Dissertations / Theses on the topic 'Cereal based products'

Les systèmes à base de biopolymères à faible teneur en humidité sont couramment rencontrés dans les aliments. Bien entendu, il est primordial de comprendre les bases physiques de leur qualité: texture, performances dans le temps ou en fonction de leur composition. Le vieillissement physique des systèmes composites rend les changements survenant dans le stockage des produits comestibles difficiles à prévoir. Les objectifs de ce travail étaient d'évaluer l'incidence de la présence de saccharose et de la teneur en eau de fabrication sur les propriétés physico-chimiques du produit fini. La stabilité physique de ces matériaux a été contrôlée grâce à une étude à différentes échelles moléculaires. Ensuite, les relations entre les données multi-échelles ont été examinées. L'effet du saccharose (0 à 20%) et de l'eau d'alimentation (10 et 15%) sur les mélanges d'extrusion a été étudié à l'aide d'un extrudeur double vis conduit dans les mêmes conditions. Les propriétés physiques et microstructurales des produits extrudés expansés ont été examinées sous diverses conditions d'humidité relative. La réduction des teneurs en sucre et en eau d’alimentation a fait augmenter la pression et l’énergie mécanique spécifique, ce qui a réduit la dégradation de l’amidon et augmenté la viscosité dans l’extrudeur en particulier à la teneur en eau la plus élevée. L'augmentation de la pression dans l’extrudeur a entraîné une expansion plus importante des extrudés. Par contre, la technique d'imagerie neutronique montré que le saccharose réduisait la taille des pores, et donc augmentait la densité apparente et ce qui était particulièrement évident en utilisant. Cette technique a été appliquée pour la première fois sur des produits extrudés. Les images de tomographie 2D ont indiqué des différences structurelles internes entre les extrudés à différentes teneurs en saccharose et stockés à humidité relative différente. Toutefois, l'analyse d'images 3D a montré que l'impact de ces facteurs sur la distribution de la taille des pores et le taux de porosité n'était pas significatif. En fin d'extrusion, les échantillons étaient à l'état amorphe à la suite de la gélatinisation de l'amidon et de la fonte du sucre. Leursrs propriétés thermiques ont été analysées par analyse enthalpique différentielle (AED) et les températures e transition vitreuse ont été étudiées. Les thermogrammess d’AED ont été minutieusement étudiés via une déconvolution de la dérivée première de la variation d’enthalpie. Cette approche a mis en évidence que les systèmes composites étudiés présentaient des phases multiples avec des transitions vitreuses distinctes. Ces dernières sont associées à une phase riche en polymère (amidon principalement) et / ou à une phase riche en plastifiant (sucre) dont le comportement dépendait de la teneur en eau de l'échantillon. Les isothermes de sorption ont montré qu’aux faibles Aw et pour une valeur donnée, a la teneur en eau des extrudés diminuait avec l’augmentation des teneurs en saccharose et que l'effet inverse était observé aux aw élevées. L’étude de la cinétique apparente de lala diffusion de l'eau a mis en évidence deux sites de sorption différents. Le premier est caractérisé par une cinétique quasi constante qui pourrait correspondre à un phénomène d'adsorption à la surface. Le second site présente d’abord un ralentissement initial de la cinétique de sorption, tandis qu’une forte augmentation est constatée lorsque la teneur en eau était plus élevée. Ce comportement peut être lié à un effondrement de la structure. Une étude par RMN à cyclage de champ rapide à basse fréquence a montré que les temps de relaxation dépendaient de la teneur en saccharose et en eau. Une carte de stabilité a été tracée pour modéliser les évolutions rhéologiques des matrices avec la teneur en eau en lien avec les transitions de phases des matériaux (...)
Low-moisture biopolymer-based systems are commonly encountered in food. Obviously, understanding the physical basis of their quality: e.g texture, or performance over time or as a function of their composition is of primary importance. The objectives of this work were to evaluate how the presence of sucrose and water content affects physico-chemical properties. The physical stability of these materials were monitored through an insight at different molecular scales. Then the relations between the multi-scale studies were investigated. The effect of sucrose (0–20%) and feed water (10 and 15%) on extrusion blends was studied using a twin screw extruder under the same processing settings. The physical and microstructural properties of extruded products were examined at various RH. Reducing both sugar levels and feed water increased die pressure and specific mechanical energy, as a consequence, it reduced starch degradation and increased in viscosity. The effect was more pronounced with increasing feed water content. The increased die pressure resulted in higher expansion of the porous extrudates. Sucrose was shown to increase the bulk density and reduce the pore size, this was particularly evident by using neutron imaging technique. This technique was applied for the first time in extrudate. 2D tomography images indicated internal structural differences between extrudates containing different sucrose content and stored at low and high % RH, while 3D image analysis showed impact of these factors on pore size distribution and % porosity were not significant. The extruded samples were in the amorphous state as a result of starch gelatinization and sugar melting. Their thermal properties were analyzed with DSC and their Tg were studied. The DSC thermograms were thoroughly studied through a Gaussian deconvolution of the first derivative of their heat low. This approach evidenced a multiple phase behavior with different glass transitions in composite systems. They were associated with either a polymer-rich phase and/or a plasticizer-rich phase which behavior depended on the sample water content. Physical aging accompanied with an increase in rigidity at low aw, resulted in an increased bulk density and more pronounced with increasing sucrose content. Sorption isotherms showed the water content of extrudates decreased when product contains high sucrose at low aw range and the inverse effect was observed at high aw. Apparent kinetics of water diffusion showed two different sorption sites, the first kinetics was almost constant and could be adsorption phenomena at the surface. The second one reflected first an initial slowing in dynamics whereas a sharp increase was found at higher water content. Addition of sucrose or water decreased both Tgs in extrudates. Young's modulus showed water acts as anti-plasticizer at low aw, while it shows a plasticizing effect at high aw. A stability map can explain the brittle-ductile transition occurred below Tg. Fast field cycling NMR study at low frequency highlighted that T1 depended on sucrose and water content. T1 and T2 measured using Low field NMR decrease as a function of water content, while the impact pf sucrose were not significant. T2 showing a minimum probably indicating the exchange of protons of water and macromolecules in composite system. The impact of sucrose content was not significant for T1 and for T2 at low water content. FFC NMR showed T1 results consistent with the LF NMR measurement.In conclusion, physicochemical studies of the influence of water and sucrose content on glassy materials showed that the material properties can be investigated at different levels from the macro- to the microscopic scale and these results clearly presented the need for complementary techniques to probe the dynamics in the glassy state of heterogeneous food systems that could be facilitated to manage the stability during storage of this type of dry products

The incidence of type 2 diabetes is considered an epidemic in Western countries, and its prevalence is more common in the Hispanic population than in non-Hispanic whites. Postprandial hyperglycemia has been associated with oxidative stress (OS), thus; reducing postprandial glycemia and/or OS through dietary consumption of resistant starch (RS) may be one approach to help modulate glucose and insulin responses. The purpose of this study was twofold: 1) to evaluate the physicochemical and sensory properties of cereal food products supplemented with RS. 2) to compare the effects of a single ingestion of granola bars with high (~18 grams of RS) and low (~0 grams of RS) RS compositions on the postprandial glucose and insulin responses (n=14) and oxidative stress parameters (cellular glutathione peroxidase, F2- isoprostanes, and oxygen radical absorbance capacity) in Hispanic women (n=9). Granola bars and cereals were developed to provide 2 levels (10% and 15%) of RS; isocaloric (0% RS) control samples were prepared with readily digestible (high amylopectin) starch. Samples were stored for up to 4 weeks at 20 °C. Mean composition of the high RS granola bars was 6% protein, 15% moisture, and 18% lipid. RS levels slightly increased from 14 to 16 g/serving after 4 weeks of storage, supporting published research that RS increases with storage due to retrogradation and crystallization of amylose chains. Color became lighter as the level of RS increased (p<0.001). Granola bars containing RS were less brittle (p=0.0043) than control granola bars. Sensory results indicated granola bars/cereals were acceptable. RS-supplemented granola bars were then used for the evaluation of RS ingestion in humans. There was no difference in postprandial glucose and insulin responses after a single ingestion of a RS-supplemented (18 g) granola bar. No differences were found in the oxidative stress parameters measured. In a subgroup of subjects (n=9), a lower glucose response 30 minutes after RS consumption was found (p=0.0496). Thus, RS consumption may lower fluctuations in blood glucose, which may help manage glucose levels in individuals at risk of type 2 diabetes. Further studies of short term RS consumption are warranted to elucidate its benefits in glucose management.
Ph. D.

