Intensive and semi-intensive aquaculture systems are dependent on nutrient input either in the form of supplemental or complete feeds. Most complete diets still include high fish meal (FM) levels (≥10%). However, as the industry attempts to reduce its reliance on FM, feeds must now be formulated with much lower levels especially for omnivorous species such as tilapia. By 2015, mean FM inclusion in tilapia diets was projected to fall below 3% and be further reduced to 1% by 2020. In the global context of competition for crops, finding suitable plant-based replacers for FM and meeting the increasing demand for seafood, lower-cost and under-utilised plant feedstuffs are now receiving greater attention. The study was divided into three distinct components – field survey, growth experiments, and life cycle assessment. Field surveys were used to contextualise the growth experiments and assess commercialisation opportunities for multi-enzyme inclusion in tilapia feeds. Two sets of digestibility and growth experiments were designed to evaluate the feasibility of using high inclusions of plant-based ingredients sourced from locally available feedstuffs in Thailand to substitute FM at low inclusion levels (0 – 5%). The research evaluated the hypothesis regarding the potential of exogenous enzymes (protease, xylanase and phytase) to minimize anti-nutritional effects on nutrient digestibility of proteins, polysaccharides and phosphorus in tilapia. The research also assessed the secondary effects of enzyme supplementation on economic efficiency and life cycle environmental impacts. Tilapia is the second most cultured finfish globally and Thailand is the sixth largest producer. Based on the findings of the field survey, feeding practices of Thai tilapia farmers were confirmed to be diverse. Feed inputs included, but were not limited to, agro-industrial by-products (e.g. rice bran, corn bran etc.) and commercial diets. Commercial diets contained 15 – 30% crude protein and lower protein livestock diets (i.e. pig ration) were often used for supplemental feeding or “fattening”. The experimental low FM diets were therefore formulated as grow-out or “fattening” diets for semi-intensive green-water systems, a prominent feature (>60%) of Thai tilapia farming. In Phase 1, the digestibility experiment assessed the digestibility and growth in tilapia fed 0%, 3% and 5% FM diets with and without xylanase (0.385 g kg-1) and phytase (0.075 g kg-1). Performance decreased significantly with declining FM levels. No differences in feed intake, feed conversion ratio (FCR), specific growth rate (SGR) and weight gain were observed between the enzyme and control diets. Nevertheless, tilapia fed the enzyme supplemented 3% FM and control 5% FM performed similarly (P < 0.05). No enzyme-related effects were noticed for protein digestibility but phosphorus (P) digestibility improved by 9%, except at 0% FM level (P > 0.05). The enzymes had no apparent influence on nitrogen (N) retention contrary to previous studies, however, higher retention for P was observed. Villus length decreased with declining FM levels yet no improvements were seen in tilapia fed enzyme diets. In a simultaneous grow-out experiment, the six experimental diets were compared to an industry 10% FM standard. Conversion ratio was the lowest (1.66) in adult tilapia fed 10% FM diet however the enzyme supplemented 0% FM fed fish had a comparatively low FCR of 1.67. There were no significant enzyme-related effects on weight gain¸ SGR and protein efficiency. Proximal villi results were inconsistent. The cost of feed decreased with declining FM levels but increased with enzyme inclusion. Nevertheless, the economic returns per kg of whole fish produced were better using enzyme supplemented diets compared to the controls. Though the size of the effects on growth and nutrient utilisation were modest, the findings suggested that xylanase and phytase had some level of synergistic action on the targeted anti-nutrients. However, further research was required. In Phase 2, two control diets (2% FM, negative control (NC) and 10% FM, positive control (PC)) were compared with three enzyme supplemented 2% FM diets (NO-PRO, 0.385 g kg-1 xylanase and 0.075 g kg-1 phytase only; LO-PRO, xylanase + phytase + 0.2 g kg-1 protease and HI-PRO, xylanase + phytase + 0.4 g kg-1 PRO). Growth performances improved with enzyme supplementation compared to the NC (P < 0.05). Of the enzyme supplemented diets, the LO-PRO diet showed the highest improvements in weight gain (26%) and feed intake (19%), the latter comparing statistically to the 10% FM PC diet. The HI-PRO diet had the best FCR (1.88), again comparable to the PC (1.73). The NO-PRO diet had the highest protein, P, lipid and energy digestibility, suggesting no additive effect of protease on these coefficients. In terms of gut histomorphology, the LO-PRO and PC diets had the highest measurements and were statistically similar which may have explained similarities in feed intake. Compared to the NC, the HI-PRO diet produced the highest level of change in net profit due to gains in feeding efficiency however, the LO-PRO showed better improvements in terms of growth. Based on these findings, the ternary combination of protease with xylanase and phytase (LOPRO) has potential in limiting FM use for tilapia grow-out feeds, however, the economic efficiencies were still below that of a 10% FM diet. Future considerations for research should target the indigestible dietary components in order to optimise enzyme dosages and maximise the benefits of each enzymes. In conclusion, a comparative life cycle assessment (LCA) was used to evaluate the environmental impacts of low FM diets and commercial feeds associated with tilapia production in Thailand. The study showed that the low FM enzyme supplemented diets had lower impact potentials and were environmental superior to the average (10% FM) commercial standard. LCA modules are recommended for least-cost formulation programmes as an option going forward. Additionally, LCA can be used as a predictive tool to guide farmers, especially small-scale producers, on the potential impacts of feed input choices and feeding practices. This will ensure higher product quality but also demonstrate environmental responsibility on the part of aquafeed and fish producers to final seafood consumers.

