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  • 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.
41

Compostos volateis importantes para o aroma de jenipapo (Genipa americana L.) e murici (Byrsonima crassifolia L. RICH)

Alves, Gisele Leticia 13 December 2004 (has links)
Orientador: Maria Regina Bueno Franco / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T01:10:12Z (GMT). No. of bitstreams: 1 Alves_GiseleLeticia_D.pdf: 821234 bytes, checksum: 548651802844ca2b712cab8e3988b6e9 (MD5) Previous issue date: 2004 / Doutorado / Doutor em Engenharia de Alimentos
42

Stanovení vonných látek rostlinného původu v potravinách / Assessment of aromatic compounds of plant origin in foods

Jelínková, Monika January 2009 (has links)
The aroma compounds suitable for food flavouring are mainly of plant origin. It is necessary to take into account the possible allergic effects of some of them. The theoretic part of this thesis is focused on aroma compounds and their biological effects. It also describes methods useful for their isolation and analysis with a nearer intent on the methods used in this thesis - solid phase microextraction and gas chromatography. The aim of the experimental part was to establish, optimise and validate the method for determination of allergic aroma compounds chosen and subsequently to enable its using in wide spectrum of food and other products.
43

Stanovení aromaticky aktivních látek v odrůdách rakytníku řešetlákového / Assessment of aroma active compounds in cultivars of sea buckthorn

Melikantová, Marcela January 2014 (has links)
The aim of the diploma thesis was the aroma active compounds assessment and sensory profile determination of various types of sea buckthorn (Hippopha rhamnoides L.). The theoretical part provides the detailed description of this plant, comprising the occurence, taxonomy, chemical composition and use. Experimental part summarizes the data obtained: identification and quantification of aroma compounds using the SPME – GC –FID and GC-MS method and evaluation of complete sensory profile. Various cultivars of sea buckthorn harvested in 2009-2012 were analysed. In total 23 various types of sea buckthorn were measured, 23 alcohols, 10 aldehydes, 11 esters, 14 ketones and 5 acids were found.
44

Study of the production and release of aromas during winemaking carried out by different Saccharomyces species and hybrids

GAMERO LLUNA, AMPARO 15 April 2011 (has links)
Aroma is one of the most important attributes involved in wine quality. Current trend in winemaking consists of producing wines with different aroma nuances to offer variety of wines to a developing market. Several studies have demonstrated that low temperature fermentations favours aroma synthesis and retention. In this background, new wine yeasts able to perform fermentation at low temperatures improving wine aroma while maintaining good fermentation rates are necessary. This doctoral thesis explores the oenological traits of different Saccharomyces species and hybrids relevant for present-day wine industry, especially regarding aroma production, as well as the molecular bases underneath. This exploration has been possible using different biochemical, analytical chemistry and molecular techniques to perform enzymatic activity detection, aroma profile determination and transcriptome analysis in wine fermentations. Through this doctoral thesis the abilities of different Saccharomyces species and hybrids regarding primary aroma release and secondary aroma production, especially at low temperatures, has been elucidated in order to know the different possibilities that these yeasts offer to create new wines with different aromatic nuances. One of the general conclusions of this doctoral thesis is that production and release of aromas in winemaking depends on the strain carrying out the fermentation process. Nevertheless, sometimes there was a species tendency. On the other hand, the fact that fermentation temperature affects aroma synthesis but not always in the direction to aroma increase has been demonstrated. / Gamero Lluna, A. (2011). Study of the production and release of aromas during winemaking carried out by different Saccharomyces species and hybrids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/10741 / Palancia
45

