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No description available.

O amido é um polissacarídeo produzido pelos vegetais para reserva de energia e está disponível em abundância na natureza. Os amidos são preparados a partir de diferentes matérias primas, tais como trigo, cevada, milho, arroz, batata, batata doce ou mandioca. Na dieta humana o amido é utilizado como fonte de energia biológica. Na indústria de alimentos, o amido é utilizado para alterar ou controlar diversas características, como textura, aparência, umidade, consistência e estabilidade. Entretanto, há uma contínua procura por novas tecnologias para o desenvolvimento de novas propriedades funcionais para melhor adequação às necessidades do mercado. A radiação ionizante pode ser aplicada na modificação de macromoléculas como a do amido. O presente trabalho teve como objetivo estudar as características de amidos de batata, milho e mandioca (polvilho azedo) tratados com radiação ionizante e os correspondentes filmes comestíveis preparados com eles. Os amidos em pó foram submetidos à radiação em fonte de 60Co Gammacell 220 com doses de 0, 1, 5, 10 e 15 kGy, taxa de dose em torno de 1 kGy h-1. Para o estudo dos amidos foram empregadas técnicas de microscopia, análises térmicas, espectroscopia no infravermelho, difração de raios-X e viscosimetria. Para os filmes foram avaliadas propriedades mecânicas, análise instrumental da cor, capacidade de absorção e índice de solubilidade. Constatou-se que a radiação não influenciou a morfologia dos grânulos, a termogravimetria e o padrão de difração de raios-X. A viscosidade dos hidrogéis dos amidos diminuiu com o aumento da dose de radiação e estes apresentaram características de fluidos não-Newtonianos e pseudoplásticos. Na avaliação instrumental da cor dos filmes houve um ligeiro aumento no parâmetro b*(cor amarela). A força de ruptura dos filmes decresceu conforme aumento da dose de radiação aplicada dependendo do tipo de amido empregado na sua fabricação. A capacidade de absorção em água diminuiu e a solubilidade aumentou com a radiação. / Starch is a polysaccharide produced by plants for energy reserve and is available in abundance in nature. Starches are prepared from different raw materials such as wheat, barley, corn, rice, potatoes, sweet potatoes or cassava. In the human diet starch is used as a source of biological energy. In the food industry, starch is used to change or control various features, such as texture, appearance, moisture, consistency and stability. However, there is a continuous search for new technologies for the development of new functional properties to better adapt to market needs. Ionizing radiation can be applied to macromolecules such as starch modification. This work aimed to study the characteristics of potato, corn and modified manioc (cassava) starches treated with ionizing radiation and the corresponding edible films prepared with them. The starch powder underwent radiation treatment in a 60Co source Gammacell 220 at doses of 0, 1, 5, 10 and 15 kGy with dose rate of approximately 1 kGy h-1. Starches were studied using microscopy techniques, thermal analysis, infrared spectroscopy, X-ray diffraction and viscometry. Films were evaluated by mechanical properties, instrumental color analysis, absorption capacity and water solubility. It was found that the radiation did not influence the morphology of the granules, the thermogravimetry and the diffraction pattern of X-rays. The viscosity of the starches hydrogels in general, decreased with increasing radiation dose, due to the degradation of the starch macromolecules, and it can be say that they presented characteristics as non- Newtonian pseudoplastic fluid. The instrumental evaluation of films color showed that there was a slight increase in parameter b* (yellow). The films of the breaking strength decreased as increasing the radiation dose depending on the type of starch used in its manufacture. The water absorption capacity decreased and solubility increased with radiation.