Resumo: A incorporação de culturas específicas associadas à solarização do solo tem sido apresentada como um avanço muito promissor para o controle de fungos fitopatogênicos habitantes do solo. Além das brássicaceas, comumente utilizadas, novos materiais vegetais como a mandioca e a mamona têm apresentado potencial para controle desses fitopatógenos. Vários fatores são apontados como responsáveis pelo controle, entre eles os voláteis oriundos da decomposição dos vegetais. Assim, este trabalho foi idealizado com dois objetivos divididos em duas etapas complementares: biológica - avaliar o efeito ocasionado pela incorporação e decomposição de parte aérea de brócolis, mamona e mandioca brava e mandioca mansa, associadas à simulação da solarização, sobre diferentes estruturas dos fungos Fusarium oxysporum f. sp. lycopersici Raça 2, Macrophomina phaseolina, Rhizoctonia solani AG-4 HGI e Sclerotium rolfsii; química - identificar e apontar dentro de cada material vegetal qual(is) é(são) o(s) volátil(eis) potencial(ais) pelo controle das estruturas dos fungos. Na primeira etapa, quatro ensaios idênticos foram instalados em conjuntos de microcosmos, com quatro períodos de exposição diferentes e independentes (7, 14, 21 e 28 dias), avaliando efeitos no crescimento micelial (inócuo, fungistático e fungicida) e na sobrevivência das estruturas de resistência dos fungos de solo. Verificou-se efeito fungistático e fungicida no crescimento micelial de F. oxysporum f. sp. lycopersici Raça 2, R. solani AG-4 HGI e de S. rolfsii. O efeito fungicida apenas ocorreu aos 21 dias de incubação para F. oxysporum e R. solani e aos 28 dias para S. rolfsii. Para M. phaseolina, observou-se apenas efeito inócuo. Os tratamentos solo+materiais vegetais, ao longo dos períodos testados, reduziram, significativamente, a sobrevivência das estruturas de resistência de todos os fungos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The incorporation of specific cultures associated with solarization has been a highly promising advance to control phytopathogenic fungi inhabiting the soil. In addition to the commonly used Brassicaceae, new plant materials such as cassava and castor plants have shown potential to control these phytopathogens. Several factors are considered responsible for this control, including volatile compounds from plant decomposition. Thus, the present work was divided into two complementary steps according to its two major aims: biological step - to evaluate the effect of the incorporation and decomposition of broccoli, castor and cassava (bitter and sweet) shoot, associated with simulated solarization, on different structures of the fungi Fusarium oxysporum f. sp. lycopersici Race 2, Macrophomina phaseolina, Rhizoctonia solani AG-4 HGI and Sclerotium rolfsii; chemical step - to identify for each plant material which volatile compound(s) present(s) potential to control fungal structures. In the first step, four identical assays were established in groups of microcosms, with four different and independent exposure periods (7, 14, 21 and 28 days), to evaluate the effects on mycelial growth (innocuous, fungistatic and fungicide) and survival of resistance structures of soil fungi. Fungistatic and fungicide effects were detected on the mycelial growth of F. oxysporum f. sp. lycopersici Race 2, R. solani AG-4 HGI and S. rolfsii. Fungicidal effect occurred only at 21 days of incubation for F. oxysporum and R. solani and at 28 days for S. rolfsii. As regards M. phaseolina, only an innocuous effect was observed. The treatments soil+plant material, over the tested periods, significantly reduced the survival of resistance structures for all fungi. In general, broccoli and bitter and sweet cassava had expressive... (Complete abstract click electronic access below) / Orientador: Edson Luiz Furtado / Coorientador: César Junior Bueno / Banca: Francisco Maximino Fernandes / Banca: Marli Teixeira de Almeida Minhoni / Banca: Flavia Rodrigues Alves Patricio / Banca: Fabio Augusto / Banca: Marcia Michelle de Queiroz Ambrósio / Doutor

Le manioc (Manihot esculenta L. Crantz) est cultivé dans toute la zone intertropicale. Compte tenu de ses utilisations potentielles, le développement de la culture du manioc a considérablement augmenté au niveau mondial, mais il est encore considéré comme une culture de subsistance en particulier dans les régions pauvres où il est cultivé par les petits producteurs. La production du manioc est fortement contrainte par des facteurs biotiques et abiotiques, dont la bactériose vasculaire du manioc (CBB) et la nécrose bactérienne du manioc (CBN) qui sont deux maladies causées par les bactéries Xanthomonas axonopodis pv. les manihotis (Xam) et X. cassavae (Xc), respectivement. CBB est considérée comme la principale maladie bactérienne, notamment au Venezuela où la CBB a été signalée pour la première fois dans les années 70. Dans les années 90, des études ont été menées pour élucider la variabilité génétique de Xam dans différentes régions du pays, au moyen d’outils moléculaires, mettant en évidence un degré élevé de polymorphisme parmi les souches analysés.Le sujet de cette thèse porte sur la situation de CBB au Venezuela 20 ans après. Quelle est la diversité génétique actuelle de Xam au Venezuela? Quelle est la structure génétique des populations de Xam dans ce pays, et comment diffèrent-elles des souches de Xam recueillies dans les années 90? En outre, étant donné que Xam et Xc provoquent des symptômes semblables sur feuilles de manioc et présentent des caractéristiques physiologiques et morphologiques similaires, nous avons également visé à développer un nouvel outil de diagnostic moléculaire permettant une détection rapide et