Browsing by Author "Fernandes, Isabel P."
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- Advances in waterborne polyurethane and polyurethane-urea dispersions and their eco-friendly derivatives: a reviewPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaPolyurethanes and polyurethane-ureas, particularly their water-based dispersions, have gained relevance as an extremely versatile area based on environmentally friendly approaches. The evolution of their synthesis methods, and the nature of the reactants (or compounds involved in the process) towards increasingly sustainable pathways, has positioned these dispersions as a relevant and essential product for diverse application frameworks. Therefore, in this work, it is intended to show the progress in the field of polyurethane and polyurethane-urea dispersions over decades, since their initial synthesis approaches. Thus, the review covers from the basic concepts of polyure-thane chemistry to the evolution of the dispersion’s preparation strategies. Moreover, an analysis of the recent trends of using renewable reactants and enhanced green strategies, including the current legislation, directed to limit the toxicity and potentiate the sustainability of dispersions, is described. The review also highlights the strengths of the dispersions added with diverse renewable additives, namely, cellulose, starch or chitosan, providing some noteworthy results. Similarly, dispersion’s potential to be processed by diverse methods is shown, evidencing, with different examples, their suitability in a variety of scenarios, outstanding their versatility even for high requirement applications.
- Almond shell-based polyols through oxypropylation reactionPublication . Pinto, João A.; Fernandes, Isabel P.; Barreiro, M.F.Almond cultivation and processing industry generate 3 main types of residues: hull, shell and skin, representing 80% (w/w) of the whole almond fruit. Presently, the shell finds use as energy source being commercialized at a cost of 0.11 €/kg. Hull and skin have no economic value. Apart from the hull, that its use needs a strategy for its recover, both shell and skin can be easily recovered at the almond processing industries and are, therefore, the more attractive residues to develop novel applications. In this work the use of almond shell as a raw material to produce polyols through oxypropylation was studied.
- Análise cromatográfica de iogurte funcionalizado com extrato etanólico de Agaricus bisporusPublication . Francisco, Cristhian Rafael Lopes; Fernandes, Isabel P.; Barreira, João C.M.; Barros, Lillian; Gonçalves, Odinei Hess; Barreiro, M.F.; Ferreira, Isabel C.F.R.Agaricus bisporus (Lange) Imbach é um cogumelo rico em compostos bioativos e os seus extratos podem ser utilizados na funcionalização de alimentos. A caracterização dos extratos e dos alimentos funcionalizados é de extrema importância, principalmente em relação ao teor em compostos bioativos (e.g., ergosterol) e à composição nutricional, respetivamente. Neste trabalho, foi obtido um extrato etanólico de A. bisporus utilizando a técnica de ultrassons para funcionalização de iogurte. O teor em ergosterol foi determinado por cromatografia líquida de alta eficiência (HPLC-UV, Knauer Smartiline 1000) em coluna de fase reversa (Inertsil 100A ODS-3) e acetonitrilo/metanol (70:30, v/v) como fase móvel. O extrato apresentou uma concentração de 19,4 mg ergosterol/g extrato, tendo sido as bandas de absorção características identificadas por FTIR (caracterização estrutural). Posteriormente, o iogurte funcionalizado foi caracterizado em relação à sua composição nutricional e perfis cromatográficos de ácidos gordos e açúcares. O perfil de ácidos gordos foi determinado por cromatografia gasosa (equipamento DANI 1000, Contone) equipado com um detetor de ionização em chama (GC-FID) a 260°C, enquanto que os açúcares foram analisados por HPLC acoplado a um detetor de índice de refração, utilizando como acetonitrilo/água (70:30, v/v) como fase móvel [2]. Não foram observadas alterações significativas em relação ao valor nutricional dos iogurtes funcionalizados em comparação com o controlo (iogurte sem adição do extrato); apresentaram ácido mirístico (C14:0, 11.1±0.4%), ácido palmítico (C16:0, 31±1%), ácido esteárico (C18:0, 10.0±0.5 %) e ácido oleico (C18:1n9, 23±1 %) como ácidos gordos maioritários, e galactose (0.82±0.05 g/100 g) e lactose (4.6±0.2 g/100 g) como açúcares predominantes. No entanto, o extrato conferiu propriedades antioxidantes ao iogurte, demonstrando que a estratégia adotada é promissora para a obtenção de alimentos funcionais.
