Compositional and analytical factors affecting the stickiness of dairy powders

Spray dying is a dehydration technique used in the dairy industry for the preservation and creation of a wide range of valuable dairy products. However, challenges associated with stickiness development are often encountered during spray drying, particularly with spray dryer feed streams containing high levels of lactose, which can lead to lower yields, reduced powder quality and shorter runs. Stickiness in lactose-containing powders is related to the glass transition phenomenon, in which a phase change occurs in the amorphous form of lactose, causing a decrease in the viscosity of the powder particle surface, leading to liquid bridging and ultimately stickiness between particles and/or to equipment surfaces. There is a wide variety of compositional and environmental factors that affect the rate and extent of stickiness development in dairy powders, such as the temperature and relative humidity of the air or the protein content of the powder. The first objective of this study was to investigate the influence of particle size on the physicochemical properties and stickiness behaviour of a selection of lactose-containing dairy powders. Using a fluidisation technique, this work demonstrated that stickiness increased with decreasing particle size for lactose-containing dairy powders. Stickiness may be characterised using a number of different instrumental approaches, which can be categorised as direct/indirect or static/dynamic techniques. However, most methods provide a binary definition of stickiness (i.e., sticky or non-sticky), which while pragmatic, does not provide information regarding the mechanical relaxations which contribute to stickiness. Therefore, the second objective of this study was to examine the use of dynamic mechanical analysis (DMA) to characterise temperature- and humidity-induced relaxation behaviour of whey protein concentrate (WPC) powders; results were also compared to two other established techniques, differential scanning calorimetry (DSC) and a fluidisation method. The results demonstrated that while DMA may not be an accurate method for stickiness determination, it could prove useful as a complementary method when combined with stickiness techniques (e.g., fluidisation) to provide more detailed information on the physical changes occurring during stickiness. Overall, the findings of this research will prove useful to dairy processors at minimising issues with stickiness during drying and may also potentially provide powder technologists with a new method for tracking the physical transitions that occur during stickiness development of dairy powders

Leite sem lactose como agente encapsulante de probiótico pelo método de spray drying e seu comportamento em processos de crioconcentração

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Alimentos, Florianópolis, 2021.Estima-se que o quadro de intolerância à lactose (seja ela temporária ou permanente) aflige parte considerável da população mundial. Os números relatados na literatura variam entre 65 e 75%. Buscando criar alternativas para essa demanda, assim como simplesmente oferecer novas possibilidades para quem não deseja consumir lactose, este trabalho investigou o potencial do leite sem lactose em tecnologias emergentes e inovadoras. Nesse sentido, o trabalho experimental foi desenvolvido em três grandes etapas: Primeiramente, leite desnatado sem lactose foi utilizado como matriz de encapsulação de uma bactéria probiótica (Bifidobacterium BB-12). Não somente o leite, como também carboidratos prebióticos (oligofrutose e inulina) foram empregados no processo de microencapsulação por spray drying. Os pós obtidos foram sujeitos às análises de rendimento de encapsulação, viabilidade microbiana durante armazenamento (temperatura de refrigeração e temperatura ambiente), e sobrevivência do probiótico durante passagem pelo sistema gastrointestinal. Num segundo momento, os pós também foram caracterizados quanto às suas propriedades físico-químicas. Para isso, extensas avaliações foram feitas, dentre elas: estudo da cor; determinação da umidade, atividade de água e densidade; investigação das propriedades de sorção de água; análises térmicas; e morfologia dos pós. O maior rendimento de encapsulação (88,01%) e a maior viabilidade de bifidobactérias durante 120 dias de armazenamento a 25 °C foram observados para o pó oriundo de leite sem lactose com inulina. Por outro lado, o pó constituído de leite sem lactose e oligofrutose foi o que apresentou melhor sobrevivência do probiótico após passar por condições gastrointestinais simuladas in vitro. Do mesmo modo, ao avaliar todas as propriedades físico-químicas dos pós, foi observado que as formulações que continham os prebióticos foram as que resultaram em características mais desejáveis de estabilidade térmica, umidade e atividade de água. Contudo, não concluiu-se que o pó constituído unicamente de leite sem lactose tenha apresentado propriedades insatisfatórias e/ou inaceitáveis. Por exemplo, sob temperaturas de refrigeração, estabilidade microbiana também foi alcançada por 120 dias de estocagem. Igualmente, ao avaliar as propriedades térmicas, constatou-se que este pó foi estável até ~130 ºC. Em relação à sorção de água, suas características foram semelhantes às do pó obtido de leite com inulina; ou seja, condições de umidade relativa acima de 33% não são indicadas para manter a estabilidade físico-química desses pós ao longo do