Acrylamide (AA) is a probable human carcinogen and undesirable contaminant which is produced by the reaction of reducing sugars with asparagine in plant foods during their thermal treatment above 120 °C. AA is most often determined by GC-MS and LC-MS/MS in isolates from the matrix in a wide range of foods. According to our observations, AA intake from food is higher among young people (from 1.8 to 3.8 µg/kg bw/day), which is consistent with the estimations of JECFA FAO/WHO from the year 2006. Considering the health risk, it is recommended to reduce AA formation in food during its processing, in particular exploiting the available experience. The aim of this thesis was to extend the knowledge of the possibility of AA elimination in selected types of thermally processed foods. The study was focused on cereal foods that contribute significantly to AA exposure, especially bread and sweet biscuits. The whole AA content in the bread is in the crust, which represents 5-15% of the bread. Crust of home-made bread contains approximately 30-75 µg/kg, however the marketed bread contains 2 to 10 times more of AA. This is due to the composition of bread mix, preparation conditions and baking. For maintaining the quality of home-made bread during the dry mixture shelf-life, optimization of bread mixtures was designed by increasing of yeast content, which proved positive effect on the reduction of AA content at sufficiently high activity of the yeast. Monitoring of AA content in assortment of sweet bakery products showed higher levels of AA in diabetic biscuits containing fructose instead of sucrose. Three of them even exceeded the reference value (500 µg/kg) more than 1.5 times for commodity "cookies". Elimination of AA by applications of the enzyme asparaginase has been designed for minimal interference in technology of their production. The concentration of the enzyme and the appropriate method of its use in industrial environment have been tested previously in model systems. In optimized conditions of the enzyme application, AA content in diabetic biscuits was reduced by more than 40% without affecting the organoleptic properties of the final product. Effect of the antioxidants on AA formation was also part of the study. AA content in gingerbread was reduced efficiently by the use of fennel, anise, cloves, vanilla and white pepper (by about 9-21%). Conversely, coriander and cinnamon significantly increased its content (by 18-54%). Since correlations between the DPPH• radical quenching activity of the spice extracts and AA content was not observed, the final content of AA was probably influenced by the chemical composition of spices and reactivity of the individual components in the matrix. Investigated methods appear to be suitable ways of elimination AA in some foods; however their specific use must be optimized with regard to the composition of the food, processing and the technology used. Estimated impact of application of the above-mentioned methods to the overall elimination of AA exposure showed that its intake in high school students from the Czech and Slovak Republic can be reduced on average by 10%. This decrease is a success to reduce the possible risk of cancer disease by eating foods with a high AA content. It is also important piece of information for food producers for further development of relevant methods for AA elimination which would help to reduce the AA intake from foods even more.

English-style crumpets (pH 6--8, aw 0.97--0.99) are a popular baked product enjoyed by consumers worldwide. However, over the past few years, outbreaks of food poisoning have been caused by the growth of Bacillus cereus in crumpets. This spore forming microorganism, which originates in flour, can easily survive the baking process and grow to >106 CFU/g within 3--5 days at ambient storage temperature. Therefore, control of this pathogen is essential to ensure the safety and marketability of English-style crumpets.
Initial studies were done to determine the effect of water activity ( aw), pH, modified atmosphere packaging (MAP), UV-light, bacteriocins, organic acids and esters, alone and in conjunction with each other, on the growth of B. cereus in model broth/agar systems.
B. cereus is a difficult microorganism to control in food using conventional preservation methods. Further studies are now under way to investigate novel methods to control the growth of this pathogen, particularly in high pH crumpets. (Abstract shortened by UMI.)

Bacillus cereus has been responsible for several food poisoning outbreaks involving high moisture-high pH (aw ~ 0.98, pH ~ 8.8) English-style crumpets. Two novel methods, involving sorbohydroxamic acid (SHA) and mastic essential oil (MO), were evaluated for their potential to inhibit the growth of this pathogen and other selected spoilage and foodborne pathogens in high moisture, high pH English-style crumpets.
While sorbic acid only controlled the growth of B. cereus at pH 5 and 5.5, SHA proved effective at all pHs and concentrations under investigation. MO also failed to inhibit the growth of B. cereus when added directly to agar plates.
Products were unacceptable when counts increased from 103 CFUIg to 106 CFU/g or sensory scores reached <3 on a scale of 5. Only SHA (0.3% w/w) proved effective in high pH crumpets. (Abstract shortened by UMI.)

El yogurt es un alimento nutritivo, de fácil digestión, alto valor nutricional y con propiedades de regular la digestión. Se elaboró un yogurt bebible a base de leche de soya sabor cereza para ofrecer al consumidor las propiedades del yogurt y de la soya. Para lo cual, se realizaron dos tratamientos, T1 inóculo con yogurt comercial y T2 inóculo marca JOINTEC. Se realizaron análisis microbiológicos (Mesófilos Aerobios, Coliformes Totales, Coliformes Fecales y Psicrótrofos), análisis de viscosidad, análisis físicos (pH y color), análisis fisicoquímicos de calidad para yogurt (Proteína láctea, ácido láctico, grasa butírica y sólidos no grasos) y la viabilidad de Lactobacillus bulgaricus y Streptococcus thermophilus. Se determinó la aceptación de cada tratamiento, mediante un análisis sensorial con consumidores no entrenados (200 consumidores). En el cual se realizaron pruebas Dúo-Trío, comparación por pares, descriptiva cuantitativa y de preferencia. El mejor tratamiento fue el T2. El cual, tuvo mayor aceptación por los consumidores y cumple con las especificaciones microbiológicas, fisicoquímicas de calidad y de viabilidad de BAL para ser denominado como yogurt, en una vida de anaquel de 21 días sin conservadores.
Universidad Autónoma del Estado de México

