Over the past couple of decades interest in particle-stabilised emulsions or Pickering emulsions has greatly increased. When using particles as stabilisers, as opposed to surfactants, the interface becomes more rigid and this can lead to interesting physical properties. In addition, the resulting emulsions are found to be longer-lived garnering commercial interest. This thesis aims to explore the mechanical properties of some specific systems containing particle-stabilised interfaces. The main system investigated was the bicontinuous interfacially jammed emulsion gel or bijel. The bijel has two continuous interpenetrating liquid phases separated by a particle-stabilised interface. Therefore, the structure has a very large interface in a fairly small volume and the pore size is under the experimentalist's control giving it promise in a variety of applications, particularly those based on catalysis. The response of bijels stabilised by either spherical particles or anisotropic rod-shaped particles to centrifugal compression has been investigated in this thesis. It was found that, in both cases, the structure was distorted to create anisotropic particle-stabilised sheets orientated perpendicular to the force. The original method for fabricating bijels involves the arrested spinodal decomposition of partially miscible liquids. This method requires partially miscible liquid pairs and particles that are equally wetted by each phase. Due to these requirements, a new method for making bijels using mixing was developed by others and the bijel made by mixing has been tested with oscillatory rheology combined with imaging and squeeze flow experiments. It was found that at low strain the bijel displayed solid-like behaviour and the structure remained intact until well past the yielding point. In addition, two further systems were investigated. The first system was rod-shaped particle-stabilised emulsion droplets that stick together by particle bridging. Bridging is where one particle can stabilise two droplet interfaces, preventing coalescence and leading to droplet clusters. Particle bridging was found to occur regardless of shear rate, particle volume fraction and to some extent aspect ratio with these anisotropic rod-shaped particles. This behaviour is hypothesised to be a consequence of the charged nature of the silica surface above pH 2. The second system was large particle-stabilised water droplets that can sprout tubes by the partitioning of solute from a bath into the droplet. By using different solutes and mixtures of different alcohols, the key requirements for sprouting behaviour have been ascertained. The most important requirement was found to be achieving the correct balance between the interfacial tension and the amount of solute partitioning into the droplet.

Thesis (Ph.D. (Pharmacy))--North-West University, Potchefstroom Campus, 2008.

Thesis (Ph.D. (Pharmacy))--North-West University, Potchefstroom Campus, 2008.

Thesis (Ph.D. (Pharmacy))--North-West University, Potchefstroom Campus, 2008.

Orientador: Daniel Barrera-Arellano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-16T14:44:14Z (GMT). No. of bitstreams: 1 Davoli_FernandaZaccarelli_M.pdf: 1950760 bytes, checksum: beddba9801d9e0ab94fdf516e8404ff5 (MD5) Previous issue date: 2010 / Resumo: As comprovações científicas que demonstram os danos causados à saúde pelo consumo de ácidos graxos trans, aliadas às novas legislações que restringem a quantidade de ácidos graxos trans ou determinam a necessidade de suas quantidades serem especificadas nas tabelas nutricionais dos rótulos dos alimentos, tornaram a interesterificação e as técnicas de misturas de diferentes fontes de gorduras, ferramentas fundamentais para o desenvolvimento de gorduras e alimentos livres de ácidos graxos trans. A indústria de alimentos precisa de conhecimento sobre a funcionalidade e aplicabilidade de gorduras formuladas com baixo conteúdo de ácidos graxos trans e sobre o efeito de aditivos, como os emulsificantes, nas suas características físico-químicas. Neste trabalho, três gorduras comerciais com baixo conteúdo de ácidos graxos trans (duas para recheio de biscoito tipo wafer e uma para recheio de biscoito tipo sanduíche) foram aditivadas com cinco emulsificantes diferentes, a uma dosagem constante de 3%. Os emulsificantes utilizados foram 5 versões de mono e mono-diglicerídios saturados, que diferiam com relação à matéria-prima usada na sua produção e o teor de monoglicerídio contido no produto. As características físico-químicas determinadas nas gorduras foram: perfil de sólidos, ponto de fusão, dropping point, curvas de cristalização e de fusão por DSC e isoterma de cristalização por RMN. Os perfis de cristalização das gorduras tanto por DSC como RMN foram as características que mais sofreram alterações. Os cinco emulsificantes promoveram aumento na velocidade de cristalização das gorduras. Dois dos emulsificantes e duas das gorduras foram cristalizados em planta piloto, utilizando-se um trocador de calor de superfície raspada e, posteriormente usadas na produção de recheios. Os recheios foram analisados quanto à densidade específica, firmeza, dureza e aderência e comparados com recheios feitos com as gorduras sem aditivos. Em geral, nenhuma alteração significativa nos recheios foi observada. Enfim, emulsificantes podem ser usados como agentes de aceleração da velocidade de cristalização de gorduras e potencialmente podem diminuir o tempo de produção de gorduras e biscoitos recheados / Abstract: Scientific evidence that demonstrates the harm to health caused by the consumption of trans fatty acids, coupled with new legislation that limits the quantity of trans fatty acids or calls for its quantities to be clearly specified on nutritional tables in product labels have made the interesterification and blending techniques, which combine different sources of fat, essential for the development of trans free fats and food products. The food industry requires knowledge of functionally and applicability of formulated fats with low contents of trans fatty acids and of the effects that additives, such as emulsifiers, produce on their physical-chemical properties. This work studies the change to the physical-chemical properties of three commercially used fats (two wafer biscuit filling fats and one sandwich biscuit filling fat) with low contents of trans fatty acids when a constant 3% dosage of emulsifier is added. The emulsifiers used were five versions of saturated mono and mono-diglycerides made from different fat bases and having different monoglyceride contents. The physical-chemical properties of the fats analyzed were: solid fat content, melting point, dropping point, crystallization and melting curves by DSC and crystallization isotherm by NMR. The most significant change observed was related to the crystallization profile both by DSC or NMR. All five emulsifiers enhanced fat crystallization rate. Two emulsifiers combined with two fats were crystallized using a pilot scraped-surface heat exchanger (SSHE) and further used to produce biscuit fillings. These filling samples were finally analyzed in terms of their specific gravity, firmness, hardness and stickiness and compared to a filling made from pure low trans fat. No significant change was identified in the comparison. Thus, the emulsifier can be utilized as an agent to speed up fat crystallization and potentially shorten the fat and filled biscuit production time / Mestrado / Mestre em Tecnologia de Alimentos

