Orientador: Giuseppina Pace Pereira Lima / Banca: Paolo Sambo / Banca: Marcia Ortiz Mayo Marques / Banca: Camila Renata Correa Camacho / Banca: Ary Fernandes Junior / Resumo: Com o aumento no interesse por produtos naturais o estudo de plantas medicinais nativas tornou-se relevante quanto aos componentes fitoquímicos e as atividades biológicas desconhecidas, em contraste com plantas nativas da Europa, que já foram exaustivamente estudadas. O presente estudo foi dividido em três artigos, a temática dos dois primeiros artigos foi a caracterização bioquímica de espécies nativas do gênero Nectandra. Durante um ano foram realizadas coletas, no meio de cada estação do ano, de folhas e cascas das espécies Nectandra lanceolata, Nectandra grandiflora e Nectandra megapotânica, na Fazenda experimental Edgárdia e Fazenda Lageado pertencentes ao Campus Botucatu - Unesp, situadas no município de Botucatu, São Paulo. O primeiro artigo objetivou avaliar a efeito da sazonalidade nos teores de compostos fenólicos e na atividade antioxidante em folhas e cascas de Nectandras. Os resultados evidenciaram que a época de coleta influenciou a presença de compostos fenólicos nas espécies nas diferentes partes da planta, dando-se um maior destaque para a espécie N. megapotâmica. Assim como, para a atividade antioxidante, cuja espécie em evidência foi N. lanceolata. O segundo artigo avaliou a influência da sazonalidade no teor, caracterização química e atividade antimicrobiana frente à cepas de Escherichia coli sp. e Staphylococcus aureus sp. Os resultados deste estudo mostraram que as espécies N. grandiflora e N. lanceolata apresentaram muita semelhança em seus compostos voláteis durante o ano, diferentemente da N. megapotâmica. As espécies N. megapotâmica e N. lanceolata se mostraram promissoras quanto à atividade antibacteriana. O terceiro artigo, realizado durante o estágio de Doutorado Sanduiche em Padova, visou avaliar o efeito das diferentes doses de macronutrientes (NPK) no ... / Abstract: The growing of the interest in natural products, the study about native medicinal plants has been relevant as the phytochemical constituents and biological activities, in contrast to Europe plants, which have been extensively studied. This study was divided into three articles, the theme of the first two articles was the biochemical characterization of native species of Nectandra genre. For a year have been collected, in the middle of each season, leaves and bark of the species Nectandra lanceolata, Nectandra grandiflora and Nectandra megapotâmica in the Edgardia Farm and Lageado Farm belonging to the Campus Botucatu - UNESP, located in Botucatu, Sao Paulo. The first article aimed to evaluate the effect of seasonality in phenolic content and antioxidant activity in leaves and barck of Nectandras. The results showed that the sampling time influenced the presence of phenolic compounds in the species in different parts of the plant, giving greater prominence to the species N. megapotamica. As for the antioxidant activity whose species was evidence N. lanceolata. The second article assessed the influence of seasonality in content, chemical and antimicrobial activity of strains of Escherichia coli sp. and Staphylococcus aureus sp. The results of this study showed that species N. grandiflora and N. lanceolata showed a lot of similarity in their volatile compounds during the year, differently of N. megapotamica. The species N. megapotamica and N. lanceolata proved promising on the antibacterial activity. The third article, accomplished during Sanduiche Doctoral stage in Padova, aimed to evaluate the effect of different doses of macronutrients (NPK) on the yield and quality of Stevia rebaudiana Berth. The experiment was conducted during the summer season in Italy in greenhouse, with a factorial split-splot 3 x 3 x3. The most ... / Doutor

El presente trabajo se propuso; evaluar la vida útil de un néctar a base de Yacón (Smallanthus sonchifolius), Maracuyá amarilla (Passiflora edulis) y Stevia (Stevia rebaudiana) en función de las características fisicoquímicas y sensoriales. Se empleó la metodología de Superficie de Respuesta (MSR) con un diseño de mezcla de 8 tratamientos para las variables cuantitativas: Yacón, maracuyá, stevia y agua. La mezcla óptima del néctar resultó: yacón (30%), pulpa de maracuyá (15 %), agua (54,9%) y stevia (0,08%); de esta mezcla resultó un néctar con una aceptabilidad del color =8,81; textura =7,57; olor =7,57 y sabor =7,21, es un alimento del tipo ácido (pH= 4), los análisis microbiológicos confirman su inocuidad. La vida útil del néctar optimizado se estableció en 45 días de almacenamiento. Del análisis de materias primas: el yacón resalta por su humedad (84 %) y la maracuyá por su acidez (3,82 %).