Analysis of Aroma Constituents in Cultivated Strawberries by GC/MS

Song, Xiling 08 June 1999 (has links)
In aroma analysis, strawberries have always been the favored fruit because of their relatively high content of typical and pleasant aroma constituents. Esters, aldehydes, alcohols and sulfur compounds have been found to be the main aroma components in strawberry. In recent years, two volatile compounds, 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMF) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DHF) were reported to contribute heavily to strawberry aroma. These two compounds have been found in all wild strawberries studied, but found only in few cultivated varieties. In this work, three kinds of cultivated strawberries were sampled and analyzed. The three strawberries all belong to the Camarosa variety. They came from different growing areas: Salinas (California), Orrville (Ohio), and Memphis (Tennessee). The volatile compounds of these three strawberries were separated by Gas Chromatography (GC), and identified by Mass Spectrometer Detector (MSD). Column and experimental conditions were optimized for this particular separation. Salinas, Orrville and Memphis strawberries have very similar aroma constituents, however, in slightly differing amounts. Several unique peaks were found in each strawberry, which may well account for the differences in the aroma qualities of the three. 2-Furaldehyde was found in both Memphis and Orrville strawberries, but not in Salinas. It is a key odor compound correlated with woody aroma and it has a low odor threshold value. These two properties make it contribute negatively to the pleasant aroma of Memphis and Orrville strawberries. A compound, 2-furanmethanol, was found only in Salinas strawberries. This compound has a faint burning aroma, however, its high odor threshold value offsets its potentially bad aroma. DMF was found in all three strawberries, but no DHF was detected in any of the three. We propose a possible explanation for the absence of DHF. Ethyl (methylthio) acetate, which is a sulfur-containing compound, was found in both Orrville and Salinas strawberries. This work is the first to report its presence in strawberries of any variety. An external standard method was employed to quantify seven main aroma components found in the strawberry extracts. Aroma values were introduced and then calculated together with sensory descriptions of these compounds. Salinas strawberry was found to have the best aroma quality of the three. These results indicate that the odors of strawberries of the same variety can be different when grown in different geographical areas. / Master of Science
46

Možnosti využití kořenících směsí a aromat v pekárenství a těstárenské výrobě

Skácelová, Andrea January 2017 (has links)
My master thesis: The Possibilities of spice blends and flavors in baked goods and pasta production deals with the use of spice mixtures in an unusual way. In this thesis, spices are described in great thought and detail, then focuses on the description of baked goods and pasta production. The practical part of this paper is created and tested from recipes for bread production using various mixtures of spices and tested by sensory and instrumental analysis. Additionally, the pastas were prepared with mixtures of spices, sensory assessment, and laboratory analysis. The results were summarized in tables and graphs, and evaluated by available statistical methods.
47

Wine Discrimination and Analysis Using Quartz Microbalance Based Electronic Nose Technology

Martin, Amanda Marie 20 March 2007 (has links)
Wines are composed of numerous compounds that are complex, making them difficult to analyze. Wine evaluation and discrimination is typically done through chemical and human sensory evaluation. Unfortunately, both of these methods are time consuming and expensive. Therefore a new rapid analysis technique for wine discrimination and analysis is desired. The electronic nose has been suggested as an alternative to current wine discrimination techniques. In this study, a quartz microbalance-based electronic nose system was utilized to analyze the overall volatile components of wine. The electronic nose was optimized for Cabernet Sauvignon and Mouvèdre wine to gain maximum sensor response from the sensors. Response surface methodology was used to determine the optimum sensor response by varying three experimental parameters: sensor temperature, sample temperature and equilibrium time. The maximum sensor response occurred at an equilibrium time of 20 min for each varietal and at a sample temperature of 55ºC and 56ºC for Cabernet Sauvignon and Mouvèdre, respectively. The optimum sensor temperature selected for this study was 40ºC for both varietals. Using the optimum sensor settings, the electronic nose was used to analyze Cabernet Sauvignon wines. Grapes were treated with ethanol spray (5%, and 10%) 13 weeks post-bloom, which has been shown to affect the overall quality of the final wine product. Wine samples were evaluated using chemical analyses, human sensory evaluation and electronic nose. Significant differences between the wines were observed based on pH, percent alcohol, and color intensity only. A consumer sensory panel consisting of 81 panelists was unable to differentiate amongst sample treatments. However, the electronic nose was able to differentiate between the control group and the treated samples 100% of the time. Canonical discriminant analysis of the data placed the 5% ethanol treatment as a sub-set of the 10% ethanol treatment. The results indicate that the electronic nose can be used as a discriminatory tool for assessing wines. / Master of Science
48

Effect of Training Systems on Viognier (Vitis vinifera L.) Grape and Wine Glycosides and Volatile Compounds

