Thesis (M.Sc.(Agric.))(Food Science)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Master of Science / Department of Grain Science and Industry / Sajid Alavi / Sorghum, millets and teff are important staple crops worldwide, especially in semi-arid regions of Africa and India because of their drought tolerance. However, lack of research and other limitations have restricted their usage in food products. This study is focused on extrusion processing of low and high tannin sorghum varieties, millet and teff for high and low moisture applications, and to investigate process characteristics such as residence time distribution and specific mechanical energy, physico-chemical properties of resultant food products (such as pre-cooked pasta and expanded snacks) and their resistance starch content. Results from preliminary lab scale extrusion, including optimization of starch type and level for pre-cooked pasta and in-barrel moisture for expanded snacks, were used to design pilot-scale studies on a twin-screw extruder. In the first pilot-scale experiment, decorticated white sorghum blends prepared with addition of mono-glycerides (0.5%, 1% and1.5%) and salt (1%) were processed at three different in-barrel moisture contents 40%, 44% and 48% (wet basis) for processing of precooked pasta. The optimum formulation containing 1% mono-glycerides and process conditions corresponding to 48% in-barrel moisture were also used to develop precooked teff and millet pasta. The non-traditional grain based pastas were investigated for cooking quality, thermal characteristics using differential scanning calorimeter, pasting properties using rapid visco analyzer and texture profile analysis. In general, increasing in-barrel moisture led to reduction in solid losses (ranging from 4.0-8.2% for all treatments), indicating improvement in cooking quality. On the other hand, increase in mono-glycerides concertation led to higher cooking losses, and also affected pasting and textural properties significantly. Sorghum-based precooked pasta was of best quality while millet pasta was poorest in cooking quality, visual and textural attributes. Cooking loss for control pre-cooked pasta produced in this experiment using semolina was 4.5%, and commercial semolina pasta was 3.2%. Residence time distribution in pilot-scale twin screw extruder, during high moisture process conditions used for pre-cooked pasta, was also investigated at three different in-barrel moistures (40%, 44% and 48%) and monoglycerides/ lipid (0.5, 1% and 1.5%) concentrations. Increase in in-barrel moisture significantly decreased mean residence time. For example, mean residence time was 4.47 min at 40% moisture, 3.89 min at 44% and 3.74 min at 48%. On the contrary, residence time significantly increased with lipid level. For example, mean residence time was 3.87 min at 0.5% concentration of mono-glycerides, 4.48 min at 1% and 4.70 min 1.5%. In the second experiment focusing on low moisture applications, pilot-scale twin screw extrusion was used to process decorticated white sorghum and high tannin sumac sorghum for expanded snacks. The addition of sumac bran decreased the specific mechanical energy input (366-578 kJ/kg) and expansion ratio (6.4-7.9), and resulted in higher piece density of extrudates. Use of sumac bran and sumac flour led to increase in resistant starch content, although it was less than 1% for all treatments. Therefore, extrusion with ingredients having high tannin content does not provide value, despite tannins being associated with resistant starch at least in raw materials.

