In southern China, Lichee has the title of “fruit king”. Due to its unique shape, red peel, glittering pulp, sweet and rich taste, and medicinal value, it is widely loved by people. Because lychee is a tropical fruit, it is as heat-sensitive as other tropical fruits. Therefore, as long as the lychee is picked from trees, it must be preserved immediately and sent to the markets all over the country for sale. Because the time of fresh lychee preservation is too short, if it is not sold out in time, it will cause waste, which will cause great economic losses for the fruit farmers.

“Because lychee ripens mainly in the hot season, some of its substances are different from other fruits. For example, Its phenolic content is high. At the same time, unlike other fruits, its protein amino acid content is also very high, as well as its sugar content. It is because of the rich content of these substances, lychee is delicious. Besides, these substances will cause a lot of Biochemical Reactions.” said from the Researcher of Guangdong Academy of Agricultural Sciences.

The biochemical reactions will shorten the preservation time of the fresh lychee. In order to prevent the fresh lychee from being unsold and wasted, fruit farmers have found a method to make the dried lychee after a long time exploration. Setting up a kiln or a coal-fired furnace and drying the fresh lychee. Finally, the dried lychee was made. Although this method can retain the aroma and taste of lychee, the drying temperature cannot be accurately controlled and drying time depends on the experience of the fruit farmers. The quality of dried lychee is difficult to guarantee. There are even hidden dangers of food safety. Although the dried lychee can be preserved for a longer time, the quality and safety of dried lychee cannot be guaranteed because of the drying process.

In a laboratory of the Guangdong Academy of Agricultural Sciences, the researchers used the IKE laboratory dryer to experiment with the method of making lychee. They hoped to find a way to maintain the taste of the dried lychee and precisely control its quality accurately. Because the structure of lychee fruit has three layers, it is very important to control the drying time and temperature to dry the middle pulp. In drying, not only the pulp but also the kernel should be dried. If the kernel is not dry enough, moisture in the kernel will permeate into the pulp, making the pulp moist and soft, which is prone to mildew.

The drying curve of lychee is different from that of other fruits. First, we need to understand the law of water migration, then we can know how to dry on the basis of the law. We set a temperature for lychee, which is the best temperature for drying. After a period of drying, we pull it out of the drying machine and moisture regain to realize lychee rehydration in the drying process." said the researcher.

Through continuous experiments, the researchers matched the drying time and temperature to the best condition. In a food processing factory, workers are using this new drying technology to process a batch of lychee. The dried lychee not only has soft and waxy meat but also retains the fragrance of fresh lychee. At the same time, it realizes environment-friendly and energy-saving production.