fiable de Xam et de Xc tout étant capable de les discriminer l’une vis à vis de l’autre.Pour atteindre nos objectifs, nous avons d'abord établi une PCR-duplex comme outil de détection moléculaire des xanthomonades infectant le manioc. Sur la base de l'analyse in silico des séquences du génome de 66 souches de Xam et une de Xc, nous avons pu sélectionner 6 paires d'amorces candidates spécifiques de Xam et six autres pour Xc. Nous avons pu développer un test de PCR-duplex qui a été validé en testant 53 souches de Xam et 25 souches de Xc issues de différents pays, 18 souches non cibles contrôles et cinq souches épiphytes associées au manioc. Cette technique représente un outil utile pour détecter et différencier Xam et Xc provenant de cultures in vitro mais aussi fonctionnelle à partir de tissues de plantes infectés.Deuxièmement, nous avons donc évalué la diversité des populations de Xam à l’aide de l’étude de microsatellites (ou MLVA pour « Multiple loci VNTR analysis »). Une enquête de terrain menée dans six États du Venezuela a permis d'évaluer la présence de la maladie, son statut et nous a permis d'établir une collection de souches de Xam dont l’analyse détaillée de la diversité a pu être réalisée. Au total nous avons isolé 202 souches de Xam issues de six localités situées dans quatre états. À l'aide d'un schéma 14-MVLA, nous avons analysé 12 populations et mis en évidence un indice élevé de la diversité génétique au sein de ces populations et entre elles, et principalement dans l'est du pays.Le développement de ce type de recherche est essentiel pour une gestion raisonnée des cultures dans le monde. Conjugué aux politiques agricoles existantes, il nous permettra de mieux comprendre les agents pathogènes d'importance agricole et les mécanismes impliqués dans leur établissement dans le temps et à travers l’espace. L'objectif à long terme est d'appliquer des mesures de contrôle efficaces et durables, ce qui conduira à des mesures de quarantaine plus efficaces pour prévenir la propagation de la maladie. / Cassava (Manihot esculenta L. Crantz) belongs to the group of roots and tubers and is cultivated in the tropics worldwide. This species is a nutritional alternative in many populations where no optimal crop production, general conditions nor technological support exist. Considering its potential uses, the global development of cassava crop has increased significantly but it is still considered a subsistence crop in poor regions lead by smallholder producers. Cassava is affected by biotic and abiotic factors during its life cycle, which heavily limiting its optimal performance. A variety of pests and diseases are known to affect cassava production. Among them are those caused by Xanthomonas axonopodis pv. manihotis (Xam) and Xanthomonas cassavae (Xc), causal agents of Cassava Bacterial Blight (CBB) and Cassava Bacterial Necrosis (CBN) diseases, respectively. CBB is considered the major bacterial disease that affects cassava crop worldwide which is also the case in Venezuela where it was first reported in the 70s. Since the 90s, studies were conducted to elucidate Xam genetic variability in different regions in the country, by means of different molecular tools available at that time. A high degree of polymorphism among the isolates was reported, whether collected from the same or different fields. The Xam population was distributed into eight clusters and no correlation was observed between genetic diversity and geographic origin.Our questions deal with the situation of CBB in Venezuela 20 years later : what is the current genetic diversity of Xam populations in Venezuela? what is the genetic structure of Xam populations and how do they differ with respect to Xam strains collected in 90s. Moreover, because Xam and Xc cause similar symptoms on cassava leaves and display similar physiological and morphological characteristics, we also aimed at developing a new molecular diagnostic tool allowing for fast and reliable detection of Xam and able to discriminate with Xc.To achieve our goals, we first established a duplex-PCR as a molecular detection tool of cassava-infecting xanthomonads. Based on in silico analysis of the genome sequences of 66 Xam and 1 Xc strains, we were able to select 6 Xam and 6 Xc primers pairs candidates, of which one set of primers for each was selected for further studies. We were able to develop a duplex-PCR assay that was validated upon testing 53 Xam strains and 25 Xc strains from different countries, 18 non-target strains, and 5 epiphytic strains associated to cassava, proving this technique a useful tool to detect and differentiate Xam and Xc from in vitro cultures and in planta.Secondly we assessed the diversity of Xam populations through a variable number of tandem repeat analysis (MLVA). A field survey conducted in six states in Venezuela enabled to evaluate the occurence of the disease, its status and allowed us to establish a strain collection for detailed diversity analysis. We isolated 202 Xam strains from six localities, localized in four states. Using a MVLA14-scheme, we analyzed 12 populations highlighting a high index of genetic diversity among and within populations, mainly in the east of the country.The development of this type of research is essential in the management of crops in the world and coupled with the existing agricultural policies, it will allow us to have a deeper understanding of pathogens of agricultural importance and the mechanisms involved in their establishment over time and across regions. The long-term objective of this is to apply control measures that are effective in time, thus establishing more stringent quarantine measures to prevent the spread of the disease.

