Orientador: Fernanda Paula Collares Queiroz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T13:53:18Z (GMT). No. of bitstreams: 1 Fontes_LucianaCristinaBrigatto_D.pdf: 6013554 bytes, checksum: 9dd45a450968a0fd95033fd89bdb37d1 (MD5) Previous issue date: 2009 / Resumo: O Brasil apresenta a maior produção de batata-doce do continente latino-americano. Uma alternativa interessante para a expansão da cultura e também devido a sua alta perecibilidade seria a utilização da batata-doce como chips que é um mercado que vem crescendo muito por se tratar de um produto de conveniência. O objetivo deste estudo foi desenvolver chips de batata-doce com mínima incorporação de óleo, pela otimização da tecnologia combinada dos pré-tratamentos: desidratação osmótica e aplicação de coberturas comestíveis, antes do processo de fritura por imersão em oleína ou estearina de palma. A estratégia utilizada foi a avaliação sequencial das seguintes etapas: (i) estudo da atuação de diferentes antioxidantes na prevenção de escurecimento enzimático do vegetal; (ii) estudo do efeito das condições operacionais e teor das soluções desidratantes e otimização do processo de desidratação osmótica; (iii) potencial de aplicação de coberturas comestíveis; (iv) otimização do processo de fritura em oleína ou estearina de palma; (v) efeito combinado da desidratação osmótica e coberturas comestíveis antes do processo de fritura e (vi) estudo da vida útil dos chips desenvolvidos. O processo de imersão de batata-doce em solução de metabissulfito de sódio 2,0% constitui-se no método mais eficiente como tratamento preliminar para a inibição do escurecimento enzimático. No processo de desidratação osmótica para chips de batata-doce, as melhores condições operacionais encontradas foram: (i) concentração de glicerol/CaCl2 de 30%/1% (p/p); (ii) concentração de xarope de glicose de 63,75%, (iii) temperatura de 48ºC e (iv) tempo de 120 minutos. De acordo com a caracterização das propriedades químicas e físicas, o filme de alginato é o mais indicado para ser aplicado como cobertura nos chips de batata-doce. No aspecto coloração após a fritura, o filme de metilcelulose é o mais indicado, pois praticamente não apresentou alteração de coloração após o processo de fritura. A otimização do processo de fritura de chips de batata-doce frito em oleína de palma visando à minimização do teor de óleo incorporado e de umidade indicou como condições mais adequadas: (i) temperatura de 160ºC e (ii) tempo de 3 minutos e 30 segundos. O desenvolvimento de chips de batata-doce com baixa incorporação de óleo foi possível devido aos processos combinados (pré-tratamentos) de desidratação osmótica e aplicação de cobertura comestível de metilcelulose, reduzindo em 55,75% a absorção de óleo após o processo de fritura. Os chips de batata-doce controle e tratamento apresentaram algumas diferenças estatisticamente significativas (p<0,05%) nas características físicas e físico-químicas com a estocagem do produto, no entanto, não foi detectada sensorialmente pelos provadores, fazendo com que os chips de batata-doce pudessem ser estocados por 60 dias sem perdas das características sensoriais. Os chips de batata-doce não submetidos aos pré-tratamentos (controle) apresentaram melhores características físicas, físico-químicas e sensoriais durante os 60 dias de estocagem, se comparado aos chips de batata-doce com baixo teor calórico. A textura foi o atributo que mais influenciou negativamente a aceitação e a intenção de compra dos chips de batata-doce. A textura rígida, possivelmente, esteja relacionada com a natureza do vegetal e espessura da fatia utilizada. O emprego de outros processos tecnológicos pode melhorar a textura deste produto, fazendo com que a aceitação e a intenção de compra aumentem / Abstract: Brazil is the greatest sweet potato producer in the Latin American continent. An interesting alternative for the expansion of the culture of this root, that would also help solve problems related to its highly perishable nature, could be the production of sweet potato chips, a market that is growing as a convenience product. The aim of this study was to develop sweet potato chips with minimal oil incorporation, through the optimization of the combined technology of the pre-treatments: osmotic dehydration and application of edible coatings before the process of frying by immersion in the palm olein and stearin. The strategy used was to evaluate the following sequential steps: (i) study the performance of different antioxidants in the prevention of enzymatic browning of vegetables, (ii) study the effect of operating conditions and content of dehydrate solutions and optimization of the process of osmotic dehydration; (iii) potential application of edible coatings, (iv) optimization of the process of frying in palm olein or stearin, (v) the combined effect of osmotic dehydration and edible coatings before the process of frying and (vi) study shelf life of chips.The process of immersion of sweet potato, in a solution of sodium metabisulphite, 2% is in the most efficient method for preliminary treatment and the inhibition of enzymatic browning. In the process of osmotic dehydration for sweetpotato chips, the best operating conditions were: (i) concentration of glicerol/CaCl2 of 30%/1% (w/w), (ii) concentration of glucose syrup of 63.75%, (iii) temperature of 48ºC and (iv) time of 120 minutes. According to the characterization of chemical and physical properties the film of alginate is the most suitable to be used as mulch in sweet-potato chips. On the color after frying, the film of methylcellulose is the most appropriate, because almost showed no change in color after the process of frying. The optimization of the process of frying sweet potato chips fried in palm olein in order to minimize the oil content and moisture showed incorporated as the most appropriate: (i) temperature of 160 ° C and (i i) time of 3 minutes and 30 seconds. The development chips sweet potato with low oil incorporation was possible due to the combined processes (pre-treatments) of osmotic dehydration and application of edible methylcellulose coating, reducing oil absorption by 55.75% after the frying process. The control and treated sweet potato chips showed some statistically significant differences (p<0,05%) in physical and physicochemical characteristics during storage of the product, but, they were not detected in the sensory analysis by the panelists, making it possible to store the sweet potato chips for 60 days without loss of sensory characteristics. Control sweet potato chips showed better characteristics, both in physical and physicochemical analyses, as in sensory analysis, during the 60 days of storage, compared to treated sweet potato chips. Texture was the attribute that showed greatest negative influence on the acceptance and purchase intention of chips sweet potato. The rigid texture may be due to the nature of the vegetable and to the slice thickness used. The use of technological processes could improve the texture of this product, increasing acceptance and purchase intention / Doutorado / Doutor em Tecnologia de Alimentos

A batata doce (Ipomoea batatas Lam) é um alimento considerado rica fonte de carboidratos, fibras, minerais, vitaminas e também antioxidantes como carotenóides, compostos fenólicos e antocianinas que contribuem na pigmentação natural das raízes de diferentes cultivares e cuja bioatividade tem sido associada com a proteção de células e tecidos no organismo prevenindo e reduzindo o risco de doenças crônicas. Recentemente tem sido despertado interesse pelo desenvolvimento de raízes de batata doce de polpa alaranjada, ricas fontes de carotenóides, como estratégia aliada na solução dos problemas de deficiência de vitamina A no mundo. O presente trabalho teve como objetivo avaliar as concentrações de compostos carotenóides individuais, compostos fenólicos totais e a atividade antioxidante de raízes de quatro cultivares de batata doce biofortificadas cruas e processadas mediante quatro tratamentos térmicos comuns, usando as técnicas de cromatografia líquida de alta eficiência, ensaios Folin- Ciocalteu, DPPH e ABTS, respectivamente. Adicionalmente foram feitos medições dos parâmetros de cor usando o sistema Hunter de medida na matéria prima. Todos os cultivares avaliados apresentaram altos teores de carotenóides, com predominância do All-trans--caroteno, sugerindo alta atividade estimada de vitamina A. O cultivar CNPH 1194 apresentou teores consideráveis de carotenóides. Os compostos fenólicos totais variaram entre os cultivares e os processamentos. Os tratamentos térmicos favoreceram, na maioria dos casos, diminuição significativa dos compostos bioativos avaliados, bem como da atividade antioxidante, sendo que a estabilidade destes compostos aparentou ser um fator dependente do cultivar. Houve correlações significativas entre os valores de cor instrumental e os carotenóides, assim como entre os compostos bioativos e a atividade antioxidante dos diferentes cultivares a níveis de 1 e 5%. / Sweet potato (Ipomoea batatas Lam) is rich in carbohydrates, fiber, minerals, vitamins and also antioxidants such as carotenoids, phenolic compounds and anthocyanins which provide cultivars with distinctive flesh colors. Recent epidemiological evidence suggests that antioxidants have health-promoting properties that may reduce the risk associated with chronic diseases. It has been recently awakened interest in the development of orange-fleshed sweet potatoes, rich sources of carotenoids, such as an intervention strategy of combating vitamin A deficiency in the world. This study was conducted to evaluate the accumulation of individual carotenoids, total phenolic compounds and antioxidant activity of roots of four cultivars of sweet potato biofortified raw and processed through four common heat treatments. Techniques of HPLC, Folin- Ciocalteu, DPPH (1,1-diphenyl-2-picrylhydazyl) and ABTS assays, respectively were used. In addition measurements were made of color parameters using the Hunter system in raw material. All cultivars evaluated have high levels of carotenoids, predominantly All-trans--carotene, suggesting a high estimated vitamin A activity. The cultivar CNPH 1194 showed significant levels of carotenoids. The total phenolic compounds varied among cultivars and heat treatments. The heat treatments favored in most cases a significant decrease in bioactive compounds as well as the antioxidant activity and stability of these compounds appeared to be a factor dependent on the cultivar. There were significant correlations between the values of instrumental color and carotenoids, and bioactive compounds and antioxidant activity of cultivars to levels of 1 and 5%.