Millard, Lindsay Theresa 12 April 2005 (has links)
Viognier (Vitis vinifera L.) grapes were grown in Northern Virginia for three seasons using three different training systems in a randomized complete block design consisting of Vertical Shoot Positioned (VSP), Smart Dyson (SD), and Geneva Double Curtain (GDC), and evaluated for the effects on grape and wine glycosides and volatile compounds. Fruit was harvested at the same Brix each season, and differences in berry weights were not observed. VSP-trained vines had the lowest crop load and lowest light levels in the fruit zone. Seventeen volatile compounds were analyzed using headspace solid-phase microextraction, GC-MS. Fruit showed differences in linalool, á-terpineol, â-damascenone, and n-hexanol concentrations among the training systems. Wines showed differences in both grape-derived and fermentation-derived volatiles. SD had the highest concentration for most of the free volatiles quantified in both the juice and wine. VSP had lower phenol-free wine glycosides all three seasons and lower phenol-free juice glycosides one season. Triangle difference sensory testing demonstrated differences between GDC and SD in wine aroma and flavor, and differences between VSP and SD in flavor, for two of three seasons. / Master of Science
49

Produção de compostos voláteis característicos do aroma em mamões (Carica papaya L. cv \'Golden\') tratados com metil jasmonato e armazenados a baixa temperatura / Production of volatile representative aroma compounds of papaya (Carica papaya cv. \'Golden\') treated with methyl jasmonate and stored at low temperature

De Fusco, Deborah Oliveira 24 February 2015 (has links)
O Brasil destaca-se como um dos maiores produtores mundiais de mamão, fruto apreciado em todo o mundo pelo sabor e polpa delicada. Os compostos voláteis contribuem para a formação do aroma do fruto, o que faz deles essenciais para o desenvolvimento de características sensoriais que definem sua apreciação pelos consumidores. Os principais compostos de aroma do mamão incluem, principalmente, terpenos, ésteres, aldeídos, álcoois, ácidos orgânicos e cetonas, com destaque para o monoterpeno linalool que é o composto mais abundante na cultivar \'Golden\'. Embora a biossíntese de compostos voláteis seja particularmente afetada pelos tratamentos para consevação pós-colheita, estes são essenciais para a comercialização do mamão, em vista de sua alta perecibilidade. O uso de baixas temperaturas tem sido um dos métodos mais empregados para extensão de vida pós-colheita do mamão. Precedentes da literatura indicam que o tratamento pós-colheita com metil jasmonato (MJ) é capaz de reduzir possíveis efeitos prejudiciais decorrentes do armazenamento a baixa temperatura. Além disso, a aplicação do metil jasmonato em frutos é capaz de estimular a atividade de enzimas das vias de produção de compostos voláteis. Desta forma, o presente trabalho tem por objetivo avaliar os efeitos da aplicação pós-colheita do MJ em mamão (Carica papaya L. cv \'Golden\'), focando os efeitos sobre as vias de biossíntese de componentes voláteis do aroma, em frutos amadurecidos a temperatura de 22ºC, assim como em outros armazenados a 10ºC seguido de transferência a 22ºC para o pleno amadurecimento. Além dos perfis de compostos voláteis, também foram avaliados os perfis de respiração, produção de etileno, cor da casca, quantificação de MJ e expressão gênica de linalool sintase (LIS). Dada a importância do linalool para o aroma característico do mamão, as variações na transcrição de um gene da linalool sintase foram avaliadas buscando correlacioná-las aos efeitos dos tratamentos na produção dos compostos voláteis. O tratamento com MJ influenciou a produção de compostos voláteis, particularmente de linalool e hexanal nos grupos mantidos a 10ºC. Os frutos tratados com o hormônio apresentaram maior abundância do composto quando comparados ao grupo controle. Embora o protocolo de tratamento empregado não tenha conseguido recuperar os altos níveis encontrados nos frutos armazenados a 22ºC, não se exclui a possibilidade de que outros desenhos experimentais possam responder de maneira ainda mais satisfatória a este mesmo tratamento / Brazil stands out as one of the world\'s largest producers of papaya, fruit appreciated worldwide for it taste and delicate pulp. The volatile compounds contribute to the formation of the flavor of the fruit, making them essential for the development of sensory characteristics that define their appreciation by consumers. The main papaya flavor compounds include mainly terpenes, esters, aldehydes, alcohols, organic acids and ketones, especially the monoterpene linalool which is the most abundant compound in the cultivar \'Golden\'. Although the biosynthesis of volatile compounds is particularly affected by postharvest treatments for conservation, those are essential for the marketing of papaya, in view of their high perishability. The use of low temperatures has been one of the most used methods for extension of papaya postharvest life. Previous literature indicate that postharvest treatment with methyl jasmonate (MJ) is capable of reducing possible adverse effects arising from storage at low temperature. Furthermore, the application of methyl jasmonate in fruits is able to stimulate the activity of the enzymes of volatiles production pathways. Thus, this study aims to evaluate the effects of postharvest application of MJ in papaya (Carica papaya L. cv \'Golden\'), focusing on the effects in the biosynthetic pathways of volatile aroma compounds in fruit ripened to temperature of 22ºC, as well as other stored at 10ºC followed by transfer to 22ºC for the complete maturation. In addition to the volatile compounds profiles were also evaluated respiration profiles, ethylene production, peel color, quantification of MJ and gene expression of linalool synthase (LIS). Given the importance of linalool to the characteristic aroma papaya, changes in the transcription of a linalool synthase gene were evaluated seeking to correlate them to the treatment effects on the production of volatile compounds. Treatment with MJ influence the production of volatile compounds, particularly linalool and hexanal in the groups kept at 10ºC. Fruits treated with the hormone had higher abundance of the compound when compared to the control group. Although the treatment protocol employee has not been able to recover the high levels found in fruits stored at 22ºC, do not exclude the possibility that other experimental designs can respond even more satisfactorily to this same treatment.
50