Resumo: Amidos e gomas são hidrocolóides usados freqüentemente em alimentos para conferir textura apropriada, controlar a umidade e a mobilidade da água. Estudos têm relatado que a interação de gomas e amidos em sistemas alimentícios pode alterar o inchamento dos grânulos, as propriedades de gelatinização e reológicas dos amidos. Em bebidas lácteas fermentadas, a maioria dos polissacarídeos de interesse comercial é incompatível com as proteínas do leite em solução, e desta forma, os hidrocolóides tipicamente utilizados são amido e carragena. Neste trabalho foi avaliado o efeito da adição das gomas xantana, carboximetilcelulose sódica e carragena (nas concentrações de 0,15, 0,25, 0,35 e 0,45% - p/v) nas propriedades de pasta, térmicas, de poder de inchamento (PI), reológicas e na microscopia do amido de mandioca, bem como o efeito de misturas de amido de mandioca e as referidas gomas nas propriedades reológicas de bebidas lácteas fermentadas. Os resultados obtidos sugerem que a goma carragena (CAR) praticamente não modifica as propriedades do amido em função da inexistência de interações entre a referida goma e o amido de mandioca; já a goma xantana (GX) envolve praticamente por completo os grânulos de amido, possivelmente através da formação de pontes de hidrogênio, promovendo desta forma aumentos nas viscosidades de pasta, poder de inchamento, nos módulos G' e G" e diminuição na tendência a retrogadação; a carboximetilcelusose sódica (CMC), por sua vez, aumenta drasticamente as viscosidades e o poder de inchamento do amido devido a sua grande capacidade de retenção de água e não a sua interação com o amido de mandioca. Nas bebidas lácteas fermentadas, as misturas quando empregadas praticamente não modificaram seu comportamento reológico, exceto para as bebidas elaboradas a partir das misturas amido - goma xantana, onde observou-se... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Starches and gums are hydrocolloids frequently used in food systems to provide proper texture, moisture and water mobility. Studies have reported that the gum and starch interaction in food systems can modify the granule swelling, the gelatinization and rheological properties of starches. In fermented dairy beverages, the majority of commercial interest polysaccharides is not compatible with milk proteins in solution, consequently, starch and carrageenan are the hydrocolloids typically used. In this work, the effect of gum addition such as xanthan, sodium carboxymethyl cellulose and carrageenan was evaluated (in the concentrations of 0,15, 0,25, 0,35 and 0.45% - w/v) in paste, thermal, swelling power (SP), rheological and microscopy properties of cassava starch, as well as the effect of mixtures of cassava starch and the referred gums in rheological properties of fermented dairy beverages. The results suggest that carrageenan gum (CAR) practically does not modify the starch properties since there is no interaction between this gum and cassava starch. Xanthan gum (GX) seems to involve the starch granules completely, possibly through the formation of hydrogen bonds, which increases paste viscosities, swelling power, increased the modulus G' and G" and decreased retrogradation behavior. Sodium carboxymethyl cellulose (CMC), in turn, drastically increases viscosities and the starch swelling power due to its great capacity of water retention and not to the interaction with the cassava starch. In fermented dairy beverages, the gum - starch mixtures practically didn't modify its rheological behavior, except for beverages with mixtures xanthan gum - starch, where an initial reduction in the shear stress as deformation rate was increased, followed by a gradual increase, suggesting a possible incompatibility between cassava starch, xanthan gum and milk proteins. Keywords: Cassava starch... (Complete abstract click electronic access below) / Orientador: Célia Maria Landi Franco / Coorientador: Ana Lúcia Barretto Penna / Banca: Ivo Mottin Demiate / Banca: Roger Darros Barbosa / Mestre

Nas últimas décadas, têm aumentado substancialmente a quantidade de pesquisas focando no desenvolvimento e caracterização de materiais biodegradáveis, particularmente, filmes comestíveis. O uso de polímeros de fontes renováveis, preparados a partir de produtos vegetais, vem ganhando importância nessa abordagem. O concentrado de proteína de soja e amido de mandioca podem ser considerados uma alternativa aos polímeros petroquímicos. O processamento pela radiação ionizante pode ser empregado para a modificação de polímeros e macromoléculas, resultando em novos materiais com grandes perspectivas de utilização industrial. A indústria de alimentos, uma das indústrias tradicionalmente mais inovadoras, exige o desenvolvimento constante de novos produtos. A capacidade de proteínas e polissacarídeos de formar filmes, amplamente conhecida, é um ponto de partida para o desenvolvimento de novos materiais que atendam os variados requerimentos dessa pungente indústria. Neste trabalho elaboraram-se filmes a base de fécula de mandioca e proteína isolada de soja em duas proporções diferentes e posteriormente irradiados e analisados quanto às suas propriedades mecânicas, cor, absorção de água, permeabilidade ao vapor de agua, análise térmica TGA e DSC entre outros. Os filmes tornaram-se aparentemente mais solúveis e menos resistentes a perfuração com o aumento da dose de radiação aplicada. Com relação às propriedades térmicas observou-se que os filmes com maior proporção de proteína são mais resistentes. Os filmes apresentaram-se menos permeáveis na dose de 40 kGy, e, com relação a