- Análise de componentes principais aplicada ao estudo da oxipropilação do resíduo da semente da Araucaria angustifóliaPublication . Rezende, Stephany; Pinto, João A.; Fernandes, Isabel P.; Leimann, Fernanda Vitória; Barreiro, M.F.A casca do pinhão brasileiro é um resíduo lenhocelulósico da semente da Araucaria angustifólia, uma espécie de conífera nativa da América do Sul. Esta semente é consumida após sofrer um processo de descasque, resultando na produção de uma quantidade significativa de resíduo sem valor comercial. Tendo por objetivo o desenvolvimento de aplicações para a valorização da casca do pinhão (PFS), este trabalho foca a produção de biopolióis a partir desta fonte lenhocelulósica através do processo de oxipropilação. O trabalho compreendeu o estudo da relação entre as variáveis do processo e as propriedades dos biopoliois, utilizando a metodologia de Análise de Componentes Principais (ACP). No que respeita à oxipropilação, selecionaram-se três razões PFS/óxido de propileno (PO) (30/70, 20/80 e 10/90; m/v). Testaram-se ainda quatro níveis de catalisador: 5, 10, 15 e 20%, (m/m, base biomassa). A oxipropilação ocorreu em condições moderadas de temperatura, pressão e tempo, resultando na produção de poliois líquidos. Numa segunda etapa, procedeu-se à caracterização dos biopoliois, no que respeita ao teor de homopolímero (POO), teor de grupos hidroxilo (IOH), viscosidade (V) e biomassa por reagir (UR) no biopoliol. Posteriormente, através da Análise de Componentes Principais, efetuou-se a avaliação das interações estabelecidas entre as variáveis do processo de oxipropilação e as propriedades dos poliois obtidos. A análise de ACP (Fig. 1) clarificou as interações estabelecidas, provando ser uma ferramenta útil para descrever e visualizar o processo de oxipropilação, com possibilidade de ser estendida a outros tipos de biomassa ou integrando diferentes variáveis de entrada.
- Anthocyanins from rubus fruticosus l. And morus nigra l. applied as food colorants: a natural alternativePublication . Vega, Erika N.; Molina, Adriana K.; Pereira, Carla; Dias, Maria Inês; Heleno, Sandrina A.; Rodrigues, Paula; Fernandes, Isabel P.; Barreiro, M.F.; Stojković, Dejan; Soković, Marina; Carocho, Márcio; Barreira, João C.M.; Ferreira, Isabel C.F.R.; Barros, LillianGiven the importance of colour in the general acceptance or rejection of a product, the use of colorants is a widespread practice, particularly in the food industry. At the same time, with the increasing consumers’ awareness of the health effects that some artificial colorants can exert, there is a growing tendency to prioritize foodstuffs containing natural additives. In this work, Morus nigra L. and Rubus fruticosus L. fruit juices were characterized in terms of anthocyanins, organic acids, free sugars, and tocopherols, as also regarding their bioactive properties. Given their richness in anthocyanins, this study also aimed to prepare different solid colouring formulations by the spray-drying technique, using as stabilizers maltodextrin and arabic gum. Six free sugars and two organic acids were detected in the fruit juices, as well as the four tocopherol isoforms. Two cyanidin derivatives were found in M. nigra (cyanidin-3-O-glucoside and cyanidin-O-rhamnoside) and other four in R. fruticosus (cyanidin-O-hexoside, cyanidin-3-O-glucoside, cyanidin-O-pentoside, and cyanidin-3-O-dioxaloilglucoside). The developed colouring formulations revealed a good stability over time, in terms of anthocyanin concentration and colour parameters, and revealed to be safe for consumption, either concerning their low microbial load and lack of cytotoxicity. Thus, they represent a promising natural alternative to the massively used artificial colorants.
