• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 54
  • 6
  • 6
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 93
  • 19
  • 12
  • 9
  • 9
  • 8
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Determination of character-impact odorants in hop essential oils using hyphenated techniques in gas chromatography

Eyres, Graham Terence, n/a January 2007 (has links)
Hops (Humulus lupulus L.) are an indispensable component of beer, with the essential oil responsible for imparting distinctive odour and aroma characteristics to beer. However, not all character-impact odorants in hop essential oil have been identified and hop aroma in beer is still not completely understood. The composition of hop essential oil is very complex with 485 compounds currently identified in the literature, and recent research suggests that up to 1000 compounds may actually be present. Only a certain number will be present at concentrations above threshold and make a direct contribution to the odour of the oil. In addition, many important odorants are only present at trace concentrations. Gas chromatography-olfactometry (GC-O) using human assessors is the best way to locate potent odorants and facilitate their identification. A novel methodology was developed to identify the character-impact odorants in hop essential oil samples using hyphenated techniques in gas chromatography. GC-O was used to locate odour active compounds and determine relative importance using CharmAnalysis[TM] according to the odour potency principle. Due to the chemical complexity of the samples, considerable co-elution of peaks occurs during single column gas chromatography (1DGC), making the detection and identification of character-impact odorants challenging. Therefore, comprehensive two-dimensional gas chromatography (GCxGC) combined with time-of-flight mass spectrometry (TOFMS) was used to resolve and identify compounds eluting in the odour active regions. The methodology was developed in a case study on coriander (Coriandrum sativum) and wild coriander (Eryngium foetidum) leaf essential oils. During GC-O analysis of these samples it was recognised that odour active regions frequently coincide with several co-eluting compounds. To address this, a heart-cut multidimensional gas chromatography-olfactometry (MDGC-O) instrument was developed to resolve these 'co-eluting odour clusters' and determine the compound(s) responsible for the odour perception. The 'spicy' character of hops is considered to be a desirable attribute in beer associated with 'noble hop aroma'. However, the compounds responsible have yet to be adequately elucidated. This character was investigated using a commercial 'Spicy' fraction of hop essential oil, selectively enriched for monoterpene and sesquiterpene alcohols. The odour active compounds in (i) the spicy fractions and (ii) the whole essential oils of four different hop varieties were compared using the presented methodology. A compound with an intense 'woody, cedarwood' odour was determined to be a potent, character-impact odorant in all samples. This odour coincided with a complex region of the chromatogram where up to thirteen compounds were co-eluting. The peak responsible for this odour was determined by (i) correlation of peak areas with odour potency (Charm) values and (ii) MDGC-O. The compound was tentatively identified by GCxGC-TOFMS as 14-hydroxy-β-caryophyllene, which has not previously been reported as an odorant in hop essential oil. It was concluded that this compound and other 'woody, cedarwood' odorants contributed to the 'spicy' character of the investigated hop samples. Compounds previously associated with noble hop aroma, notably caryophyllene oxide, humulene epoxides I and II, and humulenol II, did not contribute to the odour character of the hop samples. Other potent odorants that were identified in the whole essential oil and spicy fractions of hops were: geraniol, linalool, β-ionone, eugenol, isovaleric acid, and β-damascenone. While myrcene was a moderately potent odorant in the whole hop essential oil samples, the abundant sesquiterpene hydrocarbons α-humulene, β-caryophyllene and β-farnesene did not significantly contribute to the odour character.
52