Household food security has been described with a three-factor definition: 1) the availability of food, 2) the access thereto, and lastly 3) the food utilization patterns and practices. In previous research, both the availability and access to food were studied in a farming community in the Free State Province to understand how these factors contribute to household food security. However food utilization was not investigated at the time. Food consumption patterns of households deserve attention, particularly in relation to food gardens and nutrition, including the cultivation cycle, dietary norms and practices, and methods of food preparation and preservation. By studying utilization patterns of foods, the context of food insecurity and the resultant malnutrition can be better understood. The purpose of this study was to investigate whether the food utilization strategies of a known food crop (spinach) can be used to establish efficient utilization of a new, unfamiliar crop (orange-fleshed sweet potato) in a farm worker community. Three focus group interviews were conducted with a total of 21 participants to determine current food utilization patterns of spinach and orange-fleshed sweet potato (OFSP). The women were asked to describe how they currently utilize these crops in the same focus iv group discussion (although the focus was on the known crop (spinach)) to understand what actions they take during the process of utilization, from access to disposal. They were asked to describe which tools and methods they apply, and who participates in all these various activities. Subsequently, the respondents were asked to perform all these steps while being observed to record current practices. Data from the focus group interviews and the observations were transcribed and categorized under themes. It was found that in addition to a lack of dietary diversity and subsequent malnutrition found discovered in another study of this community, that they are also not optimally utilizing their food. This is as a direct result of lack of access to a variety of food due to monetary constraints, lack of nearby shops, a lack of cultivation and production education about crops that can be home-produced, and a lack of knowledge about nutrition and the importance of a varied diet. A food-based approach to improve the lack of knowledge of home-produced crops and nutrition was, consequently, the focus of this utilization strategy. This information was used to design a food-based strategy to improve the utilization of an unfamiliar crop (OFSP), in areas where the food crop was not being utilized optimally. Although the strategy was developed based on observations and lessons from one specific community, the principal findings were used to develop a strategy that is generic to the implementation of an unfamiliar food crop, and can then be refined for a specific community before implementation. A complete training manual was developed to complement the food-based strategy. The researcher then tested the strategy with agricultural extension officers who are active in communities where food insecurity and malnutrition exist during a training programme hosted by the Agricultural Research Council - Roodeplaat. The agricultural extension officers provided input on the strategy and identified areas for improvement. These recommendations were adapted in a manual to ensure that the developed strategy could be broadly implemented in other communities. The overall conclusion of the study is that it is necessary to investigate and understand all elements of the food utilization system to truly understand the reasons for observed behaviour, habits and practices. Planning and developing a nutrition education programme requires systematic analysis of nutrition and health-related problems in a given community. It is evident that each step of the utilization cycle is equally critical and should enjoy comparable attention to facilitate delivery of nutrient-rich foodstuffs to the end user. / Dissertation (MConsumer Science)--University of Pretoria, 2012. / gm2014 / Consumer Science / unrestricted

Thesis. (M. A. Agriculture (Agricultural Economics)) -- University of Limpopo, 2022 / Food security, poverty and hunger issues, as well as methods of addressing remain a concern for many South Africans. Smallholder farmers' agricultural production is seen as the key to simultaneously alleviating poverty and ensuring food security, especially in rural areas. The sweet potato crop is commonly produced by smallholder farmers in rural areas as a staple in many South African households with the potential to reduce hunger and poverty. Nevertheless, just like other crops, the sweet potato is impaired by external factors such as extreme weather conditions, insects, pests and diseases, thus threatening food security. The most destructive pest to sweet potatoes acknowledged in the literature is the sweet potato weevil (SPW), which can cause between 5-100% in areas where it is not controlled. While there are many SPW control measures Entomopathogenic Nematodes (EPNs) are emerging as one of the Integrated Pest Management (IPM) bio-control techniques that have shown promise in controlling SPW infestations in South Africa and globally. This study conducts a socio-economic analysis of smallholder sweet potato production and analyses the acceptability of EPNs as bio-control measures against the SPW in the Gauteng, Limpopo and North West Provinces of South Africa. This was done through an assessment of farmers‘ knowledge, attitudes, perception and practices (KAPP analysis), exploration of the acceptability of EPNs by farmers, determination of and factors influencing profitability and technical efficiency. Primary data was collected from 119 respondents who were selected through non-probability sampling techniques; purposive, census, and snowball. The analytical tools used to analyse the data were descriptive statistics, Gross Margin Analysis, Multiple linear regression model, Data Envelopment Analysis (DEA) and the Tobit regression model. From the results, an average knowledge score of 2.30 based on a 3–point Likert scale revealed that sweet potato farmers are knowledgeable of the SPW, the impacts and the control measures. Despite this level of knowledge, the farmers were impartial about the attitudes and perceptions regarding the SPW