armazenamento. Foi por causa desse conjunto de informações que o pó probiótico à base de leite sem lactose foi escolhido (assim como os demais) para ser estudado na segunda parte desta tese: aplicação dessas micropartículas em um produto lácteo sem lactose. Este produto foi desenvolvido de forma a obter um leite fermentado tipo skyr, que é um alimento típico da Islândia. Se trata de um leite fermentado concentrado e que portanto, apresenta alto teor de proteína e quantidade desprezível de gordura. Assim, foram preparadas quatro formulações de leite fermentado concentrado: três delas contendo cada pó probiótico, e uma formulação contendo a bifidobacteria no estado livre (denominada amostra controle). Como já esperado, a inserção dos pós no leite fermentado modificou algumas propriedades, como o pH, acidez, e firmeza. Por causa dessas características, os produtos adicionados dos pós probióticos foram relatados como as melhores formulações para o desenvolvimento de um novo iogurte probiótico concentrado sem lactose. A terceira e última parte trabalhada nesta tese foi o emprego da crioconcentração no leite desnatado sem lactose. Foi uma etapa realizada em parceria com a Universitat Politècnica de Catalunya (Espanha). Investigou-se a crioconcentração do leite utilizando duas técnicas em conjunto: crioconcentração progressiva como sendo um primeiro estágio do processo, e crioconcentração em bloco assistida por vácuo como sendo o segundo estágio. A condição otimizada para o primeiro estágio foi encontrada utilizando uma temperatura do líquido refrigerante a ? 5 ºC, agitação mecânica de 1035 rpm, e tempo de ensaio de 58 min. Escolhida essa condição (na qual têm-se como produtos as frações gelo e concentrado), o segundo estágio foi aplicado no gelo. Assim, a fração concentrada obtida ao final de todo o processo continha teores de 6.7 g 100 g?1 e 10.24 g 100 g?1 de proteína e carboidrato, respectivamente. Finalmente, acredita-se que este trabalho é inovador quanto à principal matéria-prima (leite sem lactose), e quanto à utilização desta matéria-prima em processos de microencapsulação e crioconcentração. O leite é um alimento rico e de alto valor nutritivo; assim, o constante estudo desse alimento auxilia na criação de produtos inovadores e que atendam às demandas/exigências da sociedade.Abstract: It is estimated that lactose intolerance (whether temporary or permanent) afflicts a considerable part of the world population. The numbers reported in the literature vary between 65 and 75%. Seeking to create alternatives for this demand, as well as simply offering new possibilities for those who do not wish to consume lactose, this work investigated the potential of lactose-free milk in emerging and innovative technologies. In this sense, the experimental work was carried out in three major steps: First, lactose-free skimmed milk was used as an encapsulation matrix for a probiotic bacteria (Bifidobacterium BB-12). Not only milk, but also prebiotic carbohydrates (oligofructose and inulin) were used in the microencapsulation process by spray drying. The powders obtained were subjected to analyzes of encapsulation yield, microbial viability during storage (refrigeration temperature and room temperature), and probiotic survival during passage through the gastrointestinal system. In a second moment, the powders were also characterized in terms of their physicochemical properties. For this, extensive evaluations were made, including: study of color; determination of moisture, water activity and density; investigation of water sorption properties; thermal analysis; and morphology of the powders. The highest encapsulation yield (88.01%) and the highest viability of bifidobacteria during 120 days of storage at 25 °C were observed for the powder from lactose-free milk and inulin. On the other hand, the powder consisting of lactose-free milk and oligofructose showed the best survival of the probiotic after undergoing in vitro simulated gastrointestinal conditions. Likewise, when evaluating all the physicochemical properties of the powders, it was observed that the formulations containing the prebiotics were the ones that resulted in the most desirable characteristics of thermal stability, moisture and water activity. However, it was not concluded that the powder consisting only of lactose-free milk had unsatisfactory and/or unacceptable properties. For example, under refrigeration temperatures, microbial stability was also achieved for 120 days of storage. Also, when evaluating the thermal properties, it was found that this powder was stable up to ~130 °C. Regarding water sorption, its characteristics were similar to those of powder obtained from milk and inulin; that is, relative humidity conditions above 33% are not indicated to maintain the physicochemical stability of these powders throughout storage. Because of this set of information, the probiotic powder based on lactose-free milk was chosen (as well as the others) to be studied in the second part of this thesis: application of these microparticles in a lactose-free dairy product. This product was developed in order to obtain a Skyr-style fermented milk, which is a typical food from Iceland. It is a concentrated fermented milk and therefore has a high protein content and is fat-free. Thus, four concentrated fermented milk formulations were prepared: three of them containing each probiotic powder, and a formulation containing bifidobacteria in the free state (called control sample). As expected, the