In the drying process of fruits and vegetables, the spe […]
In the drying process of fruits and vegetables, the speed of Freeze Dry Machine plays an important role in the quality of dried fruits and vegetables. What will affect the drying speed when fruits and vegetables are dried? When the other conditions are the same, the faster the drying speed, the better the quality of dried fruits and vegetables. Of course, the drying speed is also limited by other factors, such as temperature, humidity, air flow rate, and characteristics of fruits and vegetables.
1. Temperature and relative humidity of dried fruits and vegetables
The temperature and humidity of the drying medium determine drying speed. The higher the drying temperature, the lower the humidity, the faster the water evaporates, and the faster the drying speed. However, for some products, the temperature is too high, but it will form a reaction, affecting the quality. Conversely, with is low temperature, the drying time is prolonged, and the product is prone to oxidative discoloration or even mildew. According to the relevant experiments, for higher water content, the drying temperature can be maintained higher, and later adjustments should be made, combined with internal and external diffusion. For fruits and vegetables with low water content, it is not advisable to use excessively high temperatures to avoid splitting, coking, and crusting of the epidermis. Different temperatures are chosen for different fruits and vegetables, generally 40-90°C. Suitable equipment for drying at this temperature are: belt dryer, dehydrated vegetable dryer, hot air circulation oven, new oven, vacuum dryer.
2, Air Flow Rate
The air flow rate is large, and the fruits and vegetables dry quickly. Some fruits and vegetables need to increase the wind speed, and the drying time is shortened accordingly, and the quality is good.
3. Types and status of fruits and vegetables
The variety of fruits and vegetables differs in physical properties and structure, and the drying speed is different under the same conditions. According to the evaporation amount, moisture, color, etc., it is generally possible to slice, diced, and cut the difficult-to-dry materials to obtain better quality and optimum drying speed.
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