Orientador: Flávio Dutra de Resende / Banca: Ricardo Dias Signoretti / Banca: Paulo de Figueiredo Vieira / Resumo: O presente estudo teve como objetivo avaliar os efeitos dos estádios de maturidade do milheto (Pennisetum glaucum (L) R. Br.) sobre os parâmetros agronômicos e qualitativos da planta e das frações que a compõem, além de avaliar o perfil de fermentação e estabilidade aeróbia de silagens de milheto ensiladas com diferentes tamanhos de partícula tratadas ou não com inoculante bacteriano, constituído de Propionibacterium acidipropionici e Lactobacillus plantarum. O híbrido de milheto utilizado foi o ADR 7010 avaliado em nove diferentes pontos de maturação no ano agrícola de 2009. No experimento de perfil de fermentação os tratamentos avaliados foram silagem de milheto, tamanho de partícula pequena (5 mm) com e sem inoculante bacteriano e silagem de milheto com tamanho de partícula grande (20 mm) com e sem inoculante bacteriano avaliados com 0, 4, 7, 14, 28, 45 e 90 dias de fermentação, foi avaliado ainda a estabilidade aeróbia de silagens exposta ao oxigênio por diferentes dias. A produtividade de matéria seca (MS) da planta de milheto variou de 7,42 a 14,52 t MS/ha no corte referente a 50 dias após a semeadura (DAS) e 92 DAS, respectivamente. A porcentagem de colmo na planta variou entre 44,19 a 68,74%, no milheto avaliado 92 e 50 (DAS), respectivamente. O percentual de espiga apresentou maior porcentagem na planta com 92 DAS (46,79%). Os teores de MS da planta inteira aumentaram de 12,16 % (50 DAS) para 33,21% (106 DAS). A composição química apresentou efeito quadrático em função da maturidade, na planta e seus componentes. Os teores de MS da silagem apresentaram efeito linear crescente em função da maturidade da planta. O pH da silagem apresentou valores variando de 3,81 a 4,12. A perda por efluentes apresentou efeito quadrático (P<0,05) de acordo com a maturidade da planta, sendo o menor valor... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to evaluate the effects of the maturity stage of millet (Pennisetum glaucum (L) R. Br.) on the agronomic and qualitative parameters of the plant and its component fractions, and to evaluate the fermentation profile and the aerobic stability of millet silages ensiled with different particle sizes or not treated with inoculant consisting of Lactobacillus plantarum and Propionibacterium acidipropionici. The hybrid millet used was the ADR 7010 harvested at nine different stages of maturation in 2009. In the experiment of the fermentation profile of the treatments were millet silage, small particle size (5 mm) with and without inoculant and millet silage with large particle size (20 mm) with and without inoculant evaluated at 0, 4 , 7, 14, 28, 45 and 90 days of fermentation was also evaluated the aerobic stability of silages exposed to oxygen for different days. The productivity of plant dry matter (DM) of millet varied from 7.42 to 14.52 t DM / ha referring to 50 days after sowing (DAS) and 92 DAS, respectively. The percentage of stem on the plant ranged from 44.19 to 68.74% in millet evaluated 92 and 50 (DAS), respectively. The percentage of spike showed the highest percentage in the plant at 92 DAS (46.79%). The DM content of whole plant increased from 12.16% (50 DAS) to 33.21% (106 DAS). The chemical composition showed a quadratic effect due to the maturity of the plant, the plant and its components. The DM content of silage showed a linear increased depending on the maturity of the plant. The silage pH values ranging from 3.81 to 4.12. The loss for effluents showed a quadratic effect (P <0.05) according to the maturity of the plant, the lowest value of silage effluent produced millet 88 days after sowing. The values of crude protein (CP), ammonia nitrogen decreased with time to maturity of the plant, as well as the ... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:28:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-02Bitstream added on 2014-06-13T19:36:48Z : No. of bitstreams: 1 almeida_gbs_me_jabo.pdf: 566501 bytes, checksum: f80d469d0f795dc1413b38368115de70 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente estudo teve como objetivo avaliar os efeitos dos estádios de maturidade do milheto (Pennisetum glaucum (L) R. Br.) sobre os parâmetros agronômicos e qualitativos da planta e das frações que a compõem, além de avaliar o perfil de fermentação e estabilidade aeróbia de silagens de milheto ensiladas com diferentes tamanhos de partícula tratadas ou não com inoculante bacteriano, constituído de Propionibacterium acidipropionici e Lactobacillus plantarum. O híbrido de milheto utilizado foi o ADR 7010 avaliado em nove diferentes pontos de maturação no ano agrícola de 2009. No experimento de perfil de fermentação os tratamentos avaliados foram silagem de milheto, tamanho de partícula pequena (5 mm) com e sem inoculante bacteriano e silagem de milheto com tamanho de partícula grande (20 mm) com e sem inoculante bacteriano avaliados com 0, 4, 7, 14, 28, 45 e 90 dias de fermentação, foi avaliado ainda a estabilidade aeróbia de silagens exposta ao oxigênio por diferentes dias. A produtividade de matéria seca (MS) da planta de milheto variou de 7,42 a 14,52 t MS/ha no corte referente a 50 dias após a semeadura (DAS) e 92 DAS, respectivamente. A porcentagem de colmo na planta variou entre 44,19 a 68,74%, no milheto avaliado 92 e 50 (DAS), respectivamente. O percentual de espiga apresentou maior porcentagem na planta com 92 DAS (46,79%). Os teores de MS da planta inteira aumentaram de 12,16 % (50 DAS) para 33,21% (106 DAS). A composição química apresentou efeito quadrático em função da maturidade, na planta e seus componentes. Os teores de MS da silagem apresentaram efeito linear crescente em função da maturidade da planta. O pH da silagem apresentou valores variando de 3,81 a 4,12. A perda por efluentes apresentou efeito quadrático (P<0,05) de acordo com a maturidade da planta, sendo o menor valor... / This study aimed to evaluate the effects of the maturity stage of millet (Pennisetum glaucum (L) R. Br.) on the agronomic and qualitative parameters of the plant and its component fractions, and to evaluate the fermentation profile and the aerobic stability of millet silages ensiled with different particle sizes or not treated with inoculant consisting of Lactobacillus plantarum and Propionibacterium acidipropionici. The hybrid millet used was the ADR 7010 harvested at nine different stages of maturation in 2009. In the experiment of the fermentation profile of the treatments were millet silage, small particle size (5 mm) with and without inoculant and millet silage with large particle size (20 mm) with and without inoculant evaluated at 0, 4 , 7, 14, 28, 45 and 90 days of fermentation was also evaluated the aerobic stability of silages exposed to oxygen for different days. The productivity of plant dry matter (DM) of millet varied from 7.42 to 14.52 t DM / ha referring to 50 days after sowing (DAS) and 92 DAS, respectively. The percentage of stem on the plant ranged from 44.19 to 68.74% in millet evaluated 92 and 50 (DAS), respectively. The percentage of spike showed the highest percentage in the plant at 92 DAS (46.79%). The DM content of whole plant increased from 12.16% (50 DAS) to 33.21% (106 DAS). The chemical composition showed a quadratic effect due to the maturity of the plant, the plant and its components. The DM content of silage showed a linear increased depending on the maturity of the plant. The silage pH values ranging from 3.81 to 4.12. The loss for effluents showed a quadratic effect (P <0.05) according to the maturity of the plant, the lowest value of silage effluent produced millet 88 days after sowing. The values of crude protein (CP), ammonia nitrogen decreased with time to maturity of the plant, as well as the ... (Complete abstract click electronic access below)

