Comparison of traditional drying methods and freeze dryer for drying fruits

Drying fruits is one of the oldest and most widely used methods of food preservation. This work not only reduces the volume of raw materials, but also its weight. This leads to cheaper transportation and increased shelf life, reducing food waste. The two main methods for drying fruits are the traditional method and the freeze dryer method. In the following, these two methods will be examined and compared: Traditional drying method This method involves drying the fruits using sunlight or hot air (such as using thermal dryers). In the industry, fans are used equally for hot air circulation. There is also heating equipment to increase the temperature inside the device. Trays are used as containers for keeping fruits and vegetables. To start the fruit drying process and use the fruit drying machine, it is necessary to observe the related details. To work with a fruit dryer, you need to know the temperature required to dry each product. The heat produced in the machine is at a level that removes moisture and does not cause food to be cooked. freeze dryer method In the freeze-dry method, after preparation, the fruits are placed on trays inside special freezers and cooled to 40 degrees below zero. Then, by placing the fruits in an air-free environment with vacuum pressure, 99% of the frozen water in the fruits liquefies into steam, evaporates and leaves the fruits. In this process, no heat is given to the fruits. In this way, the fruit does not change its shape much and the useful substances and vitamins in it are preserved more. General comparison Due to the simple equipment of the traditional method, this method is easier and cheaper and it is easier to access. But it is a time-consuming process that causes quality reduction and loss of color, taste and nutrients. Controlling temperature and humidity is very difficult and causes uneven drying or the growth of microorganisms. Since the freeze-dryer method has advanced equipment, it has a higher cost and energy consumption than the traditional method and requires an expert person to work with the machine, but the produced products maintain the original quality of the fruit by preserving the color, taste and nutrients. The reason for removing water is that it can be stored for a longer period of time. Also, the growth of microbes and enzymes is almost zero. Choosing the right method for drying fruits depends on the purpose of use, available costs and expected quality. If quality and preservation of nutritional value is a priority, the freeze-dryer method is a better choice. But if cost savings and simpler implementation are considered, the traditional method is more suitable.