absorção de água, esta foi reduzida em função da dose de radiação. Filmes com boa resistência ao vapor de água e com reduzida absorção podem ser considerados adequados para embalagens de alimentos. A radiação mostrou ser uma ferramenta conveniente na modificação de materiais poliméricos principalmente para elaboração de filmes solúveis onde esta é uma nova tendência para embalagens bioativas. / In recent decades, there has been a substantial increase in the amount of research focusing on the development and characterization of biodegradable materials, particularly edible films. The use of polymers from renewable sources, prepared from plant products, has gained importance in this approach. Soy protein concentrate and cassava starch may be considered an alternative to petrochemical polymers. Processing by ionizing radiation can be used for the modification of polymers and macromolecules, resulting in new materials with great prospects of industrial use. The food industry, one of the traditionally most innovative industries, requires the constant development of new products. The widely known ability of film forming proteins and polysaccharides is a starting point for the development of new materials that meet the varying requirements of this pungent industry. In this work, films based on manioc starch and isolated soy protein were prepared in two different proportions and later irradiated and analyzed for their mechanical properties, color, water absorption, water vapor permeability, TGA and DSC thermal analysis between others. The films became apparently more soluble and less resistant to drilling with the increased radiation dose applied. Regarding the thermal properties, it was observed that the films with greater protein orientation are more resistant. Properties such as water vapor permeability and water absorption, the films were less permeable at the 40 kGy dose. With regard to water absorption, it was reduced as a function of the radiation dose. Films with good resistance to water vapor and with low absorption are considered efficient for food packaging. Radiation has proven to be a convenient tool in the modification of polymeric materials mainly for the production of soluble films where it is a new trend for bioactive packaging.

A cocção é uma característica importante na seleção de um cultivar de mandioca para uso culinário, tanto pelo consumidor como pela indústria de produtos processados. No entanto, existem épocas em que raízes de mandioca apresentam problemas no cozimento, como o de textura da massa, ou ainda, cultivares com melhores ou piores características de cozimento, independente de quanto tempo dure o processamento. O objetivo do presente estudo foi caracterizar o cultivar IAC 576-70, o mais utilizado no Estado de São Paulo para fins culinários, em diferentes idades, quanto ao tempo de cocção das raízes e à qualidade das mesmas quando cozidas. Estes parâmetros foram relacionados com composição química e características histológicas das raízes e também com características físicas e físico-químicas do amido. As raízes desse cultivar, nas condições do estudo, apresentaram variabilidade no tempo de cocção com a idade ou período fisiológico do vegetal. As raízes de plantas com 12 meses, colhidas no mês de fevereiro (período vegetativo) apresentaram menor tempo de cocção que as raízes de plantas com 15 meses, colhidas no mês de maio (repouso fisiológico). Quanto à composição as raízes de plantas aos 12 meses apresentaram menores teores de amido e de fibras e maiores teores de carboidratos redutores, de pectina total, de proteínas e de lipídeos na massa seca que as plantas de 15 meses. Nas raízes de plantas aos 12 meses o amido apresentou grânulos de menor tamanho e com menor pico de viscosidade. A textura das raízes aos 12 meses apresentou menor resistência ao cisalhamento, maior percentual de desintegração e maior aceitabilidade pelos provadores na avaliação sensorial. Os testes histoquímicos das raízes de ambas as idades não revelaram diferenças entre si. / Cooking is an important characteristic for the selection of cassava cultivars, not only by end consumers, but also by food processing companies. Cassava roots present some cooking problems, such as poor texture characteristics, when harvested in certain periods of the year. Cultivars also show different cooking characteristics, regardless of the processing time. The present study was aimed at characterizing cassava roots, IAC 576-70 cultivar, the most used for cooking in Sao Paulo State, at different ages, as regards cooking times and quality after cooking. These two parameters were related to the chemical composition and histological characteristics of roots, as well as to physical and physicochemical characteristics of the starch. Under the conditions of the study, roots showed differences in cooking times, which varied with age or with the physiological stage of plants. Roots of 12-month-old plants harvested in February (vegetative period) showed shorter cooking times than roots of 15-month-old plants harvested in May (physiological rest). Roots of 12-month -old plants showed lower amounts of starch and fibers and larger contents of reducing carbohydrates, total pectin, protein and lipids in the dry matter than roots of 15-month-old plants. Twelve-month-old plants yielded roots with smaller starch granules, lower viscosity peak. Such roots also showed lower shear strength, higher disintegration percentage and higher approval by tasters during sensory tests. Histochemcial tests revealed no differences between 12-month-old and 15-month-old roots.