M.Tech. / Sorghum (Sorghum bicolour (L) Moench) and millets are drought resistant cereals (Kent and Evers, 1994) that can grow in areas with poor soils and inconsistent rainfall (Dendy, 1995) where other crops fail. They serve as staple food for many people in tropical sub- Saharan Africa and Asia (Klopfenstein and Hoseney, 1995). Traditionally, bread is made from wheat, which is a temperate cereal not able to grow well in these tropical regions. Leavened bread is seldom made from anything other than wheat (Alais and Linden, 1991) and this is because of the unique visco-elastic property of wheat flour (Hoseney, 1994). Unfortunately in tropical regions such as South Africa wheat is imported at a premium price. The aim of this study was to produce a wheat-finger millet composite flour which is suitable for bread making. Finger millet grain (FMV6) was milled with a laboratory hammer mill fitted with a 0.8 mm screen. The following wheat-finger millet composite doughs were made using standard bread making methods, 0:100 (Control); 90:10; 80:20; 70:30, respectively. Selected quality attributes of the composite dough and the bread thereof were analysed using standard methods. The formulation with 10% finger millet showed better results than other formulations. One formulation (80:20) was selected for improvement which included mixing ingredients at elevated temperatures (50°C and 93°C) and addition of 0.002% of a lipase enzyme, lipopan F; 0.3% vital wheat gluten and a combination of 0.002% lipopan F and 0.3% gluten. All formulations (including the basic formulation) contained Fungamyl Super MA (enzyme combination which contained fungal a-amylase and a xylanase). As the mixing temperatures were elevated, loaf volume decreased but when the industrial baking enzymes were introduced there was an improvement in peak time, dough stability and loaf volume. Image analysis showed that there was an improvement in crumb structure and bubble size distribution after the application of enzyme lipopan F. The crumb colour was lighter and softer when a combination of enzyme lipopan F and vital wheat gluten was applied. The bread made from formulation 80:20 with addition of a combination of enzyme lipopan F and vital wheat gluten (WFM2GL) was more acceptable than other formulations except the control bread. The bread had a high score in taste, crust appearance and mouth feel. The results suggest that there is a potential for producing a composite bread by substituting wheat flour with finger millet flour (up to 20%); mixing at 25°C with application of a combination of a lipase and vital wheat gluten. However, more work is needed to improve the quality of the bread to a greater extent.

