Water adsorption isotherms and thermodynamic properties of cassava bagasse, Thermochimica Acta http://dx. HighlightsAdsorption isotherms and composition of cassava bagasse were determined> GAB equation was the best-fitted model to sorption data of type II isotherm> Isosteric heat of sorption was calculated in a range of equilibrium moisture content> Differential enthalpy and entropy confirmed the isokinetic compensation theory> Water adsorption by cassava bagasse is considered an enthalpy driven process> AbstractLosses of food industry are generally wet products that must be dried to posterior use and storage. In order to optimize drying processes, the study of isotherms and thermodynamic properties become essential to understand the water sorption mechanisms of cassava bagasse.For this, cassava bagasse was chemically analyzed and had its adsorption isotherms determined in the range of 293.15 to 353.15 K through the static gravimetric method. The models of GAB, 2 Halsey, Henderson, Oswin and Peleg were fitted, and best adjustments were found for GAB model with R²>0.998 and no pattern distribution of residual plots. Isosteric heat of adsorption and thermodynamic parameters could be determined as a function of moisture content.Compensation theory was confirmed, with linear relationship between enthalpy and entropy and higher values of isokinetic temperature (TB=395.62 K) than harmonic temperature. Water adsorption was considered driven by enthalpy, clarifying the mechanisms of water vapor sorption in cassava bagasse.

SUMMARY:This work reports a complete characterization of buriti oil. Physicochemical properties were determined according to AOCS methodologies and thermophysical properties were measured using a controlled stress rheometer and a digital electronic density meter. β-carotene and tocopherol contents were obtained using HPLC systems. Fatty acids and acylglycerol classes were determined using GC and HPSEC systems, respectively, while triacylglycerol composition was estimated using the software PrOleos. Thermal behavior (crystallization and melting) was analyzed using a DSC. The results attested high levels of total carotenoids with β-carotene as the major one; total tocopherols contained α-and β-tocopherols which accounted for 91% of the total; and monounsaturated fatty acids were mainly represented by oleic acid. The results showed close agreement between density and viscosity of buriti and olive oils. The crystallization and melting peaks occurred at -43.06 °C and -2.73 °C, respectively. These properties enable Buriti oil to be recommended as an excellent alternative for enriching foods with bioactive compounds. KEYWORDS: β-carotene; Carotenoids; Monounsaturated fatty acid; Oleic acid; Tocopherols; Triunsaturated triacylglycerolsRESUMEN: Parámetros de calidad y comportamiento térmico del aceite de buriti (Mauritia flexuosa L.). En este trabajo realiza una completa caracterización del aceite de buriti. Las propiedades fisicoquímicas se llevaron a cabo de acuerdo con las metodologías AOCS y se midieron las propiedades termo-físicas usando un reómetro de esfuerzo controlado y un medidor de densidad electrónico digital. Se obtuvieron los contenidos de β-caroteno y tocoferol utilizando HPLC. Los ácidos grasos y las diferentes clases de acilgliceroles se determinaron utilizando GC y HPSEC, respectivamente, mientras que la composición de triacilglicéridos se estimó utilizando el software PrOleos. El comportamiento térmico (cristalización y fusión) se analizó utilizando un DSC. Los resultados ponen de manifiesto altos niveles de carotenoides totales con β-caroteno como mayoritario, tocoferoles totales, con α-y β-tocoferoles que representan el 91% del total, y ácidos grasos monoinsaturados representados principalmente por ácido oleico. Hay una estrecha relación entre la densidad y la viscosidad del aceite de buriti y las de los aceites de oliva. Los picos de cristalización y de fusión se dan a -43,06 °C y -2,73 °C, respectivamente. Estas propiedades permiten que el aceite de Buriti sea recomendado como una excelente alternativa para enriquecer alimentos con compuestos bioactivos.

