Orientadores: Glaucia Maria Pastore, Marta Cristina Teixeira Duarte / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T06:56:55Z (GMT). No. of bitstreams: 1 Simiqueli_AnaPaulaResende_D.pdf: 14118088 bytes, checksum: fde7134a6bda63a14dbd09e77af4109b (MD5) Previous issue date: 2014 / Resumo: Nos últimos anos, produtos naturais como os biossurfactantes e óleos essenciais têm sido objeto de intensa investigação científica. As suas atividades antimicrobianas e antiadesivas fazem com que eles apresentem potencial para serem utilizados para o controle de fungos fitopatógenos na agricultura e combate à micro-organismos multirresistentes e biofilmes na área médica e em indústrias de alimentos. Apesar da surfactina produzida por Bacillus subtilis possuir elevadas atividades superficiais e biológicas e ser um dos biossurfactantes mais estudados atualmente, os seus altos custos de produção e baixo rendimento tornam impraticável a sua produção em escala industrial. Deste modo, este trabalho estudou a produção contínua de surfactina e coprodução de amilases e proteases por B. subtilis utilizando manipueira como substrato em diferentes taxas de alimentação, visando à redução dos custos de processo e ao melhor aproveitamento do arsenal metabólico do micro-organismo. As suas atividades antimicrobiana e antibiofilme do biossurfactante produzido foram estudadas em conjunto com dez óleos essenciais extraídos plantas medicinais e aromáticas. Os valores de produção de biossurfactantes e atividades enzimáticas foram crescentes com o aumento da taxa de diluição empregada, encontrando-se os valores máximos de 2,9 mg.h-1, 938,3 U.mL-1 e 3,6 U.mL-1 para a produção de biossurfactantes e atividades amilolítica e proteolítica, respectivamente. O biossurfactante produzido demonstrou atividade antibacteriana contra Bacillus cereus, Rhodococcus equi e Listeria innocua e inibiu a formação de biofilmes de Staphylococcus aureus e Escherichia coli em até 92 e 78 %, respectivamente. Além disso, ele apresentou efeito sinérgico com os óleos essenciais de Aloysia gratissima e Cymbopogon winterianus para a inibição de R. equi, L. innocua e B. subtilis, com os óleos essenciais de Cinnamomum burmannii, Cymbopogon citratus e Lippia sidoides para a inibição dos fungos fitopatógenos Alternaria solani, Alternaria alternata e Mucor hiemalis e com o óleo essencial de C. winterianus para a inibição da formação de biofilme por E. coli / Abstract: In recent years, natural products such as biosurfactants and essential oils have been the subject of intense scientific research. Due to their antimicrobial and anti-adhesive activities, they show potential for controlling the growth of phytopathogenic fungi in agriculture and combating multi-drug resistant microorganisms and biofilms in medicine and food industries. Despite the high superficial and biological activities possessed by surfactin produced by Bacillus subtilis, their low yields and high production costs hamper their production on a commercial scale. Thus, this work studied the continuous production of surfactin and co-production of amylases and proteases by B. subtilis LB5a using cassava wastewater as substrate varying the dilution rate, in order to reduce production costs and improve the utilization of metabolic arsenal from the microorganism. The antimicrobial and anti-biofilm activities of the biossurfactant produced were studied in blends with ten essential oils extracted from medicinal and aromatic plants. Biossurfactant production values and enzymatic activities were higher with the increase of dilution rate, reaching the maximum values of 2,9 mg.h-1, 938,3 U.mL-1 and 3,6 U.mL-1 for the production of biossurfactants and amylolitic and proteolitic activities, respectively. The biossurfactant showed antibacterial activity against Bacillus cereus, Rhodococcus equi and Listeria innocua and inhibited up to 92 e 78 % of biofilm formation by Staphylococcus aureus and Escherichia, respectively. Moreover, it presented synergistic with the essential oils of Aloysia gratissima and Cymbopogon winterianus for the inhibition of R. equi, L. innocua and B. subtilis, with the essential oils of Cinnamomum burmannii, Cymbopogon citratus and Lippia sidoides for the inhibition of the phytopathogenic fungi Alternaria solani, Alternaria alternata and Mucor hiemalis and with the essential oil of C. winterianus for the prevention of biofilm formation by E. coli / Doutorado / Ciência de Alimentos / Doutora em Ciência de Alimentos

Orientadores: Fumio Yokoya, Pedro de Oliva Neto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T03:17:26Z (GMT). No. of bitstreams: 1 Oliveira_Fernandade_D.pdf: 625914 bytes, checksum: 55c8ae7b1c9dc767558c9cd4439a3e98 (MD5) Previous issue date: 2011 / Resumo: O grande desafio para a produção de etanol de segunda geração consiste em determinar a melhor opção de disponibilizar a glicose a partir da hidrólise do amido em termos de custo global, rendimento glicosídico e fermentabilidade. O farelo de mandioca produzido durante o processamento da fécula foi usado como fonte econômica para a biomassa e produção de bioetanol por Saccharomyces cerevisiae M-26. A suspensão de farelo de mandioca e água 5 % (p/v) foi hidrolisada utilizando como catalisador os ácidos sulfúrico (H2SO4) e fosfórico (H3PO4) em diferentes faixas de pH (0,5, 1,0 e 1,5), a uma temperatura 120 ºC por 30, 60 e 90 minutos de reação. Os resultados demonstraram que o emprego do H2SO4 foi suficiente para hidrolisar o amido, obtendo uma concentração de 2,93 % de açúcares redutores e 2,62 % de glicose, com rendimento de 96,48 % de açúcares redutores, em pH 0,5 e tempo de reação 90 minutos. Nas