Cinética de la obtención de acetaldehído por hidratación de acetileno catalizada por resina de intercambio ácido-mercúrica

Fil: Menegalli, Florencia Cecilia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Filmes e coberturas comestíveis contendo antioxidantes – uma revisão

The incorporation of natural antioxidants into films and edible coatings can modify their structure, improving their functionality and applicability in foods, such as in fresh-cut fruits. This paper reviews the more recent literature on the incorporation of antioxidants from several sources into films and edible coatings, for application in fruits and vegetables. The use of synthetic antioxidants in foods has been avoided due to their possible toxic effects. Instead, a wide range of natural antioxidants (such as essential oils and plant extracts, as well as pure compounds, like ascorbic acid and α-tocopherol) have been incorporated into edible films and coatings to improve their bioactive properties. Films and coatings containing added antioxidants help to preserve or enhance the sensory properties of foods and add value to the food products by increasing their shelf life17298112A incorporação de antioxidantes naturais em filmes e coberturas comestíveis pode modificar sua estrutura, melhorando sua funcionalidade e aplicação em alimentos, tais como as frutas. Este artigo apresenta uma revisão da literatura mais recente sobre a incorporação de antioxidantes, de diversas fontes, em filmes e coberturas comestíveis aplicados em frutas e vegetais. A utilização de antioxidantes sintéticos em alimentos tem sido evitada em razão do seu possível efeito tóxico. Assim, inúmeras categorias de antioxidantes naturais – tais como óleos essenciais, extratos de plantas e compostos puros, como ácido ascórbico e α-tocoferol – têm sido adicionadas a filmes e coberturas comestíveis, para melhorar suas propriedades bioativas. As embalagens aditivadas com antioxidantes podem preservar ou melhorar as qualidades sensoriais dos alimentos sobre os quais são aplicadas e agregar valor a produtos alimentares pelo aumento de sua vida de prateleir

Secagem do polissacarídeo λ-carragena usando um leito de jorro fluidizado bidimensional / drying of λ-carrageenan using a two dimensional spouted fluidized bed dryer

Resumo. Suspensões de λ-carragena foram secas usando um secador de leito de jorro fluidizado bidimensional com partículas inertesplásticas de ABS (acrilonitrilo-butadieno-estireno). O desempenho do secador (produção de pó e retenção de sólidos) e qualidade do produto seco obtido (propriedades reológicas e teor de umidade) foi avaliado. Os resultados mostraram que a eficiência de produção média de pó foi de 23% com uma retenção média de 71%. A variável mais relevante na secagem das suspensões foi a vazão de alimentação, sendo que um aumento desta variável produziu um baixo rendimento de pó e aumentou a retenção de sólidos dentro do leito. O produto reconstituído de λ-carragena obtido nas condições otimizadas de secagem formou suspensões de natureza altamente pseudoplástica, porém com propriedades viscoelásticas características de suspensões altamente diluídas (G´´ and gt;G´), mostrando valores de viscosidade, módulos elástico (G´) e de perda (G´´) menores que o produto comercial. / Abstract. λ-carrageenan suspensions were dried using a two dimensional spouted fluidized bed dryer with inert particles of ABS (acrylonitrile butadine styrene). The dryer performance (powder production and solid retention) and quality properties of final product (rheological properties and moisture content) were evaluated. According to results the mean powder production of λ-carrageenan using ABS as inert particle was of 23% with a solid retention of 71%. The most significant variable in the drying of suspension was the feed mass flow rate, as its increase produced a diminishing of the powder production and increasing of the solids retention in the bed. The reconstituted suspensions of λ-carrageenan obtained from optimized conditions of drying formed highly pseudoplastic suspensions with viscoelastic properties of highly diluted (G´´ and gt;G´) systems. In addition, the rheological characteristics as viscosity, storage (G´) and loss moduli (G´´) were lower than commercial gum

Morphological characterization with image analysis of cocoa beverage powder agglomerated with steam

In this study, the morphological characteristics of cocoa beverage powder granules under minimal, average, and maximal process conditions of a steam agglomerator were studied. a stereoscopic microscope coupled to a digital camera was used for the morphological analysis. The images were analyzed to obtain shape and size descriptors. aiming to evaluate the descriptors, 150 particles were analyzed. The results showed that there was no difference between the shape descriptors - compacity, circularity, roughness, and aspect ratio - in the operating conditions evaluated. It was observed that the cocoa beverage powder granules are elongated in shape. The size descriptors, area, perimeter, perimeter of convex bounding polygon, minimal and maximal Feret diameter, were different in the process conditions for the granules of size above 600 µm. as for the minimal process conditions, especially due to low solid feed rates, there is an increase in the size descriptor values. In addition, under the minimum process conditions, in which there is low solid feed rate (400g/min) for a steam pressure of 1.0 bar, it was obtained a good granular condition with retention of 81.1% of granules on sieves with aperture size between 300 and 1190 µm34464965

