Research on Drying Nine Types of Fruits and Vegetables Using Far-Infrared Technology with Carbon Fiber Heating Tubes

Far-infrared devices utilize principles of structural chemistry and photochemistry to activate water molecules within fruits and vegetables, causing them to vibrate. This changes the aggregation state of the water molecules while combining heat radiation and other properties to facilitate the removal of moisture from the fruits and vegetables, thereby enhancing dehydration efficiency. Dehydrated fruits and vegetables are able to maintain their original color, aroma, and taste well. The advantages of far-infrared drying technology include short dehydration time, strong light penetration ability, good rehydration properties of materials, simple operation, low energy consumption, no pollution, and low investment.

The equipment used in the study was a small-scale device custom-designed by a company according to production needs, with a maximum input capacity of about 1kg. The maximum output power of the radiation source is 1000W. It uses specially made carbon fiber heating tubes. During drying, the intensity of irradiation can be adjusted by varying the distance between the lamp tube and the material. The upper and lower ventilation devices are used to remove moisture from the drying chamber and adjust the temperature inside, with an exhaust air speed of 0.3-0.4m/s.

The experiment involved various vegetables and fruits, including scallions, spinach, coriander, cucumbers, carrots, apples, pears, grapes, and cantaloupe. The method of drying involved initially washing the raw materials, removing unnecessary parts, slicing grains, and shredding vegetables. Materials with skins required peeling before slicing. During the experiment, the cut materials were evenly spread on the tray with a thickness not exceeding 5cm. The weight of the materials was periodically measured during the drying process until the desired moisture content was reached. The target moisture content was 16%-18% for fruits and 4% for vegetables.

Using carbon fiber heating tubes for drying fruits and vegetables, the moisture content dropped very rapidly at the beginning of drying. Vegetables typically lost about 60% of moisture within 45 minutes, and most of the moisture was removed from fruits within 60 minutes. After two hours, the rate of dehydration gradually decreased for both fruits and vegetables, while conventional hot air drying showed a slower decline in the drying curve and took longer, with apples requiring about 8 hours.

By measuring the drying speed of materials such as apples, pears, scallions, cucumbers, and coriander, it was found that sliced cucumbers dried the fastest, which is related to the material properties of cucumbers. Next were scallions, coriander, apples, and pears. Apples dried in a hot air oven served as a control, with a drying time of about 8 hours at 70°C. A comparative analysis of the nutritional components of the dried products showed that the equipment used a temperature below 50°C, hence the nutrients and flavor of the dried products were well preserved, and they had good rehydration properties, making them suitable for use in the fast food industry. Further analysis of the nutritional components of the dried experimental products revealed that the vitamin C in dried scallions was largely preserved using infrared drying, while conventional hot air drying at high temperatures resulted in a total loss of vitamin C. For other elements like Ca, Fe, and Zn, there was a varying increase compared to before drying.

When using carbon fiber heating tubes for drying fruit and vegetable purees, the nutritional components can be preserved to various extents by mastering drying techniques such as temperature and time. From the appearance of the products, it can be seen that chlorophyll, anthocyanins, and carotenoids in fruits and vegetables are well preserved. The dried slices of apples and pears also did not show any edge charring or yellowing, and there was no taste of baking or steaming.

However, the effects of drying some berry fruits like grapes with far-infrared were not very clear, though slicing the grapes could improve drying efficiency. However, since grapes cannot be effectively dried in slices, they are not suitable for drying with far-infrared radiation. The processing of raisins is referred to the high-temperature, low-humidity sun-drying technique used in Xinjiang, which is not detailed here.

We hope this detailed exploration into far-infrared drying technology for fruits and vegetables has been informative. At Global Quartz Tube, we specialize in innovative heating solutions tailored to enhance production efficiency. For more information and inquiries, please visit our vefsíðu eða hafðu samband við okkur á contact@globalquartztube.com.