mesmas condições, o tratamento com H3PO4 obteve 2,52 % de açúcares redutores e 1,99 % de glicose, com um rendimento de 82,87 % de açúcares redutores, concluindo que a hidrolise é tanto mais rápida quando maior o poder ionizante do ácido e que o pH 1,5 é fracamente glucogênico enquanto que a acidicidade mais drástica (pH 0,5) já é mais glucogênica. Concentrações baixas do furfural subproduto hidroximetil (HMF) foram gerados durante a hidrólise do amido quando usou H2SO4 em comparação ao H3PO4. Os tratamentos com H2SO4 produziram 0,17 g/L e 0,02 g/L de HMF após 90 minutos de reação em pH 0,5 e 1,5, respectivamente. Já os tratamentos utilizando o catalisador H3PO4 não geraram concentrações detectáveis de HMF. As amostras obtidas dos tratamentos em pH 0,5 apresentaram menor quantidade de farelo residual em relação as amostras provenientes dos tratamentos em pH 1,0 e 1,5. A linhagem de S. cerevisiae M-26 foi capaz de utilizar e fermentar o hidrolisado e o rendimento teórico de etanol (50,59 %) foi alcançado a 32 ºC após 12 horas / Abstract: The great challenge for the production of second generation ethanol is to determine the best option available bagasse produced during processing of starch was used as an economical source for biomass and bioethanol production by Saccharomyces cerevisiae M-26. The suspension of cassava bagasse and water 5% (w/v) was hydrolyzed using sulfuric acid as the catalyst (H2SO4) and phosphoric acid (H3PO4) in different pH ranges (0.5, 1.0 and 1.5), at a temperature 120 °C for 30, 60 and 90 minutes of reaction. The results showed that the use of H2SO4 was sufficient to hydrolyze the starch, giving a concentration of 2.93 % of reducing sugars and 2.62 % glucose, with a yield of 96.48 % of the reducing sugars at pH 0.5 and 90 minutes reaction time. Under the same conditions, treatment with H3PO4 received 2.52 % of reducing sugars and 1.99 % glucose, with a yield of 82.87 % of reducing sugars, concluding that the hydrolysis is much faster when the more powerful acid, and ionizing pH 1.5 that is weakly acidic glycogen while the most drastic (pH 0.5) is already more glycogen. Low concentrations of byproduct 5-hydroxymethylfurfural (5-HMF) were generated during the hydrolysis of starch when used H2SO4 in relation the H3PO4. The treatments with H2SO4 produced 0.17 g/L and 0.02 g/L of 5-HMF after 90 minutes of reaction at pH 0.5 and 1.5, respectively. Since the treatments using the catalyst H3PO4 did not generate detectable concentrations of 5-HMF. The samples of the treatments at pH 0.5 had a lower amount of bran remaining on the samples from the treatments at pH 1.0 and 1.5. The strain of S. cerevisiae M-26 were able to utilize and ferment the hydrolyzate and the theoretical yield of ethanol (50.59 %) was achieved at 32 °C after 12 hours / Doutorado / Ciência de Alimentos / Doutor em Ciência de Alimentos

The main objective of this study is to evaluate the economic potential and opportunities for introducing Genetically Modified (GM) cassava that is Cassava Mosaic Virus (CMV) resistant and has improved starch properties in South Africa. The level of cassava production in South Africa is limited and thus a study on a new technology for this crop may seem strange. However, with innovations like the CMV resistance trait or amylose free cassava starch, cassava production in South Africa can possibly become more viable and relatively more profitable than competing crops such as maize and potatoes. Various ex ante economic methods and approaches to assessing economic impacts exist in the subject literature: the partial budget approach, cost benefit analysis, consumer and producer or economic surplus approach and the computable general equilibrium (CGE) or simulation model. For the purpose of this study and due to available data, a simple gross margin analysis was applied to analyse the economic profitability of genetically modified cassava in South Africa in comparison to maize and potato. Due to data limitations, this study relies on a synthesis between secondary information from various studies in other African countries and interviews with experts. The information collected was used to assess the potential for genetically modified cassava in South Africa. Secondary information and interviews with experts were used to provide more insights and information relating to the possible opportunities, constraints, performance of the genetically modified events, and production practices for cassava and other competing crops like maize and potato in the country. The gross margin analysis results show that cassava production is not profitable at farm level for both dryland and irrigation scenarios. However, processing cassava into starch results in higher returns from the higher starch output and quality compared to potato and maize. The starch from cassava has many industrial applications. The scenario analysis for GM cassava and infected cassava at 10%, 20%, 30% and 40% expected yield loss showed that the CMV resistant and amylose free GM cassava provides additional benefits due to its better quality and higher starch yields compared to infected varieties. The higher quality starch yields a higher profit making it even more profitable to produce cassava for starch. The results of interviews with subject experts show that cassava production and utilisation has lagged behind other crops in South Africa and the crop is sparingly and informally traded. An analysis of market constraints showed that there is a strong consumer taste preference for maize and other cereals dominating the starch market. Other factors that have contributed to the lagging behind of cassava in