1 Modelagem matemática da cinética de secagem em camada de espuma da folha da gravioleira (Annona muricata Linn) e caracterização do pó obtido Mathematical modeling of drying kinetics in foam-mat drying of soursop (Annona muricata Linn) leaf and Characterization of the obtained powder Modelado matemático de cinética de secado de la capa de espuma de la hoja de guanábana (Annona muricata Linn) y caracterización del povo obtenido 2 Resumo A graviola (Annona muricata L.) vem se destacando pelas diferentes atribuições na área medicinal, sendo as folhas uma das partes mais estudadas pelo uso tradicional na forma de chás. Este trabalho teve por objetivo produzir o pó da folha da graviola pelo método de secagem de espuma, utilizando Portogel® como agente espumante. Foram verificadas a influência das variáveis, concentração de emulsificante, tempo de agitação e temperatura de secagem. Foram realizadas caracterizações físicas da espuma da folha de graviola: densidade, percentual de expansão e estabilidade da espuma. Com os dados da cinética de secagem foi possível obter os ajustes aos modelos matemáticos não lineares e com os pós obtidos foram realizadas as seguintes caracterizações físico-químicas: atividade de água (aw), rendimento, granulometria, pH, sólidos solúveis totais, acidez titulável total (ATT), índice de solubilidade em água (ISA), atividade antioxidante total e fenólicos totais. Todos os experimentos apresentaram uma curva típica de secagem, representadas por um período de taxa constante e uma taxa decrescente. Para os ajustes aos modelos matemáticos não lineares, os que melhor representaram os dados experimentais foram os de Page e Page Modificado. Um teor máximo de umidade de 4,10g/100g, atividade de água (aw) inferior a 0,406, um pH levemente ácido, uma teor de sólidos solúveis totais de aproximadamente 47 o Brix e acidez titulável total (ATT) na faixa de 2 g ácido cítrico/100g. A atividade antioxidante pelo método DPPH e fenólicos totais, apresentaram os maiores valores nas condições mínimas de secagem sendo eles: 121,07 µmol Tx/g e 1420 mg GAE/100g de pó, respectivamente. O processo de secagem da folha da graviola pelo método de camada de espuma se mostrou satisfatório quanto aos parâmetros avaliados.Palavras-chave: Estabilidade; Modelos matemáticos; Atividade de água; Antioxidante;Fenólicos. AbstractThe soursop (Annona muricata L.) stands out for the different attributions in the medicinal area, highlighting the leaves by their traditional use in the form of teas. This work had the objective of producing the powder of the soursop leaf by the method of foam-mat drying using the Portogel® as foaming agent. The influence of the variables, emulsifier concentration, agitation time and temperature drying were verified. Physical characterizations of the soursop leaf foam were performed: density, percentage of expansion and foam stability.With the data of the drying kinetics it was possible to obtain the adjustments to the non-linear mathematical models and with the obtained powders the following physical chem...
Industrial wastes containing synthetic organic compounds and heavy metals are among the most dangerous residues, whose growth has followed the increase in industrial activity. Heavy metals are readily assimilated into the food chain and therefore easily accumulated in the ecosystem. To remove heavy metals from aqueous solutions, marine algae may be used as adsorbents either in their natural form or after treatments by a cross-linking process to improve their mechanical resistance. Drying of biosorbents, such as marine algae, is mentioned in many previous works as a step preceding the adsorption/dessorption cycle. Concerning algae, drying of its fresh biomass allows for proper storage and enhances performance in the sorption of heavy metals. In this work, physical and morphological analyses of fresh and dried Sargassum sp. marine algae, harvested offshore São Sebastião, São Paulo state, Brazil, were performed in order to assess the influence of drying conditions on the biosorption process. Chromium concentrations were also determined in different parts of the algal structure before and after the biosorption process. The drying promoted structural changes in the algae, like shrinkage and porosity reduction. It was also observed that the chromium retention was dependent on the structural arrangement of the alga parts, in which the leaf was the major biosorbent.
The aim of this study is to investigate the effects of isolated and/or combined enzymatic and annealing treatments on the technological properties of black rice starch. The modification is carried out through an annealing process at 50 °C for 24 h, followed by the process of enzymatic modification by the action of transglucosidase (25 kU mL −1 ). Enzymatic hydrolysis with transglucosidase is improved as a result of the annealing action, which resulted in 7.6%. The size and shape of the starch granules are not modified by the thermoenzymatic treatments, only agglomeration of the granules in native starch modified with transglucosidase. The annealing treatment promotes a 20.60% reduction in crystallinity and a change in the type of lens from type A to Vh. Modified starch shows higher thermal and mechanical resistance when compared to native starch. The results contribute to a better understanding of the combination of annealing in enzymatic modification with transglucosidase for black rice starch.
O objetivo deste trabalho foi avaliar a composição nutricional, caracterizar e correlacionar os parâmetros de qualidade da polpa do cacau. A amostra analisada foi a polpa dos frutos do cacaueiro dos genótipos CCN51 e CEPEC 2005, denominada comercialmente de blend. Foram avaliadas a composição centesimal aproximada, valor calórico, características físicas, físico-químicas, químicas e correlação dos parâmetros analisados. A polpa apresentou baixo valor calórico (56,19 Kcal), alto teor de sólidos solúveis (20,40ºBrix), ratio (32,45) e potássio (128,61mg/100g). Além de correlações muito forte (r±0,91 a ±1,00) e forte (r±0,71 a ±0,90) ao nível de 5% de significância entre as características ratio, sólidos solúveis, Aw, açúcares totais, amido, densidade e vitamina C. A amostra apresenta potencial de utilização para desenvolvimento de produtos alimentícios, pois contém importante composição centesimal, resultados expressivos para o teor de sólidos solúveis, ratio, açúcares totais e redutores e valor calórico relativamente baixo, podendo ser adicionada em dietas, suplementação alimentar, como também em processamentos tecnológicos.
The present work aims to evaluate the influence of thickness on the drying kinetics of beet slices and to adjust mathematical models (empirical and diffusive) to experimental data. The beets were cut in three different thicknesses (4, 6 and 8 mm) and the drying kinetics were carried out in an air circulation oven with a speed of 1.5 ms-1, at a temperature of 60 ºC. The empirical (Lewis, Page and Handerson and Pabis) and diffusive mathematical models considering the infinite wall geometry and the boundary condition of the third type were adjusted to the experimental data. The Page model presented as the best fit when compared to the others because it had higher values for R2 (R2> 0.99) and lower values for the chi-square function. The analytical solution of the diffusion equation with infinite wall geometry, showed an increase in the diffusivity and convective coefficient of heat transfer with an increase in the thickness of the slices and the low values of the number of biot indicate that the boundary condition used (third type) described the process satisfactorily. However, when there was an increase in the thickness of the slices, the lesser the variations in humidity inside them over time.
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