O amido é um polissacarídeo produzido pelos vegetais para reserva de energia e está disponível em abundância na natureza. Os amidos são preparados a partir de diferentes matérias primas, tais como trigo, cevada, milho, arroz, batata, batata doce ou mandioca. Na dieta humana o amido é utilizado como fonte de energia biológica. Na indústria de alimentos, o amido é utilizado para alterar ou controlar diversas características, como textura, aparência, umidade, consistência e estabilidade. Entretanto, há uma contínua procura por novas tecnologias para o desenvolvimento de novas propriedades funcionais para melhor adequação às necessidades do mercado. A radiação ionizante pode ser aplicada na modificação de macromoléculas como a do amido. O presente trabalho teve como objetivo estudar as características de amidos de batata, milho e mandioca (polvilho azedo) tratados com radiação ionizante e os correspondentes filmes comestíveis preparados com eles. Os amidos em pó foram submetidos à radiação em fonte de 60Co Gammacell 220 com doses de 0, 1, 5, 10 e 15 kGy, taxa de dose em torno de 1 kGy h-1. Para o estudo dos amidos foram empregadas técnicas de microscopia, análises térmicas, espectroscopia no infravermelho, difração de raios-X e viscosimetria. Para os filmes foram avaliadas propriedades mecânicas, análise instrumental da cor, capacidade de absorção e índice de solubilidade. Constatou-se que a radiação não influenciou a morfologia dos grânulos, a termogravimetria e o padrão de difração de raios-X. A viscosidade dos hidrogéis dos amidos diminuiu com o aumento da dose de radiação e estes apresentaram características de fluidos não-Newtonianos e pseudoplásticos. Na avaliação instrumental da cor dos filmes houve um ligeiro aumento no parâmetro b*(cor amarela). A força de ruptura dos filmes decresceu conforme aumento da dose de radiação aplicada dependendo do tipo de amido empregado na sua fabricação. A capacidade de absorção em água diminuiu e a solubilidade aumentou com a radiação. / Starch is a polysaccharide produced by plants for energy reserve and is available in abundance in nature. Starches are prepared from different raw materials such as wheat, barley, corn, rice, potatoes, sweet potatoes or cassava. In the human diet starch is used as a source of biological energy. In the food industry, starch is used to change or control various features, such as texture, appearance, moisture, consistency and stability. However, there is a continuous search for new technologies for the development of new functional properties to better adapt to market needs. Ionizing radiation can be applied to macromolecules such as starch modification. This work aimed to study the characteristics of potato, corn and modified manioc (cassava) starches treated with ionizing radiation and the corresponding edible films prepared with them. The starch powder underwent radiation treatment in a 60Co source Gammacell 220 at doses of 0, 1, 5, 10 and 15 kGy with dose rate of approximately 1 kGy h-1. Starches were studied using microscopy techniques, thermal analysis, infrared spectroscopy, X-ray diffraction and viscometry. Films were evaluated by mechanical properties, instrumental color analysis, absorption capacity and water solubility. It was found that the radiation did not influence the morphology of the granules, the thermogravimetry and the diffraction pattern of X-rays. The viscosity of the starches hydrogels in general, decreased with increasing radiation dose, due to the degradation of the starch macromolecules, and it can be say that they presented characteristics as non- Newtonian pseudoplastic fluid. The instrumental evaluation of films color showed that there was a slight increase in parameter b* (yellow). The films of the breaking strength decreased as increasing the radiation dose depending on the type of starch used in its manufacture. The water absorption capacity decreased and solubility increased with radiation.

Thesis submitted in fulfillment of the requirements for the degree Master of Technology: Chemical Engineering In the Faculty of Engineering At the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2013 / A number of foods, pharmaceutical and industrial products are formulated as emulsions. The immiscibility of oil and water makes emulsions thermodynamically unstable, thus requiring emulsifiers. Natural and synthetic substances have been used as emulsifiers with preference for the former for safety, cost and availability purposes. Bambara groundnut (BGN) is an important source of nutrient in many African communities. Similar to soybean, flaxseed, and other leguminous products, the important blend of high protein and carbohydrate composition of BGN makes it a potential candidate as an emulsifier where, it can serve additional nutritional role in such emulsions. No literature evidence exists to support any earlier study on the potential emulsifying property of BGN. It is therefore of interest to investigate the potential of BGN flour (BGNF) and starch (BGNS) in stabilizing oil-in-water emulsions. The current study aimed to investigate the emulsifying properties of Bambara groundnut flour and starch. A batch of BGN was milled to produce the BGNF. BGNS was extracted from the BGNF. Emulsions were prepared using a wide range of flour-oil-water and starch-oil-water composition as generated through computational modelling. Emulsions were physically observed for stability, and then subjected to various stability studies using the Turbiscan® (which gives kinetic information on the process leading to phase separation; and allows for the detection of two kinds of destabilisation phenomena (particle migration): creaming and sedimentation) and optical microscope (which helps to detect particle size variation or aggregation in order to measure coalescence and/or flocculation). The most stable emulsions (one BGNF-stabilized and the other BGNS-stabilzed) were determined and subjected to same stability studies in the presence of varying physicochemical and physic-mechanical environmental conditions: effects of homogenization speed (9,000 – 21,000 rpm), pH (2 - 10), the presence of salt (2 – 10% w/v NaCl) and vinegar (2 – 10% v/v). Results were expressed in terms of relative stability (using creaming/sedimentation