Este trabalho contemplou o estudo do desenvolvimento de amidos termoplásticos (TPS) obtidos a partir da raiz de mandioca bruta e de seus derivados (amido e resíduo). A técnica de preparação deu-se por mistura física dos componentes, via estado fundido, empregando-se o plasticizante glicerol em proporções variadas. Contemplou ainda a busca de alternativas que viessem a melhorar o desempenho mecânico e a resistência à absorção de umidade dos TPS. Foi realizado um estudo inicial de caracterização dos materiais originais e constatou-se que a presença de açúcares na raiz e de fibras no resíduo é o principal diferencial com relação à composição do amido industrial. Os TPS preparados a partir de amido industrial e de raiz apresentaram fraco desempenho mecânico. Por outro lado, as fibras presentes no resíduo foram capazes de gerar TPS com melhores propriedades mecânicas. Os açúcares naturalmente presentes na raiz ocasionaram um efeito adicional de plasticização ao TPS influenciando principalmente nas propriedades de alongamento na ruptura. Os TPS preparados apresentaram comportamentos semelhantes frente à absorção de água. As estratégias empregadas na tentativa de melhorar o desempenho do TPS preparado a partir de amido de mandioca industrial foram: desenvolvimento de blendas de TPS com poli (álcool vinílico) (PVA); adição de látex de borracha natural às blendas TPS/PVA; uso de partículas minerais (alumina e carbeto de silício) aos TPS e uso de nanofibras de celulose (whiskers) como reforço aos TPS. Estas nanofibras foram extraídas a partir das fibras contidas no resíduo da industrialização do amido de mandioca. Em todos os casos foram realizados estudos da morfologia e do desempenho dos materiais resultantes. Os resultados revelaram que as blendas TPS/PVA e TPS/PVA/látex foram, em sua maioria, imiscíveis, porém compatíveis, pois o desempenho mecânico e de resistência à umidade foram aumentados. O látex, empregado em conjunto com o PVA, gerou materiais com módulo elástico cerca de 1330% maior que a combinação TPS/látex, além de reduzir a absorção de água das blendas TPS/PVA em 12%. A alumina (Al2O3) promoveu um efeito de plasticização no TPS ocorrendo um aumento de 68% no alongamento. Em contrapartida, houve uma redução de 70% no módulo elástico e de 40% na tensão de tração na ruptura. O carbeto de silício (SiC) mostrou-se efetivo no aumento do módulo elástico (aumento de 230%). O efeito de reforço acarretado pelos ´whiskers´ foi limitado devido à presença de açúcares decorrentes da hidrólise ácida do amido residual contido no resíduo. Os testes de resistência à tração não foram sensíveis para a completa determinação das propriedades mecânicas. Entretanto, os resultados de análise térmico-dinâmico-mecânica revelaram que houve um aumento de 26% no módulo de armazenamento. A principal contribuição do uso destas nanofibras deu-se na redução de absorção de água (34% em relação ao TPS sem ´whiskers´). Como um todo, os resultados obtidos nesta tese revelaram a possibilidade de obtenção de TPS a partir da mandioca e de seus derivados e que as estratégias adotadas para melhorar o desempenho final dos TPS foram satisfatórias. / In this work it was studied the development of thermoplastic starches (TPS) prepared from raw cassava root and its derivatives, starch and bagasse (residue). The TPS were prepared by melt-processing employing glycerol as plasticizer in distinct proportions. It was searched for alternatives that could improve both, the mechanical performance and resistance to water of the TPS. It was made a previous characterization of the original materials. It was verified that the presence of sugars in the cassava root and of fibres in the bagasse is the main distinction in relation to the composition of industrial starch. The TPS from industrial starch and cassava root presented the poorer mechanical performance. On the other hand, the fibres in the bagasse allowed the obtainment of a more mechanical resistant TPS in relation to the other TPS. The presence of natural sugars in the cassava root promoted an additional effect on the plasticization of TPS, influencing mainly the elongation properties. The prepared TPS presented similar behaviors in relation to water absorption. The strategies adopted to improve the performance of TPS prepared from industrial starch were: the development of TPS blends with polyvinyl alcohol (PVA); addition of latex of natural rubber to TPS/PVA blends TPS/PVA; the use of mineral particles (alumina and silicon carbide) to the TPS and also, utilization of cellulose nanofibres (whiskers), as reinforcement to the TPS. These whiskers were extracted from the fibres contained in the cassava bagasse. For all the cases the morphology and final performance of the resulting materials were investigated. The results revealed that TPS/PVA and TPS/PVA/latex blends were in a greater number immiscible, although, compatibles since, the mechanical performance and water resistance were increased. The latex, employed together PVA, promoted a 1330% increase in the elastic modulus compared to TPS/latex. Also, the water absorption of TPS/PVA blends was reduced in 12%. The alumina (Al2O3) promoted a plasticizing effect in the TPS with an increase of 68% in elongation. On the other hand, the elastic modulus and tensile strength were reduced in 70% and 40%, respectively. The silicon carbide (SiC) was effective to increase the elastic modulus (increase of 230%). The reinforcement effect of the whiskers was limited due to the presence of sugars resultants of the acid hydrolysis of residual starch present in the bagasse. The tensile tests were not sensitive to determine the mechanical properties. However, from dynamicmechanical tests it was verified an increase of 26% in the storage modulus. The main contribution of the use of nanofibers was on the reduction of water absorption in 34% compared to TPS without nanofibers. As a whole, the results obtained in this work revealed the possibility of preparation of TPS from cassava root and its derivatives and that the strategies adopted to improve the final performance of the TPS ware successful.