Ce travail est une contribution à l'évaluation du risque induit par les bacillus (sensu lato) dans les produits pasteurisés réfrigérés à base de légumes. L'étude menée au cours de la 1ère partie de cette thèse a montré, par une approche d'identification polyphasique intégrant la rep-pcr, le système api50ch/20e et l'analyse des séquences d'adnr 16s, que les conditions de conservation de purées de légumes pasteurisées influençaient fortement la composition de leur microflore et que les températures de conservation proches de 4°c pouvaient prévenir le risque de développement de pathogènes comme b. Cereus, b. Licheniformis et b. Subtilis. Cette étude soulignait également l'apparition possible de fausses identifications par le système api50ch/20e. Le séquençage partiel semblait être une étape nécessaire pour l'identification fiable des bacillus (sensu lato). Au cours de la 2ème partie de cette thése, les légumes et agents de texture (protéines de lait et amidon) étaient identifiés comme les principales sources de contamination des purées. Le typage moleculaire des souches de b. Cereus et leurs propriétés de croissance au froid, indiquaient que les contaminants psychrotrophes présents dans les produits conservés provenaient des courgettes elles-mêmes contaminées par le sol de culture, tandis les contaminants non psychrotrophes provenaient des protéines de lait. En 3ème partie, la détection, par pcr et transferts de southern, des gènes des entérotoxines présents chez b. Cereus (hbl, nhe, cytk et bcet) ainsi que la production d'entérotoxines mesurées par 2 tests immunologiques, montraient que le gène cytk, l'association des génes cytk/hbl/nhe et la production forte d'entérotoxines étaient beaucoup moins fréquents chez les souches de b. Cereus issues d'aliments comparé aux souches issues de toxi-infections alimentaires. Ces resultats appuyaient l'hypothèse selon laquelle les souches issues d'aliments à base de légumes étaient moins propices aux toxi-infections alimentaires

Memoria para optar al título profesional de Ingeniero en Alimentos
El presente trabajo hace referencia al desarrollo de hojuelas y barras de cereal a base de quínoa, a los cuales se realizó un proceso de optimización por superficie de respuesta a través de una evaluación sensorial basado en la escala de valorización de Karlsruhe. Es a partir de esta evaluación y con ayuda del software Statgraphics Plus 5.1 que se formularon dos óptimos para los productos. En el caso de la barra de cereal las variables independientes era el tiempo de horneado de la granola (componente principal de la barra) y el porcentaje de miel (constituyente de la solución aglomerante) obteniéndose luego del estudio, que con 40 minutos de horneado y con un 40% de miel la barra presentaba el valor óptimo de calidad total. En el caso de la hojuela las variables independientes eran la lecitina (%) y la temperatura de horneado (°C), obteniéndose como resultado una hojuela con 5% de lecitina y una temperatura de horneado de 120°C por 30 min. A ambos productos se realizaron estudios de nutrientes, reológicos y de vida útil, donde destacan la calidad proteica de los productos finales, la pérdida de dureza generalizada en el tiempo y una vida útil para ambos productos de 56 días. Para la hojuela de cereal además se realizó un estudio de factibilidad técnico-económico, pretendiéndose abarcar el 5% del mercado nacional con 610 ton anuales. La elaboración del estudio financiero reveló la factibilidad del proyecto con un VAN de MM$81,1 (TD 15%), un TIR de 17,5% y un PRI de 3,1 años. El estudio de sensibilización posterior dejó ver una alta dependencia del proyecto a un aumento de costo de materia prima, disminución del volumen de venta y del precio de venta a variaciones iguales o superiores al 10%.
The present work makes a reference to the development of cereal flakes and bars based in quinoa in which an optimization process by response surface through a sensorial evaluation based on the valuation scale of Karlsruhe was carried out. Based on this evaluation and through the aid of software Statgraphics Plus 5.1 two optimal products were formulated. In the case of the cereal bar the independent variables were the granola baking time (main component of the bar) and the honey percentage (a part of the binder solution) concluding after the study, that with 40 minutes of baking time and a 40% of honey, the bar got the optimal value of total quality. In the case of cereal flakes, the independent variables were the lecitine (%) and the baking temperature (°C), as result, a flake was obtained with a 5% of lecitine and a baking temperature of 120°C for 30 minutes. Both products were examined in order to study their nutrients, reologics properties and shelf life, where it is emphasize the protein quality of end items, the loss of hardness through the time and a shelf life for both products of 56 days. In addition for cereal flakes a technical – economic feasibility study was made, trying to include 5% of the national market with 610 ton annual. The elaboration of the financial study revealed the feasibility of the project with a NPV of MM$81,1 (RD 15%), a IRR of 17,5% and a PRI of 3,1 years. The latest sensibilization study let see a high dependency of the project to an increase of the raw material cost, a diminution of the sale volume and the sale price to variations equal or superior to 10%.

Memoria para optar al título de Ingeniero en Alimentos
El presente estudio trata sobre la elaboración de pastas a base de harina de quínoa, buscando obtener a través de pruebas reológicas y de resistencia la mezcla de harina de quínoa y harina de arroz más adecuada para la masa elaboradora de pastas. El estudio de las propiedades reológicas se basó en la variación de parámetros como son la cantidad de harina de quínoa presente en la mezcla, temperatura y porcentaje de agua en la masa. Se obtuvieron resultados óptimos para mezclas con 50% de harina de quínoa y 50% de harina de arroz, obteniendo valores de fuerza elástica de 167 [N]. Para la obtención de una adecuada fuerza elástica, la temperatura de la masa debe encontrarse por sobre los 45°C, mientras que el contenido de agua debe encontrarse en los rangos de 24% a 30% presentes en la masa. Dentro del estudio se realizaron pruebas de resistencia para determinar el módulo de Young para las pastas elaboradas a base de harina de quínoa, obteniendo valores del orden de 1014 [N/m2 ] tanto para las muestras de pastas de quínoa como para una muestra de pasta comercial a base de trigo. Se corrobora que para pastas con 50% de harina de quínoa existe una mejor elasticidad presentando un módulo de Young de 1,49*1014 [N/m2 ]. Finalmente se realizaron evaluaciones de aceptabilidad para las pastas elaboradas, obteniendo una aceptabilidad general de 5,7 de promedio, en una escala de evaluación de 1 “me disgusta extremadamente” a 9 “me gusta extremadamente”. El resultado obtenido se debió a que los parámetros de color, apariencia y textura obtuvieron altos porcentajes de rechazo, mientras que el aroma y sabor obtuvieron altos porcentajes de aceptación, lo cual es un buen indicador para el producto, ya que se trata de nuevos sabores, distintos a los conocidos por el consumidor.

Orientador: Lorena Benathar Ballod Tavares.
Co-orientador: Rita de Cássia Siqueira Curto Valle.
Dissertação (mestrado) - Universidade Regional Blumenau, Centro de Ciências Tecnológicas, Programa de Pós-Graduação em Engenharia Química.