- Application of spray-coagulation method to microencapsulate catechin having in view cosmetic, pharmaceutical or nutraceutical areasPublication . Viegas, Joana; Barros, Lillian; Fernandes, Isabel P.; Ferreira, Isabel C.F.R.; Barreiro, M.F.Catechin is a polyphenolic compound of the flavonoid family and a product of the secondary metabolism of various plants [1 ]. Antioxidant and chelating properties are attributed to catechin, as well as to other flavonoids, due to their aromatic hydroxyl groups. The presence of these bioactive components in diets rich in vegetables offers a protective effect in human health, including prevention of cardiovascular disorders and certain cancers, and in the ageing process itself. When ingested, catechin undergoes a process of metabolism that changes its structure affecting the antioxidant properties [2]. Microencapsulation can be used to overcome this problem offering protection by means of a cover material and enabling its controlled release over time or selectively to an intended target [3]. In this study catechin was microencapsulated in an alginate matrix by using a spray-coagulation technique. Briefly, a sodium alginate solution (4%, w/v) containing catechin was prepared under stirring at ambient temperature by using a ratio catechin:alginate of 25:400 (w/w). The solution was atomized in a Nisco Var J30 unit and microspheres consolidated upon contact with a solution of CaCI2 (4%, w/v), recovered by decantation and washed with deionized water. In order to control the process, microspheres formation was followed by optical microscopy (OM), and catechin loss evaluated after consolidation/washing steps. In conclusion, alginate-based microspheres loaded with catechin were efficiently produced. The obtained microspheres have a medium particle size comprised between 73 and 341 1-Jm and encapsulation efficiency was estimated as 87%. Overall, catechin was microencapsulated with success, and can be incorporated in different formulations in order to apply its antioxidant properties in cosmetic, pharmaceutical or nutraceutical areas. The work will proceed by evaluating the protective effect of the used microencapsulation process on catechin antioxidant properties.
- Aroma encapsulation for antibacterial and eco-friendly textile finishingPublication . Sharkawy, Asma; Fernandes, Isabel P.; Rodrigues, Alírio; Barreiro, M.F.; Shoeib, TamerEncapsulation imparts new properties and added value to conventional fabrics. Most of the commercially available microcapsules for textile applications are made of melamine-formaldehyde, urea-formaldehyde or phenolformaldehyde resins, which have significant negative health and environmental effects. Recently, there has been a growing interest in the replacement of these resins with safe and environmentally benign materials. The process of fixing the microcapsules onto textile substrates is critical in ensuring their durability and effectiveness. The commonly known industrial methods used for this involve the use of two main groups of binders; polymeric resins, and polyfunctional crosslinking agents. Polymeric resins are reported to partially inhibit the release of fragrance from the microcapsules. The chemical cross-linkers are subdivided into formaldehyde based, e.g., formaldehyde and glutaraldehyde, and non-formaldehyde based, such as polycarboxylic acids. This work aimed at conferring fragrant and antibacterial properties to cotton fabrics employing new methodologies utilizing non-toxic and environmentally friendly materials.