Microrganismos endofíticos são definidos como organismos que habitam em pelo menos durante um período de seu ciclo vital, o interior de um vegetal, sem causar aparentemente nenhum dano a este. Na busca de novos organismos e novos metabólitos secundários, um estudo foi conduzido visando avaliar a diversidade química de bactérias endofíticas por meio do isolamento e identificação de metabólitos secundários produzido por bactérias endofíticas de etnovariedades de mandioca, mantidas por tribos indígenas da Amazônia brasileira. Sessenta e sete bactérias endofíticas de mandioca foram selecionadas e submetidas à uma seleção através de testes de antagonismo in vitro. A bactéria endofítica, Bacillus pumilus foi a que apresentou forte ação inibitória contra os fitopatógenos Rhizoctonia solani, Pythium e Sclerotium rolfsii. Essa bactéria foi identificada através do sequenciamento de um fragmento do gene de 16S rRNA e por meio da análise de ácidos graxos (FAME). A obtenção dos metabólitos da bactéria selecionada foi realizada através da extração dos meios de cultura com os solventes hexano, acetato de etila e diclorometano. Após a concentração dos extratos, seus constituintes químicos foram realizados através de cromatografia em camada delgada, cromatografia em coluna, cromatografia gasosa acoplada ao espectrômetro de massas CG-EM) e cromatografia líquida acoplada ao espectrômetro de massas (CL-EM). Os extratos obtidos por meio de diclorometano e acetato de etila continham diferentes componentes químicos que mostraram atividade inibitória contra os três fitopatógenos testados. O método cromatográfico CL-EM permitiu a identificação de uma substância antifúngica produzida pela bactéria endofítica, Bacillus pumilus, conhecida como pumilacidina. / Endophytic microorganisms are defined as organisms that inhabit the interior of a vegetable at least during a period of the vital cycle, without causing any apparent damage. In the search for new organisms and new secondary metabolites, a study was conducted to evaluate the chemical diversity of endophytic bacteria through the isolation and identification of secondary metabolites produced by endophytic bacteria of cassava cultivated by Brazilian Amazon Indian tribes. Sixty seven endophytic bacteria isolated from cassava were screened using in vitro antagonisms tests. An endophytic bacterium, the Bacillus pumilus, which showed a strong inhibitory activity against Rhizoctonia solani, Pythium aphanidermatum and Sclerotium rolfsii was selected. This bacterium was identified by sequencing of 16S rRNA genes and by FAME. The bacterial endophytic localization was confirmed by cassava cell tissue examination using scanning electron microscopy. The bacterial metabolites were extracted from the culture media using the solvents hexan, ethyl acetate and dichloromethane. After concentrate the extracts their chemical constituents were analyzed using thin layer chromatography (TLC), chromatography column, gas chromatography coupled with mass spectrometry (GC/MS) and liquid chromatography coupled with mass spectrometry (LC/MS). The extracts obtained with dichloromethane and ethyl acetate contained different chemical compounds that showed inhibitory activity against the three plant-pathogenic fungi tested. The LC/MS method allowed the identification of an antifungal compound produced by the B. pumilus, which is known as pumilacidin.

A mandioca (Manihot esculenta Crantz), apesar de ser muito cultivada e consumida no país, é uma planta da qual se conhece pouco sobre características intrínsecas do vegetal e as transformações bioquímicas que ocorrem em suas raízes tuberosas. Os traços fenotípicos das raízes foram usados para classificações empíricas, mas o emprego de técnicas de biologia molecular ainda é pouco utilizado para mostrar novos marcadores moleculares que poderiam identificar, além de traços agronômicos, fatores nutricionais, sensoriais e de qualidade que afetam essas raízes comestíveis. A participação de enzimas endógenas, como a &#945;-amilase, pode estar relacionada com o processo de deterioração pós-colheita, no caso, fornecendo energia para o desenvolvimento microbiano. Os objetivos do presente trabalho foram avaliar a diversidade genética entre cultivares de mandioca, as expressões gênicas de &#945;-amilase e da amido-sintase ligada ao grânulo, e a atividade amilolítica total. Amostras de variedades de mandioca, consideradas doce, foram coletadas nas reservas indígenas de Juruti e Caxiuanã, PA, e mantidas na Embrapa Agrobiologia (Seropédica, RJ). Para as análises de diversidade genética, foi extraído o DNA de folhas de 30 amostras e utilizado como molde em PCR-RAPD, a partir de 20 oligonucleotídeos do conjunto Operon W. Os amplicons foram submetidos à eletroforese em gel de agarose e fotodocumentados. Os padrões obtidos por PCR-RAPD foram agrupados através de coeficiente de Pearson e expressos sob dendograma. As análises por RAPD, utilizando o oligonucleotídeo OPW-12, permitiram a distinção das variedades e demonstraram alto grau de similaridade genética entre as amostras de mandioca avaliadas, permitindo a identificação de três grupos. Nestes grupos, estão distribuídas 28 das 30 amostras analisadas, com 75% de similaridade genética entre elas. Paralelamente, amostras de raízes das 30 variedades de mandioca foram empregadas em ensaios de determinação da atividade amilásica, sendo observada ampla variação entre as variedades. Igualmente, para os estudos de expressão gênica da &#945;-amilase e GBSSI, o RNA total foi extraído a partir das raízes de 30 amostras de mandioca, e utilizado como molde na obtenção de c-DNA e posterior amplificação por RT-PCR em tempo