inclusion of powders in fermented milk changed some properties, such as pH, acidity, and firmness. Because of these characteristics, the products added of the probiotic powders were reported as the best formulations for the development of a new lactose-free concentrated probiotic yogurt. The third and last part worked in this thesis was the use of freeze concentration in lactose-free skimmed milk. It was a stage carried out in partnership with the Universitat Politècnica de Catalunya (Spain). Milk freeze concentration was investigated using two techniques together: progressive freeze concentration as the first stage of the process, and vacuum-assisted block freeze concentration as the second stage. The optimized condition for the first stage was found using a coolant temperature at ?5 °C, mechanical agitation of 1035 rpm, and an assay time of 58 min. After choosing this condition (in which the ice and concentrate fractions are the products), the second stage was applied to ice. Thus, the concentrated fraction obtained at the end of the entire process had contents of 6.7 g 100 g?1 and 10.24 g 100 g?1 of protein and carbohydrate, respectively. Finally, it is believed that this work is innovative in terms of the main raw material (lactose-free milk), and in terms of the use of this raw material in microencapsulation and freeze concentration processes. Milk is a rich food with high nutritional value; thus, the constant study of this food helps in the creation of innovative products that meet the demands/requirements of society

Influence of calcium chelation and enzymatic modification of protein on the hydration characteristics of high protein dairy powders

Milk protein concentrate (MPC) powders have numerous commercial applications and are integral ingredients in high quality functional dairy products and beverages. However, such high protein dairy powders pose significant technical challenges during processing and rehydration, due to high viscosity and poor powder particle dissolution, respectively. Previous work has shown that the use of calcium chelating salts is effective in improving dissolution of MPC powders; however, the use of such salts results in considerable increases in viscosity and reduction in casein micelle integrity. The objective of this research was to investigate the impact of depleting calcium in micellar casein systems after either enzymatic dephosphorylation or enzymatic crosslinking and to examine viscosity, particle size; ζ-potential and colour of the protein solutions and subsequent rehydration properties of these spray dried systems. Calcium depletion was achieved through either addition of a chelating salt (sodium hexametaphosphate; SHMP) or through ion exchange. MPC dispersions containing enzymatically dephosphorylated casein proteins exhibited lower viscosity than phosphorylated MPC dispersions; however, the former resulted in a loss of casein micelle integrity in the presence of SHMP. Phosphate nuclear magnetic resonance spectroscopy proved useful for quantifying the depletion of calcium phosphate from casein micelles and confirmed dephosphorylation. Enzymatic crosslinking of casein proteins using transglutaminase helped maintain a lower solution viscosity after calcium chelation by SHMP, and the resultant dispersions retained a higher degree of casein micelle integrity compared to non-crosslinked MPC dispersions. Co-dried crosslinked casein and SHMP powders had improved rehydration properties. As an alternative to the addition of calcium chelating salts, a strong cation exchange resin was investigated for its ability to deplete calcium to varying extents in the production of novel MPC powders with improved dissolution properties at low levels of calcium depletion. However, similar to with direct use of calcium chelating salts, concomitant increases in viscosity and decreases in micelle integrity were observed in MPC dispersions, with the effects increasing with extent of calcium removal. Solubility and dissolution properties of calcium depleted MPC powders exhibited improved rehydration ability and caused a shift in their heat stability towards lower pH values. MPC dispersions containing crosslinked proteins were observed to be more resistant to calcium depletion compared to their respective control samples. MPC dispersions containing crosslinked MPC proteins retained greater micelle integrity; however, extensive calcium reduction resulted in significantly higher viscosity than corresponding controls. This thesis provides new insights into the functionality of novel MPC powders generated using enzymatic modification of casein and chemical modification of the calcium content and distribution between colloidal and serum phases, resulting in MPC powders with enhanced functionality. The outcomes of this research have application in the formulation of MPC powders with improved dissolution properties and reduced viscosity

Synthesis of magnetic sorbents modifie with moringa oleifera extracts for the removals of environmental orgamnic pollutants

