Investigation of quality characteristics and drying oven in semi-dried frozen tomato production

Within the scope of the thesis study, semi-dry frozen tomatoes were produced by drying tomatoes in three different ways: in the sun, in the prototype oven and the industrial drying oven. In the drying experiments carried out in the prototype oven and the industrial oven, the tomatoes were not pre-treated except for washing. Salt was applied to a group of tomatoes by scattering method as a pre-treatment in sun-drying experiments. 1% sodium metabisulfite application was applied to the second group of tomatoes by spray method. A solution containing 1% citric acid and 0.25% ascorbic acid was applied to the third group of tomatoes by spraying method. The drying properties of tomatoes were observed in sun-drying and the prototype oven. In industrial type oven drying, the ability of the oven model, which is widely used in the market, to remove water from the product in the drying process has been tried to be determined. The highest brightness and redness values of the products obtained in the sun drying experiments were observed in tomatoes treated with sodium metabisulfite. The lowest brightness value was observed in tomatoes dried without pretreatment, and the lowest redness value was observed in tomatoes dried by applying salt. In industrial oven drying trials, air measurements such as temperature and humidity were taken from the oven inlet and outlet points, and hourly weight losses of the products were measured. The water removal capacity of the air used in drying and the water losses of the products were compared. In the light of the information obtained, it was observed that the drying process could not be carried out effectively when the oven was operated at normal capacity, the homogeneous distribution of air and temperature in the oven could not be achieved, and the humid air could not be sufficiently removed from the environment. When the furnace was operated at half capacity, it was observed that the theoretical water removal capacity and the measured weight losses were compatible. In light of the results obtained, it is thought that improvements should be made on the design of the industrial type furnace, which is widely used in our region. Key words: Tomatoes, semi-dried tomatoes, drying oven, semi-dried frozen tomatoes