Turning Liquids into Granules – Spray Drying vs. Spray Granulation in Nutraceutical Processing

Most people are familiar with the production of milk powder by spray drying. But when it comes to nutraceuticals, the requirements go far beyond simple drying. Here, also the precise control of particle size, structure, and functionality matters – raising the question of which technologies are best suited to meet these more demanding applications.

The transformation of liquid formulations into stable, free-flowing granules is a critical operation in nutraceutical manufacturing. Technologies such as spray drying and spray granulation in a fluidised bed are widely used to achieve this goal. The choice of technology depends on the particle characteristics required for the specific application.

author: Gudrun Ding, Head of Business Development New Technologies, Process Technology Food, Feed & Fine Chemicals, Glatt Ingenieurtechnik
originally published at www.process-worldwide.com, April 7, 2026, (Vogel Communications Group)

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Why Convert Liquids into Granules?

The industrial drying of solids-containing liquids offers several advantages:

Improved stability and extended shelf life
Reduced weight and volume, lowering transport, storage, and handling costs
Room-temperature storage capability
Enhanced handling and dosing characteristics

Especially for nutraceuticals, depending on the activity of the residual moisture left in the dried product, removing water with heat can help to extend its shelf-life.

What is Spray Drying?

Spraying liquids into a hot air stream (spray drying) is an ideal way to dry them quickly. This process has been used for decades to produce large-volume mass products such as milk powder both efficiently and economically. As well as being a high-throughput process, spray drying works well for liquids with a low solids content; this is because comparatively high process temperatures can be used.

Large amounts of water can be evaporated while sensitive products are protected because of the low cooling temperature. However, the high dust content of the products made in the spray tower can be a disadvantage. With enzymes or other proteins, for example, these often highly effective allergens can be problematic – even at low concentrations when finely distributed.

SEM image of cut granulates with microencapsulated oil

Particle formation in the process of spray granulation

Spray-granulated particles with an onion structure

What is Spray Granulation?

Spray granulation in a fluidised bed takes the basic concept of spray drying to a new technological level and offers targeted solutions for a wide range of materials, applications, and industries. The key advantage, compared with spray drying, is that the product properties in the fluidised bed process can be precisely adjusted. Depending on the process parameters and the configuration of the plant, particle shape, structure, and size can be defined within broad tolerances. This is enabled by combining two process steps: convective drying or solidification and particle formation. Particle sizes of 50 µm to 2 mm can be produced with relative ease. Spray drying is limited to particle diameters of approximately 10 µm. These then have to be agglomerated in subsequent steps to achieve larger grain sizes.

How Fluidised Bed Spray Granulation Works

The process involves several simultaneous mechanisms:

Spraying and drying: The liquid feed is atomised into the fluidised bed. The solvent – usually water or an organic solution – evaporates, leaving solid material that forms layers on existing particles.
Particle growth (layering): Droplets deposit on particle surfaces, forming concentric layers and increasing particle size.
Nucleation mechanisms: Internal nucleation: Fine particles are generated by abrasion or by droplets that dry before contacting the bed (overspray); External nucleation: Recycled fines or milled oversized particles are reintroduced into the system.
Continuous particle size control: Oversized and undersized fractions are separated, milled if necessary, and returned to the process, ensuring steady-state operation.

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Glatt Continuous Granulation and Coating by Fluidized Bed

Spray Drying vs. Granulation vs. Microencapsulation

A key difference between spray drying and fluidised bed spray granulation lies in particle size and morphology: in spray drying, the individual particles are dried from the outside in, whereas in fluidised bed spray granulation, the structure is built up layer by layer and the particles dry in the opposite direction (from the inside out). Only when spraying melts and pure suspensions does spray drying produce solid spheres.

As soon as the liquid contains a dissolved component, hollow spheres of various shapes are produced. The hot air stream in which the spray droplets dry causes the particle to be wrapped in a hard outer shell with a high concentration of the dissolved component. At the same time, the particle core still contains moisture. As the temperature rises, this escapes and produces hollow spheres or dents in the particles (depending on the drying speed and solids concentration of the liquid).

In certain fields of application, such as the microencapsulation of active ingredients, these particle properties are unsuitable. Microencapsulation aims to enclose liquids in the particle’s core and protect them from environmental conditions.