A Masters dissertation submitted to the Faculty of Science, University of the Witwatersrand in fulfillment of the requirements of the degree of Master of Science, January 2018Modern developments on nanoparticles (NPs) has led to new innovation in nanoparticles that can be used for the treatment of polluted water. Magnetic NPs are of great interest because of their unique properties and promising applications. Their stability is essential to prevent them from agglomeration, hence, modification with a specific coating layer can assist in the selectivity function and stability of the magnetic NPs. In this work, a magnetic organic nano-adsorbent was synthesized and investigated for the application in the extraction of nitroaromatic explosive compounds from aqueous solutions. The approach was to find a possible synergy between the adsorptive properties of Moringa oleifera and the high surface area of the NPs. The magnetic NPs were utilized for their ferromagnetic properties which assist in the extraction procedure. M. oleifera was used as a natural coating agent to functionalize the magnetic NPs and also to provide stability. There are numerous chemical procedures to synthesize magnetite and one of the simplest and convenient procedures, co-precipitation, was used in this study. Magnetite can be easily oxidized under ambient conditions, hence, in order to prevent oxidation, M. oleifera extracts were used as a coating agent. The synthesized uncoated magnetite NPs and M. oleifera coated magnetite NPs were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), Brunauer, Emmett and Teller (BET) and thermogravimetric analysis (TGA). The M. oleifera leaf extract was obtained using pressurized hot water extraction (PHWE) at 80°C and the seed extract was purchased as a pure oil. Both the M. oleifera leaf and seed extracts were characterized by FTIR and gas chromatography–mass spectrometry (GC-MS) for possible organic compounds assisting in the stability of the magnetite. From the BET results of the coated magnetic NPs at different times, it was observed that with increasing coating time, the surface area decreased while the pore size increased. To optimize the extraction of nitroaromatic explosive compounds (NAECs), the parameters that were investigated were sample pH, contact time, mass of adsorbent and initial concentration. The optimum value for pH of the sample was found at pH8 and for the contact time an optimum of 120 min was found. The mass of M. oleifera coated magnetic NPs for the maximum removal of explosives were found to be 100 mg. The adsorption capacity of the NAECs was obtained in the range of 0.45 and 0.76 mg g-1 at optimum conditions. During kinetic studies it was observed that the pseudo second order model explained the extent of the adsorption mechanism. It was observed that the Langmuir model was favourable as compared to the Freundlich model. The order of selectivity for the NAECs studied was observed as follows: 2-NT ≈ 3-NT > 4NT > NB > 2,6-DNT > 1,3-DNB. The limit of detection (LOD) found was 0.37 – 4.47 and 0.45 – 5.66 ng.mL-1 for extraction using magnetic NPs coated with M. oleifera leaf and seed extract, respectively. The percentage recovery for the extraction of NAECs at optimum conditions was obtained in the range 14 – 46%.XL201

ENCAPSULATION OF FOLIC ACID IN MESOPOROUS SILICA SUPPORTS: A NUTRITIONAL AND TECHNOLOGICAL APPROACH

Tesis por compendio[EN] The present PhD thesis, entitled "Encapsulation of folic acid in silica porous supports: a nutritional and technological approach", focuses on the development of new smart systems for the controlled delivery of folic acid for nutritional applications. The first part of the thesis shows folic acid encapsulation in polyamines-functionalized silica porous matrices from a nutritional approach. The first part evaluates not only the influence of the loading method and the type of silica support employed (MCM-41, SBA-15, UVM-7 and Hollow Silica) on the efficacy of folic acid encapsulation, but also the influence of the morphology and porous system on the folic acid delivery profile from different supports. Folic acid release studies from different supports with various pH values have demonstrated that the designed systems are capable of smartly modulating the delivery of the folic acid dependent on the pH of the medium (inhibition of the release at an acidic pH -stomach-, controlled release at a neutral pH -intestine-). This capacity makes these developed delivery systems an excellent alternative to direct fortification to successfully modulate the bioaccessibility of folic acid along the gastrointestinal tract. The stability of the supports during an in vitro digestive process was evaluated, and demonstrated that not only small particles can be attacked during the digestion process, but also the functionalization with organic molecules, which act as molecular gates, prevents this attack. Finally, the cell viability studies carried out with four different cell lines revealed that neither the supports nor their degradation products caused any specific toxicity during the in vitro digestive process. The second part evaluates the influence of adding different silica supports to two food matrices: gelatin gels and yoghurts. This technological approach enabled us to know that the capacity of these smart systems to deliver folic acid in a controlled manner during an in vitro digestive process is mantained even after their incorporation in stirred yoghurt. The effect of the matrices on the gel's physical properties depends on the particle size, functionalization and concentration. Finally, this thesis tested that the optimization of folic acid loading, achieved in the first part of the thesis, allowed the fortification of yoghurt with 100% of the recommended daily allowance of folic acid with a very low amount of the system. This fortification affected neither the physico-chemical properties of the yoghurt, nor bacterial viability. In summary, it was concluded that the present thesis globally deals with folic acid encapsulation in silica porous matrices to be used in nutritional and food applications, which include the optimization of loading, release studies at diferent pH, in vitro digestions, stability studies of the employed matrixes, biocompatibility studies, and studies into the influence of their addition to food matrixes. The obtained results positively exhibit that the developed smart folic acid delivery systems open up a new way of fortifying food without endangering the properties of the food to which they are added.