Lemons are rich in vitamin C and are easily oxidized, so lemon slices that are left for a period of time will oxidize and turn black. With the increasing consumer demand for lemon tea tablets, the drying demand for lemon dried tablets is increasing. The traditional drying of lemon slices is mainly by burning firewood or coal or fuel oil. The temperature is not easy to control, and the drying temperature is high. The lemon slice itself contains sugar, and the dried lemon will turn black after coking, which affects the appearance of the dried lemon. and quality. In addition, burning wood, coal, and fuel oil will produce harmful pollutants such as waste gas and waste, which affect the environment and do not meet the requirements of food production. Moreover, some simple production workshops have potential safety hazards.
Air drying is energy-saving, environmentally friendly and safe, and is more and more popular in the market, but the problem of blackening after drying still exists, because in the drying process, high-temperature air flows through the surface of the material to achieve drying. For the purpose, after the lemon slices come into contact with the air, there will be an oxidation scene, which is unavoidable. In addition, the lemon itself contains sugar, and if the drying temperature is too high, it will coke, which will eventually cause the dried lemon slices to turn black. So, how to reduce the blackening of lemon slices has become a difficult problem faced by many dealers and customers?
The main reason for the blackening of lemon slices is oxidation, so the solution is to minimize the time it is in contact with the air and the oxygen content in the drying room when drying. At present, the drying equipment on the market is mainly divided into two types: high-temperature drying and dehumidification type and closed-type dehumidification and drying type. The form exhausts the moisture in the air, and at the same time enters the fresh air from the outside, so that the air in the drying room is continuously entering until the drying is over. Therefore, in the process of dehumidification and fresh air intake, the air in the drying room is constantly exchanged with the outside air, and the amount of oxygen will not be reduced due to the oxidation of lemon slices, which will accelerate the oxidation of lemon slices and eventually increase The phenomenon of blackening of lemon slices.
On the contrary, the closed dehumidification drying dryer is relatively closed, and the air in the drying room does not contact the outside world, so the lemon slices will not be exposed to oxygen, and the dried lemon slices will not turn black. This kind of closed dryer completely condenses the moisture in the hot and humid air into water through the refrigeration system in the drying room, so as to achieve the purpose of reducing the air humidity in the drying room.
To sum up, in order to avoid the blackening of lemon slices during the drying process, we recommend using a closed heat pump dryer to dry lemon slices.