and the control measures. This was based on the findings of a 5-point Likert scale, which yielded average scores of 2.53 and 2.74, respectively. The study also revealed that the majority of the farmers prefer the use of indigenous and physical practices to control SPW. With regards to acceptance of the EPNs bio-control innovation towards control of the SPW, a mean Composite Index of Acceptancy (CIA) of 0.77 revealed the willingness of farmers to accept the EPNs as a bio-control measure. A Gross margin of R9 552.37 indicates that sweet potato farming is generally profitable, and this is influenced by socio-economic factors such as marital status, employment status, sweet potato output per cycle and access to machinery. On the other hand, while sweet potato farming was found to be profitable, the DEA score of 0.09 reveals that these farmers are technically inefficient. Their technical inefficiency is influenced by sweet potato output per cycle, gross margins, farm size, and access to credit, employment status, and chemical use. Based on these findings, the study recommends farmers‘ support through capacity development initiatives for the sweet potato farmers with regards to general economics of sweet potato production and marketing to maximise and sustain their revenue generation, as well as their general efficiency. In addition, increased training and awareness of the EPNs and their benefits as bio-control measures towards SPW infestation will work towards changing farmers‘ mindset with regard to SPW control measures. / Department of Social Innovation (DSI) and United States Agency for International Development (USAID)

Thesis (M.Sc. (Horticulture)) --University of Limpopo, 2022 / Worldwide, water scarcity, land degradation and unavailability of agricultural lands have posed serious threats on food security and income generation. Hunger, micronutrient deficiencies and starvation are likely to go up in Africa due to increasing urbanisation and rise in global food prices. As a result, it is important to identify innovative vegetable growing-based strategies, which can increase access to food by utilising the limited space available in rural and urban areas. Therefore, sack gardening technology could be a solution to both the lack of arable land and water scarcity in urban and rural areas. The objective of the study was to determine whether axillary bud number will have an effect on agronomic parameters and yield of sweet potato cv. 'Blesbok' produced using the sack gardening technology. Treatments, namely, 1, 2, 3, 4, and 5 number of axillary buds per stem cutting, were arranged in randomised complete block design, with 10 replicates. One bud (1) was used as a control. Different stem cuttings measuring from 10 to 30 cm long with approximately one (1) to six (6) axillary buds were collected from mature sweet potato plantation at a certified nursery from cv. 'Blesbok'. A total of eight (8) stem cuttings were planted in sacks consisting of growing media mixture of steam pasteurised loam soil and compost (3:1 v/v), 4 on top side of the sack and the remaining four on the side-holes of the sack. Insect pests were scouted and monitored weekly, while diseases were managed using spraying programmes as in commercial sweet potato production systems. Two weeks after transplanting, each plant was fertilised with 5 g nitrogen (N), phosphorus (P), and potassium (K) 2:3:2 (26) + 0.5% Zinc (Zn) + 5% sulphur (S) and 5% calcium (Ca). Number of axillary buds had significant effects on vine length, fresh shoot mass, number of shoots and dry shoot mass contributing 59%, 58%, 45% and 58% in total treatment variation (TTV), respectively, whereas axillary bud numbers had no significant effects on fresh tuberous root mass, chlorophyll content, vine stem diameter, tuberous root diameter, tuberous root length, dry tuberous root mass and number of tuberous roots. Relative to control (one bud), two (2), three (3), four (4), five (5) number of axillary buds decreased vine length, fresh shoot mass and dry shoot mass by 8-37, 30-55 and 26-55%, respectively. However, relative to control (one bud), number of axillary buds increased number of shoots by 8-17%. The quadratic relationship models were explained by 95, 92, 96 and 98% of vine length (VL), number of shoots (NS), fresh shoot mass (FSM) and dry shoot mass (DSM), respectively. In conclusion, findings of the study demonstrated that a single (1) or two (2) axillary bud(s) on stem cuttings of sweet potato CV. „Blesbok‟ showed better results for both yield and growth parameters as compared to three (3), four (4) and five (5) buds. / AgriSETA

The aim of this thesis is to investigate how discussions in archaeology and genetics influence the consensus on human origins and migrations in the South Pacific. By analyzing the genetic research on chicken- and sweet potato-DNA, I present a general overview of how genetics and archaeology shape the understanding of how humans have colonized the Pacific. By deconstructing a review on how the Pacific was settled based on aDNA, I analyze a geneticist’s perspective on archaeological problems. Through this analysis I suggest how archaeology should be approached on a theoretical level in order to be relevant in understanding human migrations in the Pacific. I propose that archaeology’s strength lie in interpreting material culture through an agency perspective in order to reach a dimension not obtainable by biological perspectives / Syftet med denna uppsats är att undersöka hur diskussioner i arkeologi och genetik påverkar hur vi ser på mänskliga migrationer i Oceanien. Genom att analysera den genetiska forskning som gjorts på kyckling och sötpotatis ges en övergripande bild av hur genetik och arkeologi formar den förståelse som finns för hur människan koloniserat Söderhavet. Genom att dekonstruera en sammanställning av den genetiska forskning som gjorts på mänskligt DNA i Oceanien analyseras en genetikers synsätt på arkeologiska problemställningar. Genom analysen i denna uppsats föreslår jag hur arkeologi borde arbeta på ett teoretiskt plan för att vara relevant i hur vi förstår Oceaniens migrationsmönster. Jag föreslår att arkeologins styrka ligger i att tolka den materiella kulturen genom ett agency-perspektiv för att komma åt en dimension av migrationsproblematiken som inte går att nås genom biologiska perspektiv.

