# Evaluation of Design Parameters on Drying of Kiwi Fruit
## 1 Introduction  
Since agricultural products produced in large quantities are not immediately consumed, the durability times are very short. Keeping these products fresh is possible as a result of some special operations. Drying is the leading of the processes that intended to extend the economic life of agricultural products without losing their nutritious properties during the time elapsed until the moment of consumption of the products. Drying is defined as a method of industrial scale protection with heated air to reduce water activity by reducing the water content of fruits and vegetables and thus minimize biochemical, chemical and microbiological degradation [1]. Drying is a process in which 80-95% of water within the agricultural products is reduced to 10-20% and maintained for a long time. However, the quality characteristics such as taste, appearance, color, nutritional value should be changed as little as possible and when the water is added on them for cooking, they should be able to absorb the water as close as to the amount they had when they were fresh. Drying of kiwi fruit is often followed by physical and chemical changes which dramatically influence the process itself. One of the most important consequences of these changes is shrinkage: a volume reduction, coupled with shape and porosity changes and hardness increase. Such phenomena could also be followed by surface cracking. Therefore, shrinkage has to be avoided because such physical changes contribute in general to reduce the quality perceived by the end consumer of dehydrated products, traditionally consumed fresh. Obvious exceptions are represented by foods, like dried plums and dates, usually eaten shrunken. The drying process itself is actually a heat and mass transfer phenomenon and drying agricultural products with solar energy has been used from ancient times to present as a method of product storage. The quality of food is drastically reduced in the solar drying due to rain, dust that wind causes, dirt and contact of various creatures such as insects and flies. Overcoming these problems is possible when the drying process is carried out in the designed closed systems. In the drying processes in natural environments, long periods of drying, the product being vulnerable to environmental influences and the decrease in nutritional value cause loss of quality and economic value in products. For this reason, the drying process with artificial dryers that have special purposes not only shortens the drying time but also ensures to get a higher quality and clean product with a long shelf life. Drying of a wide variety of fruits and vegetables is provided with artificial dryers; for instance, apricots [2], bananas [3], apples [4], potatoes [5], onions [6], eggplant [7], pear [8] are only some of the vegetables and fruits dried in artificial dryers and analyzed for drying. In this study, the kiwifruit is analyzed for drying and it is a fruit species grown in different regions of Turkey. Kiwifruit contains 80% water, 20% dry matter and is rich in vitamin C. 100-400 mg of vitamin C is found in 100 g of the said fresh fruit [9]. Vitamin C content is an important factor that makes kiwifruit a worthy and sought-after fruit. The proportion of vitamin C in the fruit varies according to environmental conditions, the state of development and maturation, and even where the fruit is situated on the plant [9]. The mineral content values of kiwifruit are shown in Table 1[9]. The kiwi fruit is used to obtain fruit juice and is consumed freshly. Additionally, it is used in the food industry for making pastry and dessert. Besides the nutritional value of kiwifruit, it is also used in medicine. Analyzes in China have shown that certain substances in fruit juice prevent factors that cause cancer. When used in combination with certain medicinal drinks, it has been utilized as breath spray against asthma and cough [10; 11; 12; 13].