Which mixing tools and configurations are optimal for spice blends with oil addition?
For spice blends with the addition of oil, mixing systems are suitable that combine a fine distribution of the liquid with gentle product treatment. The aim is uniform wetting with a small quantity of oil and, as far as possible, without the formation of lumps.
Precision mixers are suitable, provided they are of hygienic design. In the spice industry, horizontal ploughshare mixers and vertical helical mixers are widespread. They create a three-dimensionally moved product bed and offer a large surface area for the distribution of the oil.
Vertical cone mixers are particularly suitable for multi-stage mixing processes. They work with low mechanical loading and can also distribute larger proportions of liquid in the powder. They also permit variable fill levels and an almost residue-free discharge.
Twin-shaft paddle mixers and horizontal helical mixers
Twin-shaft paddle mixers work with mechanical fluidisation. The product is lifted and thrown in the process. The oil can thereby be worked in uniformly.
Horizontal ribbon mixers tend to be suitable for simple mixing tasks with small oil additions. At higher oil proportions, the risk of lump formation increases. Additional dispersing tools are then advisable.
Important additional functions
High-speed choppers help to break up droplets and to break open agglomerates as they form. They are particularly useful where the oil is injected directly into the active mixing zone.
The oil should be added via spray systems. Single- or two-fluid nozzles ensure fine droplets and uniform distribution. Addition in a surge should be avoided.
With viscous oils or fats, a heated feed vessel reduces the viscosity and improves the wetting behaviour.
Process management
Variable speed control is important. For dry mixing, a moderate intensity is generally sufficient. During the addition of oil, the mixing intensity can be increased. Post-mixing should then be carried out at a reduced speed in order to protect the product.
The dosing of the liquid must also be precise. Only then do aroma intensity, texture and the dust-binding effect remain reproducible.
Practical configuration
For demanding spice blends, a horizontal ploughshare mixer with choppers and fine spray nozzle technology has frequently proved successful. This combination distributes the oil quickly and uniformly, reduces lump formation and protects the sensitive spice particles.
How amixon® introduces oils, fats and liquid flavourings into powders without lumps
The liquid is introduced at the point of highest mixing activity
The main cause of lump formation is local over-wetting. amixon® therefore doses oils, fats, lecithins and liquid flavourings directly into the active zone of the cutting rotor. There the liquid is distributed microfinely. At the same time, the SinConcave®/SinConvex® mixing tool continuously conveys fresh, unwetted powder into the wetting zone. The mixing chamber thereby remains largely free of build-up. With small addition quantities, the two-fluid nozzle with air and liquid produces the finest atomisation.
Mixing tools, mixing action and flexibility
amixon® uses the proven SinConcave® and SinConvex® mixing helices. During mixing they produce a self-cleaning effect and achieve a very high mixing quality within a short time. The tools work particularly gently and preserve the structure of the raw materials. Where required, the same amixon® mixer can also work more intensively to de-agglomerate. The energy input generally remains so low that the mix hardly warms up.
With DosiFlap®, the mixed goods can be filled directly into big bags or IBCs. ComDisc® tools enable an almost residue-free discharge.
There is a reproducible dosing strategy
Liquids can be added continuously and in fine doses. At higher fat proportions, addition takes place sequentially with intermediate mixing phases. All steps can be stored as a mixing programme in the PLC. The mixing intensity is infinitely adjustable. It ranges from gentle moistening to a high energy input for rapid and complete incorporation. The fill level can vary between 10 and 100 per cent without the mixing quality deteriorating.
Tool configuration and verification
Depending on the task, vertical mixers such as VM and HM, SpherHelics® and KoneSlid® mixers as well as cone mixers such as the AM or the continuous AMK are used. The wetting behaviour, the oil binding capacity and the dosing profile are verified in advance by amixon® in the pilot plant with the original product. For tea, herbs and spices, a particularly gentle mode of operation is important so that fragile particles are preserved. The Gyraton® GM also homogenises large batches of up to 100 m³.
Hygienic design as the constructional basis
All the properties described rest on the amixon® hygienic design. Mixing chamber and mixing tool are welded free of crevices and ground smooth. The mixing tool is mounted at the top only; a lower shaft passage is eliminated. Large Clever-Cut® inspection doors with OmgaSeal® seals provide ergonomic access to all product-contact surfaces. Dead-space-free discharge devices and integrated washing lances permit validatable dry and wet cleaning.