[ES] La presente tesis doctoral que lleva por título "Encapsulación de ácido fólico en soportes porosos de óxido de silicio: una aproximación nutricional y tecnológica" está centrada en el desarrollo de nuevos sistemas inteligentes de liberación controlada de ácido fólico para aplicaciones nutricionales. La primera parte de la tesis muestra la encapsulación de ácido fólico en matrices porosas de óxido de silicio funcionalizadas con poliaminas desde una aproximación nutricional. En ella se ha evaluado la influencia del método de cargado y del tipo de soporte de óxido de silicio utilizado (MCM-41, SBA-15, UVM-7 y Hollow Silica) en la eficacia de encapsulación de ácido fólico. En esta primera parte, también se ha evaluado la influencia de la morfología y el sistema de poros de los diferentes soportes en el perfil de liberación del ácido fólico desde los mismos. Los estudios de liberación de ácido fólico desde los diferentes soportes a diferentes valores de pH han demostrado que los sistemas diseñados son capaces de modular inteligentemente la liberación de ácido fólico en función del pH del medio (inhibición de la liberación a pH ácido -estómago-, liberación controlada a pH neutro -intestino-). Esta capacidad convierte a los sistemas liberación desarrollados en una alternativa excelente a la fortificación directa para modular exitosamente la bioaccesibilidad del ácido fólico a lo largo del tracto gastrointestinal. Por otra parte, se ha evaluado la estabilidad de los soportes durante un proceso de digestión in vitro, demostrando que si bien algunos soportes pueden ser atacados durante la digestión, la funcionalización con moléculas que actúan como puertas moleculares previene este ataque. Por último, los estudios de viabilidad celular llevados a cabo en cuatro tipos de líneas celulares demuestran que ni los soportes, ni los productos de degradación de los mismos durante el proceso de digestión in vitro promueven ningún tipo de toxicidad inespecífica. En la segunda parte se ha evaluado la influencia de la adición de diferentes soportes de óxido de silicio a dos matrices alimentarias, geles de gelatina y yogures. Esta aproximación tecnológica ha permitido conocer que la capacidad de estos sistemas inteligentes para liberar controladamente el ácido fólico a lo largo de un proceso de digestión in vitro se mantiene incluso tras su incorporación en yogures batidos. Por otra parte, se ha comprobado que el efecto de las matrices sobre las propiedades físicas de los geles, es dependiente tanto del tamaño de las partículas, como de su funcionalización y concentración. Por último, se ha comprobado que debido a la optimización del cargado de ácido fólico alcanzada en la primera parte de la tesis, se puede lograr una fortificación de un yogur con el 100% de la cantidad diaria recomendada de ácido fólico con una cantidad tan pequeña de sistema que ni las propiedades físico-químicas de un yogur, ni la viabilidad bacteriana se ven comprometidas. En resumen, se puede concluir que la presente tesis ha abordado de una manera global la encapsulación de ácido fólico en matrices porosas de óxido de silicio para ser utilizados en aplicaciones nutricionales y alimentarias incluyendo estudios de optimización de cargado, estudios de liberación en función del pH, digestiones in vitro, estudios de estabilidad de las matrices utilizadas, estudios de biocompatibilidad, así como estudios de la influencia de la adición de estos sistemas inteligentes en matrices alimentarias. Los resultados obtenidos han puesto de manifiesto que los sistemas inteligentes de liberación de ácido fólico desarrollados abren la puerta a una nueva manera de fortificar los alimentos sin comprometer sus características.[CA] La present tesi doctoral, que porta per títol "Encapsulació d'àcid fòlic en suports porosos d'òxid de silici: una aproximació nutricional i tecnològica" està centrada en el desenvolupament de nous sistemes intel·ligents de lliberació controlada d'àcid fòlic per a aplicacions nutricionals. La primera part de la tesi mostra l'encapsulació d'àcid fòlic en matrius poroses d'òxid de silici funcionalitzades amb poliamines des d'una aproximació nutricional. En esta part, s'ha avaluat la influència del mètode de carrega i del tipus de suport d'òxid de silici que s'ha emprat (MCM-41, SBA-15, UVM-7 i Hollow Silica) en l'eficàcia de l'encapsulació d'àcid fòlic. En esta primera part, també s'ha avaluat la influència de la morfologia i el sistema de porus dels diferents suports en el perfil d'alliberament de l'àcid fòlic des dels mateixos. Els estudis d'alliberament d'àcid fòlic des dels diferents suports a diferents valors de pH han demostrat que els sistemes dissenyats són capaços de modular intel¿ligentment l'alliberament d'àcid fòlic en funció del pH del medi (inhibició de l'alliberament a pH àcid -estómac-, alliberament controlat a pH neutre -intestí-). Esta capacitat fa dels