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Infrared Drying systems for efficient thermal post-treatment of extrudates

The production of expanded extrudates (snacks, crispies, breakfast cereals) is already an efficient process. However, there is potential for optimization in post-treatment: the goal is to reliably reduce the moisture content, stabilize shelf life and texture, and at the same time reduce energy consumption, floor space, and process times.

Conventional hot air drying uses heated air as a heat carrier. While this method is robust it involves high recirculation volumes, long residence times, and heat losses – and requires correspondingly large production areas. Infrared drying takes a different approach, transferring heat directly to the product through radiation. In porous extrudates, the radiation reaches both the outer and inner surfaces of the open pores. Moist areas absorb the energy particularly well and immediately convert it into evaporation. This accelerates water removal, stabilizes the product surface through evaporative cooling, and ensures uniform drying to the desired final moisture content.

The Schaaf Solution: IR Drum Dryer

Schaaf technology relies on electrically operated short- and medium-wave infrared radiators for the post-treatment of extrudates. These radiators are mounted on a common frame and are directed precisely at the area with the highest product concentration. The spectral design ensures that the radiation safely couples with moist product surfaces – both externally and internally on the pore walls. The result is short drying times, homogeneous moisture profiles and consistent colour and texture. For desired roasting notes, power can be precisely increased; for particularly sensitive products, it can be gradually reduced.

The power of the IR-radiators can be adjusted seamlessly, allowing the energy flow to be precisely controlled — from gentle drying to a defined roasting finish, without any unnecessary overheating. The roasting/drying drum runs on low-noise support rollers and is fully enclosed in accordance with accident prevention regulations, to minimize energy loss. A special angled drum profile gently turns the product and ensures even irradiation. The drum speed is continuously adjustable and a discharge device, which can be adapted to the product requirements, defines the fill level.

The drive is a frequency-controlled three-phase geared motor. All parts that come into contact with the product are made of stainless steel or food-grade materials.

Thanks to smooth surfaces, cleaning and conversion are quick. For sugar-coated cereals, an anti-stick drum surface coating is available on request. In addition to single drums, Schaaf offers space-saving double drum systems for small and medium capacities. Here, the roasting and application drums are arranged one above the other, and the product is gently guided from a hopper into the lower drum, eliminating the need for a  separate transfer unit. This keeps the integration effort into existing lines low.

Physical Advantage – Without Detours

• Direct Effect: IR transfers heat without the detour through large air masses – the energy reaches exactly where it works: at the moisture.
• Uniformity: In porous extrudates, the radiation reaches many internal surfaces; together with controlled circulation in the drum, this creates a homogeneous drying pattern.
• Gentle on the surface: The heat consumed during evaporation keeps the surface temperature moderate, thereby reducing the risk of crust formation and over-browning, and enhancing texture and colour stability.
• Compact & scalable: IR drums require less floor space than bulky hot air systems and can be designed modularly.
• Electric & future-proof: Using green electricity to power the systems helps to reduce CO₂ emissions, and the lower process energy requirement reduces operating costs.

Fair Comparison – Simply Explained

• What counts? When it comes to energy comparisons, the decisive factor is energy per kg of evaporated water (SEC – Specific Energy Consumption, kWh/kg H₂O).
• Why IR? Direct absorption on moist surfaces and shorter process times lead in practice to lower SEC values than with pure hot air – at the same target final moisture.
• Advantages in the production line? More compact systems, stable product quality, and quick changeover capability increase overall efficiency for both savory snacks and breakfast cereals. Schaaf Technologie GmbH offers IR drum dryers with various throughput rates that - energy-efficient, hygienic, and compact.

 

 

Protein snacks with new TURBO tools

In recent years, numerous developments have been driven to texturize and “shape” protein-rich raw materials using the extruder. On the one hand, meat substitute products have been developed that, due to their consistency, represent vegetarian or vegan alternatives to meat dishes.

In order to reproduce the fibrous texture of meat as well as possible, long residence times are required, which are reserved for long-screw extruders.

On the other hand, the demand for alternatives to carbohydrate-rich extruded snacks, which are often viewed as disadvantageous from a nutritional perspective, is increasing.
With the introduction of TURBO extrusion technology, it was already possible to process pure pea or bean recipes on our extruders more than 30 years ago. However, acceptance among product manufacturers was not achieved for a long time because the price level was considered too high compared to the usual corn, rice or wheat recipes and the demand and profitability were considered too low.
Only higher-priced potato recipes were accepted and offered in the snack segment due to the beneficial potato aroma.
The increased nutritional awareness of consumers as well as the willingness to spend more money on nutrition and therefore also on healthier snacks has led to a significant increase in demand for protein-containing and high-protein snacks in recent years.
In order to be able to create recipes with a high protein content, the addition of protein concentrates is necessary, which consequently requires a higher proportion of water for homogenization in the extruder.

The reliable processing of protein concentrates was only possible to a limited extent with previous one- or two-stage TURBO process parts.

Only a new generation of TURBO tools has recently made it possible to realize three-, four- or five-stage turbo configurations, which, due to the increased mixing and kneading ability, achieve homogeneous doughs with higher energy inputs even with such demanding recipes.
Various protein sources can be used to produce textured protein snacks: pea, potato, wheat, rice and soy proteins can be processed with the newly developed TURBO tools, as well as animal protein sources.
With tasty spice variations you can make delicious “meatless” protein snacks like our “vegetarian kebab strips”.

 

 

 

Schaaf's new color printing process for snack extrudates

Direct expanded products such as cheese balls, onion rings or peanut flakes have a highly expanded, soft texture that has a loyal fan base.
In the snack sector, however, many consumers prefer crispier, harder crisps, tortilla or pretzel textures, which can be reproduced on Schaaf extruders with optimised dies and recipes as well as the thin-wall technology.
To achieve the desired visual appeal of the snacks, a colour made from natural raw materials is applied to the strand surface using a newly developed offset printing process.
The printing tools used are made of food-grade materials and can therefore be used without restriction.
The new printing process is particularly suitable in combination with the thin-wall technology introduced a few years ago and well established on the market.
Printed patterns of different lines, grids or dots now give the texturally convincing chip-like extrudates the finishing touch.
The same applies to normal strand extrudates, since the printing unit can be combined with all products that are further processed with a cutting or embossing machine.
In particular, it is able to print different strand widths with patterns.
After printing, the strands or thin-walled extrudates are further processed in a cutting or forming machine, dried and finally flavoured.

Soft Peanut Flips

Flips are already available in many different shapes: curved, straight, long, short – the super soft texture combined with a tasty peanut slurry makes this corn product particularly attractive.
The nozzle is available for all our extruder models.

Spoke wheel shaped snacks

We haven't reinvented the "wheel" - but we are proud of the extraordinary shape definition of this new generation of wheel nozzles, which can be used with a classic corn recipe, a tasty potato recipe or other recipe variants.
The nozzle is available for our extruder models 6400 and 9250.

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