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Wet or dry? – A question of philosophy

Simple, residue-free cleaning of bulk material components

ZRD Hygienic Plus rotary valve of Coperion
Coperion's ZRD Hygienic Plus rotary valve - best access from both sides


Production systems must be cleaned regularly to satisfy the stringent requirements of the food industry. The cleaning method – whether dry or wet – is often a question of philosophy. Both have advantages and disadvantages and each must be customized to suit the individual product requirements.

Dry cleaning is a suitable process for products with low internal moisture content. These are products that normally do not become contaminated with micro-organisms or mold or which are soon thermally treated after conveying. Dry cleaning is also used if the same product is always produced in the same plant or line and cross-contamination with other products is not possible. For the advocates of dry cleaning the advantages are obvious - if a plant is kept completely dry, as a consequence the microbiological risks are low. The decision as to whether frequent or only occasional dry cleaning is necessary depends on the product characteristics. The design of the component can be simpler than for wet cleaning. However, in all cases the bulk material components must be easily accessible, quick to dismantle and suitable for manual dry cleaning. In response to these requirements Coperion developed the WYK bulk material diverter valve, the ZRD Hygienic Plus rotary valve and the ZXD Hygienic Plus blow-through valve. All three have now been certified by the European Hygienic Engineering & Design Group (EHEDG), especially for dry cleaning (ED certificate).

With wet cleaning the use of liquid cleaning media makes it possible to clean components so thoroughly that they are absolutely free from residues. This is particularly important, for example, when producing flavors. Wet cleaning requires the use of materials that are resistant to the cleaning media. In addition, all areas in which liquid could be retained (such as seals) must be designed without dead zones or are at least freely accessible and easy to dismantle (COP = Cleaning Out of Place). Coperion supplies special components for wet cleaning that do meet all these requirements and feature a particularly smooth inner surface.

Since many components such as bulk material diverter valves are often installed in locations that are not easily accessible and where manual cleaning would be complicated and expensive, the trend is moving towards fully-automatic CIP wet cleaning (CIP = Cleaning In Place) so that the equipment can be cleaned without having to dismantle and open the components after every washing process. System operators are urgently advised to only use CIP components that have been certified, as this ensures that they can be cleaned fully automatically and are completely free from contamination. Coperion was the first manufacturer to launch rotary valves and diverter valves for CIP cleaning on the market several years ago that were certified by the EHEDG to "EL Class I". The ZRD-CIP discharge and conveying rotary valve, the ZFD-CIP blow-through valve and the WYK-CIP bulk material diverter valve are made of high-quality materials and have an outstanding, smooth-surface design without recesses and dead zones. The advantages of fully-automatic CIP wet cleaning will ensure that this method will gradually win through in the industry. For a long time CIP was still in its initial stages, as there were hardly any suitable components available. In the meantime, however, important key components are available in the form of Coperion's range of CIP rotary valves and diverter valves.

Your contact:
Jochen Sprung, Tel.: +49 751 408 584, e-Mail

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An important decision early in the equipment design process

Cleaning procedures for feeders

View into the bowl of a Coperion K-Tron screw feeder
View into the bowl of a Coperion K-Tron screw feeder

Choosing the right cleaning procedure is mandatory for feeders as well – to ensure minimal downtime for cleaning and product changeover, and to ensure that the entire feeding system is completely cleaned and safe. The correct cleaning method can make production of food more economical without sacrificing food quality or food safety.

Feeder designs can be tailored to a variety of cleaning procedures, including high-hygienic wet cleaning, and high or basic hygienic dry cleaning procedures. The optimal cleaning procedure is highly dependent upon the type of material being fed, the process requirement and environment. In addition, many food manufacturers are developing or utilizing cleaning protocols that avoid any wet cleaning. In these cases, feeding systems that include interchangeable product contact modules with quick-disconnect clamps, which allow for quick and easy changeover between product runs, may be preferable.

In cases where wet cleaning is acceptable, the use of retractable spray balls can be incorporated into the feeder hoppers and material contact components. When requesting these types of designs, the end user should also request that the feeding system manufacturer provides confirmation of cleaning via riboflavin testing. This testing provides assurance to the end user that all product contact surfaces are sufficiently wetted during cleaning. Finally, in some situations, different surface finishes and stainless steel grades must be reviewed for materials in contact with certain food products to make sure they prevent the start of microbial growth.