sistemes desenvolupats una excel·lent alternativa a la fortificació directa per a modular amb èxit la bioaccessibilitat de l'àcid fòlic a través del tracte gastrointestinal. D'altra banda, s'ha avaluat l'estabilitat dels suports en un procés de digestió in vitro, demostrant que mentre que les partícules menudes poden ser atacades durant la digestió, la funcionalització amb molècules orgàniques que actuen com a portes moleculars prevé aquest atac. Per últim, els estudis de viabilitat cel·llular duts a terme en quatre tipus de línies cel·lulars demostren que ni els soports, ni els productes de degradació dels mateixos durant el procés de digestió in vitro promouen cap tipus de toxicitat inespecífica. En la segona part, s'ha avaluat la influència de l'addició de diferents sopors d'òxid de silici a dos matrius alimentàries, gels de gelatina i iogurts. Esta aproximació tecnològica ha permés conéixer que la capacitat d'aquests sistemes intel·ligents per alliberar controladament àcid fòlic durant un procés de digestió in vitro es manté fins i tot després de ser incorporats en iogurts batuts. D'altra banda, s'ha comprovat que l'efecte de les matrius sobre les propietats físiques dels gels, és dependent tant de la grandària de les partícules, com de la seua funcionalització i concentració. Per últim, s'ha comprovat que a causa de l'optimització del carregat d'acid fòlic alcançada en la primera part de la tesi, es pot aconseguir una fortificació d'un iogurt amb el 100% de la quantitat diària recomanada d'àcid fòlic amb una quantitat tan baixa del sistema que ni les propietats físico-químiques d'un iogurt, ni la viabilitat bacteriana se'n veuen compromeses. En resum, es pot concluir que en la present tesi s'ha abordat d'una manera global l'encapsulació d'àcid fòlic en matrius poroses d'òxid de silici per a ser utilitzades en aplicacions nutricionals i alimentàries, que inclouen estudis d'optimització de carregat, estudis d'alliberament en funció del pH, digestions in vitro, estudis d'estabilitat de les matrius utilitzades, estudis de biocompatibilitat, així com estudis de la influència de l'addició d'aquests sistemes en matrius alimentàries. Els resultats obtesos han posat de manifest de forma positiva que els sistemes intel·ligents d'àcid fòlic que s'han desenvolupat obrin una porta a una nova manera de fortificar els aliments sense comprometre les seues caracterísitiques.Pérez Esteve, E. (2015). ENCAPSULATION OF FOLIC ACID IN MESOPOROUS SILICA SUPPORTS: A NUTRITIONAL AND TECHNOLOGICAL APPROACH [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58613TESISPremios Extraordinarios de tesis doctoralesCompendi

Mejoras tecnológicas para el aumento de la funcionalidad de antioxidantes y probióticos. Contribución a la sostenibilidad de la industria agroalimentaria

Tesis por compendio[ES] En el sistema actual de producción intensiva de alimentos surge la necesidad de considerar la sostenibilidad de las industrias agroalimentarias. En esta tesis se estudia la forma en que algunas tecnologías contribuyen a la mejora de la funcionalidad de alimentos con alto contenido en antioxidantes y probióticos. El tema se aborda desde dos enfoques: por un lado, la aplicación de las tecnologías existentes para la mejora de la funcionalidad de los alimentos, ya sea mediante la incorporación de ingredientes o bien a partir de la formación de estructuras; y, por otro lado, el aprovechamiento de fuentes alternativas de ingredientes alimentarios con elevado contenido en compuestos bioactivos. Las tecnologías estudiadas en esta tesis han sido el tratamiento con altas presiones de homogeneización (HPH), la encapsulación mediante HPH, la impregnación a vacío (IV) y el secado por aire caliente. Se estudió el efecto combinado de la aplicación de HPH (20, 50, 100 y 150 MPa) y la adición de trehalosa (10, 20 y 30 g/ 100 g) en zumo de mandarina con y sin Lactobacillus salivarius spp. salivarius sobre las principales propiedades fisicoquímicas y funcionales del zumo. Los resultados obtenidos mostraron que el tratamiento por HPH redujo el tamaño medio de la distribución de las partículas suspendidas en el zumo, mejoró la estabilidad de la nube y aumentó el contenido en fenoles totales y flavonoides. La incorporación de trehalosa en una cantidad de 20 g/100 g mejoró la actividad antioxidante determinada por el método ABTS. Los resultados en el zumo de mandarina con L. salivarius constataron que, tanto la aplicación de presiones de homogeneización como la adición de trehalosa mejoraron la hidrofobicidad del probiótico y su supervivencia tras el almacenamiento. De forma adicional, la encapsulación de las células microbianas mediante presiones de homogenización permite mejorar la viabilidad de L salivarius en zumo de mandarina. En los discos de manzana impregnados con el zumo de mandarina con el probiótico encapsulado no se observó una mejora en la supervivencia del probiótico durante las operaciones de IV y de secado con aire a 40 ºC, aunque la encapsulación sí que mejoró su resistencia al proceso de digestión in vitro. Se estudió el almacenamiento del zumo y de los discos de manzana, determinándose en ambos casos el efecto de la encapsulación sobre la supervivencia de L. salivarius y sobre su resistencia al proceso de digestión in vitro. Los resultados muestran que el probiótico encapsulado presentó mayor supervivencia durante el almacenamiento y el proceso de digestión in vitro que el probiótico sin encapsular. En relación al aprovechamiento de otras fuentes para la obtención