Orientador: Fernanda Paula Collares
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-08T12:10:02Z (GMT). No. of bitstreams: 1 Marangoni_AndreLuis_M.pdf: 949788 bytes, checksum: 48a3e3adcced1d1be2f35acb905676cd (MD5) Previous issue date: 2007
Resumo: O presente trabalho visou avaliar a aplicação de farinha de Yacon (Polymnia sonchifolia) em produtos à base de cereais como bolo inglês, biscoito tipo "Champurrada" e snacks à base de arroz obtidos por extrusão termoplástica. Para tanto, a incorporação de farinha de Yacon nos snacks e a substituição parcial da farinha de trigo pela farinha de Yacon no bolo e no biscoito foram analisadas quantificando-se a magnitude das mudanças físicas e sensoriais nestes produtos. Para os três estudos, utilizou-se a metodologia de superfície de resposta com um delineamento estatístico do tipo composto central rotacional (com 2 variáveis independentes no caso do bolo e biscoito, e 3 variáveis independentes para o estudo dos snacks). As variáveis independentes no estudo do bolo foram as concentrações de farinha de Yacon e de farinha de linhaça. Já, para o biscoito, as variáveis foram as concentrações de farinha de Yacon e de aveia em flocos. Em se tratando dos snacks, as variáveis foram: umidade da farinha de alimentação; temperatura na 4ª e 5ª zona do extrusor; e teor de farinha de Yacon incorporada. Os bolos e os biscoitos foram analisados quanto à textura e cor instrumental (Hunterlab), densidade da massa, volume específico, além das avaliações sensoriais. Por sua vez, as variáveis dependentes no estudo dos snacks foram: propriedades físico-químicas (textura e cor instrumental, índice de absorção de água e de solubilidade em água, e índice de expansão) e sensoriais. Para o bolo, as superfícies geradas sugeriram que concentrações de farinha de Yacon variando entre 0,0% e 3,45% e teores de farinha de linhaça entre 3,18% e 6,0% resultaram em um produto de menor dureza. Para os parâmetros de cor, com concentrações mínimas de farinha de Yacon e linhaça (0,0% e 3,18%, respectivamente), obteve-se um bolo mais claro, de coloração mais amarelada e a densidade da massa atingiu valores mínimos quando o teor de linhaça foi de 6,0%, sendo que o teor de farinha de Yacon não apresentou influência sobre este parâmetro. No estudo do biscoito, a superfície de resposta indicou que quando a concentração de Yacon foi de 3,45% ou superior, e a de aveia de 6,82%, o parâmetro L* atingiu seu valor máximo. O maior valor de intenção de compra ocorreu para uma concentração de Yacon de 3,45% e de aveia de 1,18% e 6,82%. Dessas observações pode-se inferir que a concentração recomendada de incorporação de farinha de Yacon seria 3,45% e de aveia de 6,82%, considerando a faixa de valores estudada. Os snacks que apresentaram maior expansão foram obtidos a 120ºC, com teor de umidade da matéria-prima igual a 17% e concentração da farinha de Yacon de 12%. As superfícies geradas para os atributos sensoriais textura e intenção de compra, mostraram que o valor máximo para estes dois atributos ocorreram para as mesmas condições de temperatura, umidade da farinha de alimentação e teor de farinha de Yacon que propiciaram o maior índice de expansão. A utilização da farinha de Yacon (Polymnia sonchifolia) como um ingrediente funcional em produtos panificados (bolo e biscoito) e extrudados (snacks de arroz) mostrou-se viável. Os fruto-oligossacarídeos (FOS), objeto central no desenvolvimento de um produto funcional, foram conservados no processamento do Yacon até a obtenção da farinha e permaneceram em concentrações satisfatórias, de modo a suprir a ingestão nutricional de acordo com padrões difundidos na literatura
Abstract: This study aimed at evaluating the application of yacon (Polymnia sonchifolia) flour in cereal-based products such as pound cake, "Champurrada" type biscuits and rice-based snacks produced by a thermoplastic extrusion process. Thus the effect of incorporating yacon flour into the snacks and the partial substitution of wheat flour by yacon flour in the cake and biscuit were analysed, quantifying the magnitude of the physical and sensory changes in these products. Response surface methodology was used in the three studies, with a rotatable central-composite experimental design (with 2 independent variables for the cake and biscuit, and 3 independent variables for the snacks). The independent variables for the cake study were the yacon flour and flaxseed flour concentrations, and for the biscuit, the yacon flour and oat flake concentrations. For the snacks, the variables were: moisture content of the feed flour; temperature in the 4th and 5th extruder zones; and amount of yacon flour incorporated. The cakes and biscuits were analysed for instrumental texture and colour (Hunterlab), dough density and specific volume, as well as the sensory analyses. On the other hand the dependent variables for the snacks were: the physical (instrumental texture and colour, water solubility index, water absorption index and expansion ratio) and sensory properties. For the cake, the surfaces generated suggested that concentrations of yacon flour between 0.0% and 3.45% and of flaxseed flour between 3.18% and 6.0% resulted in a cake with reduced hardness. For the colour parameters, the minimum yacon and flaxseed flour concentrations (0.0% and 3.18%, respectively), produced lighter coloured cakes with a yellowish colour. The dough density reached minimum values when the concentration of flaxseed was 6.0%, whilst the yacon flour concentration showed no influence on this parameter. In the biscuit study, the response surface indicated that when the yacon flour concentration was 3.45% or above and that of the oat flakes 6.82%, the L* parameter reached its maximum value. The highest value for purchasing intention was obtained with a Yacon flour concentration of 3.45% and an oats concentration between 1.18% and 6.82%. These observations inferred that the recommended concentrations for the yacon flour and oat flakes would be 3.45% and 6.82%, respectively, considering the range of values studied. The most expanded snacks were obtained under the following conditions: 17% moisture content in the feed flour, a temperature of 120ºC and the incorporation of 12% yacon flour. The surfaces generated for the sensory attributes of texture and purchasing intention, showed that the maximum values for these two attributes were obtained under the same conditions of temperature, feed flour moisture content and yacon flour incorporation that propitiated the greatest expansion values. The use of yacon flour (Polymnia sonchifolia) as a functional ingredient in bakery products (cake and biscuit) and extruded products (rice snacks) was shown to be viable. The fructooligosaccharides (FOS), central object of the development of a functional product, were conserved during the processing of the yacon to obtain the flour, remaining in satisfactory concentrations, sufficient to supply the recommended values for ingestion according to standards divulged in the literature
Mestrado
Mestre em Tecnologia de Alimentos

La presente investigación tiene como objeto la gestión del plan de marketing digital; esta busca ofrecer una aproximación de las estrategias de digitales más usadas en el Perú, enfocado a las microempresas que poseen limitaciones económicas para invertir en estrategias de marketing tradicionales como la publicidad pagada. Asimismo, son muchas las organizaciones que realizan diferentes acciones online para llegar a sus clientes, no obstante, la gran mayoría, cuentan con un plan poco sólido y estructurado debido a la falta de conocimiento; de ahí la importancia de analizar la gestión de un plan de marketing digital de una microempresa, con la finalidad de identificar si los pasos de este plan se encuentran alineados a los objetivos de la empresa. De tal modo, la investigación tuvo como base el caso de estudio: “Nutrishake Andino”, una microempresa peruana dedicada a la comercialización de productos hechos a base de cereales andinos, cuya temática de comunicación es la alimentación balanceada, saludable y nutritiva, es así que, la organización ha desarrollado estrategias de promoción tanto online como offline para lograr sus objetivos de atracción de clientes potenciales y fidelización de sus clientes actuales a través de un plan de marketing; sin embargo, a la fecha no ha logrado conseguir tales objetivos. Por ello, para identificar el problema de la actual gestión, se describe el actual plan de marketing, no obstante, el análisis se enfocará en su plan digital, para ello, se establecieron variables que estructuran la investigación. En ese sentido, la recolección de la información se basó en tres herramientas, en primer lugar, entrevistas a profundidad a expertos en el tema, tanto en marketing como marketing digital, a través de una guía de pregunta por cada grupo mencionado, lo que permitió encontrar concordancia y hallazgos entre ambos, bajo las variables de la investigación. En segundo lugar, con el propósito de identificar al cliente ideal de “Nutrishake Andino”, en el cual se basan las acciones de cada paso del plan de marketing digital, se realizaron encuestas a sus clientes potenciales y actuales, ambos con preguntas filtros para una adecuada segmentación. Por último, como medio de soporte para el análisis, se optó por la observación etnográfica virtual hacia las plataformas digitales de la empresa, para identificar el manejo de cada una. Finalmente, como resultado del análisis del plan de marketing digital, sintetizada en una matriz estructurada por los pasos de dicho plan, se expuso el diagnóstico final de la investigación y se generaron conclusiones y recomendaciones las cuales se articularon en una estrategia digital integral para la empresa. De este modo, se buscó también que la presente investigación sirva de modelo para las microempresas con características similares a la estudiada, en la elaboración y ejecución óptima de un plan de marketing digital.
Tesis

