What Is Spray Drying Used For?

Spray drying is a remarkably versatile process, transforming liquid raw materials into high-quality dry powders across diverse industries, from food and pharmaceuticals to chemicals and advanced materials. This technique offers precise control over product characteristics, enabling manufacturers to design specific properties into their final output.

Designing Particle Shape and Size

An important aspect of spray drying is the ability to influence the final particle shape and size. We can control various input parameters:

• Solution Concentration: How much solids is in your liquid
• Drying Gas Flow: How fast the hot air is moving into the oven
• Inlet Temperature: How hot the air is when it enters the oven
• Spraying Gas Flow: The pressure used to atomize the liquid
• Feed Rate: How quickly the liquid is introduced

By adjusting these, we can achieve different particle characteristics. Particle size has a great correlation with the original size of the solution droplet from the atomizer.

Drying Without Damaging

The drying process taking place in a spray chamber can quickly cool down the particles and produce a dried powder without burning, denaturing or damaging the material with the high heat usually present in other drying methods. This can be used on fragile materials such as proteins, food ingredients and organic materials.

Fermented Products, Proteins and Organic Materials

Spray drying is highly beneficial for fermented products and proteins, offering a gentle yet effective drying method. It rapidly transforms liquid cultures or solutions into stable powders, preserving the delicate structures and functionalities.

For fermented products, this means maintaining the viability of probiotic cultures or the activity of enzymes, crucial for their effectiveness in food, feed, or pharmaceutical applications. For proteins, it minimizes denaturation and aggregation, ensuring their biological activity, solubility, and structural integrity are largely retained.

The resulting powders are easier to handle, transport, and store with extended shelf life, while also allowing for precise control over particle size and morphology.

Catalysts and Minerals

Spray drying is a highly effective method for drying minerals and catalysts by converting liquid slurries or solutions into dry, uniform powders.

For minerals, spray drying is used to dry concentrates like iron, copper, or zinc ores, producing powders that are easier to handle, transport, and suitable for further processing steps like smelting or refining.

For catalysts, it's crucial for producing uniform spherical particles with controlled porosity and surface area, which are vital for their activity and efficiency in chemical reactions. The benefits include rapid drying times, production of highly consistent particle size and morphology, and enhanced product quality and stability.

Encapsulation - Controlled Release of Flavors and Fragrances

Spray drying is currently the most prevalent process used to encapsulate flavors and fragrances, entrapping a core within an edible shell material like starch, carbohydrate, gelatin, or gum. This process protects volatile components and enables controlled release.

Surface Modification

Spray drying offers a precise way to modify particle surfaces. This involves adding surface-active components to the liquid feed. As droplets rapidly dry, these agents move to the surface, forming a distinct, engineered layer on each particle.

This tailored surface can provide various functionalities: enhancing dispersibility, enabling controlled release, improving stability against degradation, or achieving taste masking. Adjusting drying parameters like temperature and atomizer type further refines particle morphology and surface roughness.

Agglomeration/Granulation in Food Powder Production

Spray drying is also used to agglomerate food powders, starting from native liquid raw materials. Fine droplets are sprayed and mixed with hot dry air. Sticky, semi-dried particles collide with dry fine particles (often recycled from separation), forming stable, porous agglomerates.

This is especially good for producing "instant" properties in products like infant formulas, milk powders, and soluble coffee.

Microencapsulation for Probiotics

While historically spray drying had limited use for probiotics due to high temperatures causing viability losses, there's intense activity in this area. Success has been achieved by partially drying in the spray dryer and finishing on a fluid-bed dryer, adding protective compounds, or adapting the cells before drying.