de nuevos ingredientes alimentarios con elevado contenido en compuestos bioactivos, se seleccionaron 11 azúcares de caña no refinados como alternativa al azúcar blanco y se analizaron sus propiedades fisicoquímicas y antioxidantes. Se confirmó que los azúcares de caña no refinados presentaron compuestos con actividad antioxidante y que su contenido guardaba relación con el grado de refinado del producto. Por último se aborda el aprovechamiento de subproductos para la obtención de polvos a partir de bagazo de arándano mediante secado por aire caliente y posterior triturado. Se ha analizado el efecto de la temperatura de secado (60 y 70 ºC) y de la intensidad del triturado sobre las propiedades fisicoquímicas y funcionales de los mismos. El secado disminuyó la capacidad antioxidante del bagazo de arándano pero no hubo un efecto significativo de la temperatura. La acción mecánica del triturado, redujo de manera significativa el contenido en fibra del polvo. Además, se demostró que el tamaño de partícula y el contenido en fibra de los polvos influyeron de forma decisiva en las propiedades de interacción con el agua y con el aceite, lo que condiciona en gran medida su estabilidad y su aplicación como ingr[EN] In the current system of intensive food production, there is the need to consider sustainability in agri-food industries. In this thesis, the way in which some technologies can improve the functionality of food with a high content of antioxidants and probiotics are studied. This is addressed from two approaches: on the one hand, the application of existing technologies for the improvement of food functionality, either through the incorporation of ingredients or from the formation of structures; and, on the other hand, the use of alternative food ingredients sources with high content in bioactive compounds. The technologies studied in this thesis have been the treatment with high homogenization pressures (HPH), encapsulation by HPH, vacuum impregnation (VI) and hot air drying. Combined effect of HPH treatment (20, 50, 100 and 150 MPa) and the addition of trehalose (10, 20 and 30 g / 100 g) in mandarin juice with and without Lactobacillus salivarius spp. salivarius on the main physicochemical and functional properties were studied. It was obtained that HPH treatment reduced the particle size distribution of suspended particles in juice, improved cloud stability and increased total phenols content and flavonoids. Trehalose addition in the amount of 20 g / 100 g increased the antioxidant activity determined by the ABTS method. Results of the mandarin juice with L. salivarius evidenced that both the application of homogenization pressures and the addition of trehalose improved the hydrophobicity of the probiotic and its survival after storage. Additionally, microbial cells encapsulation by means of homogenization pressures improved the L. salivarius survival in mandarin juice. In apple discs impregnated with mandarin juice including microbiane cells encapsulated, it was not observed an improvement in probiotic survival after vacuum impregnation and air drying at 40 ºC, although encapsulation does improve the resistance to in vitro digestion. Mandarin juice and apple discs storage was studied, determining in both the effect of the encapsulation on L. salivarius survival and on its resistance to in vitro digestion. Results obtained in the mandarin juice show that the encapsulated probiotic had a greater survival than non- encapsulated one. In apple discs, the encapsulation had no effect on probiotic survival after IV and air drying at 40 °C, although it improved its resistance to the in vitro digestion process. In relation to the use of other sources to obtain new food ingredients with high content of bioactive compounds, 11 non-refined sugar cane were selected as alternatives to white sugar and their physicochemical and antioxidant properties were analyzed. It was confirmed that the no refined sugar cane presented compounds with antioxidant activity and that their content was related to the degree of refining of the product. Finally, the use of by-products to obtain powders from blueberry pomace by using hot air drying and subsequent grinding is considered. The effect of the drying temperature (60 and 70 °C) and grinding intensity on the physicochemical and functional properties was analyzed. Drying decreased the antioxidant capacity of the blueberry pomace regardless the temperature. The mechanical action of the grinding significantly reduced the fibre content of the powder. In addition, it was demonstrated that particle size and fibre content of powders had a decisive influence on interaction with water and oil properties, which largely conditioned its stability and its application as an ingredient for food formulations.