Orientador: Glaucia Maria Pastore / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T14:23:04Z (GMT). No. of bitstreams: 1 Mamede_MariaEugeniadeOliveira_D.pdf: 3704106 bytes, checksum: 9f08fafe3f55058c6c5aa2d4ddd660c1 (MD5) Previous issue date: 2003 / Resumo: O vinho é uma bebida obtida pela completa ou parcial fermenta ção alcoólica do mosto de uva. A comercialização do vinho teve uma razoável evolução no Brasil. Os Champanhas/espumantes e espumantes "Asti" foram os vinhos que tiveram o maior consumo pela população brasileira nos últimos 10 anos. O Estado do Rio Grande do Sul (RG) é responsável por mais de 90 % da produção de uva para elaboração do vinho. A região da Serra Gaúcha (RG) produz uva com as melhores características para produção de vinho espumante. Durante a fermentação alcoólica, além de etanol, C02, glicerol são formados em paralelo compostos de sabor e aroma de diferentes classes de subst âncias tais como: ésteres, álcoois, ácidos, aldeídos, cetonas, lactonas, fenóis voláteis, terpenos, acetais, nitrilas, amidas entre outras. Estas classes de substâncias são provenientes da uva, da fermentação e também do envelhecimento ou amadurecimento. A análise sensorial permite a nós identificar as características ou propriedades que nos agradam em um alimento e tem sido utilizada intensamente para classificar vinhos com base na sua composição aromática. Os objetivos deste trabalho foram: a) isolar e selecionar microrganismos produtores de aroma de frutas em meio sintético; b) identificar os microrganismos produtores de aroma de frutas; c) estudar a composição de voláteis produzidos pelos microrganismos selecionados nos mostos de uvas Chardonnay e Pinot Noir; d) avaliar o grau de aceitação sensorial das amostras de mosto fermentado a 15°C em relação aos voláteis de aroma produzidos. A produção de aroma foi verificada em meio sintético contendo 5 % de glicose durante 72 horas a 30°C. A seleção dos microrganismos produtores de aroma foi realizada pela análise sensorial direta descritiva utilizando 10 provadores. A identificação das leveduras foi realizada pelo sistema automático e padronizado mini API/ID 32 C. Análises físico-químicas do mosto como densidade, álcool e açúcar foram realizados pelo densímetro Mustimetre DujardinSalleron (385200); as análises de acidez volátil, acidez total, S02 livre e total foram realizadas por titulação Os mostos Chardonnay e Pinot Noir foram fermentados com as leveduras selecionadas a 15°C e 20°C durante sete dias. Os compostos voláteis de aroma foram extraídos pela técnica de extração líquido-líquido com éter-etílico/hexano (1:1) e por ¿Dynamica Headspace¿ e identificados por cromatografia gasosa/espectrometria de massa (CG-EM) e índice de Kovats. A análise de aceitação do mosto fermentado a 15°C durante sete dias foi realizada por uma equipe composta por 25 provadores representativos do público alvo, utilizando escala hedônica não estruturada de nove centímetros. A intenção de compra foi registrada em uma escala de atitude de cinco pontos. As leveduras selecionadas foram Saccharomyces cerevisiae, Candida valida, Kloeckera apiculata e Pichia membranaefaciens. As leveduras apresentaram um maior cresicmento a 20°C do que a 15°C. Conseqüentemente a produção de compostos voláteis foi maior a 20°C do que a 15°C. Compostos formados durante a fermentação como acetaldeído, acetato de etila, etanol, isobutanol, acetato de amila, acetato de isoamila, álcool isoamflico, feniletanol, acetato de 2-feniletanol, ácido hexanóico, ácido propanóico, ácido butanóico, propanal, butanal entre outros foram detectados nos mostos e no caldo sintético em diferentes concentrações. Os resultados da análise de aceitação mostraram que oito amostras diferiram entre si na produção de aroma. Pelo teste de tukey apenas uma amostra diferiu significativamente em relação às outras amostras. Este resultado pode ser salientado pelos dados da concentração dos compostos majoritários, que mostrou ser muito similar na composição aromática das três amostras com maior aceitação / Abstract: Wine is an alcoholic drink obtained by the partial or complete alcoholic fermentation of grape