Efecto de temperatura en propiedades termodinámicas de la isoterma de GAB en galletas a base de trigo (Triticum aestivum), tarwi (Lupinus mutabilis Sweet.) y espinaca (Spinacia oleracea)
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Date
2025
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Universidad Nacional de Trujillo
Abstract
Este trabajo de investigación se desarrolló con el objetivo de evaluar el efecto de temperatura en propiedades termodinámicas de la isoterma de GAB en galletas a base de trigo (Triticum aestivum), tarwi (Lupinus mutabilis Sweet.) y espinaca (Spinacia oleracea). Se analizó la composición proximal de las galletas, que mostró un alto contenido de proteínas (12.10 %) y lípidos (16.85 %), además de una baja humedad (4.26 %). Para la isoterma, se almacenó las galletas a humeades entre 0.1 a 0.9 durante 7 días. La determinación de la humedad de equilibrio fue por gravimetría. Se determinaron los valores de monocapa de la isoterma de adsorción utilizando el modelo de GAB a tres temperaturas (20, 30 y 40 °C), observándose una disminución en el valor de monocapa con el aumento de la temperatura, lo que indica menor capacidad de adsorción de agua a altas temperaturas. La clasificación de la isoterma de acuerdo con Brunauer reveló que las galletas presentaron un tipo II, característico de la adsorción de múltiples capas. Además, se calcularon los parámetros termodinámicos: calor isostérico de adsorción (36.59 kJ/kmol a 20 °C), entropía (16.94 kJ/mol.K), energía libre de Gibbs (negativa en todo el intervalo de temperatura) y área de adsorción, que mostró una disminución con el aumento de la temperatura. Los resultados subrayan la importancia de controlar las condiciones de almacenamiento para garantizar la estabilidad de las galletas. El análisis estadístico reveló influencia estadísticamente significativa (p < 0.05) por parte de la temperatura en las variables dependientes.
ABSTRACT This research work was developed with the objective of evaluate the effect of temperature on the thermodynamic properties of the GAB isotherm in cookies made from wheat (Triticum aestivum), tarwi (Lupinus mutabilis Sweet.), and spinach (Spinacia oleracea). The proximate composition of the cookies was analyzed, which showed a high content of proteins (12.10%) and lipids (16.85%), as well as a low humidity (4.26%). For the isotherm, the cookies were stored at humidity between 0.1 to 0.9 for 7 days. The equilibrium humidity was determined by gravimetry. The monolayer values of the adsorption isotherm were determined using the GAB model at three temperatures (20, 30 and 40 °C), observing a decrease in the monolayer value with increasing temperature, indicating lower water adsorption capacity at high temperatures. The isotherm classification according to Brunauer revealed that the biscuits presented a type II, characteristic of multilayer adsorption. In addition, the thermodynamic parameters were calculated: isosteric heat of adsorption (36.59 kJ/kmol at 20 °C), entropy (16.94 kJ/mol.K), Gibbs free energy (negative throughout the temperature range) and adsorption area, which showed a decrease with increasing temperature. The results underline the importance of controlling storage conditions to ensure biscuit stability. Statistical analysis revealed a statistically significant influence (p < 0.05) of temperature on the dependent variables
ABSTRACT This research work was developed with the objective of evaluate the effect of temperature on the thermodynamic properties of the GAB isotherm in cookies made from wheat (Triticum aestivum), tarwi (Lupinus mutabilis Sweet.), and spinach (Spinacia oleracea). The proximate composition of the cookies was analyzed, which showed a high content of proteins (12.10%) and lipids (16.85%), as well as a low humidity (4.26%). For the isotherm, the cookies were stored at humidity between 0.1 to 0.9 for 7 days. The equilibrium humidity was determined by gravimetry. The monolayer values of the adsorption isotherm were determined using the GAB model at three temperatures (20, 30 and 40 °C), observing a decrease in the monolayer value with increasing temperature, indicating lower water adsorption capacity at high temperatures. The isotherm classification according to Brunauer revealed that the biscuits presented a type II, characteristic of multilayer adsorption. In addition, the thermodynamic parameters were calculated: isosteric heat of adsorption (36.59 kJ/kmol at 20 °C), entropy (16.94 kJ/mol.K), Gibbs free energy (negative throughout the temperature range) and adsorption area, which showed a decrease with increasing temperature. The results underline the importance of controlling storage conditions to ensure biscuit stability. Statistical analysis revealed a statistically significant influence (p < 0.05) of temperature on the dependent variables
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Keywords
Galletas, Tarwi, Espinaca, Isoterma, GAB, Propiedades termodinámicas