No abstract

Mastering the process of drying the palm heart (Jomare) requires knowing their isothermal sorption. The purpose of this work is the experimental determination of the palm heart sorption isotherms. the gravemitric method of saturated saline solutions is used at three different temperatures (40, 50 and 60 °C) with a water activity extending from 0.067 to 0.85. The equilibrium was obtained after about 10 days. Four mathematical models have been used (LANGMUIR, GAB, modified BET and Peleg) to model and predict hygroscopic behavior during drying and storage. After smoothing and optimization of these models on the basis of the statistical processing of the obtained data, the results shows that the GAB and modified BET models best match the sorption isotherms. The isosteric desorption heats for the heart of palm are calculated using the Clausius-Clapeyron equation. Through this study, an expression has been proposed that allow the prediction of the thermodynamic properties of the palm heart. The results of this research can be used to determine characteristic drying curves and to have optimal storage conditions.

The equilibrium water content of a product to be dried is essential during a forced convection solar drying and storage operation. These values are often taken from the so-called isothermal sorption curves. The isotherms determination is an essential step to know the distribution and the intensity of the water connections in the products. They make it possible to determine the products final water content to be reached in order to optimize the drying conditions and give valuable information on the hygroscopic equilibrium. As a result, this experimental study aims to determine the physicochemical components' and the desorption isotherms curves for deferent date type L'hmira, Bamakhlouf and Tegazza from the Touat region, in SouthWest Algeria, using the saturated salt solution method. The experiment is carried out for three temperature values 40 ° C, 50 ° C and 60 ° C, to study the influence of the temperature on the equilibrium curves of the product and finally to describe the isothermal moisture desorption for deferent date types for three temperatures using known models of GAB, SMITH, LANGMUIR and OSWIN.

The fresh tomato is a very perishable product in arid regions for that the drying is an indsipendable technique to preserve this product and used at all times, in this study the fresh tomatoe was sampled from different farms in Adrar and subjected to the drying method using an indirect dryer solar. The dried tomatoes were screened for microbiological and physicochemical analysis including E. coli, Staphylococcus aureus, Salmonella Typhi, anaerobic sulfito- redactors, molds and yeasts in addition, the value of pH, water activity, dry matter, and assay of ash. The obtained results showed the presence of mesophilic aerobic total bacteria, and coliform total, the absence of Salmonella Typhi, Staphylococcus aureus, Clostridium perfringens and spores of anaerobic sulfito reducting and some colonies of yeasts, for the pH value, activity water, dray matter and assay of ash, the results were (4.10), (0.41), (9.63%) and (5.71%) respectively, which do not affect the final quality of the dried products and satisfactory to norms imposed by the commercial legislation of Algerian. On the other hand, the isothermal sorption is indispensable step to mastering the process of drying tomatoes, and to know the distribution and the intensity of the water connections in the products as a result, this experimental study aims to determine the physicochemical components' and the desorption isotherms curves for tomato harvested from the Touat region, in South-West Algeria, using the saturated salt solution method. The experiment is carried out for three temperature values 40℃, 50℃ and 60℃, to study the influence of the temperature on the equilibrium curves of the product and finally to describe the isothermal moisture desorption for tomato product for three temperatures using known models of GAB, GAB, modified BET who showing the best models isotherms sorption to model at and predict hygroscopic behavior during drying and storage. The results of this research can be used to determine characteristic drying curves and to have optimal storage conditions.

During a forced convection sun drying and storage operation, the equilibrium water content of a product to be dried is critical. These figures are frequently derived using isothermal sorption curves. The calculation of isotherms is a necessary step in determining the distribution and intensity of water connections in products. for that this paper concentrates on the experimental determination of the adsorption-desorption isotherms for various temperatures (40, 50, and 60℃) of the Nicotiana Tabacum L plants. From which we had established the relationship between the water activity and the water content in the product. However, the aforementioned determination was carried out by the static gravimetric method. Eight saturated salt solutions have been utilized in applications such as (KOH, KCl, MgCl2, MgNO3, K2CO3, BaCl2, K2SO4, and NaCl). Hygroscopic equilibrium was completed after 13 days for temperature 40℃, 11 days for 50℃, and 9 days for 60℃. The overall experimental sorption curves are summarized by six models (HENDERSON, modified HALSEY, OSWIN, GAB, modified BET, and PELEG). The sorption isotherms built using the Clausius–Clapeyron equation were used to determine the net isosteric temperatures of desorption and adsorption of Nicotiana Tabacum L. The results for the adsorption-desorption isotherms found are type III according to IUAPC. Following the smoothing of the experimental results by different used models, it was found that the models of GAB and Peleg allow having the lowest mean relative errors and correlation coefficient.