A batata-doce é uma hortaliça de grande potencial energético, com elevado teor amiláceo e pode ser utilizada para consumo direto e para industrialização. Uma das tecnologias industriais viáveis para o processamento de alimentos amiláceos como a batata-doce, é a extrusão. Por este processo pode-se produzir snacks ou farinhas instantâneas (pré-gelatinizadas). O objetivo do presente trabalho foi avaliar o efeito dos parâmetros operacionais umidade da mistura, temperatura de processo e rotação do parafuso do extrusor sobre as características dos extrusados de batata-doce. As características avaliadas nos extrusados foram o índice de expansão (IE) e a dureza (DUR). As farinhas dos extrusados foram avaliadas quanto aos parâmetros: cor (L*, a*, b* e diferença de cor, índice de absorção de água (IAA), índice de solubilidade em água (ISA), grau de gelatinização (GG) e pontos críticos de viscosidade (Rapid Visco Analyser), ou seja, viscosidade inicial (VI), pico de viscosidade (PV) após o aquecimento e antes do resfriamento, quebra de viscosidade (QV), tendência a retrogradação (TR) e viscosidade final (VF). Foi empregada a metodologia de superfície resposta, com delineamento fatorial incompleto 33, de 3 níveis e 3 variáveis independentes: umidade (15, 18 e 21%), temperatura na 3a zona (100, 120 e 140oC) e rotação da rosca (180, 210 e 240 rpm). O modelo de regressão adotado mostrou que a umidade e a temperatura afetaram significativamente o IE dos extrusados. Mantendo-se a rotação média constante, o IE aumentou com a elevação da temperatura do processo para misturas com baixos teores de umidade. Os menores valores de IE ocorreram para baixas umidades e temperaturas e também para elevadas umidades e temperaturas. O modelo de regressão adotado para DUR dos extrusados não foi significativo para os parâmetros estudados. Ao se avaliar as características tecnológicas das farinhas extrusadas, o IAA, o ISA e a TR não apresentaram modelo de regressão de significância estatística dentro dos níveis das variáveis independentes. As farinhas extrusadas apresentaram GG variando entre 82,0 e 99,7%, contudo o modelo de regressão também não foi significativo para esta variável. Quanto a cor das farinhas extrusadas, o parâmetro L* (luminosidade) aumentou e o valor a* tendeu ao negativo (verde) com o aumento da umidade do material até aproximadamente 20-21%. O componente b* tendeu ao positivo (amarelo) e a diferença de cor (DCO) das farinhas extrusadas aumentou com a redução da umidade da massa, independentemente da variação de temperatura de extrusão. Quanto aos parâmetros de viscosidade das farinhas extrusadas, a VI, o PV e a QV diminuíram com a elevação da umidade até 20-21% e posteriormente, com elevação dos teores de umidade, mostraram aumento. Já a VF das farinhas extrusadas foi inversamente proporcional à rotação da rosca. O estudo mostrou que é viável a produção de extrusados de farinha de batata-doce com boas características utilizando-se os níveis das variáveis operacionais do processo. / The sweet potato is a vegetable of great energetic potential with high starch content. It can to be processed through extrusion which is efficient on the processing of starchy foods. In this work the effects of extrusion parameters on sweet potato extrudates and flours characteristics were studied. The properties evaluated in extrudates were expansion index (EI) and texture (hardness). The physical, physico-chemical and functional properties assayed in the extrudated flours were: water absorption index (WAI), water solubility index (WSI), color (L*, a*, b*) and color difference (CD), degree of gelatinization (DG) and pasting properties as initial viscosity (IV), raw peak (RP), breakdown (BD), setback (SB), cold viscosity (CV) and final viscosity (FV). The study was carried out by using Response Surface Methodology through an incomplete factorial design 33 with 3 levels and 3 independent variables: moisture content (15, 18, 21%), extrusion temperature (100, 120, 140oC) and screw speeds (180, 210, 240 rpm). The moisture content and extrusion temperature significantly affected expansion index of the extrudates.There was no influence of the parameters studied over extrudates hardness. The extrudates EI increased with the high extrusion temperature and low moisture content when the screw speed was medium. It decreased with the low moisture and temperature and at higher moisture content and temperature. The changes in independent variables did not result in significant regression model to extrudates hardness. The technological characteristics of extruded flours, WAI, WSI, SB and DG, did not present significant regression model to the parameters studied. The flours presented DG varying from 82.0 to 99.7%. The L* (lightness) component increased and value a* decreased with the increase of the moisture content until 20-21%. The color difference (CD) and parameter b* increased as the moisture content decreased, independent of the extrusion temperature. The IV, RP and BD values decreased with the increase the moisture until 20-21%. The flour FV decreased as srew speed increased. The study showed that is viable the production of sweet potato extrudates with good characteristics using the independent variables of the process.