Odor sensitivity in CD-1 mice for "green" odors

Murali, Sathish kumar January 2011 (has links)
―Green‖ odors comprise a group of eight structurally related aliphatic alkenals and alkenols which are characteristic for the odor of a wide variety of plant materials. Using an automated olfactometer, the olfactory detection thresholds for ―green‖ odors were determined in six CD-1 mice and compared with that of spider monkeys and human subjects. Detection threshold values for alcoholic ‖green‖ odors (cis-3-hexen-1-ol, trans-3-hexen-1-ol, trans-2-hexen-1-ol and 1-hexanol) ranged from 8.1 x 109 to 8.1 x 1011 molecules/cm3 and for aldehydic ‖green‖ odors (cis-3-hexenal, trans-3-hexenal, trans-2-hexenal and n-hexanal) , from 8.1 x 107 to 8.1 x 1011 molecules/ cm3 . Detection threshold values of ―green‖ odor with double bond ranged from 8.1 x 107 to 8.1 x 1011 molecules/cm3 and for ―green‖ odor without double bond ranged from 8.1 x 108 to 8.1 x 1011 molecules/cm3. Detection threshold value of cis- configured ―green‖ odors ranged from 8.1 x 108 to 8.1 x 1011 molecules/ cm3 and for trans- configured ―green‖ odors threshold value ranged from 8.1 x 107 to 8.1 x 1011 molecules/ cm3. Trans-2-hexenal with a double bond at C-2 position in its molecular structure yielded the lowest detection threshold value when compared the other ―green‖ odors (8.1 x 107 to 8.1 x 109 molecules /cm3) which shows not only the presence of double bond plays a major role in detection but the position of the double bond present. A comparison between the present data and data from the other species showed that CD-1 mice displayed lower detection thresholds for all ‖green‖ odors than human subjects and spider monkeys except for the cis-3-hexen-1-ol odor. These findings suggest that the differences in the threshold values between ―green‖ odors are due to the difference in the molecular structure like the presence of double bond and the position of double bond.
53

Chemical Scrubbing of Odorous Fumes Emitted from Hot-Melted Asphalt Plants

Chen, Po-cheng 11 August 2011 (has links)
Hot-melted asphalt (HMA) plants use sized gravels, asphalt and/or recycled asphalt as raw materials. In the plant, the materials are heated to certain preset temperatures and blended at fixed ratios at around 170oC to prepare the required HMA for road paving. In the asphalt-melting, hot-blending and dumping operations, fumes and particulates emit from the process equipments. The emitted gases contain various volatile organic compounds (VOCs) and poly aromatic hydrocarbons (PAHs) which are harmful to the health of the plant workers and nearby residents. Complaints from the residents also come with the fume and odorous emissions. In this study, an oxidation-reduction-in-series scrubbing process was tested to remove odorous compounds in waste gases emitted from HMA plants. Waste gas samples for test were collected from the vent hole of an oven which contains a heated sample of asphalt or recycled asphalt concrete. Sodium hypochlorite solution was used to scrub and oxidize the compounds and hydrogen peroxide to reduce the chlorine emitted from the oxidative scrubber. A gas chromatography with a mass spectrophotometric detector (GC-MSD) was used for the identification of the odorous species and their concentrations in the waste gases. Sensory tests were also used to determine the odor removal efficiency. GC-MSD examination results indicates that alkanes, arenes, alkenes, halides, esters, and carbonyl compounds were detected in the test gas. Scrubbing test results indicate that with oxidative solution of 50-60 mg/L residual chlorine at pH 7.0-7.5 and reductive solution of 35 mg/L hydrogen peroxide at pH >12, over 90% of the VOCs in the tested gas could be removed. Odor intensities could be reduced from 3,090 (expressed as dilutions to threshold) to 73. Pungent asphalt odor in the test gas was turned into slight sulfur smell after the scrubbing. For removing the odors from 500 Nm3/min of the flue gas vented from a HMA plant, an analysis indicates the required total cost for chemicals (sodium hypochlorite solution, hydrogen peroxide and sodium hydroxide) added to the scrubbers was around 2,800 NT$/day (US$ 95/day) for a daily operation time of 10 hours. The cost is far lower than that by the traditional thermal incineration one (25,000 NT$/day or US$ 850/day) or by the regenerative thermal oxidation (RTO) one (14,300 NT$/day or US$ 485/day). This study has successfully developed an economical and effective chemical scrubbing technology for the removal of odorous compounds in gases emitted from HMA plants.
54

Cellular and Synaptic Organization of the Human Olfactory Bulb

Maresh, Alison 04 March 2008 (has links)
The distribution of cell types and synapses is well characterized in the rodent olfactory bulb (OB), and from that plausible models of odor processing have been constructed. Individual olfactory sensory neurons (OSNs) express only 1 of ~1000 odorant receptors (ORs) and send their axons to specific synaptic targets in the OB glomerular neuropil. Each glomerulus is innervated exclusively by OSN axons expressing the same OR. The distribution of these glomeruli is conserved across animals, as is the numerical relationship between number of expressed ORs and number of glomeruli in the OB. Our objective is to extend such results to the level of the human OB to determine how its cellular and synaptic organization, and more specifically how the number and distribution of its glomeruli, compare to what has been elucidated in mice. As there are ~2,000 glomeruli for ~1,000 ORs in mice, we predicted ~700 glomeruli in humans based on the ~350 intact OR genes identified in the human through genomic studies. Using immunohistochemistry, the organization of cells and synapses in human OBs was evaluated and quantified. While the laminar structure of the OB is broadly conserved between species, in the human OB the laminar organization as well as additional structural features suggest a less rigorously organized OB than in rodents, perhaps suggesting that odor processing in the human OB may be less efficient than in mice. Of particular note, the total number of glomeruli in the human OB differs significantly from predicted and demonstrates a high degree of variability amongst specimens, thus far ranging from approximately 3000 - 9000/OB. These results indicate that the principles of OR-homotypic axon convergence developed from mouse studies may not be readily applicable to the human, and that central processing of odor signals in the human may differ from those characterized in the mouse.
55

Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking

Dickman, Brian D. 17 November 2008 (has links)
The main focus of the current study was to quantify the chemical signals received by a blue crab (Callinectes sapidus) tracking a source in a laboratory flume. To make a direct linkage between tracking behavior and the odorant concentration signal, we developed a measurement system to quantify the instantaneous concentration field surrounding actively tracking blue crabs. A three-dimensional laser-induced fluorescence (3DLIF) system was designed and constructed to measure odorant concentrations around crabs tracking three source types: a continuous release with exit velocity matching the mean local velocity in the flume; a continuous release with a meander created by an upstream cylinder; and a pulsed release switching on and off and with the same mass flow rate as the other two plume types. The meandering and pulsed plumes were introduced to observe the effects of large-scale spatial (meandering) and temporal (pulsed) intermittency on crab tracking. Simultaneous with the chemical concentration measurements, crab position data was recorded for kinematic analysis during post-processing. In addition, concentration measurements were collected for the three plume types without crabs present in order to quantify the statistical characteristics of the plume structure The concentration signals arriving at the antennules and outer chemosensory organs, most notably the legs, were targeted due to the hypotheses that concentration bursts at the antennules mediate upstream movement and that spatial contrast at the leg chemosensors mediates turning. A sampling zone was placed in front of the crab's mouth parts and aligned with the crab carapace orientation to extract odorant bursts at the antennules. The data generally showed an increase in upstream walking speed when high concentration bursts arrive at the antennules location, which agrees with the hypothesis. Measurement of the odorant concentration at the outer chemosensors was less direct and involved placing a box upstream of the crab and sampled earlier in time in order to avoid shadowing interference. Based on the signal at the upstream sampling box, a general bias for turning was observed. Crabs casted transversely in response to the directional bias extracted from the upstream sampling box. A statistical analysis of crab behavioral response to concentrations at the antennules and outer chemosensors can be found in a (future) companion thesis written by Jennifer Page in the School of Biology. Data were also taken for the three plume types in the absence of blue crabs. The continuous plume average statistics displayed Gaussian behavior at nozzle centerline. The meandering plume data conformed to the meandering plume model of Gifford (1959), modified for an induced pseudo-periodic meander. The pulsed plume displayed characteristics intermediate between the cloud dispersion model (Townsend 1951, Chatwin and Sullivan 1979) and the Gaussian dispersion model for a continuous release. For the three plume types, the standard deviation of the concentration fluctuations was greater than the average concentrations, as time records consisted of intermittent high concentrations interspersed with concentrations close to zero.
56

Microbead array-based artificial nose : explosives detection and simple/complex odor discrimination /

Albert, Keith J. January 2001 (has links)
Thesis (Ph.D.)--Tufts University, 2001. / Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
57

Prevalence and influence on quality of life of symptoms caused by inhaled odors, chemicals and irritants : a comparison between Hispanics and Americans

Perez, Carmen. January 2009 (has links)
Thesis (M.S.P.H.)--University of South Florida, 2009. / Title from PDF of title page. Document formatted into pages; contains 68 pages. Includes bibliographical references.
58

Processo biotecnológico para obtenção dos compostos 2-feniletanol, acetato de 2-feniletil e B-cariofileno pela utilização de resíduo de goiaba