must. The wine markets have evolved reasonably in Brazil. Champagne/sparkling and "Asti" sparkling core those most consumed by the population in the last 10 years. State of "Rio Grande do Sul" (RG) is responsible for more than 90 % the grape production for wine making. The "Serra Gaúcha"region produces grapes with the best characteristics for sparkling wine production. During the alcoholic fermentation in addition to ethanol, CO2 and glycerol are formed in parallel with flavor components derived from difterent groups of substances, such as esters, alcohols, acids, aldehydes, ketones, lactones, volatile phenols, tepenes, acetals, nitriles, etc. These groups of substances come from the grape or are formed during maturation/aging. Sensory analysis allows us to identify pleasant characteristics or properties of the food under study. It has been intensively uses to classify wines based on their aromatic composition. In this work we aimed: a) to isolate and select microorganisms that product fruit aroma in synthetic media, detectable by direct descriptive analysis; b) to identify the fruit aroma producing microorganisms; c) to study the composition of the volatiles produced by the selected microorganisms in Chardonnay and Pinot Noir grape musts; d) to evaluate the degree of sensory acceptance of must sample fermented at 15°C, with respect to the volatile aroma produced. The production of aroma was verified in synthetic media containing 5 % glucose during 72 hours at 30°C. Selection of aroma producing microorganisms in synthetic media was performed by direct descriptive sensorial analysis, using 10 testers. Yeast identification was carried out by the standard automatic system, mini APIIID 32 C. Physico-chemical analysis of the musts, such as and alcohol and sugar content, were eftected using the Mustimetre Dujardin-Salleron Densimeter (385200); the analyses of total volatile acidity, acidity, free and total S02, were carried out by titration. The Chardonnay and Pinot Noir musts were inoculated with the yeast at 15°C and 20°C incubated for 7 days. The volatile aroma compounds were extracted by the liquid ¿liquid incubated for 7 days. The volatile aroma compounds were extracted by the liquid-liquid exraction technique ethyl ether/hexane (1:1) and by the purge and trap extraction system and identified by GC;MS and by the kovats index. The acceptance fermeted must of the was determined by a team of 25 representative target consumers using a nine centimeter non-structured hedonic scale. The purchasing intention was registered on a five points attitude scale. The selected yeast were Saccharomyces cerevisiae, Candida valida, Kloeckera apiculata and Pichia membranaefaciens. The yeast grew more at 20°C than at 15°C. Consequently, they produced a higher concentration of volatiles at 20°C than at 15 oCo Compounds formed during fermentation, such as acetaldehyde, ethyl acetate, ethanol, isobuthyl alcohol, amyl acetate, isoamyl acetate, isoamyl alcohol, phenylethanol, 2-fenylethanol acetate, hexanoic acid, propanoic acid, butanoic aCid, propanal, butanal and others were detected in the must and the synthetic broth in different concentration. Results of the sensory analysis of the musts fermented at 15°C showed that the 8 samples tested differed between themselves with respect to the aromas produced. Using Tukey's test, only one sample was significant/y different in comparison with the others. This result is apparent from the data for the concentration of the major compounds, which were very similar for the three most accepted samples / Doutorado / Doutor em Ciência de Alimentos

