Dispersing powders into liquids and creating a consistent, homogeneous product is one of the most difficult of all mixing tasks. And gums and thickeners used in the food industry such as alginates, guar gum, CMC, etc. are no exception. These ingredients are difficult to disperse without forming lumps or “fish eyes” – agglomerations of partially hydrated material with a core of dry powder. Time and again Silverson Machines have helped customers to improve their mixing processes by overcoming the challenges associated with these ingredients.

Agglomerates in the mix

When adding powder ingredients into water, most powders have a tendency to float or raft on the liquid surface and agglomerates can easily form. The formation of these agglomerates can be exacerbated by operator error, as powder addition must be carried out with great care. If the powder is added into the liquid too quickly the mixing equipment cannot quickly and efficiently disperse it, agglomerates will form. Having to add the powder slowly at a controlled rate adds to processing times and labour costs without the guarantee of an agglomerate-free end product.

Conventional mixing equipment such as agitators and stirrers does not produce sufficient shear to break down any agglomerates and hydrate the dry powder within the lump, resulting in poor yield. Many formulations contain unnecessarily high levels of gum to compensate for this and so a filtration stage is often required, adding to costs. If left in the mixture, unhydrated gum can gradually hydrate during storage or subsequent processing, leading to undesired change in the product – this can also affect shelf life.

Some manufacturers try to overcome the formation of agglomerates by premixing functional ingredients with other powdered ingredients or non-aqueous phase liquids. But this doesn’t always work and continues to add to process times and costs.

A high speed, high shear rotor/stator mixer can easily overcome these problems. The high speed rotation of the rotor blades creates a powerful suction which draws the powdered ingredient from the liquid surface and into the workhead. The materials are subjected to intense shear in the confined area of the workhead. Agglomerates are broken down in the gap between the rotor blades and stator wall, exposing an increasing area of powder to the surrounding liquid. In a short mixing cycle all the material passes through the workhead, accelerating the hydration process and resulting in an agglomerate-free mix.

Costly raw materials

With high-cost functional ingredients such as Xanthan Gum or Carrageenan, Silverson mixers can help you to achieve the best yield from these ingredients, making your process much more cost effective. For example, we recently helped a customer to reduce the Pectin in their formulation by over 20% with the use of the Silverson Flashmix.

The company had previously been using conventional agitators to mix the pectin at temperatures in excess of 55°C. They were incorporating around 20% more pectin than they actually needed for their formulation to account for what they were losing due to agglomerates and partially hydrated pectin sticking to the agitator shaft, blades and the walls of the mixing vessel. This wastage was costing a considerable amount of money and after the mixing process they had to put the mixture through a filtration stage to filter out the un-hydrated pectin, further lengthening the process time. After around 40 minutes they were left with a low quality 5% pectin solution, wasting 20% of the material they had added as the agitator was unable to break down the agglomerates.

Trials were arranged at Silverson using a Flashmix FMX50 to incorporate the pectin. The trials were run at ambient temperature and after around 10 minutes the 5% of pectin that had been added was fully incorporated and mixed. Using the FMX50 there were no agglomerates and no partially hydrated powder sticking to the vessel wall, so the mixture no longer needed to be filtered after mixing.

Using the FMX50 the consistency and quality of the mix was much better even after a shorter period of time. The company would be saving a huge amount of money on pectin by being able to use 20% less pectin for each batch and by not having to heat the vessel before adding the pectin.

What Silverson can offer

With a range of mixers suitable for a different batch sizes, Silverson mixers can:

  • Produce an agglomerate-free mix.
  • Maximise yield/functionality of raw materials, allowing products to be formulated with reduced gum content, cutting raw material costs.
  • Achieve consistent product quality.
  • Reduce mixing times by eliminating the need for controlled powder addition and premixing of powders.

To find out more, or watch one of our many ‘how to’ videos on processing different types of gums and thickeners, visit: www.silverson.co.uk. Or for advice on your mixing process contact sales@silverson.co.uk