South Africa and other African countries are the post colonial government policies that favoured maize over cassava. Cassava has a number of important traits that present a competitive advantage for cassava as a commercial crop for farmers compared to other crops such as maize and potato. For example, cassava can be grown under difficult environmental conditions and has a wide range of applications ranging from food products to industrial starches. Cassava can be grown as a monoculture crop, unlike maize and potato which require rotation. In addition, the special characteristics of cassava starch present an important alternative to maize, wheat, rice and potato. Cassava flour and starch have unique properties which make them ideal for many applications in the food, textile and paper industries where flour and starch from other crops hold a quasi monopoly. For example, among starch producing plants, cassava has been considered as the highest yield producer (25 to 40 percent higher than potato, rice and maize) and as the most efficient (the highest) converter of solar energy to carbohydrate per unit area. However, despite these advantages, cassava has remained a neglected crop in South African agricultural research and development activities compared to cereals. However, the increasing demand for starch based applications in the food industry and industrial sector and the fact that the industry is searching for a cheaper substitute for cereals present an impressive market growth potential for cassava starch. For example, industries including the paper industry, food industry and textile industry are the main buyers of cassava starch in South Africa. The results from interview discussions show that there are some concerns and questions related to the introduction of GM cassava in South Africa. One of the main concerns was that empirical studies in South Africa have shown that the occurrence of cassava mosaic virus in the country is very low; it has an approximate 2 percent incidence rate. As a result, large scale producers have been able to control CMV through good management practices, natural selection and chemical control. Also, bureaucracy and lack of transparency in the South African genetically modified organism (GMO) regulatory system, especially regarding socio-economic issues consumer perception on GM cassava, may result in an extended delay before contained field trials are conducted in the country. It has also become clear that the two proposed GM events are still relatively far from being commercialisable. Furthermore, the current availability of mutant varieties of conventional cassava varieties that can produce better quality starch with a very low amylose content provide an important alternative to GM cassava. The utilisation of the former tends to be less time consuming and less expensive compared to GM cassava. It is difficult to perform a socio-economic assessment before confined laboratory tests or field trials have been conducted. Further development of the potential product would supply crucial information that is needed for an ex ante socio-economic study. It is clear that this study was conducted far too early as GM technologies are not yet remotely close to being ready for commercialisation. Many basic studies still need to be conducted, including field trials. The South African GMO Act and regulations do not clearly stipulate when a socio-economic study should be conducted, but it is clear that the worth of a study conducted before any confined field trials had been performed would be questionable. Copyright / Dissertation (MScAgric)--University of Pretoria, 2010. / Agricultural Economics, Extension and Rural Development / unrestricted

This study aims to test the performance of agricultural markets in the Democratic Republic of Congo (DRC). Although the DRC is classified as the fifth biggest producer of cassava, nearly 70 percent of its population living mainly in urban areas is suffering from food shortages. Since the markets are poorly integrated, food prices are very volatile. Small agricultural producers obtain low prices for their products, while vulnerable household’s consumers experience high prices. Over the last few years, the price of cassava has increased considerably, from US$ 72 per ton in 2007 to US$ 123 per ton in 2009. This dramatic increase in the price of a basic foodstuff has significantly affected poor people in both urban and rural areas. The increase in cassava market prices and the food insecurity level in DRC are an indication that markets have not efficiently performed their fundamental role of connecting producers and consumers. Therefore, understanding the status of value chain development and the degree of market integration is important to improve food security, as well as people’s livelihood in rural areas. Several techniques were identified in the literature for testing agricultural market performance, including: market integration, parity bound analysis, causality, symmetry, error correction mechanisms and value chain analysis. Some studies used mathematical models including deterministic analytical models and stochastic analytical models. For the purpose of this study and because of data limitations, value chain analysis and market integration techniques were applied. The value chain analysis was performed to identify critical issues and constraints that undermine value chain development, as well as to identify business and technological opportunities that can enhance the performance and competitiveness of the sub-sector. The prices of cassava products in the DRC were found to be high, due to the high costs of