Orientador: Maria Helena Andrade Santana / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-03T15:25:59Z (GMT). No. of bitstreams: 1 Martins_Fernanda_D.pdf: 4952460 bytes, checksum: 07397d44de73e8d2fc99f5c0e09195e9 (MD5) Previous issue date: 2003 / Resumo: Neste trabalho, foi estudada a estabilização dos compostos de aroma do queijo gorgonzola produzidos por fermentação com linhagem de Aspergillus sp, por complexação em _-ciclodextrina e encapsulação em lipossomas. A complexação em _-ciclodextrina foi feita pelo método da co-precipitação, e primeiramente estudada com soluções concentradas dos principais constituintes sintéticos do aroma do queijo gorgonzola, as meti1cetonas: 2pentanona, 2-heptanona, 2-nonanona e 2-undecanona, em separado e em mistura. Posteriormente, os compostos de aroma obtidos por fermentação, foram utilizados. Os compostos de aroma complexados ou encapsulados em solução foram submetidos à secagem em "spray dryer", e adicionalmente os complexos de _-CD foram secos em estufa. Os resultados mostraram que a formação dos complexos ocorre de maneira praticamente instantânea. Separadamente, com exceção da 2-pentanona, a razão molar de saturação da inclusão molecular foi 1:2 (uma molécula de meti1cetona para duas de _-CD). As razões molares de retenção total no complexo (superficies interna e externa) foram 0,06:1,0,57:1,0,74:1 e 0,63:1, para a pentanona, heptanona, nonanona e undecanona: _CD, respectivamente. Quando em mistura, as meti1cetonas competem entre si, tendo as mais hidrofóbicas preferência na complexação. A formação dos complexos de inclusão em _-CD foi caracterizada pelas técnicas de difração de Raios-X, espectroscopia de infravermelho, calorimetria diferencial de varredura e ressonância magnética nuclear. Os estudos de estabilidade com relação à proteção contra decomposição térmica, oxidação, volatilidade e a retenção durante estocagem, confirmaram a formação dos complexos de inclusão através do aumento significativo da estabilidade das moléculas em relação à forma livre. Comparando-se os métodos de secagem empregados, tem-se que a secagem dos complexos em estufa resultou em 60% de recuperação das metilcetonas enquanto que por "spray drying" o rendimento foi de 25%. O bioaroma de gorgonzola, foi complexado na forma de solução diluída obtida diretamente do caldo de fermentação, e apresentou razão mássica de retenção total no produto seco por "spray drying" de 55_g de metilcetonas / g de _-CD. Os rendimentos obtidos foram 22% e 3%, para a secagem feita por "spraydrying" e estufa, respectivamente. A encapsulação das meti1cetonas sintéticas em lipossomas multilamelares foi estudada utilizando concentrações nos níveis obtidos no caldo de fermentação, e caracterizada tanto em suspensão quanto na forma de pó obtido por "spray dryer". O rendimento da encapsulação foi de 72% em suspensão e 24% no pó seco, tendo este último apresentado a razão mássica 0,66_g / g de lecitina. As estruturas 'obtidas dos lipossomas em suspensão e das partículas secas foram aproximadamente esféricas, com tamanhos e distribuição característicos de lipossomas multilamelares. A análise sensorial dos compostos estabilizados do bioaroma de gorgonzola foi feita utilizando os complexos em _-CD (secos em estufa e em "spray dryer") e os lipossomas secos em "spray dryer", ambos adicionados à uma base de consistência pastosa. Os produtos testados foram sensoriamente aceitáveis, sendo o obtido por complexação em _CD e seco por "spray drying" o que apresentou o aroma de gorgonzola significativamente mais intenso e a melhor aceitação por parte dos provadores. Esses resultados mostram que tanto a _-CD quanto os lipossomas são eficientes na estabilização de compostos de aroma, e os produtos secos obtidos apresentam características sensoriais aceitáveis, sendo portanto potencialmente importantes para utilização no processamento de alimentos / Abstract: In this work, it was studied the stabilization of the blue cheese flavour compounds obtained from fermentation of Aspergillus sp, by complexation in P-cyclodextrin and encapsulation in liposomes. The complexation in P-cyclodextrin was carried out by coprecipitation method. Initially, the complexation was studied using concentrated solutions of the main synthetic compounds of the blue cheese flavour, the methylketones: 2pentanone, 2-heptanone, 2-nonanone and 2-undecanone, in separate and in mixture. Secondary, the fermentation broth were used. The solutions of complexed or encapsulated flavour compounds were dried by spray dryer, and some of the p-CD complexes were also dried in conventional oven. The results showed that the formation of complexes occurs almost