بررسي تاثير پيش فرآيند اسمزي بر ويژگي هاي بافتي و ريزساختاري گوجه فرنگي خشك شده با هوا

Study on the Effect of Osmotic Pretreatment on the Structural and Microstructural Properties of Air-Dried Tomato

Tomatoes (Roma cultivar) picked up for the study were obtained from Varaminelocal market. Each tomato was divided into four portions. Quarter portions of tomato were placed in osmotic solutions thatwere different in levels of sucrose andNaCI (30and40% for sucrose, and 5, 10 and 15% for NaCI). Osmotic dehydration was carried out for varied time durations from 15 up to 240 min. Temperature of dehydration process was kept constant at 30±2°C. Ratio of tomato to solution was 1:IO. Themixture wasagitated by use of an agitating system of 150 rpm. Two osmotic solutions of specified concentration and treatment times werechosen, following a determination of water loss vs solid gain for all the treatments. Samples dehydrated with these (5% NaCI+40% sucrose or 10% NaCI+40% sucrose) solutions werethen dried in a hot air dryer. Finally, dried samples were analyzed for their texture and microstructure by employing instron and scanning electron microscope (SEM) respectively. Comparing the osmosis treated samples with non-osmosed ones demonstrated that applying osmotic pretreatment caused a softening of structure. It reduced the shrinkage of dried product by restraining the rupture of productʹs cellular structure.