Page 43 - FoodFocusThailand No.189 December 2021

SMART PRODUCTION

can cause changes in appearance, color, and nutrition. Moreover, in one minute or less, depending on the types of food and rotation speed.
the amount of food in each batch must be measured appropriately The dried material is scraped off by a scraper knife.
and the food should not be stacked or overlapping to ensure 5. Freeze dryer The principle of a freeze dryer is to reduce the product
consistent heating. temperature so that the moisture content is changed from liquid to solid or

Seven industrial drying machines for food and ice crystal. Then, the process reduces the pressure to allow frozen and
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beverage production bound water to sublimate at a temperature equal to or lower than 0 C.
1. Tray dryer Is an enclosed chamber used for batch processes. Freeze-dried food still maintains most of its flavor, nutrition and texture
compared to heat drying and hence is suitable for food with distinct smell
It is mainly used for drying solid small to medium food. The dryer and texture such as herbs spices, and fruit.
consists of trays for raw material stacking on shelves with spaces 6. Fluidized-bed dryer Uses high air velocities to float materials
between them. Heat is supplied to a tray dryer by circulated hot air throughout the drying period. The airflow applied is in the range of 0.05-0.75
at between 60–80 C. The temperature can be adjusted to match
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the size, shape, and density of the food. Normally, the duration of m/s to control the raw materials at a proper level. Small solid food can move
freely in the hot airstream; therefore, the outer area is exposed to hot air
a batch is around 2-10 hours. This machine is common for fruit and and creates rapid water evaporation. This machine is commonly used for
vegetables drying. granular or powder materials around the size of 0.05-10 mm. like grains,
2. Spray dryer Are often used for drying liquid or solutions into
powders. The liquid is sprayed in small droplets and exposed to hot nuts and coffee beans.
7. Vacuum dryer Removes moisture from the product by reducing the
air to create rapid water evaporation within 1-2 minutes. The final pressure to a vacuum condition to create water evaporation at low
spray-dried product is in light powder form. This system provides temperatures. This method can preserve nutrition and some volatile
high production capacity and is suitable for beverages such as milk, substances; therefore, it is suitable for materials that are sensitive or can
tea, coffee, and creamer. easily deteriorate in heat.
3.Tunnel dryer Consists of a series of continuous processes.
The wide range of drying technologies available has resulted in
Raw materials are evenly spread on trays in a truck or trolley. These developments of various new food products. It caters to the needs of modern
loaded trolleys move through a hot air tunnel for approximately 10 consumers who crave convenience and speed amid a fast-paced lifestyle.
hours until the moisture content is at a specified level and then the Apart from stemming new food innovations, drying technology helps increase
trolley moves out of the tunnel. The direction of air movement can processing efficiency, reduce limitations, and solve agricultural issues present
be designed for various applications such as having the trolleys and
the air moving in a co-current, counter-current, and mixed current in the food industry. In this era of rapid technological change, application of
drying technology is crucial to ensure food products with good quality.
flow. This dryer can be used with products in sheets or chunks.
4. Drum dryer Consists of a rotating horizontal metal cylinder
heated by steam inside at the temperature of 120-155 C.
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Concentrated liquid is fed at the top of the roller while heat is More Information Service Info C006
transferred from the roller to the food. This method can dry the liquid

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