instantaneously. Separately, all but 2-pentanone, the molar ratio of saturation of the molecular inclusion was 1:2 (one molecule of methylketone to two of P-CD). The molar ratios of total retention in the complexes were (inner and outer surfaces) were 0,06: 1, 0,57:1, 0,74:1 e 0,63:1, for pentanone, heptanone, nonanone and undecanone: p-CD, respectively. When in mixture, the most hydrofobic methylketones were preferred in the complexation. The formation of inclusion complexes in p-CD was characterized by the following techniques: X-ray difraction, infra-red spectroscopy, differential scanning calorimetry and nuclear magnetic ressonance. The stability studies related with protection against thermal decomposition, oxidation, volatility and the retention during storage, confirmed the formation of inclusion complexes through the increasing in stability of the molecules compared with the free ones. The drying methods, comparatively, resulted in complexes with 60% of recovery of methylketones in conventional oven and 25% in spray dryer. The weight ratio ofthe total retention for the complexed blue cheese flavour, directly from the fermentation and spray dried, was 55Jlg methylketone I g p-CD. The obtained yields were 22% and 3%, for the products dried by spray-drying and conventional oven, respectively. The encapsulation of the synthetic methylketones in multilamelar liposomes was studied using the solution in the same concentration leveI of the fermentation solution, and characterized not only in suspension but also in powder produced by spray dryer. The encapsulation yield was 72% in the suspension and 24% in the powder, and the latter resulted in weight ration of 0,66jlg I g lecithin. The obtained structures of the liposomes in suspension and of the powder particles were approximately spherical, with typical size and distribution of multilamelar liposomes. The sensory evaluation of the stabilized blue cheese bioflavour compounds was carried out using p-CD complexes (dried in conventional oven and spray dryer) and liposomes dried in spray dryer, both mixed in a base of paste consistency. The flavour for all the tried products were acceptable. The p-CD complex dried by spray drying was the one which showed the highest intensity and the most preferred blue cheese flavour. These results show that not only the p-CD but also the liposomes were efficient in the stabilization of the flavour compounds, and the obtained dried products obtained were acceptable, in relation with the flavour. Therefore, they are potentially important for being used in the food processing / Doutorado / Desenvolvimento de Processos Biotecnologicos / Doutor em Engenharia Química

El proceso de fabricación de embutidos curado-madurados es crucial para el desarrollo de unas características sensoriales óptimas siendo el aroma y sabor uno de los parámetros de calidad más importantes para los consumidores. Por ello, es de interés conocer los compuestos de gran potencia aromática que determinan la aceptación de dicho producto para así, diseñar nuevas estrategias tecnológicas que potencien el aroma de los embutidos curado-madurados. En vista de ello, la presente Tesis ha abordado el estudio de los compuestos volátiles con poder aromático mediante dos pasos críticos en la identificación de los compuestos como son la técnica de extracción y detección. Desde el punto de vista de la extracción de compuestos volátiles, se ha aplicado una técnica de extracción con disolventes (SAFE) y una de espacio de cabeza (SPME) a embutidos curado-madurados tradicionales. Además, se aplicaron técnicas olfatométricas (cromatografía de gases-olfatometría y “odour activity value”) con el fin de conocer qué técnica genera un extracto representativo del aroma del embutido. Desde el punto de vista de la detección de los compuestos volátiles, se emplearon diferentes detectores específicos cromatográficos (fotométrico de llama, nitrógeno-fósforo, olfatómetro) con el objetivo de facilitar la identificación, mediante cromatografía gases acoplada a espectrometría de masas y cromatografía de gases multidimensional, de compuestos volátiles minoritarios generados a lo