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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