Galvão, Mércia de Sousa 28 February 2014 (has links)
The increasing demand for flavors in the world market requires new strategies for obtaining these compounds which can be produced via fermentation processes using low cost substrates such as agroindustrial residues. This turns out to be a viable process and the aroma compounds generated are classified as natural. Large volumes of waste in the form of bagasse, husks, kernels or seeds including from the processing of fruit pulp are generated and these can be used as substrates in these fermentations. Thus the main purpose of this work was to use agro-industrial residues for the production of volatile aroma compounds by fermentation processes. In this regard, we investigated the potential of the production of volatile compounds by submerged fermentation using guava, passion fruit and umbu processing waste as substrates using endophytic microorganisms isolated from guava, passion fruit and umbu as well as by using the pure cultures (Aspergillus niger, Kluyveromyces marxianus and Kluyveromyces lactis) to produce volatile compounds characteristic of fruity or floral aroma. Initially the fruit pulp and wastes from the processing of guava, passion fruit and umbu were chemically characterized (moisture, ash, fiber, proteins, lipids, sugars, titratable acidity, Aw, pH and soluble solids). Fermentation with different microorganisms in synthetic medium was performed and the fermented products analyzed for aroma note. From the results of this sensory analysis, the guava residue and the yeast Kluyveromyces lactis were selected since these constituents in the medium produced fruity and floral aromas. The volatile compounds produced were captured by two headspace techniques (SPME and Purge & Trap) and analyzed in a system of gas chromatography coupled to mass spectrometry. Sixty-two microorganisms were isolated and out of these six were selected. The fermented products were analyzed for pH, soluble solids and reducing sugars as well as to establish the kinetics of the fermentation process at every 24 hours for five days. The main aroma descriptors in the fermented products were fruity, honey, fruity green, plum, guava, banana and alcohol type notes. Forty-three volatile compounds were detected in the fermented product obtained by using the Guava residue in the medium. Among the compounds identified were: Ò {caryophyllene, 2-phenylethyl acetate, × n- humulene, bisabolene, humulene, 3-methyl butanol, bergamoteno, × n-cadinene, caryophyllene oxide and 2-phenylethanol. The production of volatile compounds was quite rapid and in most cases, this production occurred on the first day of fermentation and had achieved its maximum concentration between 24-48h of fermentation. According to the response surface method analysis, the conditions of the manufacturing process were optimized. Increased production of 2- phenylethyl acetate was achieved at concentrations varying from 25 and 35g/L of yeast extract, 40 to 60 g/L glucose. Ò-caryophyllene was obtained at concentrations varying between 120 and 140g/L of guava waste, and an agitation performed between 160 and 180 rpm. The production of 2-phenylethanol was obtained at agitation varying from 228rpm and 5g/L glucose. From these optimized conditions, scale-up of fermentation was performed in a bioreactor wherein 6 times larger concentration of 2-phenylethanol and Ò-caryophyllene compounds, and 1.5 times higher concentration of 2-phenylethyl acetate were obtained. This study reveals that guava residue can be used to produce aroma compounds of great importance for the flavor and fragrance industry, the compounds being 2-phenylethyl acetate, 2-phenylethanol