production, processing and marketing of cassava at different levels of the market chain. Poor market linkages lead to low utilisation of value addition technologies, and this contributes directly to poor market opportunities. This results in a wide range of negative aspects for the sector, such as decreasing incentives for the production and consumption of cassava products and lack of sufficient competitiveness to make cassava a significant commercial commodity. Investment in the sector is considered risky by different chain actors, and is limited as a result of the overall non-competitiveness of the sector. The cassava market in the DRC is organised around Kinshasa in Western Congo, and around Lubumbashi in the South-eastern part of the country. In view of the strategic importance of the two marketplaces, a market integration analysis was conducted to consider whether food policy focusing on those two reference marketplaces would be sufficient to stabilise the cassava supply nationwide, since most of the marketplaces seem to have a strong relationships with these two reference markets. Using co-integration techniques, an error correction mechanism and an index of market connection, the findings established that among the 11 pairs of trading markets, 6 of them were segmented, meaning that price changes in the reference markets were not fully transmitted to the regional markets. Four key factors, including macroeconomic environment, transportation infrastructure, market information flow and distance, played a significant role in price differentials, and caused potential and existing markets to cease to function as efficient generators of wealth and distributors of food. This is apparently one of the most important reasons for increased food insecurity and poverty among food producers and consumers alike. The results confirm the poor value chain status of cassava, which leads to the stagnation of this crop as a semi-commercial crop, and restrains its absorption into the mainstream market chain in local, national and regional markets. The market integration results showed segmented and moderated integrated markets arising from the 11 pairs of trading markets, of which 6 were identified as segmented. The results from the error correction mechanism (ECM) suggest that on average about 30% of past deviations from the long run are corrected each month. Among the 11 paired markets, the highest coefficient of price adjustment in the long run was indicated by the paired markets Bukavu–Goma (43%), Mbujimayi–Kananga (38%) and Matadi-Kinshasa (36%); and the lowest was given by the paired market Kisangani–Kinshasa (15%). In the short run, the IMC of 0.85 suggests a strong market connection between Matadi and Kinshasa, which then suggests that price shocks that occur in the market of Kinshasa affect immediately, and partially, the Matadi markets supplying it. This high IMC coefficient was also found between Bukavu and Goma (0.86), and Kananga and Mbujimay (0.81). None of the other markets trading with Kinshasa and Lubumbashi respond in the short run to price changes in these reference markets. This implies that only 3 market pairs out of 11 hav strong intgration which therefore presents clear evidence of weak market integration between production and deficient areas in the DRC as awhole. This weak linear relationship between markets can be postulated as one of major causes of food insercurity in the country. This understanding of cause of food insecurity and various issues surrounding market integration would futher help policy makers to improve efficiency of cassava marketing system, lower farm to retail price spread and consolidate food security accross the country. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Agricultural Economics, Extension and Rural Development / unrestricted

Orientador: Glaucia Maria Pastore / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T17:50:02Z (GMT). No. of bitstreams: 1 Barros_FranciscoFabioCavalcante_D.pdf: 2000120 bytes, checksum: f060d84f3896d913e5e93d9a39dd6b0f (MD5) Previous issue date: 2011 / Resumo: Um notável desenvolvimento dos bioprocessos tem sido alcançado nas últimas décadas. Entre os principais objetivos da aplicação desses processos está a obtenção de compostos de elevado valor agregado. Somado a isso há, atualmente, uma crescente demanda por materiais e energia, fato que resulta em desequilíbrios ambientais, especialmente quando esses bens são produzidos a partir de fontes não renováveis como o petróleo, por exemplo. Entre as diferentes estratégias para o desenvolvimento desses bioprocessos estão a coprodução, onde a partir de um mesmo processo são obtidos mais de um produto simultaneamente, e o uso resíduo e subprodutos agroindustriais como meios de cultura ou substrato de reações bioquímicas. Neste trabalho, foi realizado o estudo do processo fermentativo realizado pela bactéria Bacillus subtilis usando como meio de cultura a manipueira, um resíduo da industrialização de mandioca. Esse processo resultou na produção simultânea de biomoléculas de interesse industrial, no caso: lipopeptídios biossurfactantes, os compostos voláteis acetoína e diacetil e as enzimas do grupo das amilases e proteases. Adicionalmente, foi usado o método previamente descrito na literatura de recuperação primária de biossurfactantes baseado nos princípios da coluna de espuma. Esse procedimento possibilitou o arraste dos bioprodutos sem que fosse necessário o uso de compostos sintéticos, como solventes, ou a modificação dos parâmetros de fermentação / Abstract: A notable bioprocesses development was achieved in recent decades. Among the objectives of these