Sweetpotato (Ipomoea batatas (L.) Lam.) is a root crop well established throughout the world's tropical and sub-tropical regions. Despite sweepotato's importance, it has been under-researched relative to many other major crops. The main objective of this thesis is to contribute to a fuller understanding of the genetic and physiological factors underlying the production of sweetpotato storage roots for human consumption. The sweetpotato genome is diverse and subject to high levels of natural somatic mutation. Applying the AFLP (amplified fragment length polymorphism) technique allowed a direct comparison of inter and intra-cultivar DNA (deoxyribonucleic acid) base sequence variation. Analysis of the variation indicated that although sweetpotatoes are clonally propagated, clones show a lack of genetic fidelity to their source. Further, the level of genetic variation within the cultivar 'Owairaka Red' indicated the continuing emergence of distinct new strains. Plant field establishment represents the interaction of both propagation and growth phases of storage root production. A range of establishment techniques were investigated in a field trial under commercial conditions. Sprouts cut from seed roots and held for six days rather than immediate planting improved establishment as measured by growth, at little expense. Plug raised plants also improved establishment, while potentially reducing the degree of intra-cultivar genetic variation. Plant carbohydrate partitioning in three cultivars, 'Beauregard', 'Beniazuma' and 'Owairaka Red' was examined by field trial over the period of storage root growth. While cultivars differed in the proportions of dry matter partitioned to leaf, stem and root organs, the cultivar specific ratios of leaf to stem dry weight were relatively stable over time. Total storage root dry weight increased with time for all cultivars, but the distribution of storage root grades by size was cultivar specific. Within the storage roots % dry weight increased over time in all cultivars, but total sugar concentration only increased for 'Beauregard' and 'Beniazuma'. Finally, a storage root disorder called 'brown centre' curtails the temperate growing season so was investigated using low temperature storage and a field trial with various nutrition regimes. The disorder was found to be associated with susceptible germplasm, high soil nitrogen and harvest time.

Fatores ambientais e econômicos impulsionam mundialmente a produção de biocombustíveis. No Brasil, o etanol, produzido da cana-de-açúcar, já é um biocombustível estabelecido e substitui ca. 40% da gasolina, representando 13% do total de energia necessária para transportes. Nesse cenário, o Rio Grande do Sul (RS) é um grande comprador de etanol, tendo produzido nos últimos anos apenas 2% do consumo estadual de etanol hidratado combustível. O estado também consome em média 600 milhões de litros de etanol anidro por ano, adicionados na proporção de 25% à gasolina comum, e, a partir de 2010, 460 milhões de litros de etanol por ano para a produção de polietileno verde. Essa conjuntura demonstra uma oportunidade para aumentar a produção local de etanol. O presente trabalho buscou primeiramente avaliar a viabilidade da produção de etanol no Rio Grande do Sul em um modelo de microusinas descentralizadas (ca. 1.000 L.dia-1). Para tanto, foram empregados os indicadores econômicos, como valor presente líquido, taxa interna de retorno de investimento e tempo de retorno de investimento. Foram comparados cenários que empregaram apenas cana-de-açúcar e combinações de cana-de-açúcar, sorgo sacarino, mandioca e batata-doce. A utilização de cana-de-açúcar sem o consórcio com outra cultura se mostrou inviável, exceto quando mais de 40% ou 80% da produção, para as produtividades de 80 e 50 t.ha-1 respectivamente, é destinada ao consumo próprio. Entre os cenários com combinação de culturas, aqueles que combinaram sorgo com cana-de-açúcar e sorgo com batata-doce foram os únicos que se mostraram viáveis quando toda a produção foi destina à venda para terceiros. Quando produtividades médias de cana-de-açúcar próximas a 80 t.ha-1 podem ser alcançadas, verificou-se que a combinação dessa cultura com sorgo sacarino apresentou o melhor potencial entre os cenários