and Ò -caryophyllene. / A crescente demanda de aromas no mercado mundial exige novas estrategias de obtencao desses compostos. A obtencao via processos fermentativos utilizando substratos de baixo custo e uma alternativa economicamente viavel e o aroma gerado e considerado como natural. Grandes volumes de residuos na forma de bagacos, cascas, carocos ou sementes sao gerados pelo processamento de frutas, e estes podem ser utilizados como substratos nesses processos fermentativos. Diante desse contexto, esse trabalho teve como principal finalidade utilizar residuos agroindustriais para a producao de compostos volateis de aroma atraves da fermentacao submersa. Neste sentido, foi verificada a potencialidade da producao de compostos volateis atraves da fermentacao submersa utilizando residuos de goiaba, maracuja e umbu como substratos utilizando microrganismos endofitos da goiaba, maracuja e umbu de cultura puras (Aspergillus niger, Kluyveromyces marxianus e Kluyveromyces lactis) para produzir compostos volateis de aroma frutal ou floral. Inicialmente a polpa e os residuos de goiaba, maracuja e umbu foram caracterizados quimicamente (umidade, cinzas, fibras, proteinas, lipideos, acucares, acidez titulavel, Aw, pH e solidos soluveis). Foram realizadas fermentacoes com os diferentes microrganismos em meio sintetico, onde os produtos fermentados foram analisados sensorialmente. A partir dos resultados obtidos da analise sensorial, o residuo de goiaba e a levedura Kluyveromyces lactis foram selecionados uma vez que estes apresentaram a melhor capacidade de producao de aromas. Os compostos volateis produzidos foram capturados por duas tecnicas de headspace (MEFS e Purge & Trap) e analisados por cromatografia gasosa acoplada a espectrometria de massas. Foram isolados 62 microrganismos, dentre estes seis foram selecionados e os produtos fermentados foram analisados por cromatografia gasosa como tambem as caracteristicas de pH, solidos soluveis e acucar redutor para estabelecer a cinetica do processo fermentativo a cada 24h durante cinco dias. As principais descricoes de aroma para o fermentado de residuo de goiaba foram frutal, mel, fruta verde, ameixa, goiabada, banana, fermento e alcool. Foram detectados 43 compostos volateis no produto fermentado obtido pelo uso do residuo de goiaba. Dentre os compostos identificados destacam-se: Ò-cariofileno, acetato de 2-feniletil, ×-humuleno, bisaboleno, humuleno, 3-metil butanol, bergamoteno, ×-cadineno, oxido de cariofileno e 2-feniletanol. A producao dos compostos volateis foi bastante rapida, e na maioria dos casos, essa producao aconteceu a partir do primeiro dia de fermentacao e teve o seu maximo entre 24-48h de fermentacao. Segundo a analise da superficie de resposta, o processo de producao foi otimizado, onde a maior producao do acetato de 2-feniletil foi obtida em concentracoes entre 25 a 35g/L de extrato de levedura, entre 40 a 60 g/L de glicose; do Ò-cariofileno foi obtido em concentracoes entre 120 a 140g/L de residuo de goiaba, e agitacao entre 160 e 180 rpm enquanto a producao do 2-feniletanol foi obtida na agitacao entre 228rpm e 5g/L de glicose. A partir dessas condicoes otimizadas foi possivel realizar um escalonamento da producao desses compostos no biorreator e foi possivel obter uma producao 6 vezes maior para os compostos 2-feniletanol e Ò-cariofileno, e 1,5 vezes para o acetato de 2-feniletil. Desta forma, neste trabalho verifica-se que o residuo de goiaba e leveduras isoladas de frutas podem ser utilizados para produzir compostos de aroma de grande importancia para a industria de aromas e fragrancias, como o acetato de 2-feniletanol, o 2-feniletanol e o Ò-cariofileno.
59