processes is the production of high added value compounds. Moreover, there is a growing demand for materials and energy, which results in negative environmental issues, especially when those supplies are produced from non-renewable sources such as petroleum. Some of these different strategies for the bioprocesses development are co-production and the use of agro-industrial waste and by-products. The aim of this work was to study the fermentation process carried out by the bacterium Bacillus subtilis developed in manipueira that is a residue of the cassava industrialization. This process resulted in the simultaneous production of industrial interest biomolecules: lipopeptide biosurfactants, volatile compounds (acetoin and diacetil), and enzymes (amylases and proteases). It was used the primary recovery method of biosurfactants based on the principles of the column of foam. This procedure enabled the drag of bioproducts without the use of synthetic chemicals such as solvents, or modification of the fermentation parameters / Doutorado / Ciência de Alimentos / Doutor em Ciência de Alimentos

Orientador: Miriam Dupas Hubinger / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T22:10:22Z (GMT). No. of bitstreams: 1 NolascoPerez_IreneMarivel_M.pdf: 4214130 bytes, checksum: d4a3d21f56f0eb0fc6caa19ac8ae691d (MD5) Previous issue date: 2015 / Resumo: No mundo atual é crescente a demanda dos consumidores por produtos frescos, devido a sua qualidade nutricional, além de oferecer benefícios para a saúde como, por exemplo, na prevenção de algumas doenças. Frente a esta demanda, o presente trabalho estudou o uso de coberturas comestíveis de fécula de mandioca na manutenção da qualidade dos frutos de morango (Fragaria ananassa Duch.). Os frutos de morango receberam tratamentos combinando o processamento mínimo com a utilização de cobertura comestível de fécula de mandioca, cuja finalidade foi prolongar a vida útil destes em temperaturas de refrigeração. Os frutos após o processamento foram mergulhados por 10 minutos em suspensão de 3% (p/v) de fécula de mandioca e submetidos à secagem naturalmente à temperatura ambiente e armazenados em temperaturas de 10 ?C e 15 ?C. Na primeira etapa, o objetivo foi avaliar as características da cobertura aplicada nos morangos (propriedades mecânicas: forças de ruptura e penetração, cor dos morangos, taxa de respiração e resistência ao vapor de agua) depois de 24 horas do tratamento. A aplicação da cobertura nos morangos não alterou significativamente as propriedades mecânicas (forças de ruptura e penetração), cor dos morangos, taxa de respiração e resistência ao vapor de água em comparação aos morangos sem coberturas. Na segunda etapa foi realizado o estudo da vida útil dos morangos com e sem cobertura, armazenados a temperaturas de 10 ?C e 15 ?C. Na perda de peso verificou-se diferença significativa ao longo do tempo de armazenamento diferença significativa, e no tempo fixo não se observou diferenças significativas entre os tratamentos, a taxa de respiração mostrou um incremento significativo em todos os tratamentos ao longo no tempo de armazenamento e para tempo fixo não presentaram diferenças significativo entre os tratamentos exceto no dia 1 se observou que o tratamento 15 ?C com cobertura diminui significativamente com respeito a 15 ?C sem cobertura. O teor de antocianinas apresentou uma diminuição significativa ao longo do tempo de armazenamento para os tratamentos 10 ?C sem cobertura e 15 C sem e com cobertura em ambas temperaturas são não significativo nos dia 5 e 8. As amostras 10 ?C com e sem cobertura e 15 ?C com e sem cobertura foram avaliadas sensorialmente os morangos com cobertura apresentaram notas acima do limite de aceitação (4,5), o fator que determinou o tempo de vida útil foi a contaminação microbiológica observada nas amostras. As amostras armazenadas a 10 ?C com e sem cobertura apresentaram 8 dias de vida útil e as amostras armazenadas 15 ?C com e sem cobertura apresentaram 5 dias de vida útil / Abstract: Nowadays there is a growing consumer demand for fresh products, due to their nutritional quality and the health benefits they provide, for example, in the prevention of some diseases. Faced with this demand, the present work analyzed the use of edible cassava starch coating for preserving the quality of strawberry fruits (Fragaria ananassa Duch.). Strawberries underwent treatment combining minimal processing with the use of edible cassava starch coating, aiming to extend the lifetime of these fruits at refrigerated temperatures. To this aim, after the processing stage, the fruits were immersed for 10 minutes in a 3% (w/v) cassava starch suspension; then they were naturally dried at room temperature and stored at temperatures of 10?C and 15?C. During the first stage, the objective was to evaluate the characteristics of the starch-based coating applied to strawberries ¿ that is, mechanical properties (compression and penetration strengths) strawberry color, respiration rate and water vapor resistance ¿ after a 24-hour treatment. The application of the coating on the strawberries did not significantly modify the mechanical properties (compression and penetration strengths), strawberry color, respiration rate and resistance to water vapor, when compared to uncoated strawberries. During the second stage we studied the lifetime of coated and uncoated strawberries stored at temperatures of 10?C and 15?C. In the weight loss treatments, we were able to verify significant differences during the storage time, and in the fixed time no significant differences were observed, the respiration rate showed significant increase in all treatments