Jackfruit as an Object of Drying: A Hygroscopic Study

Statics of drying is based on the laws of interaction between the gas medium and the dehydration facility, which seek a thermodynamically equilibrium state. Jackfruit is a wet thermolabile material. With a static equilibrium between the product and the environment, the water content in a hygroscopic state depends on the type of the product, its energy, humidity, and a number of parameters, e.g. temperature and partial pressure of the vapor on the surface. The paper introduces graphical dependences of the activity of water of jackfruit slices on humidity at various ambient temperatures. The authors also give its analogy in semilogarithmic coordinates. It helped to define a range of humidity that determined the type of connection between the moisture of the object and the dry residue. The laws of the mechanism of heat and mass transfer are relevant in determining the dynamics of the dehydration process. Their study can help to intensify the process of moisture removal with rational operating parameters. The present study featured the equilibrium states in the system, which made it possible to find the driving force of moisture transfer and to evaluate the heat carrier potential, as well as to substantiate the values of the parameters and the environment during storage and transportation of the finished dry product. The value of relative moisture content in equilibrium was determined by isothermal sorption curves. The value depends on the pre-treatment of the drying object, the conditions of its contact with the external environment, as well as by the energy and type of relationship between the dry residue and the moisture. The empirical results were arranged in the form of graphical dependences, which made it possible to theoretically obtain their mathematical approximation. The equations of dependence between the equilibrium moisture content of the material and the relative humidity of the vapor-air medium included a lot of constants, which also needed to be determined empirically. The mathematical dependences approximate the isothermal sorption curves, i.e. the relationship between the product's moisture and water activity indices. The dependences can be used to conduct a thermodynamic analysis of the sorption process and determine the free, bound, and internal energies of the process of moisture absorption by the capillary-porous object of study. The hygroscopic examination of jackfruit is also necessary when making design decisions for the rational implementation of technological operations, including the storage and transportation of dry jackfruit slices.