Page 42 - FoodFocusThailand No.189 December 2021

SMART PRODUCTIONON
SMART PRODUCTI

Drying Technology

for Food and Beverage Industry

Drying technology is an integral part of agricultural products processing and manufacturing. This technology
helps extend the shelf life, reduce economic losses, and add value to food products.

Virtually all food has some water, but the amounts vary. Food that safety, but it can also enhance management and operation efficiency.
contains high water content can lose their quality more easily, therefore Dried food is light in weight and volume resulting in lower operating
reducing the amount of water or moisture content is an alternative to cost, easy storage, and convenience for transport and use. The
preserve quality and ensure food safety. Selecting the right drying process process can add value and increase variety of products to provide
will have a positive impact on the final product. consumers with more options. However, there are limitations in drying
Drying process is a method to preserve food by reducing or removing technology that manufacturers should be aware of. The key concern
moisture content from raw materials to slow down product spoilage. Water is that drying methods can cause changes in structural, chemical
causes food deterioration and physical change, as water activity influences composition, and nutritional values of food, such as case hardening,
chemical and enzymatic reactivity as well as microorganism growth, shrinkage, and loss of colors and vitamins. Therefore, it is necessary
which results in faster spoilage. Controlling the water activity or aw value to choose a drying technology that is suitable for each raw material
of a food assists in prevention of food product deterioration and and the desired final product to ensure that it has comparable quality
identification of shelf life as well as food safety. Generally, the food products to the original.
can be classified into three groups by the water activity -- fresh or
perishable food (aw > 0.85), intermediate moisture food (aw = 0.6-0.85), Important factors affecting product quality
and dried food (aw < 0.6). The water activity below 0.6 is free from certain 1. Food structure Is the major parameter that influences the
pathogenic microorganisms. The drying mechanism involves two different drying rate. Porous or fibrous food, especially vegetables, have a
ways of water movement. When food is exposed to heat, the water comes faster drying rate because cellular water can move through the gaps
out of cells and move through intercellular spaces to the surface. Then, between cell structures. While water in complex food containing
the water on the surface evaporates into the air, causing the food to have protein, starch, sugar, and minerals will bond with those food
lower moisture content. The final moisture content of dried food products components and hence is harder to dry. However, there are many
should be within 12-14% of the total weight. pretreatment methods before drying raw materials to reduce
The three drying processes commonly used are 1) traditional sun processing time and improve product quality, such as blanching and
drying by using solar radiation to heat up and increase water evaporation soaking in sulfite solution.
of the food, 2) the hot air drying process is done through control of 2. Size, shape and weight The raw material should be prepared
temperature, airflow, and humidity of the system and 3) the freeze-drying in the same size and shape, especially solid food, to ensure a similar
method uses low temperature to preserve and maintain the quality of drying rate. Small and thin food allows faster heat and mass transfer
food product. than large and thick food, so evaporation is more efficient.
Drying technology can be applied to various food such as fruit, 3. Drying condition The drying condition is related to various
vegetable, cereal, meat, liquid, and slurry food. The dried food products factors including temperature, pressure, air velocity, and relative
are shelf stable and can be stored for more than one year at room humidity which must be controlled at an appropriate level to obtain
temperature. The drying process is not only beneficial in terms of food standardized food products. If the drying temperature is too high, it

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