during storage time, and in the fixed time, no significant differences among treatments were seen, except for day 1, when it was observed that the coated fruits under treatment at 15 ?C showed a significant decrease with regard to the uncoated fruits treated at 15?C. The anthocyanin content showed significant decrease during storage time for uncoated fruits at 10?C and for coated and uncoated fruits at 15?C; at both temperatures there were no significant results on days 5th and 8th. Sensory analysis was performed on samples at coated and uncoated stored at 10?C and 15?C . Coated strawberries showed numbers above the acceptance limit (4.5). The factor that determined the lifetime was the microbiological contamination observed in the samples. Coated and uncoated samples stored at 10?C had an 8-day lifetime and the coated and uncoated samples stored at 15?C had a 5-day lifetime / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

Os problemas ambientais provocados pelas embalagens à base de materiais sintéticos não biodegradáveis têm provocado um importante aumento nos estudos sobre filmes à base de biopolímeros. Entretanto, esses filmes têm limitações em suas propriedades, devido, sobretudo à sensibilidade a umidade relativa ambiente. Dentre as alternativas estudadas para melhorar as características desses materiais está o uso de nanopartículas, com destaque para a montmorilonita, que tem problemas de dispersão em água. Outra nanopartícula pouco usada em estudos à base de biopolímeros é a laponita, que é uma nanoargila sintética. Assim, o objetivo geral desta tese foi o desenvolvimento de filmes à base de biopolímeros (colágeno, gelatina e fécula de mandioca), reforçados com uma nanoargila (laponita). Foi estudado o efeito da concentração do biopolímero e da laponita, assim como o método de produção dos filmes (casting e espalhamento mecânico), além da qualidade da dispersão da nanopartícula, sobre as principais propriedades físicas dos filmes nanocompósitos, com especial interesse nas propriedades de superfície. Os filmes foram preparados pela desidratação de soluções formadoras de filmes (SFF), com 2, 4 ou 8 g de biopolímero/100 g SFF; 25 ou 30 g glicerol/100 g de biopolímero; e 0, 1,5; 3; 4,5 e 6 g laponita/100 g de biopolímero. A laponita foi dispersa em água destilada, utilizando-se ultraturrax com velocidade de agitação de 20.000 rpm, por 30 minutos. As partículas de laponita em água tiveram tamanhos menores que 50 nm. Não houve efeito da concentração do biopolímero, nem do método de produção (casting ou espalhamento mecânico) sob as propriedades de topografia superficial e físico-químicas estudadas nos filmes nanocompósitos. As análises de raios X e espectroscopia de infravermelho por transformada de Fourier revelaram que as plaquetas de laponita estiveram esfoliadas e/ou intercaladas nos filmes, e que não houve nenhuma formação de ligação química entre as plaquetas de laponita e os biopolímeros em estudo. A presença de laponita incrementou a irregularidade superficial dos filmes, especialmente naqueles produzidos com colágeno e fécula de mandioca. Outras propriedades dos filmes nanocompósitos, tais como densidade, umidade, cor, opacidade, propriedades térmicas, propriedades mecânicas, solubilidade em água, ângulo de contato à água, isotermas de sorção e permeabilidade ao vapor de água não sofreram alterações com a presença de laponita. / The environmental problems caused by packaging based on non-biodegradable synthetic materials have lead to a significant increase in studies about biopolymer films. However, these films have limited physicochemical properties due mainly to its sensitivity to ambient relative humidity. Among the alternatives studied to improve the physicochemical properties of these materials is the use of nanoparticles, especially the montmorillonite, which has problems of dispersion in water. Another nanoparticle no so much studied in films based on biopolymers is laponite, which is a synthetic nanoparticle. Thus, this these aims to development and characterize films based on biopolymers (collagen, gelatin and cassava starch), with a nanoparticle (laponite). The effects of biopolymer and laponite concentrations were studied, as well as, the film production method (casting and spreading), besides the quality of laponite dispersion and its relationship with the physicochemical properties of the films were investigated, with special interest on the surface properties. The films were produced by the dehydration of filmogenic-forming solutions (FFS), with 2, 4 or 8 g of biopolymer/100 g FFS; 25 or 30 g glycerol/100g of biopolymer; and 0, 1.5, 3, 4.5 and 6 g of laponite/100g of biopolymer. The laponite was dispersed in water using ultraturrax, at 20,000 rpm, for 30 minutes. The laponite particles in water had sizes smaller than 50 nm. There was not effect of biopolymer concentration and film production method (casting or spreading) on the surface and physicochemical properties studied in the nanocomposite films. X-ray analysis and Fourier transform infrared spectroscopy revealed that laponite platelets were exfoliated and/or intercalated in the films, and that there were no formed chemical bonds between laponite platelets and the biopolymers studied. The presence of laponite increased the surface irregularity of the films, especially in those produced with collagen and cassava starch. Other properties in the nanocomposite films, such density, moisture content, color, opacity, thermal properties, mechanical properties, water solubility, water contact angle, sorption isotherms and water vapor permeability were not altered by the presence of laponite.

