Abstract This study’s main highlight to the effect of replacement of milk by different proportions of concentrated whey in the elaboration of ice creams and the characterization of their physicochemical and microstructural properties. Ice creams have high levels of total solids, acidity, and low pH values. All ice creams exhibited Newtonian fluid behaviors while the Power and Casson Law model adequately explained the flow properties. Viscosity and hysteresis area increased as a higher ratio of concentrated whey was added. Ice cream formulations containing a higher proportion of milk showed greater brightness, the ice creams showed a greenish-yellow coloring tendency. The overrun values ranged from 27 to 44%, and ice cream with partial replacement of milk by concentrated whey showed greater resistance to melting. The addition of concentrated whey did not influence the size of the ice crystals, fat globules, and air bubble diameters. However, the higher total solids content influenced the texture of the ice creams, promoting smoother and creamy ice creams. These results highlight the application of concentrated whey on the 50% substitution level, thus being an attractive alternative for the food industry, mainly about the cost-benefit and added value to the product, by enhancing the color, flavor, and texture.

Abstract Freeze concentration process was used to concentrate milk until the third stage of freeze concentration. Thus, two samples of ice creams were manufacture, one with milk and the other with concentrated milk from the first stage of block freeze concentration, and denominated ice cream 1 and ice cream 2, respectively. Both ice creams were characterized according to physicochemical characteristics, overrun, microscopy, melting rate, texture, color, and rheological properties. The use of concentrated milk influenced the physicochemical properties of ice cream 2, promoting an increase in the total solids, protein, carbohydrates, and ashes content. Moreover, it was noted that ice cream 2 had a higher overrun, lower firmness, smaller ice crystals, and tended to color greenish and yellowish, however had a higher melting rate and larger hysteresis area. The models of the Power Law and Casson satisfactorily described the rheological behavior of ice creams, which proved to be a Newtonian fluid.

Abstract: The influence of important factors related to fluid preparation on shear-thickening fluids (STF) is not well explored in literature. Thus, this paper aimed at analyzing the statistical significance of experimental conditions, such as fumed silica concentration (Cs), stirring time (tst), stirring speed (Sst) and sonication time (tso ), on the rheological behavior of fumed silica particles and PEG 400 dispersions. For that, a 2k factorial Experimental Design (DOE), with three center points, was accomplished. The investigated response variables were: maximum viscosity (ηm); critical shear rate ( γ ˙ m) where the viscosity is maximum; and agglomerate size of particles during preparation (R). All factors were statistically significant for all three response variables. Higher viscosity values for shear rate range analyzed was obtained with longer tst, lower Sst and longer tso. An important contribution of this paper was to show discontinuous shear thickening (DST) for lower concentrations than previously found in literature only changing the preparation protocol.

Os precursores mais empregados para obtenção da fibra de carbono são a poliacrilonitrila, o piche e o rayon. Com o aumento da demanda de materiais compósitos leves e de alta resistência, a produção da fibra de carbono tem aumentado exponencialmente e novos precursores têm sido requisitados. A lignina, um material orgânico natural, tem sido estudada como possível candidata para a produção das fibras. Além de ser rejeito industrial e de biorrefinarias, as fibras de carbono obtidas com a lignina podem ter um custo mais vantajoso quando comparado com os demais precursores comerciais. Em decorrência da biodiversidade de vegetais na natureza, a lignina pode apresentar diferentes estruturas. O método de recuperação também é parâmetro que influencia diretamente na sua composição. Como as propriedades térmicas para extrusão são fortemente dependentes dessas e de muitas outras variáveis, muitas pesquisas têm sido reportadas utilizando lignina pura de diversas fontes, lignina modificada e com adição de plastificantes. As etapas de pré-tratamento, termoestabilização e carbonização/grafitização também têm sido avaliadas para conferir melhores propriedades mecânicas ao produto final. Não obstante serem muitas as condições para a produção da fibra de carbono a partir da lignina, resultados bastante promissores têm sido alcançados. As aplicações em diversas áreas estão diretamente relacionadas com o conjunto de propriedades mecânicas inerentes a ela. A fibra de carbono proveniente da lignina vem contribuir com inúmeros empregos no mercado, de maneira a baratear sua produção, minimizar a dependência de materiais fósseis e tornar sua manufatura ecologicamente sustentável.

The most applied precursors to obtain carbon fiber are polyacrylonitrile, pitch and rayon. With the increased demand of lightweight composites and high strength, carbon fiber manufacting has increased exponentially and new precursors are been request. Lignin, a natural organic material, has been studied as possible candidate. Besides being an industrial and biorrefinary waste, lignin-based carbon fibers have a lower cost compared to other commercial precursors. Because of the biodiversity of plants in nature, lignin can present different structures. The lignin extraction method can directly influence the composition. As thermic extrusion properties are hardly dependent on this and other properties, many researches have been reported using pure lignin from different sources, modified lignin and plasticizers addiction. Steps of pretreatment, thermostabilization and carbonization/graphitization have also been evaluated to give better mechanical properties to the final product. Nevertheless many conditions required to manufacture lignin-based carbon fiber, promising results have been achieved. The set of mechanical properties inherent to the fiber allows its application to different areas. Lignin-based carbon comes to collaborate on cheapening its production, minimizing the dependence of fossil materials and making its manufacture process ecologically sustainable.