Orientador: Antonio Carlos de Laurentiz / Resumo: Um experimento foi realizado na UNESP – Faculdade de Engenharia – Campus de Ilha Solteira Setor de Avicultura, tendo como objetivo avaliar a matriz nutricional, preconizada pela literatura, da enzima fitase e da goma de soja, isoladas e associadas em dietas para frangos de corte nas fases inicial, crescimento e final, avaliando características de desempenho zootécnico ( consumo de ração, ganho de peso e conversão alimentar) nas fases de 7 a 21, 22 a 35, 36 a 42 e na fase total de 7 a 42 dias de idade, sendo estes dados utilizados para a análise econômica. Foram utilizadas 700 aves da linhagem Coob® (lote sexado – machos), as aves foram distribuídas em um delineamento inteiramente casualizado, contendo 7 tratamentos e 5 repetições de 20 aves. Os dados foram submetidos à análise de variância e quando apresentaram diferenças significativas as médias foram comparadas pelo teste SNK 5% de probabilidade, utilizando o programa estatístico SISVAR 5.1 (2001). A valorização individual da matriz nutricional da enzima fitase e da goma de soja, na formulação de ração para frango de corte é uma alternativa para reduzir custos de produção sem afetar o desempenho zootécnico, entretanto ao associar essas matrizes o efeito acumulativo não ocorre. / Abstract: An experiment was carried out at UNESP - Faculty of Engineering - Campus de Ilha Solteira Poultry Sector, with the objective of evaluating the nutritional matrix, recommended by the literature, of phytase enzyme and soybean gum, isolated and associated in diets for broiler chickens. (feed intake, weight gain and feed conversion) in stages 7 to 21, 22 to 35, 36 to 42 and in the total phase of 7 to 42 days of age , and these data are used for economic analysis. A total of 700 birds of the Coob lineage were used (batch sexed - males), the birds were distributed in a completely randomized design, containing 7 treatments and 5 replicates of 20 birds. The data were submitted to analysis of variance and when significant differences were found the mean values were compared by the SNK 5% probability test, using the statistical program SISVAR 5.1 (2001). The individual valorization of the nutritional matrix of the enzyme phytase and soybean gum in the formulation of ration for broiler chickens is an alternative to reduce production costs without affecting the zootechnical performance, however when associating these matrices the cumulative effect does not occur. / Mestre