Cinética de la obtención de acetaldehído por hidratación de acetileno catalizada por resina de intercambio ácido-mercúrica

Fil: Menegalli, Florencia Cecilia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Development and characterization of unripe banana starch films incorporated with solid lipid microparticles containing ascorbic acid

Incorporation of additives into polysaccharide-based films has emerged as a new strategy to release additives in food under specific conditions. However, there are no reports on the microencapsulation of additives with a hydrophobic agent prior to their addition to the polymer, which could stabilize the active compound and control its release. Therefore, this work aimed to produce films consisting of starch isolated from plantain bananas of the variety “Terra” incorporated with lipid microparticles containing ascorbic acid. Films produced by casting were characterized with regard to moisture, density, mechanical properties, color and opacity, light transmittance, water solubility, water vapor permeability, water uptake, XRD, and antioxidant properties. As a result of the lipid fraction enveloping the particles present in the packaging material, films additivated with lipid microparticles containing ascorbic acid showed lower water vapor permeability and elongation as well as higher tensile strength as compared with a control film containing no additives. In addition, films incorporated with solid lipid microparticles containing ascorbic acid displayed lower light transmission than the control films and a commercial polyethylene film. The microparticles acted as protective agents of the ascorbic acid antioxidant activity during film production. The antioxidant activity remained as high as 84% after the drying process55210219CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP131425/2012-92952/20112012/50411-

Cubiertas y Peliculas Comestibles Aditivos Bioactivos para la Conservación de la Fruta

Edible films and coatings have been applied on fruit to reduce aromatic compounds and texture loss and to increase the barrier to transport of fats and solutes. Furthermore, the surface layer on theproduct can protect the fruit crating a modified atmosphere that by controls the O2 and CO2 exchange, reducing respiration rate, metabolism and, consequently, the senescence. A new potential application of this technology is the use of edible coatings and films as carriers of diverse food additives such as antioxidants and antimicrobial agents. This review discusses the incorporation of functional ingredients into the edible coatings and films and highlights of the recent advance in the search for these incorporations. The future trends for the study area are also presented.Filmes e coberturas comestíveis são aplicados em frutos por terem a capacidade de retardar a perda de compostos aromáticos, permitir a manutenção das propriedades mecânicas dos produtos e por funcionarem como barreiras a gorduras e solutos. Além disso, formam uma camada de proteção adicional para os produtos e podem criar uma atmosfera modificada ao redor dos mesmo, em função da permeabilidade seletiva aos gases O2 e CO2, reduzindo assim a taxa de respiração, o metabolismo e, consequentemente, sua senescência. Um uso potencial desta tecnologia é a capacidade das coberturas e filmes de agirem como carreadores de aditivos alimentícios, como antioxidantes e antimicrobianos, para a superfície do alimento. Esta revisão discute o uso de coberturas e filmes comestíveis aditivados de compostos com propriedades funcionais e destaca os recentes avanços obtidos pela incoporação desses agentes. As tendências futuras para a área de estudo também são apresentada

Cellulose nanofibers produced from banana peel by chemical and enzymatic treatment

Cellulose nanofibers were isolated from banana peel bran using chemical treatment (CT—alkaline treatment, bleaching, and acid hydrolysis) and enzymatic treatment (ET—alkaline treatment and hydrolysis with xylanase). Both bran and cellulose nanofibers were characterized by size distribution, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR); the morphological features of the bran and the nanostructures were studied by scanning (SEM) and transmission electron microscopy (TEM), respectively. TEM analysis evidenced that both treatments effectively isolated banana fibers in the nanometer scale. Nanofibers originating from CT and ET had an average diameter of 10.9 and 7.6 nm and a length of 454.9 and 2889.7 nm, respectively. The aspect ratio of all the samples lay in the range of long fibers. In neutral water, the nanofiber suspensions exhibited high and negative zeta potential, which prevented the nanofibers from aggregating and yielded a more stable colloidal suspension. XRD studies revealed that CT afforded more crystalline cellulose nanofibers (58.6%) as compared with ET (49.2%). FTIR confirmed that the treatments removed most of the hemicelluloses and lignin present in the banana fibers. Nanoparticles isolated from the banana peel by both treatments have potential application as reinforcing elements in composites5922CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES477842/2011-92952/201