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2018-01-25T11:25:48Z No. of bitstreams: 1 texto completo.pdf: 1309742 bytes, checksum: 67507ca85e3eb2be0a8c188ce489a217 (MD5) / Made available in DSpace on 2018-01-25T11:25:48Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1309742 bytes, checksum: 67507ca85e3eb2be0a8c188ce489a217 (MD5) Previous issue date: 2017-02-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Stevia rebaudiana Bertoni (Asteraceae) popularmente conhecida como erva-doce do Paraguai é uma planta perene nativa da Serra de Amambai e ocorre espontaneamente no Paraguai e em regiões adjacentes do Brasil e Argentina. É uma fonte importante de adoçante natural em cujas folhas encontram-se glicosídeos (esteviosídeos e rebaudiosídeos) que podem ser 300 vezes mais doces que a sacarose da cana-de açúcar. As suspeitas de que o consumo dos adoçantes sintéticos tenha efeitos nocivos para a saúde têm ocasionado um aumento na demanda dos edulcorantes naturais, e neste caso a S. rebaudiana tem chamado atenção, pois além de ser um produto natural ainda apresenta propriedades farmacêuticas. Com o rápido aumento do cultivo e comercialização da cultura ocorre o inevitável surgimento de problemas fitossanitários relacionados a doenças fúngicas. Até o momento pouco se sabe sobre os patógenos associados a S. rebaudiana, não apenas no Brasil, mas no mundo todo. Com objetivo de esclarecer e complementar as informações relacionadas aos fungos fitopatogênicos de S. rebaudiana, foi realizado um levantamento dos fungos associados a esta planta no Brasil e no Paraguai visando produzir uma descrição mais completa da sua micobiota. Durante o levantamento foram obtidas amostras da região sul e sudeste do Brasil e do Paraguai. Foram encontrados, descritos (através de morfometria e análises moleculares) e ilustrados doze fungos, dentre os quais dois são aqui reconhecidos como novos taxa, são eles: cinco hifomicetos/formas assexuadas de ascomicetos (Alternaria burnsii, Alternaria novae-guineensis, Cercospora sp., Corynespora cassiicola e Fusarium sp.), cinco celomicetos/formas assexuadas de ascomicetos (Colletotrichum truncatum, Elsinoë sp. nov., Macrophomina phaseolina, Phoma omnivirens e Septoria sp. nov.), uma ferrugem (Aecidium minimum) e um basidiomiceto (Athelia rolfsii). / Stevia rebaudiana Bertoni (Asteraceae) commonly known as Paraguay sweet herb is a perennial plant native from the Amambay region and occuring spontaneously in Paraguay and adjacent regions of Brazil and Argentina. It is an important source of natural sweetener with leaves contain glycosides (steviosides and rebaudiosides) that can be 300 times sweeter than sugarcane. The suspected negative health effects of the consumption of synthetic sweeteners have caused an increase in the demand for natural sweeteners. Stevia rebaudiana has attracted much attention an option, because besides being a natural product it has other benefitial pharmaceutical properties. The rapid increase in cultivation and commercialization has been accompanied - inevitably - by the emergence of phytosanitary problems, including fungal diseases. Until now, little is known about the pathogens associated with S. rebaudiana, not only in Brazil, but also worldwide. In order to clarify and complement the information related to phytopathogenic fungi of S. rebaudiana, a survey of fungi associated with this species in Brazil and Paraguay was carried out in order to produce a more complete description of its mycobiota. During the survey, samples were obtained from the southern and southeastern regions of Brazil and from Paraguay. Twelve fungi were collected, described (through morphometry and molecular analysis) and illustrated, are: five ascomycete/hyphomycete asexual morphs (Alternaria burnsii, Alternaria-novae-guineensis, Cercospora sp., Corynespora cassiicola and Fusarium sp.), five ascomycete/coelomycete asexual morphs (Colletotrichum truncatum, Elsinoë sp. nov., Macrophomina phaseolina, Phoma omnivirens and Septoria sp. nov.), a rust fungus (Aecidium minimum) and a basidiomycete (Athelia rolfsii).