Orientador: Jorge de Lucas Junior / Resumo: As demandas por energia e alimento aumentarão com as projeções do crescimento populacional mundial. O Brasil está entre os países com o desafio de atender essas demandas. O tratamento dos resíduos gerados na agropecuária tem potencial para produção de biogás e biofertilizante por meio de biodigestores, insumos essenciais para alavancar a produção de alimentos e o desenvolvimento sustentável. Com isso, analisou-se a viabilidade técnica e econômica da codigestão de cama de frango com batata doce ou mandioca visando aumentar a produção de energia e reciclagem de nutrientes dos resíduos da produção de frangos. A utilização de culturas energéticas para codigestão anaeróbia é uma inovação para geração de energia renovável em propriedades rurais e tem ganhado atenção em economias emergentes, que tem como desafio suportar a produção de alimentos com sustentabilidade. O ensaio foi realizado com três tratamentos, cama de frango, cama de frango com batata doce e cama de frango com mandioca. A codigestão com as culturas energéticas foram mais eficientes que a monodigestão. A mandioca superou a batata doce em 17,09% no rendimento médio de biogás diário e reduziu 12 e 3,32% mais sólidos totais e voláteis, respectivamente. No entanto, o potencial de biogás da batata doce 0,449 m3 kg-1SVad e da mandioca 0,457 m3 kg-1SVad não apresentaram diferença significativa, assim como os teores de metano com 61,92 e 61,79%, respectivamente, demonstrando o potencial equivalente das duas culturas na geraç... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Demand for energy and food will increase with projections of world population growth. Brazil is among the countries with the challenge of meeting these demands. The treatment of waste generated in agriculture has the potential to produce biogas and biofertilizer through biodigesters, essential inputs to leverage food production and sustainable development. With this, the technical and economic feasibility of codigestion of chicken with sweet potatoes or manioc was analyzed in order to increase energy production and recycling nutrients from chicken production residues. The use of energy crops for anaerobic codigestion is an innovation for the generation of renewable energy in rural properties and has gained attention in emerging economies, which have the challenge of supporting sustainable food production. The trial was carried out with three treatments, chicken bed, chicken bed with sweet potato and chicken bed with cassava. Codigestion with energy crops was more efficient than monodigestion. Cassava exceeded sweet potatoes by 17.09% in the average daily biogas yield and reduced 12 and 3.32% more total and volatile solids, respectively. However, the biogas potential of sweet potato 0.449 m3 kg-1SVad and cassava 0.457 m3 kg-1SVad did not show any significant difference, as well as the methane contents with 61.92 and 61.79%, respectively, demonstrating the equivalent potential of both cultures in the generation of bioenergy. In addition to the generation of renewable energy, th... (Complete abstract click electronic access below) / Doutor

Orientador: Cláudio Cabello / Banca: Rogério Lopes Vieites / Banca: Luis Fernando Barbisan / Resumo: A farinha de mandioca é consumida intensamente na culinária brasileira, participando como fonte importante de carboidratos na dieta. Em algumas regiões onde condições sócio econômicas impõe restrições a uma dieta balanceada, esta fonte de carboidrato se apresenta talvez como a única fonte de nutrientes para o consumo. A mandioca possui baixas concentrações de proteínas e matérias graxas quando comparada a outras fontes de alimento concorrentes nestes nichos, tais como o feijão e o milho e, portanto esta característica não a recomenda como constituinte principal nas dietas. Aproveitar materiais residuários descartados na colheita significa aproveitamento mais racional do custo de produção. As pesquisas sempre focaram a presença de proteínas nas folhas de mandioca, bem como a importância dessa fonte alternativa de nutrientes, disponível para o consumo humano, onde normalmente são consumidos na forma desidratada e crua, adicionado aos alimentos em diferentes proporções. No entanto, não foi encontrado nenhum trabalho onde a utilização desse alimento não se apresentasse na forma crua, e que fosse submetido ao processo de cocção em temperatura suficiente para diminuir a presença de compostos fenólicos, haja visto que estes compostos são sensíveis à exposição de temperatura elevada, onde supõe-se a possibilidade do processo de degradação parcial dos mesmos compostos, considerando, as condições de tempo de cocção, umidade do material, concentração de fibras presentes na variedade, concentração de ácidos orgânicos, entre outros, onde essa farinha fosse preparada, adicionando proporções dessa folha, antes do processo de cocção e na seqüência submetidos a fornos abertos em temperatura em torno de 150 a 200ºC. O processo de fabricação da farinha pode afetar positivamente ao provocar a redução dos compostos considerados antinutricionais... (Resumo completo, clicar acesso eletrôncio abaixo) / Abstract: The cassava flour is largest consumed in Brazil and is an important carbohydrate source. Due the social and economic situation of some Brazilian regions, this product shows it the main nutrient source. The cassava has low protein and lipids when compared with other important foods as bean and corn. Because of nutrient deficiency, cassava is not recommended as principal food in diets. The use of harvest residues means a rational production with low cost for industries. In the same way, the addition of plant parts without additives with low alterations in process is other argument for cost reduction with low nutrition risk. The research always aiming the protein presence in cassava leaves, as well as the importance of leaves as alternative source of nutrients, available for the human consumption. The cassava leaves are normally consumed in the dehydrated and raw form and are added in different percentage in food preparations. However, is difficult to observe researches that objective to use temperature aiming to reduce the phenolic components in cassava leaves. The phenolic composites are high temperature sensible and in this conditions occur the partial degradation of these components. It is important to consider the time of exposition, humidity of material, fiber percentage, organic acids concentration, process of flour preparation, percentage of leaves and dryer temperature in opened oven (150ºC to 200ºC) in this process. The cassava flour processing can affect positively due the decrease of anti-nutritional components, increase of digestibility and protein absorption, and the use of the enriched flour can be an alternative to recoup the nutritional state of individuals group with alimentary deficiency. The objective of this work was to evaluate the composition and nutritional value of cassava flour added of leaves aiming to analyze the viability as alimentary source, as well as the... (Complete abstract click electronic access below) / Mestre

