and H 2S) concentrations at different locations in the landfill site from July 2007 to June 2009 were also investigated by using classical spectrophotometric methods. Results showed that a total of 68 volatile compounds were identified among which H 2S (56.58–579.84 μg/m 3) and NH 3 (520–4460 μg/m 3) were the notable odor components contributing to 4.47–10.92% and 83.91–93.94% of total concentrations, respectively. Similar spatial and temporal shifts of H 2S and NH 3 concentrations were observed and were significantly affected by environmental factors including temperature, air pressure and wind direction. Odor pollution was worse when high temperature, high humidity, low air pressure, and southeast, northeast or east wind appeared. Moreover, the environmental sampling points of the dumping area and the leachate treatment plant were found to be the main odor sources at the Tianziling landfill site. The odor control technologies used in this project had a good mitigating effect on the primary odorous compounds. This study provides long-term valuable information concerning the characteristics and control of odors at landfill sites in a long run.

Chemical and sensory characterisation of aroma of Viburnum opulus fruits by solid phase microextraction-gas chromatography–olfactometry

The aroma profile of four cultivars of Viburnum opulus and one cultivar of V. opulus var. sargentii fruits was studied by solid phase microextraction of headspace volatiles and subsequent analysis by gas chromatography, mass spectrometry and olfactometry (SPME-HS-GC–MS–O). In total, 41 compounds were identified, 3-methyl-butanoic acid (63.0–71.8% of identified volatile organic compounds) being the major constituent in the three V. opulus cultivars, while 2-octanone was dominant in one cultivar of V. opulus and in V. opulus var. sargentii, amounting to 28.1% and 25.6% of identified volatile compounds, respectively. Ten odour active compounds were detected and characterised by the trained panel of judges in the course of GC–O by using detection frequency analysis (DFA). 3-Methyl-butanoic and 2-methyl-butanoic acids as well as linalool and ethyl decanoate were found to be the main odour active components for V. opulus aroma.

Combining different analytical approaches to identify odor formation mechanisms in polyethylene and polypropylene

In a previous study, we identified carbonyls as highly odor-active compounds in both unprocessed and processed polypropylene (PP) with higher intensities after processing, indicating a temperature-driven forming mechanism. In the presented work, we studied whether (a) these carbonyls are the major odor drivers to the overall odor of polyolefins, (b) their formation is taking place already at moderate temperatures well below the typical processing temperatures, (c) conventional antioxidants in polyolefins can prevent or reduce their formation, and (d) whether reducing the amount of oxygen present can decrease the overall odor. One polyethylene (PE) and one PP were selected, and both stabilized and unstabilized polymer powder samples were exposed to conditions differing in oxygen concentration and aging time. The changes in the volatile fraction as well as the formation of odor-active compounds were monitored using a multidisciplinary approach by combining analytical methods based on gas chromatography (GC), multivariate data analysis, and sensory methods (GC-olfactometry and a sensory panel). Both investigated materials (PE and PP) showed similar degradation products (aldehydes, ketones, carboxylic acids, alcohols, and lactones) which increased dramatically with increasing aging time and the lack of stabilization. Oxidation products, mainly carbonyl compounds, were responsible for the odor of the investigated materials. The main odor drivers were unsaturated ketones and aldehydes with a chain length between six and nine C-atoms. Interestingly, similar odor patterns were found for both stabilized and unstabilized samples, indicating that similar formation processes take place independent of the stabilization.