Which hygienic design features are particularly important for powder mixers in infant formula production under EU GMP requirements?
In the manufacture of infant formula, particularly strict requirements apply to plant hygiene, contamination control and cleanability because of the highly sensitive target group. Powder mixers must therefore be designed so that microbiological, chemical and particulate contamination is effectively prevented and the relevant EU GMP and food law requirements are met.
Essential design features
Material selection and surface quality
Product-contact parts should consist of corrosion-resistant materials that comply with food law, typically stainless steel 1.4404 or of a higher grade. Smooth surfaces with low roughness that can be ground well reduce build-up and facilitate cleaning. Weld seams must be fully penetrated, ground and hygienically executed so that no gaps or dead spaces arise.
Dead-space-free and self-draining design
All product-contact areas should be shaped so that powder cannot accumulate in niches, gaps or undercuts. Self-draining geometries, flush discharge fittings and cleanly executed transitions are important so that product and cleaning residues can be removed as completely as possible.
Hygienic shaft seals and separation of the drive
Shaft passages are critical zones and must be hygienic, easy to monitor and reliably sealable. Separating the drive from the mixing chamber facilitates inspection and reduces the risk of contamination by lubricants or components that are difficult to clean.
Cleanability and validatability
The design must allow complete cleaning and disinfection, both dry and wet. Integrated CIP or WIP solutions, good accessibility for inspection and sampling and validatable cleaning procedures are decisive, particularly in order to minimise risks from Cronobacter or salmonella.
Sealing and connection technology
Connections in the product area should be hygienic, with few crevices and easy to inspect. Threaded connections in product contact are to be avoided; welded or hygienically clamped connections are preferable where they are executed cleanly and are completely cleanable.
Contamination protection and environmental control
The environment of the plant also plays a major role. Filtered process media, low-dust product feed and discharge, hygienically designed external surfaces and appropriate protection classes for electrical components help to avoid cross-contamination and dust carry-over.
Minimising microbiological risks
Keeping the product-contact areas dry, avoiding condensate and well-controlled temperature management are particularly important. In addition, inspection and sampling points should be arranged so that hygienic condition, wear and any product deposits can be assessed regularly.
Documentation and GMP conformity
Material certificates, traceability of the materials, welding documentation and qualification documents such as DQ, IQ, OQ and PQ are important parts of a GMP-compliant design. Cleaning validation and the documented release of cleaning and maintenance measures also belong to this.
How amixon® implements dead-space-free construction and hygienic design
Dead-space-free design as the basic principle
In amixon® precision mixers such as VM, HM, AM, the KoneSlid® mixer KS and the Gyraton® silo mixer, the product-contact design is consistently laid out for hygiene. The mixing chamber and mixing tool are welded free of crevices and ground smooth; there are no gaps, screwed joints or capillary crevices in the product-contact area. The mixing tool is supported and driven exclusively from above, so that the lower shaft passage, classically critical for contamination, is eliminated.
The standard connection with a discharge flap closes flush and free of dead space with the inner wall of the mixing chamber; dead-space-free ball segment fittings are available as an alternative. The large inspection doors are manufactured by the Clever-Cut® process and seal permanently free of dead space with the OmgaSeal® door seal – vacuum-tight or against overpressure on request.
Cleaning, residual discharge and accessibility
Integrated washing lances allow wet cleaning of the mixing chamber; on request amixon® supplies fully automatic wet cleaning with WaterDragon®. The SinConcave®/SinConvex® mixing tool supports the complete drainage of product and cleaning medium. The mixers are designed for dry and wet cleaning regimes, so that switching between dry and wet cleaning is provided for.
Depending on the design, further hygiene features ensure residual discharge: ComDisc® elements support almost complete discharge and minimise residues, particularly in vertical mixers and flat-bottomed versions. In KoneSlid® mixers, the lowerable closure system allows discharge within seconds and almost without any residual quantity. In the Gyraton® silo mixer, the discharge system also discharges large batches in a controlled manner and with little residue.
Access for inspection and sampling
The Clever-Cut® doors provide complete, ergonomic access to all product-contact surfaces. This is the basis for visual cleaning inspection and for sampling by swab or rinse.
Hygiene features for process reliability
amixon® has developed numerous technical solutions in order to improve cleaning, ergonomics and hygienic safety further. These include, among others:
- ComDisc® for complete or almost complete residual discharge.
- OmgaSeal® for permanently dead-space-free door sealing.
- SinConcave®/SinConvex® helical mixing tools for gentle mixing and good drainage.
- MultiPlane® solutions for structurally clean, hygienic transitions and process integration.
- ElTrunk® for hygienically considered process and connection solutions.
- DosiFlap® for accurately metered, dead-space-free discharge and filling functions.
- WaterDragon® for automated wet cleaning with reproducible cycles.
- KwickKlamp® as hygienic, smooth-running and self-locking closure technology on inspection doors.
Certified standards
On request, amixon® mixers meet the EHEDG guidelines, the FDA hygiene guidelines, the design rules of the 3-A Sanitary Standards and GMP requirements. VM and HM can be used in FDA-compliant form as sterile mixers and reactors. With free-flowing materials, ComDisc® residual discharge can achieve very high rates of residual discharge and minimises residues as well as cross-contamination risks during formulation changes.
In dairy and infant formula production, amixon® mixers are in use worldwide at manufacturers and contract manufacturers. Vitamins, minerals, trace elements, encapsulated omega-3 fatty acids and probiotics can be mixed in homogeneously and gently after the spray tower, without destroying agglomerates.
Manufacture in Paderborn as the quality foundation
amixon® develops and manufactures exclusively at the Paderborn works with the greatest depth of manufacture and uses components from Germany exclusively. As a certified welding company with European, Japanese, Korean and American qualifications, amixon® designs every apparatus as a one-off on the basis of the operator's URS. Quality control remains entirely in-house without gaps, and every specification is verifiable down to component level. This manufacturing autonomy also secures long-term supply: every component can still be re-manufactured reproducibly decades later.
Verification in the amixon® pilot plant
Whether the specific formulation delivers the expected results is verified by amixon® in advance at the pilot plant with 35 test units under real conditions. The trials are carried out, evaluated and documented jointly and form a robust basis for decision-making before the investment.