[CA] En el sistema actual de producció intensiva d'aliments sorgeix la necessitat de considerar la sostenibilitat en les indústries agroalimentàries. En aquesta tesi s'estudia la forma en què algunes tecnologies contribueixen a la millora de la funcionalitat d'aliments amb alt contingut en antioxidants i probiótics. El tema s'aborda des de dos enfocaments: d'una banda, l'aplicació de les tecnologies existents per a la millora de la funcionalitat dels aliments, ja siga per mitjà de l'incorporació d'ingredients o bé a partir de la formació d'estructures; i d'altra banda, l'aprofitament de fonts alternatives d'ingredients alimentaris amb elevat contingut en compostos bioactius. Les tecnologies estudiades en aquesta tesi han sigut el tractament amb altes pressions d'homogeneïtzació (HPH), l'encapsulació per mitjà de HPH, la impregnació a buit (IV) i l'assecat per aire calent. Es va estudiar l'efecte combinat de l'aplicació de HPH (20, 50, 100 i 150 MPa) i l'addició de trehalosa (10, 20 i 30 g/ 100 g) en suc de mandarina amb i sense Lactobacillus salivarius spp. salivarius sobre les principals propietats fisicoquímiques i funcionals del mateix. Es va obtindre que el tractament per HPH va reduir la distribució de la grandària de partícula de la polpa, va millorar l'estabilitat del núvol i va augmentar el contingut en fenols totals i flavonoids i a més, que la trehalosa va millorar l'activitat antioxidant determinada pel mètode ABTS quan es va afegir 20 g/100 g. Els resultats en el suc de mandarina amb L. salivarius van constatar que, tant l'aplicació de pressions d'homogeneïtzació com l'addició de trehalosa van millorar l'hidrofobicitat del probiòtic i la seua supervivència després de l'emmagatzenament. De forma addicional, l'encapsulació de les cèl¿lules microbianes mitjançant pressions d'homogenización permet millorar la viabilitat de L. salivarius en suc de mandarina. En els discos de poma impregnats amb el suc de mandarina incloent les cèl¿lules microbianes encapsulades no es va observar una millora en la supervivència del probiótic durant les operacions d'IV i d'assecat amb aire a 40 °C, encara que l'encapsulació si que va millorar la seua resistència al procés de digestió in vitro. Es va estudiar l'emmagatzematge del suc i dels discs de poma, determinant-se en tots dos casos l'efecte de l'encapsulació sobre la supervivència de L. salivarius i sobre la seua resistència al procés digestiu in vitro. Els resultats obtinguts mostren que el probiótic encapsulat va presentar major supervivència durant l'emmagatzematge i el procés de digestió in vitro que el probiótic sense encapsular. En relació a l'aprofitament d'altres fonts per a l'obtenció de nous ingredients alimentaris amb elevat contingut en compostos bioactius, es van seleccionar 11 sucres de canya no refinats com a alternativa al sucre blanc i es van analitzar les seues propietats fisicoquímiques i antioxidants. Es va confirmar que els sucres de canya no refinats presentaren compostos amb activitat antioxidant i que el seu contingut guardava relació amb el grau de refinat del producte. Finalment s'aborda l'aprofitament de subproductes per a l'obtenció de pols a partir de bagàs de nabiu per mitjà d'assecat per aire calent i posterior triturat. S'ha analitzat l'efecte de la temperatura d'assecat (60 i 70 ºC) i de la intensitat del triturat sobre les propietats fisicoquímiques i funcionals dels mateixos. L'assecat va disminuir la capacitat antioxidant del bagàs de nabiu però no va haver-hi un efecte significatiu de la temperatura. L'acció mecànica del triturat, va reduir de manera significativa el contingut en fibra de la pols. A més, la grandària de partícula i el contingut en fibra de les pols van influir de forma decisiva en les propietats d'interacció amb l'aigua i amb l'oli, que condicionen en gran manera la seua estabilitat i la seua aplicació com a ingredient en la formulació d'aliments.Calabuig Jiménez, L. (2018). Mejoras tecnológicas para el aumento de la funcionalidad de antioxidantes y probióticos. Contribución a la sostenibilidad de la industria agroalimentaria [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/111829TESISCompendi

Flow and Physical Properties of Dry and Moist Cornmeal Powder

Cornmeal powder is used in the food industry to manufacture a variety of food products. The knowledge of its flow behavior and physical properties is critical for efficient design of storage and handling processes. Factors affecting powder flowability are moisture content and the presence of conditioners. The main goal of this study was to quantify the effect of moisture content and addition of a conditioner, on the flow properties of cornmeal powder. Flow characterization based on standard physical properties is not always accurate and needs to be complimented with the measurement of other properties. The flow properties of the cornmeal powder at different moisture content levels and concentrations of conditioner were measured. The moisture content at which the cornmeal was tested varied as 10.0%, 13.5% 17.0%, and 20.0% wet basis. The concentration of the conditioner, calcium stearate (caking agent classified at GRAS) was varied as 0.00%, 0.50%, 0.75%, and 1.00% wt/wt. The optimum flow behavior characteristics of cornmeal powder were achieved at 0.50% wt/wt calcium stearate and 10.0% (w.b.) moisture content based on the flow function test. Overall, the sample flowability decreased with increase in moisture content which was characterized by the high values for Hausner’s Ratio, Carr’s Index, and angle of repose. The value of flow index (ffc) obtained by the flow function test decreased from 6.47 to 3.82 with increasing moisture content indicating cohesive behavior of the cornmeal powder. Calcium stearate increased the flowability of cornmeal powder at 0.50% wt/wt, beyond which, the flowability was not affected significantly. Hygroscopicity of the samples was found to be in Class IV which means that the samples were very hygroscopic. The correlation coefficient for Hausner’s ratio, Carr’s Index, and angle of repose were 0.91, 0.88, and 0.88, respectively, which showed a strong linear relationship with flow index that can be used to relate to the flowability of the cornmeal powder