rate) and absolute oil droplet growth (coalescence and flocculation). The emulsifier-oil compositions (emulsifier and water make 100 mL gelatinized mixture before the addition of oil) that gave the most stable emulsions were 9 g BGNF-39 g oil and 5 g BGNS-30 g oil. The two emulsions had only 15% and 30% growth in oil droplet diameter respectively by day 5, compared to over 3000% in the unstable ones. The emulsions were generally observed physically to be stable till day 5 with minimal creaming. Emulsions prepared with BGNS were physically observed to have increasing viscosity with time. There was microbial growth on the emulsions after 3 days. This might have been encouraged because of the rich nutritional composition of BGN. The stability of the emulsions increased significantly (p < 0.05) with the speed of homogenization (up to 15, 000 rpm beyond which the difference in stability was not significant). Compared to control (pH 7), emulsion stability decreased significantly (p < 0.05) with decreasing (up to 16% instability by Day-5 at pH 2) and increasing pH (10% instability at pH 10) with corresponding increase in droplet size. Emulsion stability increased significantly (p < 0.05) with increasing NaCl concentration (35% instability at 2% NaCl compared to 18% instability at 10% NaCl). Stability however decreased sharply with increasing concentration of vinegar (55% instability at 10% vinegar compared to 19% instability at 2% vinegar). The BGNF-stabilized emulsions were more stable (ordinarily and in the presence of the additives) than the BGNS-stabilized ones. Instability values in the BGNS emulsions, in most cases, double those for BGNF. Emulsions were successfully stabilized with BGNF and BGNS. The emulsions were optimal when prepared at a homogenization speed of 15,000 rpm and at neutral pH. The higher the concentration of salt, the more stable the emulsions. Increasing concentration of vinegar however, destabilized the emulsions.

Starch is used in many food applications as thickeners, texturisers and fat substitutes. Native starches, although useful, have low stability to conditions such as high shear, extreme pH and high temperatures encountered during food processing. Starches are modified to make them more suitable for processing conditions. The modification of starch by the use of a naturally occurring compound (for example stearic acid) may produce desirable properties and also removes the risk of a chemical residue in the starch. Starch can be from several grain sources. Teff grain is highly underutilized and underresearched. The work conducted in this project investigates the pasting properties, gelling tendencies, clarity and flow properties (using a rheometer) of teff starch pastes treated with stearic acid, in comparison to maize starch pastes. X-Ray Diffraction (XRD) and Confocal Laser Scanning Microscopy (CLSM) were also used to investigate the possible impact of stearic acid on the structure of the starch granules and pastes. Starch suspensions containing stearic acid (0.25% - 4%) were pasted in a Rapid Visco Analyser using a short pasting cycle of approx. 30 min (held for 5 min at 91°C). Maize starch (treatments) showed a reduced peak viscosity within the holding period, while teff starch (treatments) did not. Teff starch showed increasing viscosity without reaching a peak during the holding time. The pasting cycles were then extended (holding time extended to 2 hr) to investigate the pasting behaviour of teff starch. The extended pasting cycle resulted in a reduced first viscosity peak for maize starch with added stearic acid. Teff starch with added stearic acid showed a large increase in viscosity without the formation of the first viscosity peak. However, both starches displayed a second pasting peak. The addition of stearic acid resulted in an increase in the viscosity of the second pasting peak from about 175 Rapid Visco Units (RVU) to 228 RVU for maize starch, and from 113 RVU to 250 RVU for teff starch. The final viscosity of maize starch increased from 186 RVU to 227 RVU, while that of teff starch increased from 194 RVU to 261 RVU. The second viscosity peak was not observed with waxy maize starch (approx. 97% amylopectin). This suggests that amylose-stearic acid complexation might have been responsible for the formation of this peak. Complexation Index (CI) values increased as the concentration of stearic acid was increased. This further suggests that some interaction between amylose and stearic acid had taken place. The pastes of maize and teff starches modified with stearic acid were more opaque and showed reduced gelling compared to their non-modified counterparts. Maize and teff starches and their stearic acid-treated counterparts followed the Power-Law Model and were shear thinning (n < 1). However, teff starch pastes (control and treatment) seemed to be less shear thinning than their maize starch paste counterparts. An increase in consistency, k, after the extended pasting cycle was used (compared to the short pasting cycle) for the treated starches, reflects the increased viscosities obtained during extended pasting. XRD further suggested that amylose-lipid complexes may have been present in the starch pastes (after extended pasting) due to the occurrence of the 4.4 Å and 12 Å peaks (characteristic of V-type starches). CLSM showed that stearic acid diffused into maize starch granules but not into teff starch granules. This was probably due to the pores of the surfaces of maize starch granules which may have facilitated the diffusion process. In contrast, teff starch granules do not have pores on their surfaces. This structural difference may be attributed for the pasting differences between teff and maize starches. The effects of stearic acid on the pasting (effect on first and second peaks and final viscosity), and functional properties (reduced gelling and increased opacity of pastes) of maize and teff starches have been attributed to the formation of amylose-lipid complexes. These high viscosity and low gelling starches may be extremely useful as fat replacers. Teff starch has the added benefit of its small starch granules which may add to its ability mimic the mouthfeel of fat globules. / Dissertation (MSc)--University of Pretoria, 2011. / Food Science / unrestricted

