Spray Drying vs Freeze Drying

Spray drying vs freeze drying — spray drying

Working principle:Spray drying machine
The working principle of spray drying is to disperse the material to be dried into very fine mist-like particles (to increase the evaporation area of the water and accelerate the drying process) through mechanical action and contact with the hot air to remove most of the water in an instant so that the solid matter is dried into a powder.

Advantages:

Advantages of spray drying — retain the taste, color and nutrition of food

Spray drying is often the last step in the manufacturing process. It is through continuous spraying, mixing and drying to change the substance from liquid to powder. Among the many food storage technologies, the spray drying method has its unique advantages. Because the temperature used by this technology is not very high, while removing microbial contamination, it can still effectively retain the taste, color and nutrition of food.
This is a comparison table of nutrients of spray-dried pumpkin powder and fresh pumpkin:
Fresh pumpkin Spray-dried pumpkin powder.

Fresh pumpkinSpray-dried pumpkin powder
Moisture88.9%4.5%
Protein1.3%12.8%
Fat0.1%0.6%
Cellulose1%5.1%
Carbohydrate7.9%71.2%
Ca17mg/100g17mg/100g
Fe0.4mg/100g4mg/100g

Advantages of spray drying — change substance’s size, shape, and density and improve quality

Spray drying machine is usually used to remove moisture from raw materials. In addition, it has many other uses, such as: changing the size, shape or density of the substance, it can help add other ingredients in the production process, and help produce the most stringent quality products.

Advantages of spray drying — reduce food weight and make it easy to carry or transport

The production of fruit and vegetable powder by spray drying can retain the nutrients of fresh fruits and vegetables, and the volume has been reduced by 70%, which is easy to eat and transport.

Advantages of spray drying — remove toxicity of some foods

Some plants require a certain temperature to remove toxicity. For these plants, the spray drying technology is ideal. Taking soybeans as an example, the concentration process requires a certain temperature to remove a substance called trypsin inhibitors(this substance will hinder digestion and decomposition of protein).

Spray drying vs freeze drying — freeze dryingvacuum freeze drying machine

Working principle:
Freezing water-containing materials below freezing point, turning water into ice, and then turning ice into steam under high vacuum. The material can be frozen in the freezing device before being dried. However, it can also be frozen directly in the drying room by quickly drawing into a vacuum. The water vapor generated by sublimation is removed by a condenser. The heat of vaporization required in the sublimation process is generally supplied by thermal radiation.

Advantages

Advantages of freeze drying — keep substances’ biological vitality

Freeze-drying is carried out at low temperatures, so it is particularly suitable for many heat-sensitive substances, such as proteins and microorganisms. These substances will not be denatured or lose biological vitality.

Advantages of freeze drying —small loss of volatile components

When drying at low temperature, the loss of some volatile components in the substance is very small, suitable for drying some chemical products, medicines and foods.

Advantages of freeze drying — keep the original characters

During the freeze-drying process, the growth of microorganisms and the action of enzymes cannot be performed, so the original characters can be maintained.

Advantages of freeze drying — maintain the volume and structure

Because it is dried in a frozen state, the volume is almost unchanged, the original structure is maintained, and concentration does not occur.

Advantages of freeze drying — long shelf life

Freeze drying can remove more than 95-99% of the water, so that the dried product can be stored for a long time without deterioration.

Spray drying vs freeze drying — conclusion

Spray drying and freeze drying are used in different situations. There is no final conclusion on which one is better. As have mentioned, spray drying is suitable for plants that require high temperatures to remove toxicity, but there are plants of which the nutrients will be lost due to high temperature. For these plants, vacuum freeze drying machine is more suitable.