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Drying Red dates

Drytech heat pump dryer use for drying red dates

As a traditional healthy food of Chinese people, red dates contain a plenty of nutrients. Fresh red dates are edible, but most of them are dried up and are directly eaten by consumers as a dried cleaning-free fruit. In addition, the growing areas are relatively centralized, and most of fresh red dates are harvested in autumn almost at the same time, and serve the whole market. For the sake of storage, transport and selling, the fresh red dates have to be rinsed, dried, cooled, softened, sterilized and packed.
Applications of DRYTECH dryer in drying red dates
What is the most important to cure red dates is to dry them up. The drying process is composed of evaporation of water and sugar conversion on the premise of maintaining the original quality of red dates as far as possible. Red dates abound in sugars. Among them, polysaccharide is not sweet, and becomes sweet only after inverted into simple sugars by the function of the biological enzyme. It is the reason why cured red dates is sweet. If we want to invert sugars fully, we need to strengthen the activity of biological enzyme. After a long time of practices, we have found the right temperature at which the complete conversion can be achieved is about 60°C.

How to dry red dates with DRYTECH dryer
Preheating: If we directly put red dates in the environment where the temperature is suitable for sugar inversion, the cell orifice in the skin will shrink and their crust will become hard, preventing water from evaporating because the extreme temperature difference makes red dates set off the protective reaction. First, preheat the cabinet completely on a gradual basis to evaporate most of water; and dry red dates at 35°C for 6-10 hours. When the temperature of red dates reaches 45°C, that is, your finger feels hot when touching it, dry them for 7-8 hours. After that, use your finger to press the red date and its skin wrinkles. When the temperature is at 45-48°C, there will be some small water drops on their skin.

Evaporation: Raise the temperature to 65°C (Note: the temperature shall not be higher than 70°C) within 8-12 hours to evaporate most of free water. Removal of moisture contributes to water evaporation. Keep the indoor temperature stable for constant evaporation. The drying process goes well in case the skin wrinkles.
Drying up: When the temperature in the red date is well-distributed, this phase will end within 6 hours. In this phase, moisture content of red dates is not high, and thus more attention shall be paid to temperature control. It is better that the temperature is held at 50°C. At this moment, the humanity has been reduced. If the humanity is higher than 60%, dehumidify a little. Water in red dates become balanced, and red dates are dried well. Note that the dried red dates shall be taken out in time
Cooling: Keep good ventilation and heat dissipation for dried red dates. Pile them up until being cooled. If the dried red dates are just taken out from the cabinet, and directly piled up in the warehouse, their sugars will ferment and go bad, and the pectose will be broken down into pectin and pectic acid due to high heat. Red dates become very soft, and some acid threads are available due to change of sugars. Therefore, don’t store dried red dates after they are cooled completely.

The drying effect

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