M.A. Thesis:

: study effect of pre-treatment ٫ microwave and ozone drying with hot air on the physicochemical characteristics of the combination of osmosis-sensory features plum

Drying is one of the oldest methods for keeping foods by people. The traditional method of drying has several disadvantages, including the production of products with high microbial load, the necessity of using sulfur compounds, undesired color and appearance, lack of transparency and high wrinkling. Osmotic drying is a pretreatment, improving the nutritional, sensory and functional properties of foods. Given the many advantages and applications of osmotic drying, this method can be used for many fruits and vegetables and other food samples. Based on the researchers, the severity of the osmotic process depends on factors such as the type and concentration of materials dissolved in the solution, time of sinking, environment temperature, ratio of the solution to the foods, the shape and level of the foods. The osmotic dehydration process has been considered due to maintaining sustainability, creating high quality, modifying applied properties, and reducing energy consumption. In this research, fresh plums were washed and peeled. Before drying the samples, samples were immersed in osmotic solution at a concentration of 40 and 60% and at 120 and 160 minutes. After osmotic dehydration process, they were dried in dryer at 65 and 75 ° C for 2 and 2.5 hours. The amount of moisture, acidity, water reabsorption, vitamin C and antioxidant properties of the samples were investigated. The obtained results showed that by increasing the concentration of osmotic solution, vitamin C, acidity, water reabsorption percentage, and antioxidant properties increased. Additionally, by increasing the concentration of osmotic solution, the moisture content in plum significantly decreased.

Keywords: plum, osmotic, drying, physicochemical properties, antioxidant