Modelo experimental de diferenciação por odores entre migrânea e outras cefaleias primárias

SILVA-NÉTO, Raimundo Pereira da 01 April 2016 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-10-20T11:59:35Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Doutorado_Raimundo Pereira da Silva-Néto.pdf: 12833897 bytes, checksum: 61d0b7e980e72887cfbdb059a1866d40 (MD5) / Made available in DSpace on 2016-10-20T11:59:35Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Doutorado_Raimundo Pereira da Silva-Néto.pdf: 12833897 bytes, checksum: 61d0b7e980e72887cfbdb059a1866d40 (MD5) Previous issue date: 2016-04-01 / Cefaleias primárias são decorrentes de disfunção cerebral e incluem migrânea, cefaleia do tipo tensional, cefaleias trigêmino-autonômicas e outras. Diversos fatores podem desencadear crises de cefaleia, mas os odores, especialmente o perfume, estão associados à migrânea. Objetivos: Caracterizar a estimulação olfatória como fator desencadeante de crises de cefaleia e de diferenciação entre migrânea e outras cefaleias primárias. Sujeitos e Métodos: O estudo foi prospectivo, experimental, randomizado com comparação de grupos, realizado no período de março a junho de 2015. Foram convidados 158 voluntários (73 homens e 85 mulheres) diagnosticados com cefaleias primárias, de acordo com os critérios da International Classification of Headache Disorders, Third Edition (beta version) (ICHD-3β). O estudo foi realizado por dois examinadores; atribuiu-se ao primeiro, diagnosticar a presença e o tipo de cefaleia primária, enquanto o segundo foi responsável pela exposição dos voluntários ao odor e pelo registro dos efeitos dessa exposição. Resultados: Dos 158 voluntários com cefaleia, houve 72 (45,6%) casos de migrânea e 86 (54,4%) com outras cefaleias primárias. Dos 72 migranosos, 53 (73,6%) eram mulheres e 19 (26,4%), homens e dos 86 casos de outras cefaleias primárias, 32 (37,2%) eram mulheres e 54 (62,8%), homens. A idade dos voluntários com migrânea e com outras cefaleias primárias foi, respectivamente, 22,5±3,10 e 22,9±3,10 anos. Essas diferenças não foram significantes (tmédias=0,666; p=0,566). Nos dois grupos, houve diferença nas características da cefaleia (c2=4,132; p=0,046). O odor desencadeou cefaleia (25/72; 34,7%) e náusea (5/72; 6,9%) apenas nos voluntários com migrânea, correspondendo a 19,0% (30/158) da amostra e em nenhum com outras cefaleias primárias (χ²=43,78; p<0,001). A cefaleia ocorreu mais frequentemente associada à náusea (p=0,146) e de localização bilateral (p=0,002) nos migranosos que apresentaram cefaleia desencadeada por odor. A cefaleia foi desencadeada após 118,0±24,6 min e a náusea após 72,8±84,7 min da exposição ao odor. Conclusões: O odor desencadeou crises de cefaleia ou náusea apenas nos pacientes com migrânea. Portanto, cefaleia desencadeada por odores poderá ser considerada um fator de diferenciação entre migrânea e outras cefaleias primárias e esse gatilho parece muito específico da migrânea. / Primary headaches are due to brain dysfunction and include migraine, tension-type headache, trigeminal autonomic cephalalgias and others. Several factors can trigger headache attacks, but odors, especially perfume, are associated with migraine. Objectives: To characterize the olfactory stimulation as a trigger of headaches and differentiation of crises between migraine and other primary headaches. Subjects and Method: The study was prospective, experimental, randomized with comparison of groups and conducted from March to June 2015. One hundred fifty-eight volunteers (73 men and 85 women) were diagnosed with primary headaches, according to criteria of the International Classification of Headache Disorders, third edition (beta version) (ICHD-3β). The study was conducted by two examiners and assigned to the first to diagnose the presence and type of primary headache, while the second was responsible for exposing the volunteers to odor and the recording the effects of this exposure. Results: Of the 158 volunteers with headache, there were 72 (45.6%) cases of migraine and 86 (54.4%) with other primary headaches. Of the 72 migraineurs, 53 (73.6%) were female and 19 (26.4%) male and 86 cases of other primary headaches, 32 (37.2%) were female and 54 (62.8%) male. The age of subjects with migraine and other primary headache was, respectively, 22.5 ± 3.10 and 22.9 ± 3.10 years. These differences were not significant (tmean=0.666; p=0.566). In both groups, there were differences in headache characteristics (c2=4.132; p=0.046). Headache attacks (25/72; 34.7%) and nausea (5/72; 6.9%) were triggered only in subjects with migraine, corresponding to 19.0% (30/158) of the sample, but in no with other primary headaches (χ²=43.78; p<0.001). Headache occurred more often associated with nausea (p=0.146) and bilateral location (p=0.002) in migraineurs who had headache triggered by odor. Headache was triggered after 118.0±24.6 min and nausea after 72.8±84.7 min of exposure to odor. Conclusions: The odor triggered headache attacks or nausea only in migraineurs. Therefore, headache triggered by odors may be considered a factor of differentiation between migraine and other primary headaches and this trigger seems very specific of migraine.
60

Composição de volateis e earoma de salames nacionais tipos Italiano e Milano / Volatile composition and flavour of Italian types dry fermented sausage produced in Brazil