real. A análise da expressão relativa demonstrou discreta variação entre as amostras analisadas. Entretanto, somente a amostra 19 (variedade Açaí-Tinga) apresentou variação expressiva na quantificação relativa (3,18) para MEAMY, e as amostras 19 (variedade Açaí-Tinga) e 29 (Jabuti) apresentaram variação expressiva na quantificação relativa de GBSSI (4,13 e 2,58 respectivamente). / Cassava (Manihot esculenta Crantz) is a worldwide important crop, but some intrinsic feature of this plant remained unclear. Phenotypic characteristics of the roots of cassava are still used to classified them in spite of molecular biology technics to identify agronomic traits, nutritional factors, quality and sensorial parameters of the eatable parts of this plant. Endogenous enzymes, like &#945;-amylase, may be involved on the deteriorative process after harvest by the release of sugars to the microbial proliferation into the roots. The objectives of this study were to use a RAPD assay to identify some DNA variations within and between cassava varieties, expression of &#945;-amylase and granule-bound starch synthase gene, as well as amylolitic activity in the roots. Several cassava accessions were collected from indigenous community Caxiuanã and Juruti, state of Pará. The cultivars were grown in EMBRAPA Agrobiologia, state of Rio de Janeiro. Thirty cassava accessions were sampled to prepare DNA templates from cassava leaf. RAPD was performed using twenty commercial primers OPW, and the amplified DNAs for each sample were run in agarose gel. RAPD patterns were grouped following Pearson\'s coefficient, used to construct a dendogram. RAPD-PCR with primer OPW-12 showed that most varieties of this work showed a very similar fingerprint pattern, indicating that they were likely related. Twenty eight from 30 cassava cultivars analyzed presented more closely genotype, and were distributed into three groups by dendogram. These groups showed similarity coefficient of 75%. Amylolytic activity was determined by quantification of the amount of reducing sugars released during enzymatic reaction with aqueous extract from cassava roots, and variations were observed among cultivars. The evaluation of gene expression showed &#945;-amylase and granule-bound starch synthase genes have been shown to be differentially expressed in some cultivars, with higher expression of MEAMY gene on sample 19, Açaí-Tinga variety, and the same sample 19 and 29, Jabuty variety, for GGSSI gene.

Cette thèse vise à comprendre pourquoi une grande partie de la population malgache souffre de malnutrition alors que le pays est connu pour ses richesses en ressources naturelles, comme les feuilles de Moringa oleifera (MO). L’hypothèse principale est que la malnutrition est liée non seulement à la pauvreté, mais aussi aux croyances et comportements alimentaires. Une démarche en trois phases a été utilisée. La caractérisation nutritionnelle et sensorielle des poudres de MO a tout d’abord montré des variations des taux en protéine, lipides, acides aminés et gras, calcium, magnésium et fer et des propriétés organoleptiques en fonction du lieu d’origine de MO. Des études de croyances et pratiques alimentaires ont ensuite été réalisées dans deux régions en zones rurales et urbaines. Elles ont montré que les aliments glucidiques dominent dans l’alimentation. En revanche, les légumes-feuilles ne sont pas considérés comme nutritives. Les attitudes et comportements alimentaires sont plus basés sur les propriétés sanitaires des aliments que sur l’équilibre en nutriments et le caractère énergétique. Les facteurs déterminants le choix alimentaire de la population ont été identifiés:disponibilité, prix, pouvoir rassasiant, habitude et préférence. Enfin, quatre formulations combinant manioc et MO ont été évaluées par des enfants : le produit avec 1,2 % de poudre de MO et sucré est le plus accepté et choisi face aux autres qui contiennent moins de MO et non sucrés. Il serait possible de contribuer dans la lutte contre la malnutrition en proposant des produits pas chers et incorporant le MO avec des programmes d’éducations adaptés à chaque zone cible. / This work aims at understanding why a high proportion of Malagasy population suffer frommal nutrition, while Madagascar is rich on natural resources, like Moringa oleifera leaves (MO). The hypothesis is that malnutrition is related not only on poverty but also on food beliefs and behaviour. The studies integrating sociopsychology, food sciences and nutrition were conducted on three phases. First, nutritional and sensory characterizations of MO powder showed variations of protein, fat, amino acids, fatty acids, calcium, magnesium and iron contents and organoleptic proprieties depending on locations. Secondly, a study of food beliefs and practices was performed in two regions in urban and rural zones. It showed that Malagasy food is mostly based on carbohydrates foods and that leafy vegetables are not considered as nutritious. Food attitudes and behaviours were mostly based on sanitary proprieties of food than on the equilibrium of nutrients and the caloric characters. The determinants factors of food choice of the Malagasy population were identified: availability, price, satiating power, habit and preference. Finally, four formulations combining cassava roots and MO were evaluated by school age children: the sweet product with 1.2% of MO was the most accepted and chosen in front of the others containing less MO and not sweet. It is possible to contribute to fight against malnutrition by proposing cheap foods containing MO and by integrating information about MO in nutrition education programs adapted to each target area.