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Ciências dos Alimentos, Florianópolis, 2017. / Made available in DSpace on 2017-08-01T04:12:52Z (GMT). No. of bitstreams: 1 348396.pdf: 1675720 bytes, checksum: 0e2ecf374c9b627190e55517e767a98a (MD5) Previous issue date: 2017 / Stevia rebaudiana (Bert.) é uma planta que vem atraindo o interesse da indústria e da comunidade científica nos últimos anos devido aos efeitos do extrato de estévia quanto a sua atividade antioxidante, anti-hiperglicêmica, antimicrobiana e adoçante. Dessa forma, a adição de extrato de S. rebaudiana (Bert.) com o intuito de enriquecer produtos como o iogurte torna-se interessante. Os principais objetivos deste trabalho foram avaliar o comportamento do iogurte incorporado de extrato liofilizado de estévia (FSE) quanto aos aspectos físico-químicos, microbiológicos e ao teor de compostos fenólicos totais (CFT) e atividade antioxidante nos dias 1, 15 e 30 de armazenamento a 4 ± 2 ° C, bem como avaliar a atividade antioxidante através dos métodos FRAP e ABTS e a bioacessibilidade dos compostos fenólicos durante a simulação gastrointestinal in vitro após 30 dias de armazenamento. Foram avaliados iogurtes enriquecidos com 0,25 % e 0,5 % (m/m) de extrato de estévia e um iogurte controle (sem adição de extrato). Tanto a adição quanto a quantidade de FSE adicionado no iogurte contribuíram para o aumento da atividade antioxidante, do teor de CFT, dos parâmetros de cor (a* e b*) e do teor de sólidos totais dos iogurtes. Por outro lado, a acidez, o pH, a sinerese e as contagens de S. thermophilus e L. bulgaricus do produto final não foram significativamente afetadas (p > 0,05). A amostra enriquecida com 0,5 % de FSE apresentou os maiores valores para CFT, ABTS e FRAP. Ao longo do tempo de armazenamento, o teor de de sólidos totais, a sinerese, a cor e o teor de CFT das amostras adicionadas de FSE permaneceram estáveis, enquanto que a atividade antioxidante e o pH diminuíram significativamente. Após a simulação da digestão in vitro, a bioacessibilidade dos compostos fenólicos e a atividade antioxidante dos iogurtes enriquecidos aumentou cerca de 2,5 e 7,5 vezes, respectivamente, em relação às frações não digeridas. Assim, comprova-se que o enriquecimento do iogurte com extrato de estévia aumenta as propriedades antioxidantes e o teor de compostos fenólicos do iogurte, podendo ser uma opção promissora para o desenvolvimento de alimentos funcionais.<br> / Abstract : Stevia rebaudiana (Bert.) is a plant that has been attracting the interest of industry and the scientific community in recent years due to the effects of the stevia extract on its antioxidant , antihyperglycemic, antihypertensive, antimicrobial activity and sweetener. In this way, it became interesting to add extracts such as S. rebaudiana (Bert.) in order to enrich products such as yogurt. The main objectives of this work were to evaluate the behavior of the incorporated yogurt of freeze-dried stevia extract (FSE) regarding the physicochemical, microbiological and total phenolic compounds (CFT) and antioxidant activity on days 1,15 and 30 of storage at 4 ± 2 °C, in addition to evaluating the antioxidant activity through the FRAP and ABTS methods and the bioaccessibility of the phenolics during in vitro gastrointestinal simulation at the end of the shelf life (day 30). The yogurts enriched with 0,25 and 0,5 % (w / w) of stevia extract and the control sample (without extract) were evaluated. The incorporation of FSE and the percentage of addition contributed to increase antioxidant activity, CFT, color parameters (increased values for a* and b* and decreased value for L *) and total solids; while the acidity, pH, syneresis and counts of S. thermophilus and L. bulgaricus of the final product were not significantly affected (p> 0,05). The sample enriched with 0.5 % FSE presented the highest values for CFT, ABTS and FRAP. Throughout the storage time, the parameters of total solids, syneresis, color and CFT of the samples added of FSE remained stable, whereas the antioxidant activity and pH decreased significantly. After in vitro digestion simulation, the bioaccessibility of the CFT and the antioxidant activity of the enriched yogurts increased by 2,5 and 7,5 times, respectively, in relation to the undigested fractions. Thus, it is proven that the enrichment of yogurt with stevia extract actually increases the antioxidant properties and the amount of phenolic compounds of the yogurt, being to be a promising option for the development of functional foods.