Arthrospira platensis ou Spirulina é uma microalga com alto valor nutricional. Foram preparados extratos de Spirulina, caracterizados e aplicados como estabilizadores de emulsão de óleo de girassol comercial em água (O/A) (10% v/v) na ausência e na presença de quatro tipos de hidroxipropil metilcelulose (HPMC). Os extratos brutos de Spirulina foram preparados em tampões a pH 6 (EB6) e pH 8 (EB8) por sonicação para promover a lise celular e a libertação de proteínas e fosfolípides; Parte dos extratos foi centrifugada (EC6 ou EC8). Independentemente das condições de extração, todos os extratos apresentados apresentaram valores de potencial-&#950 médio variando de - (16 ± 2) mV a - (20 ± 2) mV, tamanho médio variando de (108 ± 52) nm a (306 ± 68) nm e atividade interfacial. As emulsões O/A preparadas com extratos de Spirulina (10 g / L) exibiram partículas com potencial- médio variando de - (16 ± 2) mV a - (27 ± 4) mV, tamanho médio variando de ~ 70 nm (EB6 ou EB8) a ~ 700 nm (EC6 ou EC8). No entanto, o EB6 levou a emulsões ligeiramente mais estáveis do que as outras. A combinação de EB6 (10 g / L) e HPMC (1,0 % m/m) levou a um aumento substancial na estabilidade da emulsão, embora os valores de potencial- diminuíram uma ordem de grandeza. Em particular, a HPMC com a maior massa molar e o maior grau de substituição de grupos metila conduziu a i) camada interfacial mais robusta resultante da formação de complexos entre cadeias HPMC e proteínas EB6 e (ii) meio contínuo mais viscoso. / Arthrospira platensis or Spirulina is a microalga with a high nutritional value. Extracts of Spirulina were prepared, characterized and applied as oil in water (O/W) (10 % v/v) emulsion stabilizers in the absence and presence of four types of hydroxypropyl methylcellulose (HPMC). The emulsions were prepared with edible sunflower oil. Crude extracts of Spirulina were prepared in buffers at pH 6 (CE6-Crude extract pH6) and pH 8 (CE8-Crude extract pH8) by sonication to promote cell lysis and protein and phospholipids release; part of the extracts was centrifuged (CCE6 or CCE8). Regardless of the extraction conditions, all extracts presented mean -potential ranging from (16 ± 2) mV to (20 ± 2) mV, mean diameter ranging from (108 ± 52) nm to (306 ± 68) nm and interfacial activity. The emulsions prepared with Spirulina extracts (10 g/L) displayed particles with mean -potential ranging from (16 ± 2) mV to (27 ± 4) mV, mean diameter ranging from ~ 70 nm (CCE6 or CCE8) to ~ 700 nm (CE6 or CE8). However, CE6 led to emulsions slightly more stable than the others did. The combination of CE6 (10 g/L) HPMC (1.0 wt %) led to substantial increase in the emulsion stability, although the -potential values decreased one order of magnitude. Particularly, the HPMC with the highest molecular weight and highest methyl substitution degree led to the most (i) robust interfacial layer resulting from the complex formation between HPMC chains and CE6 proteins and (ii) viscous continuous medium.

Oil-in-water emulsions have wide range of applications in food industry because of their structure-forming properties, and as delivery systems of polyunsaturated fatty acids into foods. The thermodynamic instability of oil and water, and high susceptibility of unsaturated fatty acids to oxidation lead to physical and oxidative stability in oil-in-water emulsions. These instability processes are generally controlled by incorporating proteins and polysaccharides into oil-in-water emulsions. The objective of this study was to evaluate xanthan/enzymatically modified guar (XG/EMG) polysaccharides on the physical and oxidative stability of 2 wt% whey protein stabilized oil-in-water emulsions containing 20% v/v menhaden fish oil. Enzymatic modified guar gum was obtained by hydrolyzing native guar gum using α-galactosidase enzyme. Emulsions were prepared for guar gum (GG), xanthan gum (XG), xanthan/guar (XG/GG), and xanthan/enzymemodified guar (XG/EMG) gum mixtures using 0, 0.05, 0.1, 0.15, 0.2, and 0.3% gum concentrations. Emulsions were then evaluated for creaming, viscosity, particle size, and microstructure to evaluate the physical stability, and peroxide value, TBARS value and GC-MS solid phase micro extraction (SPME) experiments were performed to evaluate the oxidative stability. Emulsions containing XG/EMG gum mixtures exhibited better creaming stability and higher viscosity of all the emulsion types. However, XG/EMG gum concentrations did not affect the droplet size of the emulsions. The microstructures revealed decreased flocculation in emulsions with XG/EMG mixtures. The primary and secondary lipid oxidation measurements indicated that emulsions containing XG/EMG gum mixtures were more effective in preventing the lipid oxidation of all the emulsion types. From the results, it is evident that XG/EMG gum mixtures can be used as emulsifiers in oil-in-water emulsions to increase both physical and oxidative stability.