Advantages of Fluidised Bed Technology

Continuous fluidised-bed spray granulation in a multi-chamber plant enables several process steps to be combined. In theory, a rectangular fluidised bed plant can be constructed to any length. This allows different product properties to be adjusted in successive process zones to produce tailor-made particles. In a customer project, Glatt’s process engineers produced highly soluble, powdery particles from a hydrolysed protein solution using a fluidised bed in an upstream spray-drying step.

In later steps, these were agglomerated until higher-density particles were produced that sank better and, thus, dissolved faster and more completely than spray-dried products. Although spray granulation has mainly been used to produce compact particles, such as for enzymes or fertilisers, the targeted adjustment of product properties from finely soluble granules to compact particles in a single process presents new horizons for liquid spray drying.

Glatt spray drying+agglomeration in the fluidized bed: Several processes in one step for improved solubility of proteins

Fluidised bed spray granulation processes enable tailor-made solutions for a wide range of material systems, applications, and industries

Comparing Spray Drying and Spray Granulation

Feature	Spray Drying	Spray Granulation
Particle Size	~ 10 µm	50 µm – 2 mm
Process Steps	Drying only	Drying + granulation
Particle Control	Limited	Highly adjustable
Dust Formation	High	Low
Temperature Exposure	Higher	Lower
Downstream Processing	Often required	Usually reduced

Customised Plant Design and Process Parameters

Multi-chamber fluidised bed systems can spray from above or below. Intermediate drying and cooling steps are both possible, and/or subsequent cooling can be done in the same apparatus. In addition, fluidised bed spray granulation systems for handling organic solvents or oxidation-sensitive products can be operated in a closed-loop environment.

protein product, spray dried by Glatt fluid bed technology, REM

Fluidised bed spray granulates (left) compared with the same product from a conventional spray drying process (right)

protein product, spray dried in a spray tower, REM

Onion-shaped structure in an amino acid granule

Spray Granulation: Ideal for Sensitive Nutraceuticals

Spray granulation involves the layer-by-layer formation of solid, compact spheres with an onion-like structure. This layering facilitates flexible and complex product design; particles can be formed from different layers of solid material, and cores can be loaded and coated. This enables manufacturers of nutraceuticals, for example, to functionalise their products in a targeted manner and add value. In addition, spray granulated particles can be coated in the same apparatus to achieve a retardant effect, protect the active component from external influences or mask an unpleasant taste or odour.

Fluidised bed spray granulation is particularly suitable for sensitive nutraceuticals, such as when converting emulsions or oils into very compact particles. Owing to their smaller surface area compared with spray-dried products, nutraceuticals are better protected against oxidation than in powdered agglomerates. In addition, the lower process temperatures compared with spray drying enhance product stability.

Glatt Ingenieurtechnik Develops Custom Plants

With experience in this field, Glatt Ingenieurtechnik develops fluidised bed plants tailored to each customer’s product. Laboratory trials and pilot tests are a central component of process and product development in fluidised bed spray granulation. As such, the company closely monitors every project from initial development work to plant construction, commissioning, and process acceptance at the customer’s site.

Further information on this topic and related topics can also be found in the following publications:

Glatt. GFC 16 - Glatt fluidized bed system for continuous fluid bed coating on a pilot scale

June 2024: GFC 16 closes the gap for fully continuous coating on pilot scale

Glatt technical article on ''How to safely stabilise vitamins and probiotics'', published in the trade magazine 'foodeurope', issue 01/2017, Hoskins & Fall Publishing

Published article: ‘Hot-melt applications for the food and beverage industry – How to safely stabilize vitamins and probiotics’ PDF, English

Glatt article on ''Drying liquids - Selecting the best technology for nutraceuticals'', published in the magazine 'Nutraceutical Business Review', issue 05/2022, HPCi Media Limited

Published article: ‘Drying liquids – Selecting the best technology for nutraceuticals’ PDF, English

Glatt advertorial on the topic ''With short time-to-market from process development directly to contract manufacturing", originally published in the Pharma+Food-Kompendium 'Produzieren im Kundenauftrag', Edition 2023, Hüthig GmbH, Glatt reprint

Published article: ‘With short time-to-market from process development directly to contract manufacturing’ PDF, English Reprint

Glatt technical article on 'How to Tame Recalcitrant Ingredients with Technological Processes'

Published article: ‘How to Tame Recalcitrant Ingredients with Technological Processes’ PDF, English

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Turning Liquids into Granules – Spray Drying vs. Spray Granulation in Nutraceutical Processing

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