Magíster en Gestión y Dirección de Empresas / Estudios realizados para El Diabetes Atlas de la FID, calcula que en Nicaragua hay más de 1,300 niños menores de 14 años que padecen de diabetes tipo 1 y 416,800 personas entre 20 y 79 años con diabetes. Analizando la situación actual de esta enfermedad en Nicaragua, se decide crear un plan de negocio, el cual se dedicará a producir y comercializar un endulzante 100% natural extraído de una planta llamada Stevia. Esta planta posee numerosas propiedades que no altera los niveles de glucosa en la sangre, lo que permite que las personas que padezcan de diabetes puedan consumirla sin afectar su salud . El presente tema de tesis, pretende estudiar el mercado actual de endulzantes que operan en Nicaragua, con el fin crear productos de bajos costos para aumentar la calidad de vida de los diabéticos, junto a esto ayudar a proveer productos innovadores a la industria de los endulzantes, manteniendo alta calidad, generar empleo y ayudar al desarrollo del mercado local para los productos naturales. El proceso de producción consiste básicamente en la trituración y molienda de materia prima (Planta Stevia) de la cual se obtendrá, el producto final. Entre la tecnología utilizada que necesitará el modelo de negocio, será en su mayoría equipos, herramientas y maquinarias con sistemas automatizados, así como obreros altamente capacitados que ayudarán a reducir los costos en las distintas fases de producción. El producto será comercializado a través de intermediarios, con el fin de fortalecer los canales de distribución. De esta manera se podrá llegar a distintos canales de comercialización como cadenas de supermercados, tiendas especializadas de productos naturales, tiendas de conveniencia y directamente al consumidor final. Para esto, se contará con medios de transportes especializados, con el fin transportar el producto hacia los distintos puntos de ventas establecidos. A largo plazo, se pretende ser totalmente reconocidos en el país. Por lo tanto se producirá grandes volúmenes de endulzante, alcanzando un nivel de producción de 240,000 cajas mensuales de 100 sobres de 2 gramos. Dicha organización contará con tres obreros y siete operarios; los cuales serán supervisados por el Gerente de Producción, para garantizar la calidad e inocuidad del producto. Por otra parte la empresa contara con cargos de Gerente General, Gerente Administrativo y de Recursos Humanos, un contador y un axilar contable; tres vendedores, dos vigilantes y dos afanadoras. Al terminar el plan de negocio, se concluye que es rentable la construcción de una planta procesadora de endulzante a base de Stevia. Siguiendo el modelo de flujos de caja, y con una tasa de descuento del 16.92% y un valor presente neto de $20,164.56 adicionales al patrimonio después de 5 años (tiempo de pay-back), se concluye que es una inversión muy atractiva.

This diploma thesis deals with sweet substances from Stevia rebaudiana and with their determination in beverages. The ambition was to adjust the separation method for major steviol glycosides (stevioside and rebaudioside A) by HPLC so as to be fast and effective enough, too. In experimental part was successfully developed the separatin method, so it is possible to determine the steviol glycosides and conservation substances, specifically benzoic and sorbic acid (eventually their sodium or potassium salts). At first, for analysis was used monolithic column, on which stevioside and rebaudioside A weren´t separated. Other analyses were performed on column Ascentis express C18 (150 x 4.6; 2.7 µm). The most suitable separation method was performed by mobile phase made up with 29:71 v/v mixture of acetonitrile and acetate buffer (with pH 4.2). The flow rate was 0.28 ml/min and the column temperature was kept constant at 50 °C. The analysis of steviol glycosides and conservation substances with these condition was verified on the samples of real beverages.