Wagner, Roger 23 July 2008 (has links)
Orientadores: Maria Aparecida Azevedo Pereira da Silva, Maria Regina Bueno Franco / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-11T06:51:20Z (GMT). No. of bitstreams: 1 Wagner_Roger_D.pdf: 16615627 bytes, checksum: b068e5da383032c870abd8ff386a4d07 (MD5) Previous issue date: 2007 / Resumo: Os salames são produtos cárneos fermentados e desidratados/maturados apreciados mundialmente e possuem características sensoriais peculiares, principalmente envolvendo o aroma e sabor. No Brasil este produto tem conquistado sucessivos recordes em faturamento no mercado interno, registrando R$ 265,3 milhões em vendas no ano 2005. Apesar de sua importância econômica, poucos estudos envolveram o perfil de voláteis do produto brasileiro e, nenhum deles avaliou a importância odorífera dos compostos voláteis. Assim, os objetivos do presente estudo foram: otimizar as condições de isolamento dos voláteis de salame para duas técnicas diferentes, headspace dinâmico (HD) e microextração em fase sólida (SPME); a partir destes métodos, caracterizar quantitativamente (CG-DIC) e identificar (CG-EM) os voláteis das amostras de salame brasileiro; determinar o impacto odorífero dos compostos voláteis (CV) presentes na amostra mais aceita pelos consumidores, por duas técnicas de CGO, OSME e Freqüência de detecção dos odores; determinar através da ADQ, o Perfil Sensorial dos salames e verificar a aceitação destes por consumidores potenciais; e por fim, correlacionar as medidas instrumentais com as sensoriais por métodos estatísticos multivariados. Foram analisadas seis amostras de salames brasileiros de dois tipos -Italiano (SI-1, 2 e 3) e Milano (SM-1, 2 e 3)- produzidos por três grandes fabricantes. As condições ótimas de isolamento obtidas com o auxílio da metodologia de superfície de resposta para o método de HD corresponderam à 3h e 26¿ de captura a 40°C, enquanto que para o de SPME, foram 45 minutos de extração a 50°C. A representatividade do aroma original da amostra de salame obtido nas condições otimizadas por SPME (7,2) foi superior à alcançada pelo método de HD (6,4). No entanto, ambos os métodos foram eficientes para discriminar as amostras de salame através da composição de voláteis, apesar dos diferentes perfis cromatográficos. Nos dois casos, os resultados da Análise de Componentes Principais (ACP) revelaram que as amostras dos fabricantes 1 e 2 foram caracterizadas por compostos provindos principalmente da oxidação de lipídeos, da atividade proteolítica e da fermentação de carboidratos (aldeídos, ésteres, álcoois e cetonas alifáticas), enquanto que as amostras do fabricante 3 apresentaram áreas maiores dos compostos com o grupo funcional fenol e de algumas cetonas cíclicas. Adicionalmente, os salames SI-2, SM-2 e SI-3 distinguiram-se das amostras SI-1, SM-1 e SM-3, pela maior quantidade de terpenos, o que sugere um maior grau de condimentação para aquelas amostras. As análises realizadas por CG-O (OSME e Freqüência de detecção dos odores) revelaram elevada correspondência quando aplicada a um mesmo método de isolamento. Além disso, apesar das diferenças entre os métodos de isolamento empregados, foram comumente importantes para o aroma de salame tipo Italiano os compostos metilalilsulfeto, os ésteres acetato de metilpropila, butanoato de etila, 2- e 3-metilbutanoato de etila, 1-octen-3-ona, 2-ciclohexen-1-ona, 1-octen-3-ol, 2-nonanona, (E)2-octenal, linalool, ácido 3-metilbutanóico, p-guaiacol, p-creosol e 1,4-dimetoxi-2-metilbenzeno. No teste de aceitação, realizado com 96 consumidores, a amostra SM-1 apresentou maior escore de aceitação global, e juntamente com as amostras SI-1 e SI-2 formaram um segmento com a maior parte dos consumidores ajustados no Mapa Interno de Preferência. Os resultados da ADQ foram analisados em dois grupos de atributos: aparência/textura e aroma/sabor das amostras. No primeiro grupo, os atributos distribuição da gordura e tamanho dos glóbulos de gordura discriminaram as amostras em função dos tipos dos salames e a cor vermelha diferenciou os fabricantes. Já os atributos de aroma e sabor foram correlacionados com 51 compostos voláteis (SPME), selecionados pelo seu elevado poder de discriminação das amostras e importância odorífera, juntamente com as propriedades físico-químicas, por PLSR-2. Assim, as amostras do fabricante 3 foram caracterizadas por aroma e sabor de defumado, as quais mostraram elevada correlação com os compostos fenólicos e cetonas cíclicas. O salame SM-2 apresentou maior proporção de compostos provenientes da oxidação lipídica e foi fortemente correlacionado com os atributos aroma e sabor de ranço. Já as amostras SI-2 e SM-1 foram descritas com aromas ácido e de gordura e sabor de gordura, e foram correlacionadas com teores elevados de gordura e por CVs originados da oxidação de lipídeos e da degradação de proteínas e carboidratos. A amostra SI-1 apresentou elevada quantidade de ácido acético, metionol e dos compostos recentemente relatados e, ainda foi caracterizada pelo maior teor protéico. Com as mesmas variáveis, os modelos desenvolvidos para prever os escores dos atributos sensoriais mostraram ajustes adequados (r>0,9) e habilidade de previsão (erro padrão médio de 15,3%). Desta forma, este estudo proporcionou informações sobre a qualidade dos salames brasileiros, incluindo os perfis dos constituintes voláteis e sensoriais das amostras, além de determinar a importância odorífera dos voláteis da amostra mais aceita com