Estudo das relações entre etileno e 1-metilciclopropeno (1-MCP) em mamões \'Golden\' / Study of the relationship between ethylene and 1-methylcyclopropene (1-MCP) in \'Golden\' papayas

Façanha, Rafaela Vieira 12 August 2016 (has links)
O mamão está entre as frutas mais exportadas e consumidas no Brasil, no entanto, sua comercialização é dificultada devido ao seu curto período de vida útil pós-colheita. O 1- metilciclopropeno (1-MCP) tem sido utilizado para retardar o amadurecimento de frutos climatéricos e como ferramenta para estudos de processos relacionados ao etileno. Entretanto, a aplicação de 1-MCP em mamões parcialmente verdes, estádio utilizado para comercialização, leva às respostas variáveis, o que tem inviabilizado seu uso comercial nesta fruta. Desta forma, o objetivo deste trabalho foi estudar as relações entre etileno e 1-MCP e investigar os fatores que inviabilizam o uso comercial do 1-MCP em mamões \'Golden\'. Para tal propósito a pesquisa foi desenvolvida em três etapas. Na primeira, foi feita a avaliação fisiológica, bioquímica e de qualidade em mamões submetidos à aplicação de etileno e 1- MCP. Na segunda, foram identificados os compostos voláteis responsáveis pelo aromaem mamões submetidos às mesmas condições da primeira etapa, assim como as possíveis interferências do etileno e 1-MCP sobre a produção desses compostos.A terceira etapa consistiu em determinar a influência da concentração endógena de etileno (CEE) de mamões \'Golden\' na sensibilidade ao 1-MCP. Para a primeira e segunda etapa, mamões provenientes do sul da Bahia foram submetidos aos seguintes tratamentos: controle, etileno, 1-MCP, etileno + 1-MCP (simultâneo), etileno + 12h +1-MCP e etileno + 1-MCP (sem intervalo) e, em seguida, armazenados em câmara de refrigeração a 22 ±1°C até o completo amadurecimento para as avaliações. Na primeira etapa foi possível observar que o uso do 1-MCP isoladamente, bem como quando aplicado 12 horas ou imediatamente após a aplicação de etileno prejudicou o amolecimento da polpa de mamões \'Golden\', no entanto, a coloração finalda casca não foi prejudicada pelo uso do inibidor. O 1-MCP, associado ou não ao etileno alterou a o mecanismo de retroalimentação normal de produção de etileno e, provavelmente, a enzima ACC sintase foi afetada. A aplicação de etileno + 1-MCP, simultaneamente, aumentou a vida de prateleira de mamões \'Golden\' sem comprometer a qualidade final do fruto. Na segunda etapa, vinte compostos voláteis em mamões \'Golden\' foram identificados. O 1-MCP afetou o aroma dos frutos e estes não recuperaram o aroma no mesmo teor dos frutos sem tratamento até o oitavo dia de armazenamento. Os tratamentos com 1-MCP, com ou sem etileno, afetaram mais os compostos responsáveis por nuances de aroma, mas não afetaram prejudicialmente os compostos de impacto do aroma. Na terceira etapa, mamões \'Golden\' provenientes de Linhares, foram submetidos a tratamentos que visaram reduzir ou aumentar a CEE e relacionar com a sensibilidade do fruto ao 1-MCP. Para isso, um grupo de frutos foi submetido a 2% de O2 para reduzir a CEE, outro grupo foi exposto à atmosfera de 2,5 μL L-1 de etileno visando aumentar a CEE. O terceiro grupo de frutos foi submetido à atmosfera ambiente. Ao final dos tratamentos, metade dos frutos de cada grupo foi submetida à aplicação