Orientador: Antonio Carlos de Laurentiz / Resumo: O experimento foi conduzido na Universidade Estadual Paulista – UNESP, Faculdade de Engenharia de Ilha Solteira no Setor de Avicultura, com a finalidade de avaliar o efeito da valorização energética da goma de soja na dieta de poedeiras comerciais e verificar a viabilidade econômica de sua utilização como um produto comercial derivado da soja. Foram utilizadas 240 poedeiras da linhagem Lohmann LSL, com 49 semanas, durante um período de 112 dias (quatro ciclo de 28 dias) distribuídas em um delineamento inteiramente casualizado em um esquema fatorial (4x2) sendo esses: quatro níveis de energia metabolizável (2.610, 2.690, 2.770 e 2850 kcal/kg de ração) x dois níveis de inclusão de goma na dieta (0 e 2%), com cinco repetições de seis poedeiras cada. A goma de soja aumentou o consumo de ração, auxiliou no aumento do peso do ovo, da massa do ovo e do tamanho da gema do ovo, melhorou a digestibilidade do Extrato etéreo e da energia da ração. O índice Economic Feed Efficiency apontou melhor retorno econômico com o tratamento de menor nível de energia (2610 kcal/kg) independente da inclusão da goma. / Mestre

Made available in DSpace on 2014-06-11T19:27:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-07Bitstream added on 2014-06-13T19:56:24Z : No. of bitstreams: 1 guerreironeto_ac_me_botfmvz.pdf: 152275 bytes, checksum: 49ac3d6c5fe4ca8819efcb2f7165b21b (MD5) / Universidade Estadual Paulista (UNESP) / Esta pesquisa avaliou a ação de um emulsificante comercial Avilac E em rações com óleo de soja, óleo de vísceras e mistura de ambas em partes iguais na alimentação de frangos de corte. Foram feitos dois experimentos, no experimento 1 foram alojados 720 pintos machos em 24 boxes com 30 aves/box, distribuídos em um delineamento em blocos casualisados com esquema fatorial 3x2, com três fontes de óleo: óleo de soja, óleo de vísceras e mistura de 50% de óleo de soja e 50% de óleo de vísceras; e com e sem adição do emulsificante, totalizando seis tratamentos. Foram avaliados desempenho para os períodos acumulados de 1 a 7, 1 a 14 e 1 a 42 dias de idade para peso corporal, ganho de peso, ganho de peso diário, consumo de ração, conversão alimentar, mortalidade e no último período, fator de produção.Foram avaliados rendimentos de carcaça, partes e gordura abdominal ao abate com 42 dias de idade. Também foram avaliados nesta idade níveis séricos de colesterol, triacilglicerol, HDL colesterol e através de analise do pâncreas a atividade da lipase pancreática. No experimento 2 foram alojados, em uma câmara com controle de temperatura, 72 pintos machos em baterias com 24 gaiolas, com delineamento em blocos casualisados com esquema fatorial 3x2, com três fontes de óleo: com óleo de soja, com óleo de vísceras e com 50% de óleo de soja e 50% de óleo de vísceras; e com e sem adição do emulsificante, totalizando seis tratamentos, com 4 repetições (gaiolas) de 3 aves cada, onde se avaliou a partir do 21º dia, por 3 dias consecutivos, o coeficiente de digestibilidade dos excretas para matéria seca (MS), extrato etéreo (EE), proteína bruta (PB) e fibra bruta (FB). As análises estatísticas dos experimentos 1 e 2 foram feitas pelo método de análise de variância com auxílio do procedimento GLM do programa... / This research evaluated the action of a commercial emulsifier in diets with soy oil, poultry fat and the blend of both sources in equal fraction as fat sources in feeding of broilers. Two experiments were conducted, in experiment 1, 720 male chicks in were housed 24 boxes with 30 chicks/box, in a randomized blocks design with a factorial arrangement 3x2, with three sources of oil: soy oil, poultry fat and the blend of 50% of soy oil and 50% of poultry fat, with emulsifier or not, resulting in six treatments. The performance was estimated for the accumulating periods of 1 to 7, 1 to 14 and 1 to 42 days old for body weight, weight gain, daily weight gain, feed intake, feed conversion ratio and mortality. The carcass yield, parts and abdominal fat were estimated on 42nd day old Blood levels of cholesterol, triacilglicerol, HDL cholesterol and pancreatic analysis of the lipases activity were also estimated on the 42nd day old. In experiment 2; 72 male chicks were housed, in a climatic chamber, in a battery of 24 cages, in a randomized blocks design with a factorial arrangement 3x2, with three sources of oil: soy oil, poultry fat and the blend of 50% of soy oil and 50% of poultry fat; with emulsifier or not, resulting in six treatments, with 4 repetition (cages) with 3 chicks each, the rate of digestibility of excrements for dry matter (MS), ether extract (EE), crude protein (PB) e crude fiber (FB), were estimated on the 21st day old, for 3 consecutives days. The statistical analyses of experiments 1 and 2 were submitted to analysis of variance using the GLM procedure of SAS (1996), and the different means were compared using the Tukey's Test. The performance of the broilers with the use of emulsifier was better for weight...(Complete abstract click electronic access below)