MSCAGR (Plant Production) / Department of Plant Production / Agricultural production under rain-fed conditions is largely dependent on the availability of water stored in the soil during rainfall events. The production of cassava (Manihot esculenta Crantz) under rain-fed conditions in the north-eastern part of South Africa is constrained by low and erratic rainfall events. Improving cassava production in the area requires the use of cassava varieties which are efficient in the use of limited soil moisture. The current climate change and increasing population growth on the planet will place more pressure on agriculture to produce more food using less water. Therefore, previously under-researched and underutilised crop like cassava could be used to bridge the food gap in the future. Although the crop currently occupies low levels of utilisation in South Africa and it is cultivated by smallscale farmers in the Low-veld of Mpumalanga, Limpopo and Kwazulu-Natal provinces using landraces with no improved varieties available in the country. Information on the actual pattern of water extraction, water use and water use efficiency of cassava landraces grown in the dry environments of South Africa is limited. Therefore, the objective of the study was to determine the differences in water use efficiency, gaseous exchange and yield among four cassava landraces grown under rain-fed conditions. Two field experiments were conducted during the wetter (2016/2017) and drier (2017/2018) cropping season at the University of Venda's experimental farm. The trials were laid in a Randomized Complete Block Design (RCBD) consisting of four cassava landraces (ACC#1, ACC#2, ACC#3, and ACC#4) replicated three times. Mature cassava stem cuttings of 30 cm long, were planted manually at a spacing of 1 m x 1 m in both seasons. Each experimental unit consisted of six plant rows of 6 m length (36 m2) and 8 rows of 8 m length (64 m2) in the 2016/17 and 2017/2018 cropping season, respectively. The experiments were under rain-fed conditions without fertilizer additions and the plots were kept weed-free throughout the experimental period. Data collected in the field included soil moisture content, gaseous exchange parameters (net leaf ܥܱଶ uptake, stomatal conductance, and intracellular carbon dioxide concentration), chlorophyll content index (CCI), maximum photochemical quantum yield of PSII (Fv/Fm), effective quantum yield of PSII (ФPSII) and photosynthetic active radiation (PAR). Yield and yield components (root length (cm), root girth (cm), number of storage roots and mean root weight (g plant-1), root yield and aboveground biomass), as well as water use efficiency (WUE), were determined at harvest. Soil moisture content was measured at seven-day interval from sowing until harvest using a neutron probe. Soil moisture data were used to determine crop water use using the water balance approach. There was no variation in the root yield and yield components amongst the landraces in 2017/2018 cropping season but, genotypes affected aboveground biomass, root girth, number of roots per plant and root yield in 2016/2017 cropping season. There was a significant difference (P<0.01) in number of roots (per plant) 81% and 62% greater in ACC#3 and ACC#2 (6.7 & 6.0, respectively) compared with ACC#1 and ACC#4, which both recorded 4 roots per plant. Similarly, root girth was greater in ACC#3 (17.8 cm) and ACC#2 (18.2 cm) compared to ACC#1 (14.1 cm) and ACC#4 (12.9 cm), which were statistically the same. In contrast, total biomass (P<0.01) and root yield (P<0.05) were greater in ACC#3 (20.7 and 11.9 t ha-1, respectively) and ACC#1 (22.0 and 11.3 t ha-1, respectively) compared to ACC#2 and ACC#4 with root yields of 10.2 and 9.5 t ha-1, biomass of 17.1 and 16.3 t ha-1, respectively. Although the genotype x cropping season interaction did not affect root yield and yield components, root yield (by 33.8%; 2.7 t ha-1) and yield components were greater in the wetter compared to the drier season as expected. Water use efficiency of root yield (WUErt) and water use efficiency of biomass production (WUEb) varied with landraces in season I from 37.0 kg ha-1 mm-1 (ACC#4) to 46.60 kg ha-1 mm-1 (ACC#3), and between 71.30 kg ha-1 mm-1 (ACC#2) and 86.0 kg ha-1 mm-1 (ACC#1), respectively. Landraces did not differ in their water use and soil moisture extraction in both seasons but differed in season. However, there was a significant positive correlation between water use efficiency of root yield (WUErt) (0.963***) and water use efficiency of biomass production (WUEb) (0.847***). WUE of biomass production was greater in the drier than the wetter season partly because of dry matter accumulation per evapotranspiration within the landraces. Photosynthesis did not vary with landraces, however, stomatal conductance varied with landraces from 0.08 mmol m-2 s-1 (ACC#4) to 0.2 mmol m-2 s-1 (ACC#2). In contrast, ACC#1 and ACC#3 recorded the same value of stomatal conductance, which is 0.1 mmol m-2 s-1. The effective quantum yield of PSII photochemistry (ΦPSII) did not vary with landraces but the maximum photochemical quantum yield of PSII (Fv/Fm) varied with landraces from 0.652 (ACC#4) to 0.792 (ACC#3) in season II. The proportion of intercepted radiation was affected by landraces in 2017/2018 cropping season. Highest proportion of intercepted radiation was observed in ACC#3 and the lowest in ACC#2. Proportion of intercepted radiation varied with landraces from 22.62% (ACC#2) to 86.45% (#ACC#3). There were significant genotypic variations in chlorophyll content recorded in both season. Chlorophyll content varied with landraces from 33.1 CCI (ACC4) to 55.4 CCI (#ACC3) in the 2016/2017, and in 2017/2018 cropping season chlorophyll content varied with landraces from 36.9 CCI (ACC4) to 78.7 CCI (#ACC3). The highest genotypic variation in chlorophyll content was observed in ACC#3, whilst the lowest chlorophyll content was recorded in ACC#4 in both seasons. / NRF