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Effect of intermittent high-intensity sonication and temperature on barley steeping for malt production, (2018),

Density of binary solutions and combinations of sucrose, glucose, fructose, citric acid, malic acid, pectin, and inorganic salts were measured with an oscillating tube density meter in the temperature range from 10 to 60 C, at varying concentrations. Density can be predicted with accuracy better than 5 Â 10 À5 g cm À3 using predictive equations obtained by fitting the experimental data. Available literature values agreed well with experimental data. Relations for the excess molar volume of these solutions were derived in terms of mole fraction and temperature. A thermodynamic model for the volumetric analysis of multicomponent aqueous solutions containing electrolyte and non-electrolyte compounds was also proposed. These models can be used for prediction of density of liquid food systems, specially fruit juices and beverages, based on composition and temperature, with high accuracy and without elaborate experimental work.

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Geometrical, morphological, and shape factors are crucial for the accurate prediction of mass transfer rate of caffeine and water in the extraction of caffeine in aqueous medium from coffee beans. A new expression for the sphericity was deduced considering the hydrated coffee bean as a triaxial semilipsoid with moving boundaries applied to a nonsteady state analytical solution to describe the diffusion phenomena for the hemispherical geometry to best represent the morphology of the coffee bean during the caffeine extraction at varying temperatures from 30 to 60 °C. The sphericity increases with moisture in a power law trend. The hemisphere mathematical model presented an excellent adjustment to the data, with diffusion coefficients between 1.03 ×·10−11 and 9.00 ×·10−10 m2/s for caffeine and 0.69 ×·10−10 and 2.03 ×·10−10 m2/s for water; strongly influenced by temperature with activation energy of 59.93 and 41.24 kJ/mol, respectively, for caffeine and water. Practical applications The decaffeination of coffee beans satisfies an important segment of the coffee market. Currently, many industries use the decaffeination technology based on organic solvents; others extract caffeine in aqueous medium and on a smaller scale the supercritical fluid extraction process. The present research provides important properties and a mathematical model to better represent the mass transfer phenomena, with the associated diffusion coefficients, along with a suitable expression for the size and shape of the coffee beans changing with the process, which can be used for the proper and accurate design and control of the extraction process. The proposed model used the hemispherical geometry approach with a reduced number of variables (e.g., only one equivalent radius), unlike other approaches that need three dimensions to represent the coffee bean size and the associated shape factor, which makes it time consuming, requiring more complex calculations, and not necessarily more accurate.

O objetivo do presente trabalho foi avaliar a infl uência do branqueamento em água quente, da desidratação osmótica em solução de sacarose e da aplicação de cobertura comestível de pectina na cor e atividade de água de fatias de mamão Formosa, após secagem convectiva. Nos experimentos iniciais, com base em planejamento fatorial, avaliou-se a infl uência da concentração da solução desidratante e do tempo de desidratação osmótica na cor e atividade de água de fatias frescas e branqueadas de mamão. Não foram verifi cadas alterações signifi cativas na cor das amostras nos intervalos estudados. Encontrou-se expressão para a atividade de água das frutas branqueadas desidratadas osmoticamente. Posteriormente avaliou-se a infl uência do branqueamento, da desidratação osmótica, da aplicação de cobertura comestível e de combinações entre esses pré-tratamentos na cor e atividade de água das fatias de mamão após secagem convectiva. Verifi cou-se que o branqueamento não representou pré-tratamento vantajoso para a manutenção da cor e para a redução da atividade de água das frutas secas. As frutas frescas desidratadas osmoticamente com ou sem aplicação de cobertura comestível apresentaram os melhores resultados. MAMÃO -SECAGEM. PALAVRAS-CHAVES: DESIDRATAÇÃO OSMÓTICA; BRANQUEAMENTO; COBERTURA COMESTÍVEL;

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