<p>The papermaking industry uses a large amount of starch each year, both as a wet-end additive and as a rheological modifier in surface sizing and coating colors. It is important to be able to reduce the amount of chemicals used in the papermaking and surface treatment process, to reduce costs and to make the process even more efficient. Interest in new high-performance starches is great. By using these new types of starches, improved recycling of barrier products may be obtained as well as a reduction in the use of synthetic sizing agents. The objectives of this work were to understand the behavior of temperature-responsive hydrophobically modified starches, where the solubility in water simply can be adjusted by temperature or by polymer charge, to improve the barrier properties, like the water vapor permeability, mechanical properties and water resistance (Cobb and contact angle) of papers surface sized by starch-containing solutions, and to investigate the potential for industrial use of these temperature-responsive starches. It was demonstrated that the temperature-responsive starches phase separate upon cooling and, depending on the charge density of the starch, a particulate precipitation or a gel-like structure was obtained. The starch with zero net charge showed a larger increase in turbidity than the starch with a cationic net charge, indicating that particulate precipitation is favored by a zero net charge and that the formation of a gel network is favored by charged starch molecules. Further, the starches formed inclusion complexes with surfactants, giving stabilization to the starches in the presence of surfactants. The net charge density of the starch and the charge of the surfactant determined whether or not an inclusion complex would form between them. Important mechanisms for the stability of the starch seemed to be formation of mixed micellar-like structures between the hydrophobic chain of the starch and the surfactant along the starch backbone in addition to formation of inclusion complexes between the starch and the surfactant. The hydrophobically modified starches showed higher hydrophobic surface character when applied to the paper surface above the critical phase separation temperature than with application at room temperature. Free films of the temperature-responsive starches showed good barrier against oxygen, but no barrier against water vapor. The mechanical properties decreased with addition of glycerol to the films.</p>

Atualmente, muitas pesquisas são realizadas com o objetivo de desenvolver novas formulações, sejam elas cosméticas ou farmacêuticas baseadas em nanocarreadores. Devido às suas características favoráveis, nanopartículas poliméricas são propostas como veículos tópicos, principalmente para fotoprotetores, com o intuito de prolongar o tempo de resistência dos filtros na pele, evitando assim o processo de fotodegradação. Filtros solares, de uma maneira geral, são formas cosméticas emulsionadas as quais são termodinamicamente instáveis. Para evitar este processo é necessário um componente capaz de manter esta estabilidade, isto é, um tensoativo. Em alguns sistemas, polissacarídeos ou proteínas atuam como tensoativos/estabilizantes em emulsões óleo/água (O/A). Neste contexto, a proposta deste trabalho é introduzir amidos modificados (catiônicos e aniônicos) e hidrolisados como tensoativo em uma formulação para a encapsulação da benzofenona-3 com uma matriz polimérica de poli(?-caprolactona) (PCL), avaliando a influência deste estabilizante nas características físico-químicas das nanopartículas. As nanopartículas foram preparadas mediante a técnica de deposição interfacial do polímero pré-formado, empregando-se um planejamento de experimentos de mistura. Previamente, foram avaliadas as condições da hidrólise enzimática, via planejamento de experimentos, para verificar quais parâmetros (tempo e concentração da enzima) maximizariam este processo reduzindo de maneira satisfatória a massa molar do amido para posterior aplicação como estabilizante. Foram realizados testes de tensão para avaliar a capacidade tensoativa das soluções aquosas dos amidos hidrolisados, para posterior aplicação na formulação de nanopartículas. Os resultados indicaram que dois lotes de amido, de quatro avaliados, podem ser empregados como tensoativos na formulação de nanopartículas, sem alterar significativamente propriedades, como diâmetro, polidispersão e teor de encapsulação. / Currently, many researches are conducted with the aim of developing new formulations, whether cosmetic or pharmaceutical-based nanocarriers. Due to its favorable characteristics, polymeric nanoparticles are proposed as topics vehicles, mainly for sunscreens, in order to prolong the resistance of the filters on the skin, thus preventing the photodegradation process. Sunscreens, in general, are emulsified cosmetic forms which are thermodynamically unstable. To avoid this process requires a component capable of maintaining this stability, i.e., a surfactant. In some systems, polysaccharides or proteins act as surfactants/stabilizers in oil-water emulsions (O/W). In this context, the purpose of this work is to introduce modified starches (cationic and anionic) and hydrolyzed as surfactant in a formulation for the encapsulation of benzophenone-3 with a polymer matrix of poly(?-caprolactone) (PCL), evaluating the influence of this stabilizer the physical-chemical characteristics of nanoparticles. The nanoparticles were prepared by interfacial deposition pre-formed polymer technique, using a design of experiments like mixture. Previously evaluated the conditions of enzymatic hydrolysis, by design of experiments to determine which parameters (time and enzyme concentration) to maximize this process satisfactorily reducing the molecular weight of the starch for subsequent use as a stabilizer. Tension tests were conducted to assess the ability of surfactant aqueous solutions of hydrolyzed starch for application in the formulation of nanoparticles. The results indicated that two batches of starch, four-valued, can be employed as a surfactant in the suspension of nanoparticles, without significantly altering properties such as diameter, polydispersity and the content of encapsulation.