relação ao aroma / Abstract: Dry-fermented sausages are meaty products resulting from fermentation and dehydration/ripening processes. They are produced and consumed worldwide because of their typical sensory characteristics mainly in relation to the aroma and flavor. In Brazil this product has reached successive record sales in the internal market, with a total sale of R$ 265 million during the year 2005. In spite of its increased commercialization in the country, few studies about the volatile compounds of Brazilian dried sausages were found and their odoriferous importance had not been evaluated. The aims of the present study were: to optimize the conditions for the isolation of the salami volatile compounds by two different techniques, dynamic headspace (HD) and solid phase microextraction (SPME); to characterize the volatile compounds of some Brazilian salami samples by a gas-chromatograph equipped with a flame ionization detector (GC-FID) and by massspectrometry (MS), using the optimized techniques of isolation; to determine the odoriferous impact of the volatile compounds of the most accepted sample by two olfactometric techniques, OSME and Frequency of odor detection; to determine the sensory profile of the samples by Quantitative Descriptive Analysis (QDA), verifying also their acceptability by potential consumers; and finally to correlate the instrumental and sensory data using multivariate statistic techniques. Six different Brazilian dried sausage samples of the Italian (SI-1,2,3) and Milan types (SM-1,2,3) from three important national producers were analyzed. The optimized conditions for the isolation of the volatile compounds determined with the aid of Response Surface Methodology were 3h 26¿ (trapping time) and 40°C (temperature trapping) for the HD technique and 45¿ (extraction time) and 50°C (extraction temperature) for the SPME. Evaluation of the original aroma of the sample extracted by SPME obtained a higher score (7.2) than that of the HD technique (6.4). However, both methods were efficient in discriminating the salami samples by comparison of the volatile compounds in spite of their different chromatographic profiles. The data obtained from the two methods interpreted by Principal Component Analysis revealed that the samples from producers 1 and 2 were characterized mainly by compounds arising from lipid oxidation, proteolytic activity and carbohydrates fermentation (aldehydes, esters, alcohols and aliphatic ketones). The samples from producer 3 were characterized by greater areas of phenolic compounds and by cyclic ketones. Additionally, the samples SI-2, SM-2 and SI-3 could be distinguished from the SI-1, SM-1 and SM-3 by a higher amount of terpenes, suggesting that more condiments were added to these samples. On the other hand, the analyses carried out by GC-O (OSME and Frequency) showed good agreement when applied to volatile compounds isolated by the same procedure. In spite of the different chromatographic profile obtained by the two methods, the compounds methylallylsulfide, methylpropyl acetate, ethyl butanoate, ethyl 2- and 3-methylbutanoate, 1-octen-3-one, 2-cyclohexen-1-one, 1-octen-3-ol, 2-nonanone, (E)2-octenal, linalool, 3-methylbutanoic acid, p-guaiacol, p-creosol and 1-4 dimethoxybenzene were considered important for the Italian type salami aroma by both olfactometry techniques. An acceptability test applied to 96 potential consumers showed that the SM-1 sample obtained the highest score of overall acceptability and together with the SI-1 and SI-2 samples, they formed a segment with the major part of the consumers adjusted in the Internal Preference Mapping. The QDA data were interpreted after division of the samples¿ attributes in two groups: appearance /texture and aroma/flavor. In the first group, the distribution of fat and size of fat globules discriminated the samples in terms of the salami types while the red color differentiated the producers. The attributes of aroma/flavor were correlated to 51 volatile compounds (SPME) which were selected because of their high discriminatory power in relation to the samples and the odoriferous importance, and to the physicchemical properties by PLSR-2. Thus, the samples of producer 3 were characterized by a smoke aroma/flavor and they showed a high correlation to phenolic compounds and cyclic ketones. The SM-2 sample, characterized by a high proportion of compounds arising from lipid oxidation, was strongly correlated to the aroma and flavor attributes of rancidity. The samples SI-2 and SM-1 were described by acidic and fatty aroma attributes and fatty flavor and they were correlated to high amounts of fat and also to the volatile compounds originating from lipid oxidation and from protein / carbohydrate degradation. The SI-1 sample showed high amounts of acetic acid, metionol, the recently reported compounds and total protein. Considering the same variables, the models developed in order to predict the scores of the sensory attributes of the samples showed adequate adjustment (r>0.9) and prediction ability (mean standard error of 15.3%). Thus, this study provided some information concerning the quality of Brazilian salami samples, including the volatile and sensory profiles, in addition to the determination of the odoriferous importance of the volatile compounds present in the most accepted salami aroma / Doutorado / Consumo e Qualidade de Alimentos / Doutor em Ciência de Alimentos

Page generated in 0.0348 seconds