L’objectif de cette thèse était d’isoler de nouvelles glycoside-hydrolases à partir d’une souche de Bacillus issue d’un Biotope sud-tunisien. Cette souche a montré des potentialités à produire une amylase et une lichenase à 45°C et à pH 9. La production de ces deux hydrolases a été optimisée en fermentation solide sur millet, une agro-ressource de faible coût. Cette optimisation a été conduite en adoptant la méthodologie des plans d’expériences. Nous avons ainsi obtenu des niveaux de production de l’ordre de 540 Unités d’activités amylase par gramme de substrat solide et 503 U/g d’activité lichenase. Ces deux protéines ont été par la suite purifiées et caractérisées biochimiquement. L’amylase présente un pH et une température d’activité optimaux de 5 et 70°C, respectivement. La lichenase a montré une thermoactivité et une thermostabilité remarquables qui la distinguent des lichenases précédemment décrites. En effet, l’enzyme conserve plus de 20% de son activité à 100°C, et plus de 60% de son activité après une incubation de 30 min à 90°C. Le gène codant pour cette protéine a été isolé par la construction d’une banque fosmidique dans E. coli. La comparaison de sa séquence avec la banque de données NCBI a montré que le gène de la lichenase UEB-S possède une très forte homologie avec celle de Bacillus subtilis 168, avec les positions de deux acides aminés seulement qui divergent. Un modèle de la lichenase construit au cours de cette étude laisse supposer que l’un de ces deux acides aminés (Val 69) pourrait être impliqué dans sa thermostabilité, et ce en modifiant la géométrie du site de fixation au calcium / The aim of this thesis was to isolate new glycoside hydrolases from a Bacillus strain isolated from a Biotope in the south of Tunisia. This strain was able to produce a lichenase and an amylase at 45 ° C and pH 9. The production of these two hydrolases was optimized in solid state fermentaion using millet, a low cost. agro-resource as solid substrate. This optimization was carried out using response surface methodology (RSM) based on Doehlert design. We obtained production levels of around 540 units of amylase activity per gram of solid substrate and 503 U / g of lichenase activity.Both proteins were subsequently purified and characterized biochemically. The amylase has a pH and a temperature optimum of activity of 5 and 70 ° C, respectively. The lichenase showed a remarkable thermostability which distinguish it from described lichenases. Indeed, the enzyme retained more than 20% of its activity at 100 ° C, and more than 60% of its activity after incubation for 30 min at 90 ° C. The gene encoding this protein was isolated by the construction of genomic a library in E. coli. Comparison of its sequence with the NCBI database showed that the gene coding for UEB-S lichenase has a very high homology with that of Bacillus subtilis 168, with a difference in the position of only two amino acids A model for UEB-S lichenase built during this study suggests that one of these two amino acids (Val 69) could be involved in its thermostability probabely by changing the geometry of the calcium binding site

Please read the abstract in the section 00front of this document / Thesis (DPhil (Food Science))--University of Pretoria, 2007. / Food Science / DPhil / unrestricted

This study evaluates the economic feasibility of a biological control industry in Niger. Farmers in the Sahel region of Niger are vulnerable to high millet yield losses due to the millet head miner, and their pest control options are extremely limited. Researchers have begun to support small businesses which sell a beneficial insect (Habrobracon Hebetor) that is very effective in limiting millet yield losses due to the millet head miner. This study discusses a wide range of questions related to the economic prospects of these businesses using two main analytical methods, an economic feasibility assessment and an econometric analysis. The economic feasibility assessment provides budget analysis for the potential businesses and discusses business options for scaling, price setting, and organizing. A central question in this analysis is whether farmers can cooperatively purchase beneficial insects as a means of preventing free-riding. With free-riding as a prominent concern for businesses, this study also provides an econometric analysis of the factors that affect farmer's willingness-to-pay for beneficial insects. / Master of Science

Biochar amendment to agricultural soils has been promoted for use in agricultural systems, both to mitigate global warming by increasing long-term soil carbon (C) sequestration and to enhance soil fertility and crop productivity. The objective of this study was to evaluate the effects of a single biochar application from peanut shell (Arachis hypogea L.) and mixed pine (Pinus spp.) wood to a Typic Hapludults in Blacksburg (VA, USA) and from peanut shell and eucalyptus (Eucalyptus camaldulensis) wood to a tropical, sandy, salt-affected soil in Ndoff (Fatick, Senegal) at 0, 10, and 20 Mg ha⁻¹ on soil chemical properties, inorganic nitrogen supply, and pearl millet production responses under field conditions for two growing seasons (2014 and 2015). Biochar application to temperate soils (Blacksburg) significantly increased total soil carbon, nitrogen, and plant available potassium in both years. In addition, pearl millet yields significant increased (53%) at the 20 Mg ha⁻¹ rate of peanut shell biochar in 2014 but did not persist in year 2. Beneficial effects largely appeared due to nutrient additions. Biochar treatment to tropical, sandy, salt-affected soils (Ndoff) had no effect on soil chemical properties. These results suggest that biochar application could improve soil fertility and crop productivity in temperate soils but had limited effects on tropical, sandy, salt-stressed soils in this study. The disparate results between these two field studies could be explained by differences in soil properties and climate, biomass feedstock, pyrolysis processes, and biochar handling, as well as experimental set-up. / Master of Science

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