Efecto de la temperatura sobre los parámetros termodinámicos de la isoterma de GAB y calor isostérico en harina de linaza (Linum usitatissimum)
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2025
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Universidad Nacional de Trujillo
Abstract
Determinar las isotermas de sorción de humedad es importante para predecir cómo un producto interactuará con la humedad ambiental y temperatura, lo que permite optimizar procesos de secado, garantizar la estabilidad y vida útil del producto, diseñar estrategias de almacenamiento adecuadas, mejorar la calidad y seguridad, y formular productos que mantengan su integridad bajo diferentes condiciones climáticas. En tal sentido, esta investigación tuvo por objetivo evaluar el efecto de la temperatura sobre los parámetros termodinámicos de la isoterma de GAB y calor isostérico en harina de linaza (Linum usitatissimum). Para ello se acondicionaron ambientes con actividad de agua entre 0.1 y 0.9 en los cuales se dispuso las muestras de harina de linaza hasta alcanzar una humedad de equilibrio constante en las temperaturas de 20 y 40 °C. Los datos de humedad de equilibrio experimentales fueron ajustados con el modelo de GAB obteniendo un r2 y error medio relativo alrededor de 1 e inferior del 10 %, respectivamente. El calor isostérico fue determinado a través de la ecuación de Clausius-Clapeyron. Los resultados mostraron que las isotermas de la harina de linaza exhiben una configuración tipo II en la clasificación de Brunauer. Se observó que, al incrementar la temperatura para una misma actividad de agua, la humedad de equilibrio disminuye. El valor de monocapa (X0) de la harina de linaza fue de 0.0503 y 0.0448 g H2O/g m.s. a 20 y 40 °C, respectivamente. La constante C fue de 8.2723 y 5.9069 y la constante K de 0.9617 y 0.9742 para las temperaturas de 20 y 40 °C, respectivamente. Por su parte, el calor isostérico (Qst) en la harina de linaza bajó de 61.17 kJ/mol a 20 °C, hasta 56.96 kJ/mol a 40 °C. El análisis estadístico mostró que la temperatura ejerce efecto estadísticamente significativo sobre los parámetros X0, C, K y Qst en las isotermas de la harina de linaza.
ABSTRACT Determining moisture sorption isotherms is crucial to predict how a product will interact with ambient humidity, allowing for the optimization of drying processes, ensuring product stability and shelf life, designing appropriate storage strategies, improving quality and safety, and formulating products that maintain their integrity under different climatic conditions. In this sense, this research aimed to evaluate the effect of temperature on the thermodynamic parameters of the GAB isotherm and isosteric heat in linseed flour (Linum usitatissimum). To this end, environments with water activity between 0.1 and 0.9 were conditioned in which the linseed flour samples were placed until reaching a constant equilibrium humidity at temperatures of 20 and 40 °C. The experimental equilibrium humidity data were adjusted with the GAB model obtaining an r2 and relative mean error around 1 and less than 10 %, respectively. The isosteric heat was determined through the Clausius-Clapeyron equation. The results showed that the isotherms of linseed meal exhibit a type II configuration in the Brunauer classification. It was observed that, as the temperature increases for the same water activity, the equilibrium moisture content decreases. The monolayer value (X0) of linseed meal was 0.0503 and 0.0448 g H2O/g d.m. at 20 and 40 °C, respectively. The C constant was 8.2723 and 5.9069 and the K constant was 0.9617 and 0.9742 for the temperatures of 20 and 40 °C, respectively. On the other hand, the isosteric heat (Qst) in linseed meal decreased from 61.17 kJ/mol at 20 °C to 56.96 kJ/mol at 40 °C. Statistical analysis showed that temperature exerts a statistically significant effect on the parameters X0, C, K and Qst in the isotherms of linseed flour.
ABSTRACT Determining moisture sorption isotherms is crucial to predict how a product will interact with ambient humidity, allowing for the optimization of drying processes, ensuring product stability and shelf life, designing appropriate storage strategies, improving quality and safety, and formulating products that maintain their integrity under different climatic conditions. In this sense, this research aimed to evaluate the effect of temperature on the thermodynamic parameters of the GAB isotherm and isosteric heat in linseed flour (Linum usitatissimum). To this end, environments with water activity between 0.1 and 0.9 were conditioned in which the linseed flour samples were placed until reaching a constant equilibrium humidity at temperatures of 20 and 40 °C. The experimental equilibrium humidity data were adjusted with the GAB model obtaining an r2 and relative mean error around 1 and less than 10 %, respectively. The isosteric heat was determined through the Clausius-Clapeyron equation. The results showed that the isotherms of linseed meal exhibit a type II configuration in the Brunauer classification. It was observed that, as the temperature increases for the same water activity, the equilibrium moisture content decreases. The monolayer value (X0) of linseed meal was 0.0503 and 0.0448 g H2O/g d.m. at 20 and 40 °C, respectively. The C constant was 8.2723 and 5.9069 and the K constant was 0.9617 and 0.9742 for the temperatures of 20 and 40 °C, respectively. On the other hand, the isosteric heat (Qst) in linseed meal decreased from 61.17 kJ/mol at 20 °C to 56.96 kJ/mol at 40 °C. Statistical analysis showed that temperature exerts a statistically significant effect on the parameters X0, C, K and Qst in the isotherms of linseed flour.
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