Face aux pathologies de malnutrition en croissance exponentielle en particulier dans les pays du Sud, le développement d’aliments fonctionnels à base de céréales fermentées représente une alternative aux produits laitiers déjà commercialisés. L’incorporation, la stabilité de composés bioactifs liposolubles tels que les caroténoïdes et les phytostérols, ainsi que leur devenir lors de la digestion gastro-duodénale doivent être étudiés afin de démontrer le potentiel nutritionnel de ce nouvel aliment. En effet, il est connu que les phytostérols diminuent la biodisponibilité des caroténoïdes. Le principal objectif de ces travaux a été de concevoir un aliment fonctionnel probiotique à base de maïs fermenté enrichi en caroténoïdes et phytostérols, et d’étudier la stabilité, la bioaccessibilité et l’absorption intestinale de ces composés liposolubles. La formulation et la standardisation du procédé, incluant la sélection de starters de fermentation afin d’obtenir un aliment probiotique, ont été mis au point. Au cours de la fabrication, la stabilité des composés liposolubles a montré un taux de rétention de 73 %. L’effet des phytostérols dispersibles sur la bioaccessibilité de la β-cryptoxanthine, du β carotène et du lycopène de l’aliment fonctionnel a été évalué à l’aide d’un modèle de digestion in vitro simulant les conditions gastriques et duodénales. L’absorption intestinale des composés a également été mesurée en couplant le modèle de digestion in vitro aux cellules de type Caco-2 (TC7). L’étude a démontré que grâce à leur véhicule, les phytostérols dispersibles apportent un potentiel hypocholesterolémiant au produit, sans affecter la bioaccessibilité des carotènes. In fine, cet aliment fonctionnel a été optimisé d’un point de vue organoleptique et nutritionnel par l’utilisation de protéines sériques
Because of the exponential growth of malnutrition pathologies particularly in South countries, the development of functional foods based on fermented cereals represents an alternative to dairy products already marketed. The incorporation, the stability of lipophilic bioactive compounds such as carotenoids and phytosterols, as well as their behavior during the gastro-duodenal digestion have to be studied, in order to demonstrate the nutritional potential of this new product. Indeed, it is known that phytosterols decrease the carotenoid bioavailability. The main objective of this work was to design a probiotic functional food based on maize and enriched with carotenoids and phytosterols, and study the stability, the bioaccessibility and the intestinal absorption of these fat-soluble compounds. The formulation and the standardization of the manufacturing process, including the selection of starters for fermentation in order to obtain a probiotic product, were developed. During the production, the stability of fat-soluble compounds showed a retention level of 73%. The effect on dispersible phytosterols on the β-cryptoxanthine, β-carotene and lycopene bioaccessibilities was evaluated thanks to an in vitro digestion model mimicking the gastric and duodenal conditions. The intestinal absorption of these compounds was also estimate by crossing the in vitro digestion model with a Caco-2 cells model (TC7). The study demonstrated that thanks to their vehicles, dispersible phytosterols provide a potential cholesterol-lowering effect to this food, without affecting the carotene bioaccessibility. In fine, this functional food was optimized in terms of sensory and nutritional levels, by using whey protein isolates

Les folates sont des vitamines indispensables à tous les âges, particulièrement pendant la grossesse et l’enfance, étant donné leur fonction dans la division cellulaire. Le régime alimentaire en Afrique est essentiellement basé sur les céréales, consommées toujours après transformation. La fermentation est l’un des moyens de transformation des céréales pouvant augmenter les folates dans les aliments. L’objectif de ce travail était d’utiliser la fermentation pour augmenter les ingérés en folates des populations africaines via la consommation d’aliments céréaliers fermentés. Sept aliments céréaliers fermentés couramment consommés en Afrique de l’Ouest ont été investigués. La plupart des aliments avaient des teneurs en folates (1,8–31,3 µg/100g matière fraîche) inférieures à celles des céréales de départ (13,8-73,4 µg/100g matière fraîche). Des pertes en folates ont lieu au cours de certaines étapes de procédés dont le décorticage, le séchage, le trempage, le broyage et la filtration. Toutefois, la fermentation a permis une augmentation de la teneur en folates dans certains aliments. La bioaccessibilité des folates, évaluée à l'aide d'un modèle de digestion statique in vitro, variait de 23% à 81%. Elle était influencée par la matrice alimentaire et la stabilité des folates au cours de la digestion. Il a été calculé qu’au maximum 8% des besoins journaliers en folates des jeunes enfants consommant l’un des aliments étudiés pourraient être couverts. Des essais d’inoculation de bouillies fermentés à base de mil avec des souches de bactéries lactiques sélectionnées pour leurs propriétés nutritionnelles (synthèse de folates, hydrolyse de l’amidon) permettaient d’augmenter significativement les teneurs en folates (jusqu’à 8,7 µg/100 g matière fraîche) par rapport à leur équivalent préparées de manière traditionnelle (2,5-5,4 µg/100 g matière fraîche). L’inoculation par un pied-de-cuve provenant d’une fermentation spontanée permettait aussi une augmentation significative des teneurs folates (jusqu’à 7,4 µg/100 g matière fraîche). La caractérisation de la diversité bactérienne de 7 aliments céréaliers fermentés du Burkina Faso, d’Ethiopie et de la Finlande montrait que les bactéries lactiques du genre Lactobacillus, Enterococcus, Weissella, Pediococcus, Lactococcus et Streptococcus étaient les principaux acteurs de la fermentation de ces aliments. Toutefois, une présence non négligeable d’autres microorganismes potentiellement pathogènes des genres Bacillus, Pseudomonas, Staphylococcus, Erwinia, Klebsiella, Escherichia et Acinetobacter a été identifiée. Cette contamination était liée à certaines étapes du procédé de transformation des céréales dont le stockage et broyage dans les moulins publics. Ces microorganismes pathogènes étaient réduits par fermentation et finalement éliminés après l'étape de cuisson
Folates represent an essential vitamin in the human diet at all ages, particularly during pregnancy and infancy, as it is required for the production of new cells. In many African countries, the main staple foods are based on cereals, which are always consumed after processing. Fermentation is one of the processing, which could increase folate contents in foods. The objective of this work was to increase folates intake of African people through the consumption of cereal-based fermented foods using fermentation. Seven types of cereal-based fermented foods (CBFF), commonly consumed in West Africa, were investigated in this study. Total folate content of cereal-based fermented ranged between 1.8 and 31.3 µg/100g fresh weight, and was almost always lower than in the raw material (13.8-73.4 µg/100g fresh weight). Folate losses occurred during some processing steps like debranning, soaking and drying steps. However, fermentation was able to increase the folate content in some CBFF. Folate bioaccessibility was assessed using a static in vitro digestion model, and ranged from 23% to 81%. The bioaccessible folate content was influenced by total folate content, the structure of food matrices that modulated folate release, and folate stability during digestion process. Calculations of the contributions of CBFF to the reference nutrient intake for folate showed that folate intakes from these foods would cover a maximum of 8% of the folate requirements for young children. Porridges prepared with starter cultures of lactic acid bacteria selected for the nutritional properties (folate synthesis, starch hydrolysis) had significantly higher folate contents (up to 8.7 µg/100 g fresh matter) than the porridge prepared using the traditional process (2.5-5.4 µg/100 g fresh matter). Back slopping using an inoculum from a spontaneous fermentation also enabled an interesting increase in folate contents (up to 7.4 µg/100 g fresh matter). The bacterial diversity of seven cereal-based fermented foods from Burkina Faso, Ethiopia and Finland were assessed using 16S rRNA amplicon sequencing. Lactic acid bacteria genus, including Lactobacillus, Enterococcus, Weissella, Pediococcus, Lactococcus and Streptococcus were the main bacteria present in cereal-based fermented foods. Several potentially pathogenic bacteria, namely, Bacillus, Pseudomonas, Staphylococcus, Erwinia, Escherichia, Klebsiella and Acinetobacter were also found in some intermediary products resulting from storage and wet milling. These microorganisms were reduced by fermentation and finally removed after the cooking step