- Aroma-loaded microcapsules with antibacterial activity for eco-friendly textile application: synthesis, characterization, release, and green graftingPublication . Sharkawy, Asma; Fernandes, Isabel P.; Barreiro, M.F.; Rodrigues, Alírio; Shoeib, TamerFragrant and antimicrobial properties were conferred to cotton fabrics following microencapsulation using green materials. Limonene and vanillin microcapsules were produced by complex coacervation using chitosan/gum Arabic as shell materials and tannic acid as hardening agent. The effect of two emulsifiers; Span 85 and polyglycerol polyricinoleate (PGPR), on the encapsulation efficiency (EE%), microcapsule’s size and morphology, and cumulative release profiles was studied. The mean diameter of the produced microcapsules ranged between 10.4 and 39.0 μm, whereas EE% was found to be between 90.4% and 100%. The use of Span 85 resulted in mononuclear morphology while PGPR gave rise to polynuclear structures, regardless of the core material (vanillin or limonene). The obtained microcapsules demonstrated a sustained release pattern; namely the total cumulative release of the active agents after 7 days at 37 ± 1 °C was 75%, 52% and 19.4% for the polynuclear limonene microcapsules, the mononuclear limonene microcapsules and the polynuclear vanillin microcapsules, respectively. Grafting of the produced microcapsules onto cotton fabrics through na esterification reaction using citric acid as a nontoxic cross-linker followed by thermofixation and curing, was confirmed by SEM and FTIR spectroscopy. Standard antibacterial assays conducted on both microcapsules alone and impregnated onto the fabrics indicated a sustained antibacterial activity.
- Avaliação da estabilidade da cor de curcumina encapsulada por análise de componentes principaisPublication . Leimann, Fernanda Vitória; Gonçalves, Odinei Hess; Bona, Evandro; Fernandes, Isabel P.; Ferreira, Isabel C.F.R.; Barreiro, M.F.Alternativas aos corantes alimentares sintéticos estão disponíveis a partir de fontes vegetais, como a curcumina, que pode ser extraída da Curcuma longa L e possui reconhecida bioatividade. No entanto, a curcumina é termicamente instável e degrada rapidamente durante o aquecimento, o que constitui um desafio para o seu uso em alimentos sujeitos a processamento por calor. Neste estudo, a nanoencapsulação da curcumina em polímeros biocompatíveis, como a k-carragena, poli(álcool vinílico) (PVA) e poli(vinil pirrolidona) (PVP), utilizando a técnica de dispersão sólida seguida de spray drying foi aplicada aproveitando os efeitos protetores do encapsulamento. Avaliaram-se o efeito do pH do meio durante a obtenção das partículas, e os percentuais de curcumina e surfactante (Tween 80) (estes relativos à massa de polímero). Uma análise de componentes principais (PCA) foi realizada para identificar as condições experimentais que levariam à melhoria da estabilidade da cor da curcumina quando submetida a processos de aquecimento. Os resultados indicaram que os polímeros protegeram de forma diferente a cor durante o período de aquecimento (180°C por 30, 60 e 120 min). Para tempos menores de aquecimento (30 min) o PVA foi o encapsulante que melhor protegeu a cor, seguido da k-carragena que protegeu a cor de forma mais efetiva para 60 min de exposição e o PVP que manteve a cor estável pelo maior período de tempo de exposição (120 min). A curcumina não encapsulada foi avaliada como controle sendo observada perda completa da sua coloração após 30 min de tratamento térmico.
- Bacteriostatic ecffect of waterborne polyurethane-ureia films containing bioactive plant extracts incorporated by different routesPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Arbelaiz, Aitor; Barreiro, M.F.; Corcuera, Maria Angeles; Eceiza, ArantaxaThe environmental awarenessh as promoted the development of new materiats towards eco-friendty systems based on both,green synthesis processes as well as the renewable origin of the raw compounds. In this way,focusing on synthesis methods, the use of waterborne polyurethane-urea dispersions have gained attention due to their versatility leading to a wide variety of apptications broadening the range of appLications. In addition, it is worth nothing that the dispersibitity in water offers the possibitity of incorporating soluble additives such as plant extracts. Therefore, in this work Melissa officinalis L . ptant was setected in order to obtain bioactive plant extract, in order to be incorporated to a waterborne polyurethane-urea disspersion varying their content as well as using three differernt incorporation routes. These dispersions were characterized and employed in the preparation of films which were analyzed from the viewpoint of physicochemical, thermal and mechanical properties, among others. Finatty, the antibacterial properties of the films were analyzed after 1 and 4 days of incubation. Where it was observed that the content and incorporation route of the extract influenced in the behavior of the films against common pathogens (Staphylococcus aureus, Escherichio coli ond Pseudomonas aeruginosa.