Atualmente, muitas pesquisas são realizadas com o objetivo de desenvolver novas formulações, sejam elas cosméticas ou farmacêuticas baseadas em nanocarreadores. Devido às suas características favoráveis, nanopartículas poliméricas são propostas como veículos tópicos, principalmente para fotoprotetores, com o intuito de prolongar o tempo de resistência dos filtros na pele, evitando assim o processo de fotodegradação. Filtros solares, de uma maneira geral, são formas cosméticas emulsionadas as quais são termodinamicamente instáveis. Para evitar este processo é necessário um componente capaz de manter esta estabilidade, isto é, um tensoativo. Em alguns sistemas, polissacarídeos ou proteínas atuam como tensoativos/estabilizantes em emulsões óleo/água (O/A). Neste contexto, a proposta deste trabalho é introduzir amidos modificados (catiônicos e aniônicos) e hidrolisados como tensoativo em uma formulação para a encapsulação da benzofenona-3 com uma matriz polimérica de poli(?-caprolactona) (PCL), avaliando a influência deste estabilizante nas características físico-químicas das nanopartículas. As nanopartículas foram preparadas mediante a técnica de deposição interfacial do polímero pré-formado, empregando-se um planejamento de experimentos de mistura. Previamente, foram avaliadas as condições da hidrólise enzimática, via planejamento de experimentos, para verificar quais parâmetros (tempo e concentração da enzima) maximizariam este processo reduzindo de maneira satisfatória a massa molar do amido para posterior aplicação como estabilizante. Foram realizados testes de tensão para avaliar a capacidade tensoativa das soluções aquosas dos amidos hidrolisados, para posterior aplicação na formulação de nanopartículas. Os resultados indicaram que dois lotes de amido, de quatro avaliados, podem ser empregados como tensoativos na formulação de nanopartículas, sem alterar significativamente propriedades, como diâmetro, polidispersão e teor de encapsulação. / Currently, many researches are conducted with the aim of developing new formulations, whether cosmetic or pharmaceutical-based nanocarriers. Due to its favorable characteristics, polymeric nanoparticles are proposed as topics vehicles, mainly for sunscreens, in order to prolong the resistance of the filters on the skin, thus preventing the photodegradation process. Sunscreens, in general, are emulsified cosmetic forms which are thermodynamically unstable. To avoid this process requires a component capable of maintaining this stability, i.e., a surfactant. In some systems, polysaccharides or proteins act as surfactants/stabilizers in oil-water emulsions (O/W). In this context, the purpose of this work is to introduce modified starches (cationic and anionic) and hydrolyzed as surfactant in a formulation for the encapsulation of benzophenone-3 with a polymer matrix of poly(?-caprolactone) (PCL), evaluating the influence of this stabilizer the physical-chemical characteristics of nanoparticles. The nanoparticles were prepared by interfacial deposition pre-formed polymer technique, using a design of experiments like mixture. Previously evaluated the conditions of enzymatic hydrolysis, by design of experiments to determine which parameters (time and enzyme concentration) to maximize this process satisfactorily reducing the molecular weight of the starch for subsequent use as a stabilizer. Tension tests were conducted to assess the ability of surfactant aqueous solutions of hydrolyzed starch for application in the formulation of nanoparticles. The results indicated that two batches of starch, four-valued, can be employed as a surfactant in the suspension of nanoparticles, without significantly altering properties such as diameter, polydispersity and the content of encapsulation.