For this reason, it is imperative that detailed cleaning requirements be discussed in depth between the feeder system supplier and the food processor, as some hygienic requirements may be overkill for the design of the process, thus making the design cost inefficient. It is also important to note that regulatory design standards which apply to cleaning may differ between countries, such as between the United States and Europe. US standards, like USDA or 3A, focus on construction and design, while European standards, like EHEDG, focus on validation tests providing cleanability.

Due to the variety of options available, discussions regarding cleaning must be held early in the equipment design process. For example, during the request for quote and project definition stages, open communication between the food manufacturer and feed-system supplier to discuss all options available for cleaning and product contact accessibility are key. By designing these features into the system at the forefront of the project stage, many of the issues which occur due to contamination and subsequent food safety can be avoided.

Your contact:
Sharon Nowak, Tel.: +1 856 256 3119, e-Mail

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Wide varieties of vegetable raw materials

HMEC for high-grade meat substitutes

Texturiated meat-like product
Meat-like products that have a fibrous, meaty structure resulting in flavor and texture profiles similar to chicken, pork, beef or even fish
Prepared end product
Typical example for high-grade meat substitutes: completely vegetarian marinated chunks with a tasty meat flavor

Plant-based products are in demand for many reasons. Some people want to reduce the amount of meat they consume or completely cut it out for ethical reasons. Others see tofu and similar products as a useful addition to their diet. For a long time, tofu was the only alternative to meat. However, the structure and strong unique taste of soybean curd is very different from the desired “meat taste experience”. By using extrusion technology today it is possible to produce meat-like products that have a fibrous, meaty structure resulting in flavor and texture profiles similar to chicken, pork, beef or even fish.

Coperion has worked together with the German Institute of Food Technologies (DIL), Quakenbrück, Germany, for quite some time. One focus of the cooperation is the further development of high-moisture extrusion cooking of textured protein concentrate into a vegetarian meat substitute. Within this process the moisture content exceeds 50% (up to 70% in individual cases), which is comparable with the moisture content of lean meat. Developed up to production levels in the meantime, this high-moisture extrusion cooking process can be used for the production of meat substitutes featuring desirable sensory properties from raw plant materials with high protein content such as wheat, soy, pea and lupine flours protein concentrate. Decisive factors here are the process of protein denaturation in the extruder and the control of the downstream cooling and fibrillation process in the special cooling die, the length of which may considerably exceed that of the extruder process section.

This high amount of water is added to the vegetable protein directly after the feeding into the extruder. Further ingredients, such as minerals, fibers and flavors, can be added during the extrusion process. The substitute obtained through extrusion are semi-finished products that are then subsequently processed into different end products, typical examples are fried nuggets, marinated chunks or salad toppings – all completely vegetarian but with a tasty meat flavor. The combination of vegetable and animal proteins (meat, poultry, fish, etc.) as starting materials is likewise possible with high-moisture extrusion cooking.

Your contact:
Stefan Gebhardt, Tel.: +49 (0)711 897 3048, e-Mail

NAFTA contact::
Ed Beecher, Tel.: +1 201 512 3509 , e-Mail

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Smart solutions for the handling of bulk materials

Coperion und Coperion K-Tron at Powtech 2014

Powtech 2014

At this year’s > Powtech exhibition (Nuremberg, Germany, Sep 30 - Oct 02, 2014) we present ourselves as the comprehensive technology provider for the handling of powders, granules and a wide variety of other bulk materials. On our booth 363 in hall 4 next to the IBP 250 Integrated FFS Packaging Machine, we show our entire range of bulk material and process components in a totally new and innovative digital form. In addition the new Microfeeder family, the T35/S60 Quick Change Feeder and the principle of operation behind SFT Weighing Technology will be presented.

We look forward to your visit!


Coperion’s intelligent FFS Packaging Machine IBP 250
Coperion’s intelligent FFS Packaging Machine IBP 250
Microfeeders MT16 and MS12 of Coperion K-Tron
Microfeeders MT16 and MS12 of Coperion K-Tron
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