How to Dry Longan/Dehydrate Longan in a Dehydrator

Jul 17, 2021

Introduction to longan：

Longan are nearly spherical, usually yellow-brown or sometimes gray-yellow, with a slightly rough outside, dark brown seeds, and shiny, all wrapped in fleshy arils. Longan is rich in glucose, sucrose, protein, etc., and has a relatively high iron content, which can increase heat energy and supplement nutrition.

Longan processing steps：

1. Select the fruit
Longan varieties used for baking and drying require large fruit, thick flesh, slightly thicker or moderately thick husk, and high sugar content in the flesh. Longan fruits made from Wulongling, Youtanben, Red Shell, Gemini, Chuliang, Wuyuan, etc. require full maturity and timely picking.
2. Cut the stem
After the fruit is sent to the processing plant, cut off the stalks one by one with flat-nose scissors, and cut them from the base of the stalks.
3. Immersion
The cut-stemmed fruits are put into a bamboo basket and soaked in water for 5-10 minutes to wash away the dirt on the fruit surface and make the shell soft, then lift up and drain the water to prepare for shaking.
4. Shake the sand and wipe the skin
Pour the soaked longan fruit into a special shaker cage, add fine sand and shake to remove the rough surface of the shell. The longan that has been shaken is easy to be dried and more uniform. The surface of the finished product is smooth and the color is beautiful.

Longan drying process：

Drying is carried out in two times, namely, primary baking and rebake. The key to the technology is to control the temperature and uniformity, and the turning baking should be timely and uniform. The initial baking takes about 24 hours, and the temperature is controlled at 65°C-70°C, so that the bottom longan husk will be heated and hardened quickly to avoid depression. After drying for 6 hours, perform the first roasting. The fruits are taken out in the upper, middle, and lower layers respectively, and placed in a bamboo basket, and then the upper and lower layers are reversed, the middle layer does not move, and then spread on the shed to continue drying. After 6 hours of drying, a second turn-bake is carried out. At this time, the middle layer is used as the bottom layer, the upper layer is used as the middle layer, and the lower layer is used as the upper layer. Roast for the third and fourth times every 4 hours. The third time was an exchange of upper and lower levels, and the fourth time was an exchange of two levels before and after. If it is turned only 3 times, it will be turned once every 6 hours, and the third and fourth turning operations will be combined, that is, the upper and lower layers are reversed on one side, and the front and back sections are reversed on the other. At this time, the first-baked excellent finished product has a hard outer shell, yellowish brown or russet flesh with oily finish, small wrinkles, easy peeling of the core, and pale white kernels.

Recommendation of longan dryer/drying machine

Commercial 100-3000kg/h large amount of dehydration wide application and easy operation

Heat pump drying machine use the principle of inverse Carnot cycle. It absorbs low-temperature heat energy in the air, which becomes high-temperature heat energy after efficient heat collection and integration by the heat pump system, and is transported to the drying room for cyclic heating and drying of materials.It refers to exhausting the hot and humid air in the drying room directly to the outside of the drying room through dehumidification device, and then replenishing natural fresh air.

Hot air circle drying machine belongs to high temperature heat pump unit. Its working principle is: the working fluid of the heat pump is compressed by the compressor, becomes high temperature and high pressure gas, enters the condenser, condenses and liquefies the heat, and is used for air heating in the drying room. The moisture in the material is vaporized and evaporated by the form of hot air, and the evaporated water vapor is discharged by the moisture discharge system, thereby achieving the purpose of drying the drying material.