de 1-MCP e a outra metade imersa em água deionizada. Os resultados confirmam que a concentração endógena de etileno modula a sensibilidade de mamões \'Golden\' ao 1- MCP. / The papaya is one of the most exported and consumedfruit in Brazil, however, due the short shelf life the commercialization have some obstacles. The 1-methylcyclopropene (1- MCP) has been used for delaying the climacteric fruit ripening and as a tool for studies of ethylene processes. Nevertheless, the application of 1-MCP in partially green papayas, which is the commercialization stage, leads to uncertainty results, which has made impossible the commercial use in this fruit. Thus, the aim of this work was to study the relationship between ethylene and 1-MCP to understand the factors that do not allow commercial use of 1-MCP in Golden\' papayas. For this purpose the research was conducted in three steps. The first was composed by physiological, biochemistry and quality measurements in papayas submitted to ethylene and 1-MCP treatments. In the second, the volatile aromas compounds were identifiedin papayas subjected to the same conditions of the first step, as well as, the possible interferences of ethylene and 1-MCP on the production of those compounds. The third step was to determine the influence of endogenous ethylene concentration (EEC) in the sensitivity of \'Golden\' papaya to 1-MCP. In the first and second steps, papayas from the south of Bahia were submitted to the following treatments: control, ethylene, 1-MCP, ethylene + 1-MCP (simultaneously), ethylene + 12h + 1-MCP and ethylene + 1-MCP (no interval) and then stored in refrigerator at 22 ± 1 ° C until to complete ripening, condition that they were evaluated. In the first step it was observed that the use of 1-MCP alone and applied 12 hours or immediately after ethylene impaired softening of papaya pulp \'Golden\', however, the final skin color was not impairment by the use of the inhibitor. The 1-MCP, with or without ethylene, altered normal feedback ethylene production and probably the ACC synthase was affected. The application of ethylene + 1-MCP, simultaneously, increased shelf life of papayas \'Golden\' without affect the final fruit quality. According to the second step, twenty volatiles in \'Golden\' papaya were identified. The 1-MCP affect the aroma of fruits and these did not recover the same aroma content of the fruits untreated until the eighth day of storage. Treatments with 1-MCP, with or without ethylene, affected more compounds responsible for flavor nuances, but not detrimentally affect the aroma impact compounds. In the third and last study part, \'Golden\' papayas from Linhares were submitted to treatments aimed at reducing or increasing the EEC and relate to the sensitivity of fruit to 1-MCP. For this, a group of fruits was subjected to 2% O2 to reduce the EEC, other group was exposed to the atmosphere of 2.5 μL L-1of ethylene to increase the EEC. The third group was subjected fruits ambient atmosphere. At the end of treatment, half part of each fruit group was subjected to the application of 1-MCP and the other half part immersed in deionized water. The results confirm that the endogenous ethylene concentration modulates the sensitivity of papayas \'Golden\' to 1-MCP.

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