avaliados. Já para regiões onde esses valores não são atingidos, o consórcio de sorgo sacarino e batata-doce se mostrou a melhor opção. Posteriormente, foram realizados experimentos em shaker para estudar a influência da concentração de substrato e da proporção de enzima na hidrólise a frio da batata-doce, determinar o melhor pré-tratamento, verificar a necessidade de suplementação do meio e do controle de pH na condução das hidrólises e fermentações simultâneas e finalmente testar a melhor condição em biorreator. Para hidrolisar o amido, empregou a mistura de enzimas Stargen™ 002 e, para suplementar o meio, o fertilizante NITROFOS KL. Em todos os experimentos, usou-se a cultivar BRS Cuia, cuja caracterização indicou teor de carboidratos de 28,7%, possibilitando a produção de 185 L.t-1 de etanol e 7.400 L. ha-1. A metodologia de superfície de resposta indicou a condição 200 g.L-1 de batata-doce e 45 GAU.g de batata–doce-1 como a que apresentou o melhor compromisso entre alta taxa de formação de glicose na primeira hora (8,3 g.L-1.h-1) e baixo consumo de enzimas. O pré-tratamento de uma hora que levou a maior concentração de glicose (14,3 g.L-1) foi na temperatura de 52°C na presença da mistura de enzimas. O estudo da hidrólise e fermentação simultâneas mostrou que a suplementação do meio não apresenta influência significativa, enquanto o controle de pH aumentou em aproximadamente 40% a produção de etanol. Os testes em biorreator reproduziram os resultados anteriores mesmo sendo realizados em ambiente semiestéril, que se aproxima da condição industrial. / In Brazil, sugarcane ethanol is already a reality as a biofuel and replaces 40% of gasoline, meaning 13% of energy for transportation. In this scenario, Rio Grande do Sul has produced only 2% of the annual demand for hydrate ethanol in the last years; therefore it is a big importer of ethanol from other states. Additionally, it consumes every year 600 million liters of anhydrous ethanol mixed in the gasoline and 460 million liters for production of green plastic. These numbers highlight the opportunity of producing ethanol locally. In regard to these facts, the present work aimed to evaluate the feasibility of producing ethanol in small scale plants (ca. 1 000 L.dia-1) in Rio Grande do Sul. For this purpose, economic indicators, such as net present value, internal rate of return and payback period were employed. The compared scenarios involved combinations of sugar cane, sweet sorghum, cassava and sweet potato. When only sugarcane was used, the scenarios for 80 and 50 t.ha-1 were unfeasible if less than 40% or 80% of the production, respectively, was used by the own producer. Regarding the scenarios with mix of crops, the mix of sweet sorghum with sugar cane and sweet sorghum with sweet potato presented the best performances. For regions, where 80 t.ha-1 of sugar cane productivity can be achieved, it was verified that the first combination leads to the best result. For other regions, the combination of sweet sorghum and sweet potato presented itself as the more feasible scenario. As a consequence, in the second part of this work, the cold hydrolysis and fermentation of sweet potato was experimentally studied. For that, it was employed the sweet potato strain BRS Cuia, whose carbohydrate level reaches 28,7%. What it can be translated into a potential to produce 185 L.t-1 ethanol, or equivalently 7 400 L. ha-1. The enzymes blend adopted for the hydrolysis stage was Stargen™ 002, while the fertilizer NITROFOS KL was used for fermentation medium supplementation. The surface response method indicated 200 g.L-1 of sweet potato and 45 GAU.g of sweet potato-1 as the best balance between high glucose formation rate in the first hour (8,3 g.L-1.h-1) and low enzyme consume. The one hour pre-treatment that achieved the highest glucose concentration (14,3 g.L-1) was at 52°C in the presence of the enzymes blend. The study of the simultaneous hydrolysis and fermentation showed that the medium supplementation has no significant effect over the fermentation performance, while the pH control is beneficial, improving the ethanol production in 40%. Finally, the tests in bioreactor could reproduce the previous results, even though the experiments were carried out non-sterilely.