La consommation excessive de sucres conduit à l’augmentation de désordres métaboliques, tels que l’obésité et le diabète. Les consommateurs souhaitent une alimentation plus saine à base de produits d’origine naturelle. Stevia rebaudiana, l’herbe sucrée du Paraguay, accumule dans ses feuilles des glycosides de stéviol (SGs) considérés comme des édulcorants naturels intenses, dont le marché est en pleine expansion au niveau mondial. Dans ce contexte, la société Oviatis implante une filière BIO de Stevia rebaudiana en Nouvelle-Aquitaine. Les objectifs de cette thèse CIFRE sont de caractériser la variabilité phénotypique d’une collection de cette espèce en vue de la mise en place future d’un programme de sélection. Les composantes du rendement, de biomasse foliaire, de quantité et qualité des SGs et de la réponse à Septoria sp. ont été finement décrites en condition de production pluriannuelle et multi-sites ou en conditions contrôlées. Ces travaux ont permis de 1) développer des outils de phénotypage métabolique, pathologique et au champ, 2) évaluer la variabilité phénotypique de cette collection de Stevia rebaudiana en condition de production et identifier les descripteurs de cette variabilité, 3) identifier les facteurs ontogéniques, abiotiques et culturaux impliqués dans la variabilité de cette collection, 4) évaluer la variabilité de réponses face à la septoriose. Ces résultats permettent d’identifier les critères de sélection de cette espèce pour une production BIO en Nouvelle Aquitaine, ainsi que des génotypes d’intérêt. Ils constituent les bases de la mise en place d’un programme d’amélioration variétale. / Obesity and diabetes are consequences of metabolic disorders due to excessive sugar consumption. Consumers want a healthier diet with natural products. Stevia rebaudiana, the Paraguayan sweet herb, accumulates steviol glycosides (SGs) into its leaves. Considered as intense natural sweeteners, SGs represent a global market constantly increasing. In this context, Oviatis establishes a complete organic sector in the Nouvelle-Aquitaine region. The aims of this CIFRE thesis are to characterise the phenotypic variability within a collection of genetic resources, in order to implement a breeding program. Yield components, leaves biomass, SGs quality and quantity and responses against Septoria sp. were described in perennial and multi-site field conditions or in controlled conditions. This work allowed to: 1) develop tools for metabolic, pathology field-phenotyping, 2) evaluate the phenotypic variability of this Stevia rebaudiana collection in field conditions and identify variability descriptors, 3) identify ontogenic, abiotic and cultural factors implicated into phenotypic variability, and 4) evaluate response variability against septoria disease. These results led to the identification of genotypes of interest, as well as selection criteria for the organic production in Nouvelle-Aquitaine, which are the basis for the implementation of a breeding program.

L’alimentation des pays industrialisés, souvent trop riche en glucides et en lipides, a engendré une augmentation marquée de l’obésité et favorisé le risque de diabète. Face à ce constat, l’industrie agroalimentaire s’est efforcée de développer des produits allégés. Au sucre, ont ainsi été substitués les édulcorants acaloriques, molécules au goût sucré non métabolisées par le corps humain. Ces édulcorants sont souvent obtenus par voie de synthèse chimique comme l’aspartame, l’acésulfame K ou encore le sucralose. S’ils sont autorisés dans la confection de produits alimentaires, la toxicité de ces édulcorants et leur impact sur la santé humaine nourrissent cependant les débats au sein de la communauté scientifique, ainsi des solutions alternatives sont envisagées. Stevia rebaudiana Bertoni est une plante originaire du Paraguay. Son intérêt principal réside dans le fait qu’elle contient des molécules acaloriques au goût sucré, les glycosides de stéviol, dont les plus connus sont le rébaudioside A et le stévioside. Les études effectuées sur ces