07:39, 04/09/2023
Freeze drying is one of the advanced agricultural processing technologies that operates on the principle of complete dehydration to dry the product. In particular, products after undergoing freeze drying retain most of the nutrients, vitamins, flavors, colors...
During the COVID-19 pandemic, many types of agricultural products are stagnant, farmers are in a situation of heavy losses, which is one of the reasons why deep processing of agricultural products has become more urgent than ever. This is not only a matter of processing to extend the waiting time for consumption but also helps diversify products and increase the value of agricultural products. Among the solutions, drying is considered one of the most widely applied options for agricultural products. There are many drying methods such as: natural drying, high temperature drying, cold drying, freeze drying, etc. Of which, cold drying and freeze drying are being chosen by many agricultural product manufacturers.
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| Workers of Agricultural Products Processing Joint Stock Company No. 1 prepare to freeze-dry products. |
Freeze-drying and freeze-drying both help to retain the original flavor, color, and nutritional value of the finished product. However, freeze-drying does not retain the original shape of the product, while freeze-drying does.
Freeze drying is processed through stages, including: The stage of quickly freezing the product at a temperature of -30oC to -50oC. When the product is completely frozen, it will be transferred to a vacuum chamber to suck out all the air inside the drying chamber, creating a vacuum environment, the resistor will heat up to carry out the sublimation process, converting the ice in the product into gas. After that, the product is transferred to drying, completely removing the remaining water. The sublimation drying time is often extended to several tens of hours. Freeze dried products are crispy, not tough. In particular, these products can return to their original state by about 90% when soaked in water. On average, 100 kg of fresh products after processing will produce 30 kg of freeze dried products.
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| Before being put into the vacuum machine, the product must be quickly frozen at a temperature of -30oC to -50oC. |
Dried Agricultural Products Processing Joint Stock Company No. 1 (Krong Pac district) is one of the units that freeze-dry local products, such as durian, pepper, corn... According to Mr. Tong Van Hieu, the founding shareholder of the company, all high-value products are suitable for freeze-drying, such as bird's nest, pepper, cordyceps, fruits... This is a new direction in agricultural product processing to create convenient, easy-to-use products. Most freeze-dried products are expensive. Currently, at Dried Agricultural Products Processing Joint Stock Company No. 1, durian is sold at prices ranging from 1.8 million VND - 2.4 million VND/kg, corn is sold at 1.2 million VND/kg...
Meanwhile, N&H Agricultural Products Joint Stock Company (Buon Ma Thuot City) has also applied freeze-drying technology since 2021 to process local agricultural products. Over the years, the company's freeze-dried products such as durian, mangosteen, jackfruit, pepper, etc. have always received good feedback from customers. Currently, the company regularly exports about 10 tons of dried agricultural products to customers each month.
Ms. Nguyen Thi Huong, Director of N&H Agricultural Products Joint Stock Company, said that although investing in processing machinery using freeze-drying technology is expensive, the products are of good quality and ensure the safety of consumers' health. "Freeze-drying technology has been used for a long time, commonly used in food processing for astronauts. In Vietnam in recent years, this technology has been applied to process agricultural products, thereby creating conditions for local products to be classified and deeply processed, creating valuable, highly nutritious products," Ms. Huong said.
In addition, when products have good quality but their appearance does not meet the required standards in some domestic and foreign markets, freeze-drying technology will help consume a large amount of those products. It can be seen that freeze-drying is suitable for many types of local agricultural products and helps increase their value.
Dinh Hang
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