largo del proceso de maduración. Por otro lado, es de gran interés para la industria cárnica satisfacer los intereses cardiosaludables de los consumidores. A este efecto, se ha determinado el efecto de la reducción de sal sobre la calidad de embutidos curado-madurados, asi como, la reducción de grasa y sal/grasa. Además, se ha empleado una cepa de Debaryomyces hansenii como alternativa para potenciar el aroma de dichos embutidos reformulados. De tal forma que se han estudiado los parámetros físico-químicos, microbiológicos y sensoriales de embutidos reducidos en sal y/o grasa inoculados con D. hansenii. Al igual que se ha estudiado la generación de los compuestos volátiles y su potencial aromático en dichos embutidos reformulados / Corral Silvestre, S. (2014). EFECTO DE LA REDUCCIÓN DEL CONTENIDO DE NaCl Y/O GRASA EN LA CALIDAD DE EMBUTIDOS CURADO-MADURADOS Y ESTUDIO DE NUEVAS ESTRATEGIAS PARA LA POTENCIACIÓN DEL AROMA [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48477 / TESIS

[EN] Monoterpenes (C10) are isoprenoids usually employed as aromatic additives, are important components of wine aroma and some of them have antimicrobial and health beneficial properties. An efficient microbial production of these metabolites could be an inexpensive and environmentally friendly alternative to current techniques: chemical synthesis or extraction from natural sources. They are usually produced in plants from geranyl pyrophosphate (GPP), a common intermediate of isoprenoid pathway in microorganisms and higher organisms; what opens the possibility of producing them in yeasts as Saccharomyces cerevisiae, qualified as GRAS, and that has been widely employed for biotransformation and production of enzymes and metabolites of biotechnological interest. In this work, the inherent ability of this yeast for heterologous production of monoterpenes (linalool, geraniol, etc.) capable to improve organoleptic and/or functional properties of certain foods either being used as additives or produced during the elaboration process (e.g. vinification) has been characterized and improved by metabolic engineering approaches. Among the most relevant results we can find the selection of wine strain T73 because of its better ability to produce monoterpenes, and the improvement of this production by overexpressing a deregulated version of Hmg1p (catalyzes mevalonic acid synthesis, MVA) and IDI1 (encodes isopenthenyl pyrophosphate isomerase, that catalyzes the isomerization of farnesyl pyrophosphate synthase -FPPS- substrates). In addition, characterization of the FPPS role in GPP availability for the Clarkia breweri linalool synthase resulted in a 50 times increased production in yeast strains with wild-type enzyme (encoded by ERG20) replaced by one modified in its active site (K197E), encoded by erg20-2 allele; reaching a global improvement of 80 times the basal linalool production (14.51 ± 0.90 µg/L) when coexpressing IDI1 gene and erg20-2 allele in linalool producing strains lacking endogenous FPPS activity (1144.68 ± 139.39 µg/L). Geraniol producing strains (bearing Ocimum basilicum -sweet basil- GES gene that encodes geraniol synthase) derived from T73 were included in microvinification assays and geraniol concentration was over its perception threshold and a metabolic dispersion to other monoterpene (linalool, nerol and citronellol) and aromatic esters (geranyl and citronellyl acetate) was also detected. Increased monoterpene production established in IDI1 overexpressing strains under laboratory conditions was reproduced in these assays, demonstrating that the modification of key steps of MVA pathway is a valid strategy to modulate and/or improve wine aroma. / [ES] Los monoterpenos (C10) son isoprenoides habitualmente utilizados como aditivos aromáticos, son componentes importantes del aroma de los vinos y algunos tienen propiedades antimicrobianas y/o beneficiosas para la salud. La producción eficiente de estos metabolitos en microorganismos podría ser una alternativa más económica y respetuosa con el medio ambiente que las técnicas empleadas en la actualidad: síntesis química y/o extracción de fuentes