diterpènes glycosilés tendent à souligner leur innocuité. Ils présenteraient même des vertus thérapeutiques, comme des propriétés anti-hypertensive ou antidiabétique, et semblent ainsi être une alternative prometteuse au sucre et aux édulcorants artificiels. Notre étude s’est orientée sur l’extraction aqueuse des glycosides de stéviol des feuilles de Stévia. A l’échelle laboratoire, nous avons pu mettre en évidence que la cinétique d’extraction des molécules cibles est principalement limitée par la diffusion des solutés dans la matrice solide végétale. Il n’y aurait pas de réaction chimique, de gonflement de la matière ou de modification de la porosité pendant le processus d’extraction. Nous avons également pu souligner que la préparation de la matière (séchage et broyage) et les conditions opératoires (température, ratio liquide-solide et agitation) sont des facteurs prépondérants sur l’efficacité d’extraction des édulcorants. A l’échelle pilote, les résultats obtenus en systèmes discontinu et continu ont pu mettre en exergue des influences similaires de la préparation de la matière et des conditions opératoires ; nous avons de plus pu démontrer que la qualité du mélange des phases solide et liquide était un facteur clé à l’efficacité de l’extraction. Fort de ces résultats nous avons pu développer un procédé d’extraction en système continu, adapté à l’extraction des glycosides de stéviol des feuilles de Stévia, et combiné à une étape de séparation solide-liquide. Au travers de nos différentes expériences, nous avons pu décrire précisément son fonctionnement et optimiser l’extraction afin de pouvoir envisager une transposition à l’échelle industrielle. / Industrialized countries food, often too rich in carbohydrates and fat, has resulted in an important increase in obesity and risk of diabetes. Given this fact, the food industry tries to develop diet products. Sugar was substituted by calorie-free sweeteners, sweet-tasting molecules non-metabolized by the human body. These sweeteners are often obtained by chemical synthesis such as aspartame, acesulfame K or sucralose. Even if they are allowed in the manufacture of food products, the toxicity of these sweeteners and their impact on human health raise debate within the scientific community, so alternatives are being considered. Stevia rebaudiana Bertoni is a plant native from Paraguay. Its main interest lies in the fact that it contains calorie-free sweet tasting molecules, steviol glycosides, of which the most common are rebaudioside A and stevioside. Studies of these glycosylated diterpenes tend to highlight its safety. They even present therapeutic characteristics, such as anti-hypertensive or anti-diabetic properties, and thus seem to be a promising alternative to sugar and artificial sweeteners. Our study focused on the aqueous extraction of steviol glycosides from Stevia leaves. At thelaboratory scale, we were able to demonstrate that extraction kinetics of target molecules are mainly limited by diffusion of solutes in the plant solid matrix. There would be no chemical reaction, swelling of the plant material, or modification of the porosity during the extraction process. We have also shown that the preparation of the plant material (drying and milling) and the operating conditions (temperature, liquid-solid ratio and agitation) are overriding factors on the sweeteners’ extraction efficiency. At the pilot scale, the results obtained in batch and continuous systems could highlight similar influences with the preparation of the plant material and the operating conditions. We have also shown that the quality of the mixing of solid and liquid phase was a key factor in extraction efficiency. With these results we have developed a continuous extraction process, suitable for the extraction of steviol glycosides from Stevia leaves, which has combined with a step of solid-liquid separation. Through our experimentation we have accurately described its operation and optimized the extraction in order to consider a transposition to the industrial scale.

