M.A. Thesis:

optimization of mango drying by combined osmo-ultrasound and coating with Plantago psyllium Gum

Because Mango has high humidity and little shelf life, using appropriate methods such as drying for increasing shelf life is necessary. The use of hot air for drying food is a common way, although it has bad effects such as color changing, hard texture and reducing the quality final products. In this study, the effect of using osmotic dehydration, ultrasound and edible coatings as a pretreatment, before drying process, to improve the taste of the product, reducing thermal damages and reducing tissue water and ease of mass transfer has been studied. The samples of mango with a thickness of 10 mm has been cut and then the effects of coverage factors with psyllium hydrocolloid with a concentration of 1% and 2%, rock candy syrup osmotic solution with a concentration of 40%, 50%, 60%, the use of the ultrasound treatment (25kHz) on water decreasing, absorbing of solid materials, weight loss ,shrinkage, water recoating,acidity, pH, vitamin C, sugar and the color of samples examined. The results showed that with increasing concentration of osmotic solution, as well as the concentration of covering, the amount of water loss and solid gain increases. It also the use of ultrasound, the rate of sugar, acidity, wrinkles and changes the color of mango fruits have significantly decreased. Vitamin C, pH and water recoating increased. Keywords: drying, mango, psyllium hydrocolloid, osmotic, ultrasound

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