Les effets d'une quinzaine d'ingrédients sur le procédé de cuisson-extrusion ont été étudiés. Des ingrédients de nature très diverses ont été testés: produits amylacés, émulsifiants, matière grasse, bicarbonate de sodium. Ils ont été ajoutés individuellement à deux mélanges de base : l'un composé de grits de maïs, l'autre constitué de farine de blé et de granules de pomme de terre (50/50). Leurs effets ont été analysés à deux niveaux : sur le procédé de cuisson-extrusion lui-même, et notamment sur la viscosité apparente d'extrusion, ainsi que sur quelques propriétés physiques des extrudés telles que l'expansion, l'alvéolation et la croustillance. Globalement, il ressort de cette étude que l'on peut aisément modifier la texture des extrudés en agissant sur les recettes. Bien souvent, les ingrédients n'ont pas le même effet sur les deux mélanges de base employés. Une analyse des propriétés physiques des extrudés a permis d'établir des corrélations très globales entre certains de ces paramètres. A titre d'exemple, les expansions sont fortement corrélées avec la densité alvéolaire. En revanche, il n'existe pas de relation globale entre la viscosité apparente d'extrusion et les propriétés physiques des extrudés.

L’objectif principal de ce travail vise à améliorer la qualité sanitaire des bouillies infantiles à base de céréales fermentées de mil, consommées en Afrique comme aliments de complément à l’allaitement maternel. Ces bouillies doivent être exemptes de germes susceptibles de provoquer des toxi-infections alimentaires. L’évaluation de la qualité bactériologique des produits issus de 10 sites de la commune de Ouagadougou au Burkina Faso, nous a permis d’isoler et d’identifier 449 souches des échantillons prélevés à différentes étapes de la fabrication de la bouillie que sont : avant la fermentation de la pâte, à la fin de la fermentation, après la cuisson de la pâte fermentée et lors de la confection des granules. Des dénombrements microbiens réalisés sur les milieux Mac Conkey, Baird Parker, Mannitol-Yolk-Polymyxin et Tryptone Sulfite Cyclosérine de tous les échantillons montrent la présence en grand nombre de différents germes, signe pour certains sites d’une mauvaise hygiène des produits et des procédés. Pour les entérobactéries, l’espèce la plus rencontrée est Klebsiella pneumo. Ssp pneumonia. Pour les autres bacilles Gram négatif, c’est l’espèce Chryoseomonas luteola. Pour les staphylocoques, c’est l’espèce Staphylococcus xylosus. Pour les bacilles gram positif aptes à sporuler ce sont des souches de Bacillus cereus et de Clostridium beijerinckii /butyricum. D’un point de vue toxi-infections alimentaires, les espèces suivantes ont été isolées et identifiées : Bacillus cereus (19 souches), Enterobacter sakazakii (03), Klebsiella pneumo. Spp pneumonia (16), Escherichia coli (04) et Staphylococcus aureus (02). Globalement, on observe une diminution importante des niveaux de population après la fermentation mais les bacilles capables de sporuler se maintiennent dans les produits après cette étape importante du procédé. La cuisson entraine une diminution drastique voir la disparition de la majorité des germes sauf pour les bacilles aptes à la sporulation. L’analyse des dangers lors de la fabrication des bouillies a montré que la fermentation et la cuisson de la pâte fermentée sont deux points critiques qu’il faut maitriser. Des challenge-tests réalisés avec les souches Escherichia coli ATCC 25922, Enterobacter sakazakii CIP 103183T, Bacillus cereus ATCC 9139 de collection ou les souches Escherichia coli AMC2-1, Enterobacter sakazakii AMC8-3, Bacillus cereus BMYP7-3 isolées des ateliers ont permis l’évaluation du risque de leur développement et ce à certaines étapes des procédés de transformation. La fermentation lactique et surtout la cuisson s’avèrent efficaces pour réduire les populations d’entérobactéries testées. Pour les souches de Bacillus cereus testées, elle ne constitue pas une barrière efficace contre le maintien de leurs formes sporulées. Il en ressort que pour ces différents germes utilisés, la maîtrise du processus de fermentation lors de la décantation de la pâte, la maîtrise de la cuisson à travers le couple temps/température, les contaminations croisées liées à la qualité des ustensiles et à la propreté des productrices sont à maitriser pour l’obtention d’une bouillie « saine ». La recontamination de la bouillie cuite reste un danger. L’ajout de nisine dans les bouillies, est sans effet sur les entérobactéries testées alors que cet ajout permet de réduire efficacement les populations de bacillus cereus. Cette molécule thermostable pourrait être ajoutée en fin d’étape de fermentation et avant cuisson pour cumuler les deux effets : destruction thermique par cuisson et inhibition par la nisine
The aims of this work were to improve the quality of traditional millet-based fermented gruels for young children consumed in Africa as complementary foods. These gruels must be free from pathogens likely to cause food infections. The evaluation of the bacteriological quality of the products resulting from 10 production units of Ouagadougou town in Burkina Faso, allowed us to isolate and identify 449 bacteria from the samples taken at different steps during gruel manufacture: before the fermentation of the dough, at the end of the fermentation, after cooking of the fermented dough and granule production. Microbial enumerations were carried out on Mac-Conkey, Baird Parker, Mannitol-Yolk-Polymyxin and Trypton Sulfite Cycloserin mediums. All the samples showed the presence in great numbers of various pathogens, because of the bad hygiene of the products and process. For the enterobacteria, the most frequent was Klebsiella pneumo. Ssp pneumonia. For the other Gram negative bacilli, it was Chryoseomonas luteola. For the staphylococci, it was Staphylococcus xylosus. For sporulating Gram positive bacteria, we are identified Bacillus cereus and Clostridium beijerinckii/butyricum. With regard to food infections, the following species were isolated and identified: Bacillus cereus (19 species), Enterobacter sakazakii (03), Klebsiella pneumo. Spp pneumonia (16), Escherichia coli (04) and Staphylococcus aureus (02). Globally, we observed a major reduction in population levels after fermentation, but the bacilli able to sporulate were maintained in the products after this important step of the process. Cooking involved a drastic reduction in the majority of pathogens except the bacilli able to sporulate. Challenge-tests carried out with Escherichia coli ATCC 25922, Enterobacter sakazakii CIP 103183T, Bacillus cereus ATCC 9139 from a collection or Escherichia coli AMC2-1, Enterobacter sakazakii AMC8-3 and Bacillus cereus BMYP7-3 isolated from the production units, allowed the evaluation of the risk of their development and that with different steps of the process. Lactic fermentation and especially cooking were effective at reducing the populations of enterobacteria tested. For Bacillus cereus, it does not constitute an effective barrier against the maintenance of the spores. This reveals that for the various pathogens used, control of the process of fermentation during the decantation of the dough, control of cooking through time/temperature, cross contaminations related on the quality of the utensils and general cleanliness have to be controlled to obtain a “healthy” gruel. The cross contamination of the cooked gruel remains a danger. The addition of nisin in the gruel is without effect on the enterobacteria tested, whereas this addition makes it possible to reduce effectively the populations of Bacillus cereus. This heat-resistant molecule could be added at the end of the fermentation step and before cooking to combine the two effects: thermal destruction by cooking and inhibition by nisin

