Gums and thickeners

Starch is used as a thickening, stabilizing and binding agent for many foods, including soups, sauces, gravies and baked goods.

Gums, such as xanthan gum or guar gum, are widely used for their binding, gelling, thickening or stabilizing effects on emulsions and suspensions. They are often mixed with other rheology modifiers, especially Xanthan Gum, as the two combine to produce greatly increased effects.


The Process

Gums can be dispersed in hot or cold liquids and many grades of gum are available.

Starches are typically added cold and generally do not increase in viscosity until heated or cooked, except for CWS (cold water swelling) starches.

Powders have a strong tendency to form lumps when added to water and several methods of dispersion and hydration are used in an attempt to overcome this problem. These methods vary depending on the scale of production, other ingredients used, etc., here are some examples:

  • Slow addition of the xanthan powder in the vortex of a stirred tank. Once the mixture is dispersed, the product continues to hydrate.
  • The gum can be pre-mixed with other powdered ingredients to reduce the formation of agglomerates by separating the particles.
  • Guar gum (like other rheology modifiers) has a strong tendency to form lumps when added to water. To reduce this risk, it can be mixed beforehand with other powdered ingredients, such as sugar (which will not affect the hydration rate), which will facilitate dispersion by reducing the formation of agglomerates by separating the particles.
  • With easily soluble gums such as guar, the powder should also be added quickly as the addition of the powder becomes increasingly difficult as the viscosity increases.
  • Particle size should be reduced as finely as possible to maximize yield.
  • The powder/liquid mixing system must be able to quickly incorporate the starch powder and disperse it throughout the contents of the mixture.

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The Challenge

Dispersing gums and thickeners using conventional stirrers can cause several problems:

  • Agglomerates can form easily, even if the above precautions are taken to reduce the risks. Agitators do not produce enough shear to break them up quickly.
  • Optimum yield is difficult to achieve with traditional methods.
  • Many formulations contain unnecessarily high levels of gum to compensate for low yield, increasing the cost of raw materials.
  • Once the increase in viscosity has started, agitating the solution and therefore dispersing the powder becomes increasingly difficult.
  • Long mixing times are required to achieve dispersion/hydration. This can degrade the gel.
  • Premixed powders or liquids in the non-aqueous phase with the gum increase processing time and costs.
  • Non-hydrated gum may gradually become hydrated during storage or subsequent processing, causing undesirable changes in product viscosity.
  • It is not possible to create high percentage gum solutions with traditional methods. Solutions of this type may be necessary in certain applications where the formulation contains little water.

Our solutions

A high shear mixer can produce an agglomerate-free dispersion and completely hydrate gums and starches in a fraction of the time required by conventional methods.

Jetequip offers several solutions for your gum and thickener mixing applications

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The Advantages

These benefits arise from the mixing/shearing action. It works as follows:

The fluid experiences shear as it moves through the rotor at a different speed relative to an adjacent area. The tip velocity, or fluid velocity at the outside diameter of the rotor, will be greater than the velocity at the center of the rotor, and it is this difference in velocity that creates the shear.

A component used in combination with the rotor is called a stator. The stator creates a tight clearance between the rotor and itself and forms an extremely high shear zone for the product as it exits the rotor.

Key design factors include the diameter of the rotor and its rotational speed, the distance between the rotor and the stator, the time spent in the mixer and the number of passages of the product through the rotor/stator. Variables include the number of rows of teeth, their angle, and the width of the openings between the teeth.

  • Consistent product quality and repeatability.
  • Pre-mixing gum with powders or non-aqueous phase is not required.
  • Fast mixing times.
  • Operator error is effectively eliminated.
  • Maximized yield/functionality allows products to be formulated with reduced gum content, thereby reducing raw material cost.
  • Mixture without agglomerates.