Powder induction, wetting and dispersion without agglomerates, dust and losses

Ystral GmbH

By Dr Hans-Joachim Jacob
Monday, 07 June, 2021

Powder induction, wetting and dispersion without agglomerates, dust and losses

Hydrocolloids such as thickeners, stabilisers and proteins are shear sensitive. When mixed into liquids, agglomerates are initially created, which subsequently have to be broken down through dispersing. During dispersing the agglomerates, the polymer structure of the already hydrated gel is damaged. Viscosity and texture decrease irreversibly.

The solution to that problem is a technology, in which the primary particles of the hydrocolloid powders are separated by vacuum expansion before entering the liquid, are fully wetted upon first contact with the liquid and are then dispersed in situ under vacuum conditions and hydrated agglomerate-free under overpressure. The powder is immediately solubilised completely. No agglomerates are formed. There is no further dispersion required. The texture is not damaged.

The Conti-TDS powder wetting and dispersing machine differs from other systems on the market. Powder is inducted dust- and loss-free directly from bag, hopper, container, big-bag or silo into liquids and wetted and dispersed in seconds. The machine works according to the rotor/stator principle. It is installed outside the process tank and is connected to it like a pump. The machine recirculates the liquid in a loop with the tank. Because of the special geometry of the rotor, a strong vacuum is created within the dispersing chamber. With this vacuum, powder is inducted directly from the powder container dust- and loss-free. The liquid stream is dispersed in the dispersing chamber with high shear. Under these conditions the surface of the liquid, into which the powder is inducted, is extremely enlarged.

Powder always contains air in the spaces between the particles. Air expands under vacuum. Because of the increasing vacuum on the way into the dispersing zone, the air between the particles expands. Therefore, the particles are released from each other. The wide distances enable an easy and complete wetting of every single particle. Powder and liquid enter the dispersing chamber via completely different paths and are only brought together in the dispersing zone at defined shearing gradients. There is no chance for an uncontrolled agglomerate formation. These are ideal conditions for wetting the individual particles. This process facilitates the fine distribution at the moment of wetting and ensures significantly better product properties compared to standard powder addition.

Depending on the recipe, several different raw materials can be dispersed consecutively and fully automatically, whereby the induction can be performed from different containers. After the induction of solids has been completed, additional dispersing and homogenising is possible, until the required particle size distribution is reached or the dissolving process is completed.

The production of emulsions is possible with the same machine. The oil phase is inducted and emulsified in the agglomerate-free solution or suspension. The high flow rate in recirculation and the fine distribution in the high shear zone result in a very fine, homogeneous and stable emulsion so that in most cases there is no need for additional high-pressure homogenisation.

In contrast to conventional processes, the powder induction and the dispersion are constant and independent of the operator. This guarantees reproducibility. As a result of defined processes, properties such as droplet and particle size distribution can be set reproducible.

Alongside the option of integrating the Conti-TDS into existing systems, compact turnkey systems with minimum footprint can be supplied. The possibilities here extend to fully automatic process systems with automatic recipe control and documentation, including dosing, weighing, monitoring and quality control.

As another feature, the Conti-TDS dispersing machine can also serve as CIP pump. It can do the tank cleaning process in recirculation and it can be integrated in the inline pipe cleaning procedures. The machine is designed according to hygienic design standards, fully drainable and 3A certified.

Suitable for not only easy powders, even the strongest adhesive, sticky and thickening powders like pure milk proteins, spontaneously swelling Xanthan gums, PVP or high-concentrated guar can be dispersed without any problems. Liquids such as oils or syrup can also be inducted directly from a drum and emulsified or diluted. Maximum pectin concentrations are possible.

Example applications

In the production of yoghurt, ice cream premix or dessert, as an example, different thickeners and stabilisers are used. By using the Conti-TDS, it is possible to disperse these hydrocolloids much more effectively and immediately agglomerate-free. Their thickening effect is not destroyed by additional dispersion of agglomerates like in the traditional processes. This unavoidable dispersion in the traditional process destroyed not only the already hydrated thickener but also the protein structure, which required even more thickener. With Conti-TDS, users can save the protein structure. The concentration of thickeners can be significantly reduced and the quality of the final products is higher. The raw material savings are really high. The lower thickener concentrations and the lower shear on the protein positively affect the taste and improve stability and mouth feeling.

During the conventional production of a salad dressing in a vacuum process system, the hydrocolloids have never been dispersed colloidally. The product passes a plate heat exchanger downstream. After five or six batches, it inevitably became jammed and then had to be cleaned. The cause was the clumps of gel that could never be dissolved completely. These disruptions have been removed completely by using Conti-TDS. In addition, apart from the relevant hydrocolloids, all the other powder materials can now be processed with the same machine as well.

When using the Conti TDS, it is not generally necessary to premix the powders. The recipe components can be weighed in a hopper or container, layer by layer. The most favourable layering for the process is selected.

Ystral is represented in Australia by Technomik Pty Ltd — https://www.technomik.com.au.

Image credit: ©stock.adobe.com/au/fahrwasser

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