Fatores ambientais e econômicos impulsionam mundialmente a produção de biocombustíveis. No Brasil, o etanol, produzido da cana-de-açúcar, já é um biocombustível estabelecido e substitui ca. 40% da gasolina, representando 13% do total de energia necessária para transportes. Nesse cenário, o Rio Grande do Sul (RS) é um grande comprador de etanol, tendo produzido nos últimos anos apenas 2% do consumo estadual de etanol hidratado combustível. O estado também consome em média 600 milhões de litros de etanol anidro por ano, adicionados na proporção de 25% à gasolina comum, e, a partir de 2010, 460 milhões de litros de etanol por ano para a produção de polietileno verde. Essa conjuntura demonstra uma oportunidade para aumentar a produção local de etanol. O presente trabalho buscou primeiramente avaliar a viabilidade da produção de etanol no Rio Grande do Sul em um modelo de microusinas descentralizadas (ca. 1.000 L.dia-1). Para tanto, foram empregados os indicadores econômicos, como valor presente líquido, taxa interna de retorno de investimento e tempo de retorno de investimento. Foram comparados cenários que empregaram apenas cana-de-açúcar e combinações de cana-de-açúcar, sorgo sacarino, mandioca e batata-doce. A utilização de cana-de-açúcar sem o consórcio com outra cultura se mostrou inviável, exceto quando mais de 40% ou 80% da produção, para as produtividades de 80 e 50 t.ha-1 respectivamente, é destinada ao consumo próprio. Entre os cenários com combinação de culturas, aqueles que combinaram sorgo com cana-de-açúcar e sorgo com batata-doce foram os únicos que se mostraram viáveis quando toda a produção foi destina à venda para terceiros. Quando produtividades médias de cana-de-açúcar próximas a 80 t.ha-1 podem ser alcançadas, verificou-se que a combinação dessa cultura com sorgo sacarino apresentou o melhor potencial entre os cenários avaliados. Já para regiões onde esses valores não são atingidos, o consórcio de sorgo sacarino e batata-doce se mostrou a melhor opção. Posteriormente, foram realizados experimentos em shaker para estudar a influência da concentração de substrato e da proporção de enzima na hidrólise a frio da batata-doce, determinar o melhor pré-tratamento, verificar a necessidade de suplementação do meio e do controle de pH na condução das hidrólises e fermentações simultâneas e finalmente testar a melhor condição em biorreator. Para hidrolisar o amido, empregou a mistura de enzimas Stargen™ 002 e, para suplementar o meio, o fertilizante NITROFOS KL. Em todos os experimentos, usou-se a cultivar BRS Cuia, cuja caracterização indicou teor de carboidratos de 28,7%, possibilitando a produção de 185 L.t-1 de etanol e 7.400 L. ha-1. A metodologia de superfície de resposta indicou a condição 200 g.L-1 de batata-doce e 45 GAU.g de batata–doce-1 como a que apresentou o melhor compromisso entre alta taxa de formação de glicose na primeira hora (8,3 g.L-1.h-1) e baixo consumo de enzimas. O pré-tratamento de uma hora que levou a maior concentração de glicose (14,3 g.L-1) foi na temperatura de 52°C na presença da mistura de enzimas. O estudo da hidrólise e fermentação simultâneas mostrou que a suplementação do meio não apresenta influência significativa, enquanto o controle de pH aumentou em aproximadamente 40% a produção de etanol. Os testes em biorreator reproduziram os resultados anteriores mesmo sendo realizados em ambiente semiestéril, que se aproxima da condição industrial. / In Brazil, sugarcane ethanol is already a reality as a biofuel and replaces 40% of gasoline, meaning 13% of energy for transportation. In this scenario, Rio Grande do Sul has produced only 2% of the annual demand for hydrate ethanol in the last years; therefore it is a big importer of ethanol from other states. Additionally, it consumes every year 600 million liters of anhydrous ethanol mixed in the gasoline and 460 million liters for production of green plastic. These numbers highlight the opportunity of producing ethanol locally. In regard to these facts, the present work aimed to evaluate the feasibility of producing ethanol in small scale plants (ca. 1 000 L.dia-1) in Rio Grande do Sul. For this purpose, economic indicators, such as net present value, internal rate of return and payback period were employed. The compared scenarios involved combinations of sugar cane, sweet sorghum, cassava and sweet potato. When only sugarcane was used, the scenarios for 80 and 50 t.ha-1 were unfeasible if less than 40% or 80% of the production, respectively, was used by the own producer. Regarding the scenarios with mix of crops, the mix of sweet sorghum with sugar cane and sweet sorghum with sweet potato presented the best performances. For regions, where 80 t.ha-1 of sugar cane productivity can be achieved, it was verified that the first combination leads to the best result. For other regions, the combination of sweet sorghum and sweet potato presented itself as the more feasible scenario. As a consequence, in the second part of this work, the cold hydrolysis and fermentation of sweet potato was experimentally studied. For that, it was employed the sweet potato strain BRS Cuia, whose carbohydrate level reaches 28,7%. What it can be translated into a potential to produce 185 L.t-1 ethanol, or equivalently 7 400 L. ha-1. The enzymes blend adopted for the hydrolysis stage was Stargen™ 002, while the fertilizer NITROFOS KL was used for fermentation medium supplementation. The surface response method indicated 200 g.L-1 of sweet potato and 45 GAU.g of sweet potato-1 as the best balance between high glucose formation rate in the first hour (8,3 g.L-1.h-1) and low enzyme consume. The one hour pre-treatment that achieved the highest glucose concentration (14,3 g.L-1) was at 52°C in the presence of the enzymes blend. The study of the simultaneous hydrolysis and fermentation showed that the medium supplementation has no significant effect over the fermentation performance, while the pH control is beneficial, improving the ethanol production in 40%. Finally, the tests in bioreactor could reproduce the previous results, even though the experiments were carried out non-sterilely.