Stevia rebaudiana Bertoni, une herbe vivace de la famille des Asteraceae originaire du Paraguay, est d'un intérêt croissant en tant que source d’édulcorants naturels acoloriques, les glycosides de steviol (SVglys). Ces diterpénoïdes sont organisés autour d’un noyau de steviol et diffèrent par le nombre et la nature d’unités de sucre liées à ce noyau. Ils sont accumulés à des concentrations allant de 4 à 20% de la masse sèche des feuilles, selon le génotype, le stade phénologique et les conditions de croissance. S. rebaudiana apparaît comme une espèce alternative prometteuse en Europe, mais nécessite au préalable une évaluation de ses besoins en culture et un travail de sélection variétale afin d’optimiser la teneur et la composition en SVglys en milieu tempéré. L'objectif de ce travail était d'étudier les sources de variabilité génotypique et environnementale pour l’accumulation en SVglys et la production de biomasse foliaire. Une forte variabilité génotypique a été observée pour la composition en SVglys et, à un degré moindre, pour la teneur en SVglys ainsi que pour des critères morphologiques et de précocité. L’environnement (fertilisation, durée du jour, stade phénologique, âge de la plante) a également eu un effet sur l’élaboration de la biomasse foliaire et sur la teneur en SVglys, alors que la composition en SVglys a été moins affectée par ces facteurs. Ces résultats suggèrent des mécanismes biochimiques et génétiques complexes régissant la voie de biosynthèse des SVglys. Ils laissent également entrevoir des possibilités de sélection variétale et donnent des indications sur les exigences de S. rebaudiana pour sa culture sous nos climats. / Stevia rebaudiana Bertoni, a perennial shrub of the Asteraceae family originating from Paraguay, is of increasing interest as a source of zero-calorie natural sweeteners: the steviol glycosides (SVglys). These diterpenoids differ in the number and the nature of sugar units bound to a steviol skeleton. They accumulate in leaves at concentrations ranging from 4 to 20%, according to genotype, phenological stage, and growth conditions. S. rebaudiana appears as a promising alternative culture in Europe, but requires investigations to assess its cultivation plant requirements and a breeding effort to optimize SVgly content and composition under temperate climate. The objective of this work was to explore the sources of genotypic and environmental variability for SVglys accumulation and leaf biomass production. High genotypic variability has been observed for SVgly composition and, to a lesser extent, for SVgly content as well as for morphological criteria and precocity. Leaf biomass and SVgly content varied also with the environment (fertilization, daylength, phenological stage) and over the years in perennial culture, while SVgly composition was less affected by these factors. These results suggested complex biochemical and genetic mechanisms regulating SVglys biosynthetic pathway. In parallel they revealed breeding potentialities and gave indications on S. rebaudiana requirements for its cultivation under temperate climate.

Determina y evalúa la actividad inhibitoria del extracto etanólico al 1,07mg/ml de Stevia rebaudiana en etanol a 70° y la solución acuosa a 1mg/ml de xilitol sobre el crecimiento de los microorganismos presentes en flora mixta salival, in vitro. Para el desarrollo de la prueba se incubaron en aerobiosis a 37°C por 24 horas 0,2 ml de saliva recolectada por estimulación en 0,8 ml de cada solución preparada (Stevia rebaudiana, Xilitol, etanol de 70°, clorhexidina al 0,12% y Caldo BHI infusión cerebro corazón). Posteriormente, se realizó la siembra sobre superficie por diseminación con espátula de Digralsky en placa de Petri con Agar Tripticasa soya TSA de 0,1 ml de inóculo en dilución seriada 1:10 hasta alcanzar el factor de dilución 10-2 y se procedió a la incubación en aerobiosis a 37°C por 24 horas para luego realizar el recuento de unidades formadoras de colonias (UFC/ml). El análisis estadístico se realizó con el programa estadístico Stata versión libre 12.0., se calcularon medidas de tendencia central y dispersión, se aplicó la prueba de normalidad de Shapiro – Wilk para conocer la normalidad de los datos, y el Test de Kruskal – Wallis y post hoc “Test de Dunn” para la prueba de hipótesis. Se trabajó con un nivel de significancia del 5% (p < 0,05). Encuentra que el extracto etanólico al 1,07mg/ml de Stevia rebaudiana en etanol a 70°, la Clorhexidina al 0,12% y el etanol de 70° presentan 0 unidades formadoras de colonias. Y la solución acuosa a 1mg/ml de Xilitol presento un índice de crecimiento bacteriano de 816 x 10-4 ± 657,91 UFC/ml, con una diferencia altamente significativa con respecto al extracto etanólico al 1,07mg/ml de Stevia rebaudiana en etanol a 70°, clorhexidina al 0,12% y etanol de 70°, siendo el segundo con mayor crecimiento bacteriano después del caldo BHI infusión cerebro corazón. Concluye que el extracto etanólico al 1,07mg/ml de Stevia rebaudiana en etanol a 70° posee actividad inhibitoria sobre el crecimiento de los microorganismos presentes en flora mixta salival, mientras que la solución acuosa a 1mg/ml de Xilitol disminuye el crecimiento bacteriano, pero no de manera significativa. / Tesis