Which mixers are proven in practice for hygienic mixing of baby food with validatable cleaning?
Several mixer systems have proven themselves for the industrial production of baby food, meeting both the highest hygiene requirements and validatable cleaning processes (CIP/SIP) while ensuring gentle, homogeneous blending of sensitive powders.
Mixer types proven in practice
Vertical conical screw mixers (vertical mixers)
Particularly suitable for the gentle mixing of sensitive powders such as milk powder, whey protein concentrates or cereal bases.
The gravity-assisted, vertical design with only one shaft seal at the top reduces dead spaces and the risk of lubricant ingress. At the same time a very good residual discharge with minimal product residues is achieved, which reduces cross-contamination.
Horizontal ploughshare mixers
Proven for larger batches with very short mixing times. The fluidised bed technology enables mixing times of in part less than 60 seconds at high degrees of homogeneity. For baby food, designs in hygienic design are used: polished surfaces (typically Ra ≤ 0.8 µm), dead-space-free hygienic shaft seals and self-draining geometries.
Twin-shaft paddle mixers (twin-shaft mixers)
They offer overlapping mixing zones with a fluidising effect and are ideal for the precise addition of micronutrients such as vitamins, minerals and probiotics. The construction enables low-shear mixing, which protects the spray-dried particle structure and minimises thermal and mechanical stress.
Container mixers / IBC blenders
Product handling takes place in the container specific to each recipe, which considerably reduces the risk of cross-contamination between different product variants, particularly with allergen-containing raw materials. The mixing system itself remains more independent of the product, while handling, filling and discharge take place in closed form.
Core requirements for hygienic design and validatable cleaning
For the hygienic mixing of baby food with validatable cleaning, mixer systems in hygienic design are used above all which ensure very good residual discharge, reproducible cleaning and gentle treatment of sensitive powders.
Hygienic design and cleaning
Construction
Dead-space-free, radius-optimised geometries with fully welded, ground and polished seams as well as a self-draining internal contour. Product-contact parts are usually made of stainless steel 1.4404 / AISI 316L with Ra ≤ 0.8 µm, frequently electropolished.
Seals and explosion protection
Hygienic shaft passages with a sterile sealing concept, arranged outside the product chamber in order to avoid lubricant ingress. Pressure-bearing parts are unusual in baby food; explosion suppression and relief panels are provided only with particularly dust-explosive components, which is rather rare.
CIP capability and validation
Integrated spray heads or rotary nozzles ensure complete wetting of all product-contact surfaces. Cleaning is managed via the TACT principle (temperature, concentration, time, mechanics) and monitored by means of sensors (conductivity, temperature, flow). Riboflavin tests serve as the standard procedure for validating cleaning coverage.
Residual discharge and process integration
A mixer is regarded as hygienically suitable for practice in baby food production where residual discharge rates of more than 99.9 % are achievable. This is supported by optimised outlet geometries, small tool-to-wall clearances and suitable discharge aids, and it reduces cleaning times as well as cross-contamination risks.
These amixon® mixers are suitable for infant formula with validatable cleaning
For the hygienic mixing of baby food with validatable cleaning, amixon® has two solutions particularly proven in practice: the twin-shaft large mixer for batches of up to approximately 15 m³ and the KoneSlid® mixer for batches of up to 4 m³. Both secure the highest mixing quality with maximum product protection and very good cleanability.
Twin-shaft large mixer for large batches
amixon® twin-shaft mixers homogenise baby food in large batches (typically up to 10–15 m³) particularly gently. Spray-dried instant powders retain their agglomerate structure, while micronutrients, vitamins, minerals, omega-3 fatty acids and probiotics are distributed precisely.
Two helical mixing tools each convey around a quarter of the batch volume per revolution. The bulk material flows upwards in a spiral and flows downwards again along the shafts; the mixing action arises three-dimensionally in the boundary areas of the macro flows and covers the entire volume.
Ideal mixing qualities are achieved after just about 20–90 revolutions, at circumferential speeds of only approximately 0.8–3.5 m/s. This creates energy-efficient, extremely gentle processes with a technically ideal random distribution of the particles.
From fill levels of approximately 10–15 % the mixer already achieves ideal mixing qualities; residual discharge rates of 99.997 % and better reduce product losses and cross-contamination and make validation of the cleaning easier.
An essential advantage in the large-batch concept: only one representative sample per batch is necessary in order to demonstrate the homogeneity of the declared ingredients across the entire volume, which considerably lowers analytical effort and costs.
KoneSlid® mixer for smaller batches
For smaller or frequently changing batches, amixon® offers the vertical KoneSlid® mixer. It combines very short mixing times with equally short residual discharge times and is ideally suited to baby food in an "end-of-the-line" concept.
The helical mixing tools work at low rotational frequencies but achieve ideal mixing qualities within just 20–60 seconds. Sensitive, agglomerated instant powders can thereby also be mixed gently.
The conical, rotationally symmetrical closing system permits total discharge within a few seconds. Free-flowing mixes are discharged without segregation, so that large volume flows can be homogenised in a short cycle time with relatively small mixers.
KoneSlid® mixers are available for usable volumes of approximately 400 to 3,000 litres and thereby cover the typical batch spectrum for smaller baby food lines.
Hygienic design, cleaning and validation
All amixon® mixers for baby food are hygienically optimised in accordance with EHEDG, FDA and HACCP principles.
Dead-space-free geometries, Clever-Cut®/OmgaSeal® inspection doors and gas-tight O-ring seals close to the product minimise residues and facilitate inspection and cleaning.
Residue-free discharge (99.997 % and better) as well as convenient access to all product-contact surfaces support validation; riboflavin tests and documented CIP and wet cleaning processes enable reproducible, measurable cleaning.
Systems such as DosiFlap® enable a dead-space-free, gas-tight closure and at the same time highly precise, reproducible portioning into big bags or IBCs with integrated weighing technology.