Experimental Measurement of Isothermal Sorption, Microbiological and Physicochemical Analysis of Dried Tomatoes Cultivated in Adrar, Algeria

摘要

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°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 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.