La neuroimagerie est confrontée à des difficultés pour analyser et réutiliser la masse croissante de données hétérogènes qu’elle produit. La provenance des données est complexe – multi-sujets, multi-analyses, multi-temporalités – et ces données ne sont stockées que partiellement, limitant les possibilités d’études multimodales et longitudinales. En particulier, la connectivité fonctionnelle cérébrale est analysée pour comprendre comment les différentes zones du cerveau travaillent ensemble. Il est nécessaire de gérer les données acquises et traitées suivant plusieurs dimensions, telles que le temps d’acquisition, le temps entre les acquisitions ou encore les sujets et leurs caractéristiques. Cette thèse a pour objectif de permettre l’exploration de relations complexes entre données hétérogènes, ce qui se décline selon deux axes : (1) comment gérer les données et leur provenance, (2) comment visualiser les structures de données multidimensionnelles. L’apport de nos travaux s’articule autour de trois propositions qui sont présentées à l’issue d’un état de l’art sur les domaines de la gestion de données hétérogènes et de la visualisation de graphes. Le modèle de données BMI-LM (Bio-Medical Imaging – Lifecycle Management) structure la gestion des données de neuroimagerie en fonction des étapes d’une étude et prend en compte le caractère évolutif de la recherche grâce à l’association de classes spécifiques à des objets génériques. L’implémentation de ce modèle au sein d’un système PLM (Product Lifecycle Management) montre que les concepts développés depuis vingt ans par l’industrie manufacturière peuvent être réutilisés pour la gestion des données en neuroimagerie. Les GMD (Graphes Multidimensionnels Dynamiques) sont introduits pour représenter des relations complexes entre données qui évoluent suivant plusieurs dimensions, et le format JGEX (Json Graph EXchange) a été créé pour permettre le stockage et l’échange de GMD entre applications. La méthode OCL (Overview Constraint Layout) permet l’exploration visuelle et interactive de GMD. Elle repose sur la préservation partielle de la carte mentale de l’utilisateur et l’alternance de vues complètes et réduites des données. La méthode OCL est appliquée à l’étude de la connectivité fonctionnelle cérébrale au repos de 231 sujets représentées sous forme de GMD – les zones du cerveau sont représentées par les nœuds et les mesures de connectivité par les arêtes – en fonction de l’âge, du genre et de la latéralité : les GMD sont obtenus par l’application de chaînes de traitement sur des acquisitions IRM dans le système PLM. Les résultats montrent deux intérêts principaux à l’utilisation de la méthode OCL : (1) l’identification des tendances globales sur une ou plusieurs dimensions et (2) la mise en exergue des changements locaux entre états du GMD
Neuroimaging domain is confronted with issues in analyzing and reusing the growing amount of heterogeneous data produced. Data provenance is complex – multi-subjects, multi-methods, multi-temporalities – and the data are only partially stored, restricting multimodal and longitudinal studies. Especially, functional brain connectivity is studied to understand how areas of the brain work together. Raw and derived imaging data must be properly managed according to several dimensions, such as acquisition time, time between two acquisitions or subjects and their characteristics. The objective of the thesis is to allow exploration of complex relationships between heterogeneous data, which is resolved in two parts : (1) how to manage data and provenance, (2) how to visualize structures of multidimensional data. The contribution follow a logical sequence of three propositions which are presented after a research survey in heterogeneous data management and graph visualization. The BMI-LM (Bio-Medical Imaging – Lifecycle Management) data model organizes the management of neuroimaging data according to the phases of a study and takes into account the scalability of research thanks to specific classes associated to generic objects. The application of this model into a PLM (Product Lifecycle Management) system shows that concepts developed twenty years ago for manufacturing industry can be reused to manage neuroimaging data. GMDs (Dynamic Multidimensional Graphs) are introduced to represent complex dynamic relationships of data, as well as JGEX (Json Graph EXchange) format that was created to store and exchange GMDs between software applications. OCL (Overview Constraint Layout) method allows interactive and visual exploration of GMDs. It is based on user’s mental map preservation and alternating of complete and reduced views of data. OCL method is applied to the study of functional brain connectivity at rest of 231 subjects that are represented by a GMD – the areas of the brain are the nodes and connectivity measures the edges – according to age, gender and laterality : GMDs are computed through processing workflow on MRI acquisitions into the PLM system. Results show two main benefits of using OCL method : (1) identification of global trends on one or many dimensions, and (2) highlights of local changes between GMD states

Vitamin A deficiency is the leading cause of childhood blindness affecting over 190 million preschool children around the world where the highest rates are found in Sub-Saharan Africa (1). The coexistence of this deficiency with shortfalls in iron and zinc has resulted in a shift in intervention strategies from single targeted approach to broader diet diversification. As a result, food-based strategies leveraging local nutrient-dense plants as natural fortificants have gained significant interest for their potential to simultaneously address multiple micronutrient, and in some instances macronutrient, deficiencies. However, the efficacy of such approach depends upon several factors including knowledge on the nutritional composition of native plant materials as well as strategies for their incorporation into staple consumer products. Additionally, there is lack of information on impact of concurrent introduction of mineral and provitamin A rich plants on the stability and bioavailability of each individual nutrients including changes in these factors over extended periods of exposure. This is a key point considering that many of these materials are reported to have potential inhibitors of carotenoid absorption (minerals, fiber and phenolics).

To address these research gaps, this dissertation focuses on three areas including 1) micronutrient, phytochemical and polysaccharide characterization of three commercially available native micronutrient dense African plant materials [Adansonia digitata (baobab), Moringa Oleifera (moringa) and Hibiscus Sabdariffa (hibiscus)] that have been targeted for use as natural iron fortificants; 2) determination of the impact of these materials on the bioaccessibility and intestinal uptake of provitamin A carotenoids from model composite cereal products and 3) assess the effect of longer term exposure to baobab and moringa on provitamin A carotenoid absorption and cellular differentiation biomarkers of human intestinal Caco-2 cells to better understand the potential impacts of extended exposure periods on long term micronutrient uptake.

Characterization of the plant fortificants focused on understanding both nutritive components and potential limiters of carotenoid bioavailability. Baobab, moringa and hibiscus all were found to contain key phytochemical and polysaccharide components that could be leveraged as nutritional and function ingredients. The relatively higher levels of lutein (57  4.6 g/g), zeaxanthin (11  0.1g/g) and -carotene (20  2 g/g) in moringa leaf powder support the notion that this plant material can be used as a source of provitamin A and non-provitamin A carotenoids. Phenolic analysis revealed the presence of substantial amounts of flavan-3-ols (1234  16 mg/100g) in baobab, anthocyanins (2001  56 mg/100g) in hibiscus, and flavonols (5352  139 mg/100g) in moringa leaf powder. Polysaccharide analysis demonstrated that the primary monosaccharide in baobab was found to be xyloglucan (47 %) which is in agreement with the tentative identification Xyloglucans (hemicellulosic polysaccharide) based on linkage analysis. Hibiscus was found to contain similar amounts of xylose (20%) and galactose (27%) supporting the presence of similar proportions of xyloglucans and pectic polysaccharides (type I, type II AG, RG I). The main monosaccharide in moringa was found to be galactose (36%) followed by glucose (23%) and linkage analysis revealed the presence of high proportions of pectic polysaccharides (type I, type II AG, RG I). These results provide insight into presence of potential enhancer or inhibitors of target micronutrient (provitamin A carotenoids or iron/zinc) bioavailability when used as functional and nutritional food ingredients.