naturales. En las plantas los monoterpenos son producidos por monoterpeno sintasas que utilizan como sustrato geranil pirofosfato (GPP), siendo éste un intermediario común de la ruta de isoprenoides en microorganismos y organismos superiores, lo que abre la posibilidad de producirlos en la levadura Saccharomyces cerevisiae, que tiene el calificativo GRAS, y que ha sido además ampliamente utilizada para la biotransformación y producción de enzimas y metabolitos de interés biotecnológico. En este trabajo se ha caracterizado y mejorado, mediante técnicas de ingeniería metabólica, la capacidad inherente que tiene esta levadura para la producción heteróloga de monoterpenos (linalol, geraniol, etc.), que puedan mejorar las características organolépticas y/o funcionales de ciertos alimentos al ser usados como aditivos o al aumentar su concentración durante el propio proceso de elaboración (p. ej. vinificación). Entre los resultados más destacados están la selección de la cepa vínica industrial T73 por su mayor capacidad para producir monoterpenos, y la mejora de dicha producción mediante la sobreexpresión desregulada de la enzima Hmg1p (cataliza la formación del ácido mevalónico, MVA) y del gen IDI1 (codifica isopentenil pirofosfato isomerasa, que cataliza la isomerización de los sustratos de la farnesil pirofosfato sintasa, FPPS). Además, la caracterización del rol de la enzima FPPS en la disponibilidad de GPP para su aprovechamiento por la enzima linalol sintasa de Clarkia breweri, derivó en una producción de linalol 50 veces mayor en cepas en las que una versión modificada en su centro activo (K197E), codificada por el alelo erg20-2, reemplazaba a la enzima silvestre (codificada por ERG20); alcanzándose una mejora global de 80 veces respecto a la producción de linalol inicial (14,51 ± 0,90 µg/L), al sobreexpresar conjuntamente el gen IDI1 y el alelo erg20-2 en cepas productoras de linalol que carecen de la función FPPS endógena (1144,68 ± 139,39 µg/L). Las cepas productoras de geraniol (expresan el gen GES que en Ocimum basilicum -albahaca- codifica geraniol sintasa) derivadas de T73 se incluyeron en ensayos de microvinificación y la concentración de este monoterpeno en el vino final no sólo estuvo por encima de su umbral de percepción, sino que se produjo una dispersión metabólica del geraniol hacia otros monoterpenos (linalol, nerol y citronelol) y esteres (geranil y citronelil acetato) aromáticos. Además, el incremento de la producción de monoterpenos observado en condiciones de laboratorio en cepas que sobreexpresan el gen IDI1 se reprodujo en estos ensayos, demostrando que la modificación de pasos clave de la ruta MVA es una estrategia válida para modular y/o mejorar el aroma del vino. / [CAT] Els monoterpens (C10) són isoprenoids habitualment utilitzats com additius aromàtics, són components importants de l'aroma dels vins i alguns tenen propietats antimicrobianes i/o beneficioses per a la salut. La producció eficient d'aquests metabòlits en microorganismes podria ser una alternativa més econòmica i respectuosa amb el medi ambient que les tècniques emprades en l'actualitat: síntesi química i/o extracció de fonts naturals. A les plantes els monoterpens són produïts per monoterpeno sintases que utilitzen com a substrat geranil pirofosfat (GPP), sent aquest un intermediari comú de la ruta dels isoprenoids en microorganismes i organismes superiors, el que obri la possibilitat de produir-los en el llevat Saccharomyces cerevisiae, amb qualificatiu GRAS, i que ha sigut a més àmpliament utilitzat per a la biotransformació i producció d'enzims i metabòlits d'interès biotecnològic. En aquest treball s'ha caracteritzat i millorat, mitjançant tècniques d'enginyeria metabòlica, la capacitat inherent que té aquest llevat per a la producció heteròloga de monoterpens (linalol, geraniol, etc.), que puguen millorar les característiques organolèptiques i/o funcionals de certs aliments en ser usats com additius o en augmentar la seua concentració durant el propi procés d'elaboració (p. ex. vinificació). Entre els resultats més destacats es troben la selecció de la soca vínica industrial T73 per la