Propiedades Termodinámicas e Isotermas de Sorción de Sales con Interés Alimentario

Abstract

Autor a quien debe ser dirigida la correspondencia _____________________________________________________________________________________________________________________________________ ResumenEl objetivo del presente trabajo fue determinar las curvas de humedad de equilibrio de sales comúnmente utilizadas como sustitutos de NaCl en la elaboración de alimentos, modelar su comportamiento de sorción y determinar parámetros termodinámicos como el calor isostérico y la entropía de sorción. Se utilizó la técnica gravimétrica a temperaturas de entre 5°C y 45°C, en el rango de actividad acuosa (Aw) entre 0,1 -0,9. Las curvas obtenidas se modelaron con siete ecuaciones y se determinó el calor isostérico neto de sorción y la entropía de sorción para cada sal. Con el modelo de Caurie se obtuvo un buen ajuste, lo cual permitió determinar que la humedad de seguridad (Xs) presenta fuerte dependencia con la temperatura, al igual que la entropía de sorción para las sales estudiadas, mientras que el calor isostérico presenta comportamientos diferentes en función de la sal y la humedad de equilibrio Xw. Palabras AbstractThe aim of present study was to determinate experimentally the curves of equilibrium moisture of salts usually used like replacers of NaCl in elaboration of food, modeling their sorption behavior and determining their thermodynamics parameters of isosteric heat and sorption entropy. The gravimetric technique was used at temperatures between 5 and 45 °C, within the range 0.1 to 0.9 of water activity Aw. The curves obtained were modeled with seven equations and net isosteric heat and sorption entropy were estimated for each salt. Good fitting was found using Caurie's model which allowed to stablish that safety moisture (Xs) depends on temperature as well as on entropy for all the studied salts, while net isosteric heat shows different behaviors depending on the salt and on the equilibrium moisture (Xw).

Shelf‐life study of a Salicornia ramosissima vegetable salt: An alternative to kitchen salt

“…The value of Q st is therefore related to stability since the lower the Q st the easier the adsorption–desorption processes occur, that is, the more unstable the product becomes. Guzmán‐Hincapié and Zapata (2018), reported the same behavior for NaCl and KCl and the opposite behavior for other salts (MgCl 2 , C 3 H 5 KO 3 , and CaCl 2 ). Sormoli and Langrish (2016) also reported that the increase in M e lowered the Q st in orange juice powder.…”

“…To construct this plot, a w values at different temperatures are required at constant moisture content. The relationship between M e and a w between each point was established by the best model that could be adjusted to the experimental data (Guzmán‐Hincapié & Zapata, 2018). …”

Prediction of storage stability parameters of spray dried powders of maltodextrins and corn syrups with different levels of hydrolysis (conversion)

“…Thermodynamic functions establish optimal storage and stability conditions. For example, the free energy necessary for the transfer of a water molecule, from the vapor state to the adsorbed state, is a quantitative measure of the affinity between the dry product and water and indicates the degree of spontaneity of the adsorption process (Guzmán-Hincapié and Zapata, 2018). The differential enthalpy of sorption is a differential molar quantity derived from the dependence of the temperature towards the isotherm, and represents the energies for the binding of water molecules at a particular hydration level, in contrast to the integral enthalpy, which is the average energy of all molecules already consolidated at that level (Schneider, 2013).…”

“…The minimum integral entropy is interpreted as the water activity in which a food product has the highest stability (Baptestini et al, 2020). This minimum occurs when strong bonds take place between the adsorbate (water) and the adsorbent (food) (Guzmán-Hincapié and Zapata, 2018).…”