Subsequently, the impact of mineral-rich baobab formulated at levels relevant for iron fortification on the bioaccessibility of provitamin A carotenoids (proVAC) from composite millet porridges containing dried carrot and mango was assessed using in vitro digestion. Proportions of millet flour and plant materials were dry blended to deliver ~25% of the RDA for vitamin A(VA) and iron(Fe) as follows: decorticated extruded millet (Senegalese Souna var.) (40-60%), dried proVA rich carrot and mango blend (30%), and dried Fe and ascorbic acid rich Adansonia digitata (baobab) (0-25%). While there were no significant differences in proVAC bioaccessibility from porridge formulations with 5 and 15% baobab (18.8+/-2.0 and 18.8±2.0% respectively) as compared to control containing no mineral-rich plant (23.8 +/- 1.2%), 25% baobab resulted in a significant decrease (p<0.05) in bioaccessibility of proVAC (13.3+/-1.6%). However, baobab inclusion did not impact intestinal uptake efficiency of provitamin A carotenoids by Caco-2 human intestinal cells

(3.3-3.6% -carotene and 3.7-4.5% for -carotene) across all formulation. These results suggest that any potential negative effects of baobab inclusion may be limited to food matrix interactions and digestion. This was confirmed in separate experiments that with experiments on baobab and carotenoid blends showing that digested baobab did not affect carotenoid absorption by Caco-2 cells. Overall these data support the notion that that modest inhibition of carotenoid bioaccessibility by baobab may not significantly limit carotenoid delivery from composite porridges. Furthermore, bioaccessible provitamin A content of a serving (200 g) of composite porridges can provide 27 - 48% of the RDA of vitamin A for children 1-3 years of age.

Finally, we evaluated the impact of long-term exposure to baobab and moringa digesta on Caco-2 cell differentiation biomarkers and provitamin A uptake to gain insight into how inclusion of these materials in to a daily diet may alter absorption and transport of nutrients or otherwise have potential negative effects on the intestine. Based on NMR analysis of intracellular metabolites in differentiating Caco-2 monolayers, significant alterations in specific osmotic pressure regulators, particularly glycerophosphocholine, taurine and myo-inositol were observed with repeated exposure to all treatment groups including the control (digested 0.9% saline solution). Changes in these metabolites levels have been linked with specific cellular function including protection against hyperosmotic stress and regulation of paracellular permeability of Caco-2 cells. Evaluation of carotenoid uptake comparing acute and acute on repeated exposure to treatment groups demonstrated that there was an overall significant reduction in carotenoid uptake with repeated exposure across all treatment groups including the control. Despite the reduction in carotenoid uptake, mRNA and protein levels of carotenoid transporters (CD-36, SR-B1 and FABP1) were not significantly altered with exposure through differentiation (except for SR-B1 protein levels). Decrease in SR-B1 levels may be due to bile acid accumulation from the digesta matrix which is known to regulate its own biosynthesis by a mechanism that involves the down-regulation SR-B1 expression to protect cells from cytotoxicity. Our results provide some insight into the impact of simulated gastrointestinal fluids alone on provitamin A uptake in this model system which are usually not taken into consideration in most Caco-2 cell studies. However, overall, these findings indicate that the introduction of baobab and moringa at levels relevant for delivery of meaningful levels of iron (15-23% RDA) should not have negative impacts on human intestinal function or carotenoid uptake over chronic use.

Taken together, our findings indicate that the three native Africa plant materials selected for investigation in these studies can be important sources of key micronutrients (iron, zinc and provitamin A carotenoids) and have potential as natural fortificants with application in staple foods such as cereal porridges. Incorporation of these plant materials, do not appear to negatively affect carotenoid bioavailability although there is a potential for their interaction during micellarization of carotenoids during normal digestion. While in vivo studies evaluating the bioavailability of provitamin A carotenoids from such composite formulations are required, these data support the further exploration of such natural fortification strategies in addressing micronutrient deficiencies in local African communities.

The incidences of diarrhoeal episodes in infants and children have mostly been associated with the consumption of contaminated weaning foods. This is especially true in developing countries where factors such as the lack of sanitation systems and electricity have been found to contribute to an increase in the incidence of microbiologically contaminated weaning foods. The process of fermentation has been found to reduce the amount of microbiological contamination in such foods as a result of the production of antimicrobial compounds such as organic acids, peroxides, carbon dioxide and bacteriocins. In this study, microbiological surveys were conducted on sorghum powder samples and their corresponding fermented and cooked fermented porridge samples collected from an informal settlement of the Gauteng Province of South Africa. The process of fermentation was found to result in significant decreases (P>0.05) in Gram-negative counts and spore counts, while aerobic plate counts decreased slightly. Lactic acid bacteria counts, however, increased significantly (P>0.05). The cooking process was found to result in further significant decreases (P>0.05) in all counts. Sorghum powder samples and fermented porridge samples were found to be contaminated with potential foodborne pathogens, including Bacillus cereus, Clostridium perfringens and Escherichia coli, however, none of the pathogens tested for were detected in any of the cooked fermented porridge samples. SDS-PAGE and phenotypic analysis of 180 lactic acid bacteria isolated from sorghum powder samples and their corresponding fermented and cooked fermented porridge samples showed that a majority of the isolates were lactobacilli and leuconostocs, however, some isolates were identified as pediococci and lactococci. These results demonstrated the heterogeneity of the lactic acid bacteria isolates that were associated with fermentation processes in this study. Of the lactic acid bacteria identified, Lactobacillus plantarum and Leuconostoc mesenteroides strains were found to have the highest distribution frequencies, being distributed in 87% and 73% of the households, respectively. Analysis of Lactobacillus plantarum (58) and Leuconostoc mesenteroides (46) strains isolated from sorghum powder samples and corresponding fermented and cooked fermented porridge samples by AFLP fingerprinting showed that they originated from a common source, which was sorghum powder. There was, however, evidence of strains that may have been introduced at household level. Antimicrobial activity of selected lactic acid bacteria was found to be mainly due to a decrease in pH in fermented and cooked fermented porridge samples. None of the lactic acid bacteria tested seemed to produce bacteriocins.

碩士
國立中興大學
食品科學系
89
Two brown rice varieties, Tainung Sen 19 (TNS 19) and Tai Keng 9 (TK 9) of second crop of 1997, were used as test samples. The brown rice products with different levels of wheat germ and steamed by autocalve with different temperature. The objective of this study is to evaluate the nutritive value, physicochemical properties and antioxant properties. The nutrition composition of the products including protein, crude fiber, total dietary fiber, essential amino acid, unsaturated fatty acid, mineral and vitamin E were increased by adding wheat germs. The products with 20% wheat germ had the highest nutritive value. Lower temperature (100℃, 30mins) result in higher content of amino acid and fatty acid. The physicochemical properties of the products change with supplementing the wheat germ. At 20% level, the products had the highest solubility, swelling power and the lowest absorption index. Higher temperature (120℃, 15mins) result in higher solubility, swelling power and water absorption index. But no significantly difference between different steam treatment. In addition, the color of the products of the different levels wheat germ and different steam temperature had significantly difference. Supplementing the products with wheat germ increasing, the amount of vitamin E, antioxidant properties and the ability of scavenging free radical increase, too. The brown rice products were vacuum and storage at ambient temperature for up to 9 months. The gradual loss of vitamin E was found during the storage peroid, and had the greatest losses (＞50%) occuring on the 9th month, which result in the highest acid value and peroxide value and the lowest peroxidant inhibition effect. At this time, the amount of hyperoxidant of the products at 20% level was even more than no adding wheat germ. Wheat germ is enriched in vitamin E. However, the unsaturated fatty acids of wheat germ also can promote the products to oxidize during the storage. Therefore wheat germ provides higher nutritive value, the quality of the products which storage over 6 months were get bad. The possible beneficial effect for prolonging the shelf life of the brown rice products still have to take the further investigation.