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The current worldwide energetic situation implies in researches about new resources and technologies capable of producing biofuels, such as the peanut processing residues. To design operations associated to bioethanol processing, understanding material properties, as density and rheology, is necessary. In this study, peanut shells were firstly chemically characterized, showing 37.1% cellulose, 33.4% hemicellulose and 15.0% lignin. Aqueous acid suspensions of powdered peanut shell were prepared and their physical properties were determined. Rheological parameters and density could be correlated with solid content and temperature by exponential and quadratic equations, respectively, while pH did not present significant effect on these parameters. Dilute suspensions showed Newtonian behavior, but at concentration above 8% (w/w) of solids, a non-Newtonian behavior was observed, showing yield stress and shear thinning. By evaluating the relative viscosity behavior with increasing solids concentration, Farris effect was also evidenced in suspensions above 8% of solids due to the presence of fine particles. Such result indicates the possibility of processing peanut shells for biofuel production in solids concentration higher than 10%, without a significant influence on viscosity.

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

The study of sugar release kinetics is an essential step prior to developing new technologies for applying in the bioethanol industry. To this end, the kinetics of reducing and total sugar release (extraction/hydrolysis) from artichoke waste were obtained in different conditions to evaluate the solubility of free sugars from raw matter and the hydrolysis of larger chain molecules separately. Thus, experiments of extraction with water (WE), hydrolysis (HY) in acid solutions and a conventional industrial hydrolysis (IHY), which combines dissolution and hydrolysis effects, were carried out. All of the treatments were studied with ultrasound application (US) or with conventional agitation (AG). Compared to AG experiments, US application accelerated the sugar dissolution reducing 50% the time to reach the equilibrium. The decrease in the biomass concentration in the suspensions increased the US effects in HY experiments. In IHY experiments, US was also able to enhance the final yield of sugars achieving relative reducing sugar and total sugar amounts 213% and 175%, significantly higher than AG experiments. The rheological changes in the suspensions during treatments can explain the different magnitude of ultrasound effects. The acoustic field characterization and the measurement of viscosity in the acid suspensions agreed with these results.

-The benefits of high-intensity ultrasound in diverse processes have stimulated many studies based on biomass pretreatment. In order to improve processes involving ultrasound, a calorimetric method has been widely used to measure the real power absorbed by the material as well as the cavitation effects. Peanut shells, a byproduct of peanut processing, were immersed in acidified aqueous solutions and submitted to an ultrasonic field. Acoustic power absorbed, acoustic intensity and power yield were obtained through specific heat determination and experimental data were modeled in different conditions. Specific heat values ranged from 3537.0 to 4190.6 J·kg -1 ·K -1 , with lower values encountered for more concentrated biomass suspensions. The acoustic power transmitted and acoustic intensity varied linearly with the applied power and quadratically with solids concentration, reaching maximum values at higher applied nominal power and for less concentrated suspensions. A power yield of 82.7% was reached for dilute suspensions at 320 W, while 6.4% efficiency was observed for a concentrated suspension at low input energy (80 W).

Drying of orange seeds representing waste products from juice processing was studied in the temperatures of 40, 50, 60 and 70 °C and drying velocities of 0.6, 1.0 and 1.4 m/s. Experimental drying kinetics of orange seeds were obtained using a convective air forced dryer. Three thin-layer models: Page model, Lewis model, and the Henderson-Pabis model and the diffusive model were used to predict the drying curves. The Henderson-Pabis and the diffusive models show the best fitting performance and statistical evaluations. Moreover, the temperature dependence on the effective diffusivity followed an Arrhenius relationship, and the activation energies ranging from 16.174 to 16.842 kJ/mol. Index terms: Dehydration; diffusive model; Henderson-Pabis model; moisture content. RESUMOA secagem de sementes de laranja que representam produtos residuais do processamento de suco foi estudada nas temperaturas de 40, 50, 60 e 70 °C e velocidades de secagem de 0,6, 1,0 e 1,4 m/s. As cinéticas de secagem experimental de sementes de laranja foram obtidas utilizando um secador de ar forçado por convecção. Três modelos de camada fina: modelo de Page, modelo Lewis, e o modelo de Henderson-Pabis e o modelo difusivo foram utilizados para prever as curvas de secagem. Os modelos de HendersonPabis e difusivo mostraram o melhor desempenho adequado e avaliações estatísticas. Além disso, a dependência da temperatura na difusividade efetiva seguida a relação de Arrhenius, e as energias de ativação variam entre 16,174-16,842 kJ / mol. Termos de indexação:Desidratação; modelo difuso; modelo Henderson-Pabis; teor de umidade.