seua major capacitat per a produir monoterpens, i la millora d'aquesta producció mitjançant la sobreexpressió desregulada de l'enzim Hmg1p (catalitza la formació de l¿àcid mevalònic, MVA) i del gen IDI1 (codifica isopentenil pirofosfat isomerasa, que catalitza la isomerització dels substrats de la farnesil pirofosfat sintasa, FPPS). A més, la caracterització del rol de l'enzim FPPS en la disponibilitat de GPP per al seu aprofitament per l'enzim linalol sintasa de Clarkia breweri, va derivar en una producció de linalol 50 vegades major en soques en les que una versió modificada en el seu centre actiu (K197E), codificada per l'al¿lel erg20-2, reemplaçava a l'enzim silvestre (codificada per ERG20); aconseguint una millora global de 80 vegades respecte a la producció de linalol inicial (14,51 ± 0,90 µg/L), en sobreexpressar conjuntament el gen IDI1 i l'al¿lel erg20-2 en soques productores de linalol que no tenen la funció FPPS endògena (1144,68 ± 139,39 µg/L). Les soques productores de geraniol (expressen el gen GES que en Ocimum basilicum -alfàbrega- codifica geraniol sintasa) derivades de T73 es van incloure en assajos de microvinificació i la concentració d'aquest monoterpè en el vi final no només va estar per sobre del seu llindar de percepció, sinó que es va produir una dispersió metabòlica del geraniol cap a altres monoterpens (linalol, nerol i citronel¿lol) i èsters (geranil i citronel¿lil acetat) aromàtics. A més, l'increment de la producció de monoterpens observat en condicions de laboratori en soques que sobreexpressen el gen IDI1 es va reproduir en aquests assajos, demostrant que la modificació de passos clau de la ruta MVA és una estratègia vàlida per modular i/o millorar l'aroma del vi. / Rico Molins, J. (2015). Producción heteróloga de monoterpenos en Saccharomyces cerevisiae: selección y mejora de cepas mediante técnicas de ingeniería metabólica [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/49359 / TESIS

The subject of this thesis was the determination of the profile of volatile aromatic compounds of varietal wines and the subsequent statistical analysis, aiming to find varietal markers of selected varieties – individual substances, their typical contents, mutual correlations. The HS-SPME-GC-MS technique was used to determine the aromatic profile. The main focus of this work was the analysis of the varieties Pálava, Hibernal, Johanniter and Solaris. The data obtained were statistically processed using descriptive and multivariate statistical methods. On the basis of these analyses, models were developed which, from the contents of 14 selected compounds of the aromatic profile, allow the Piwi varieties Hibernal, Johanniter and Solaris to be distinguished from each other and from the Pálava variety and, for the Pálava variety wines, to determine their origin in the Znojmo or Mikulov wine sub-region.

Echinacea purpurea is a rich source of biologically active compounds, which are attributed to several therapeutic effects. This thesis is focused on the optimization of the extraction process, considered these substances. Maceration was chosen as a type of extraction, due to its simplicity. The Optimal conditions were solid-solvent ratio 1: 5, 40% ethanol, 60 °C, 60 minutes. An extract from the dried flowers of Echinacea purpurea was prepared by this optimized process. The content of total phenolic compounds was set on 365.18 ± 3.51 [mg_GAEl^(-1)] and the antioxidant activity was 507.50 ± 6.89 [mg_TEACl^(-1)]. The percentage of radical scavenging activity ABTS•+ was 95.45 ± 1.30. The antimicrobial activity of the extract was tested against 3 microorganisms – Escherichia coli, Bacillus cereus and Candida glabrata. There was not detected inhibitory effect on the growth of microorganisms. In a total, 39 volatile compounds were identified, and the biggest group were represented sesquiterpenes (70.9%). The obtained results confirm that Echinacea extract has antioxidant activity and contains several interesting aromatic substances, In the future, it can be used as a natural resource of nutritionally and sensory valuable compounds, e.g., into various foods and delicacies.

This diploma thesis deals with the comparison of aroma compounds in goat and cow milk. The content of aroma active substances in samples of goat and cow milk, which were analyzed by HS-SPME-GC-MS method, is monitored. In the theoretical part, milk is characterized, its formation in the dairy mammary gland is described, its composition including an overview of aromatic active substances, physical and chemical as well as its sensory properties, milk defects and differences between cow's and goat's milk are described. Further, gas chromatography in combination with solid phase microextraction technique in tandem with mass spectrometry is described. In the experimental part, 13 samples of goat and 8 samples of cow milk were subjected to HS-SPME-GC-MS analysis. Samples were analyzed fresh and after heat treatment. Altogether, 78 volatile substances were identified in the samples. Ketones were the most numerous, aldehydes, alcohols and carboxylic acids were the most abundant chemical groups. There were differences between samples in number as well as in content of the identified compounds, 64 in goat milk and 48 in the cow milk.

Plectranthus amboinicus is a herb that was found to have a lot of bioactive compounds, most of them are polyfenolic compounds. Extraction is neccesary to obtain bioactive compounds and to use them subsequently in food or cosmetic industry. Three methods of extraxtion – maceraction, PHWE and PFE, were used in this study. The best yield of extracted polyfenols was observed by maceration. Maceration was, in the next step, optimized using mathematical statistical method of planned experiment (DOE). The optimal conditions found for extraction were: temperature 60 °C, solvent 40% ethanol, time 90 minutes, solid-solvent ratio 1:10. Total phenolic compunds content in this extract was 0,18 ± 0,05 mgGAE·ml-1, which means 1,83 ± 0,53 mgGAE·g-1 of plant. The antioxidant activity was 148,69 ± 26,92 gTEACml-1. Percentage of radical scavenging activity ABTS•+ was 30,03 ± 5,44 %. Further, 27 of volatile aroma compounds were identified in optimal extract, the most important were: -selinene (16,67 %), trans--bergamotene (14,22 %), caryophyllene (14,11 %), 3-carene (8,22 %), -copaene (7,55 %), -terpinene (6,28 %), humulene (5,87 %), cadina-1(10)-4-diene (5,19 %).

The thesis deals with the issue of potentially allergenic aroma compounds in food. Aroma compounds suitable for food flavouring are mainly of plant origin. These aroma compounds and their mixtures have a lot of positive and negative effects on human organism. Although the aroma compounds are not among main groups of allergens, several studies indicate a potential risk of allergenic effects of some aroma compounds. The theoretic part of this thesis focuses on aroma compounds of plant origin and gives an overview of 26 the most important fragrance allergens according to the European cosmetic legislation. The aim of the experimental part was to verify the selectivity and appropriateness of the currently used methodology of headspace solid-phase microextraction and gas chromatography-flame ionization detection (HS-SPME-GC-FID) for determination of selected allergenic aromatic active compounds. Secondly, it is to use a proven method for a wide spectrum of real food products.

This diploma thesis deals with the determination of aroma volatile compounds in elderberry. The theoretical part describes the botanical characteristics of elderberry, the incidence and the other known species. Further, this work is focused on the chemical composition of elderberry, there are described in detail the content substances and briefly mentioned are medicinal effects of elderberry. Another theoretical part describes the natural processing of this significant plant and technological production of fruit juices. The second half of the theoretical part deals with the method of determining aroma volatile compounds by gas chromatography in combination with SPME technique, which is suitable for identification of aroma substances. In the experimental part of this diploma thesis SPME-GC method was applied to some samples of elderberry and aroma volatile compounds of individual samples of elderberry were determined.