Homogenisation in Fruit Puree: Position Matters More Than Pressure

Product texture decides whether homogenisation is useful. Its position before or after sterilisation determines the hygiene requirements; product trials establish pressure settings. When puree separates, assess this step alongside the recipe and heat treatment, rather than increasing pressure alone.

Does every puree line need homogenisation?

Homogenisation refers to pushing product through a narrow gap under high pressure, making particles or fat droplets smaller and more evenly dispersed. This can help slow separation. It may also remove a pulp texture that you want to keep, so the finished product should guide the decision.

Specify the required texture before selecting the equipment. A product intended to retain pulp needs a different trial from a drink intended to feel smooth.

Where should the step sit, before or after sterilisation?

Before sterilisation, the homogeniser handles product that will be heat treated afterwards, so a suitable hygienic machine can be used. After sterilisation, the product is already sterile. The homogeniser, its seals and connecting pipework must keep it that way, with a validated sterilisation procedure. That difference affects purchasing, cleaning and maintenance.

With upstream homogenisation, judge the sample after heating and cooling, rather than only at the machine outlet. Check deposits and cleaning needs with the actual product too. A downstream machine adds equipment that must remain sterile, including after maintenance. Moving the machine alone does not settle every fouling or stability question.

Why is the second stage not run at the same pressure?

The first stage does most of the size reduction. The second keeps a steady pressure at the first stage outlet and breaks up clusters that form afterwards. Before changing settings, check whether each gauge shows total pressure or the pressure difference across a stage. Then compare samples; one fixed ratio will not suit every machine and puree.

At the same total pressure, a higher second stage pressure leaves less pressure difference for the first stage to work with. Finer particles are therefore not guaranteed. For a pulp product, compare the feel of the sample as well as separation. A smoother drink may have lost texture that customers expect.

The three choices are right, so why does the valve still wear?

If the valve wears quickly, inspect the parts and the feed together. Hard debris or oversized particles can damage the valve. Air in the product and an inadequate supply can make operation unstable. Cavitation, where vapour bubbles form and collapse, depends on feed temperature and inlet pressure together, rather than temperature alone.

Choose a screen that meets the machine inlet requirements without removing pulp the product needs. Air can be removed before homogenisation when the feed contains gas. If a later step introduces more air, investigate that source separately. Place the deaerator to suit the actual flow route, temperature and sterile sections of the line.

What should acceptance actually measure?

Keep the pressure record and take samples before and after homogenisation. Use the same particle measurement method and storage conditions for both. Checks after 24 and 72 hours can show early separation and help compare settings. The particle size target should match the required texture and stability.

If particles are finer but the product still separates, look at the recipe, heating and storage too. If particle size barely changes, check the pressure differences, valve and feed. Short observations help select a setup; shelf life still needs testing under the intended storage conditions.

The selection comes down to three decisions: texture sets the need, process position sets the equipment requirements, and trials set the pressure. Accept the result against both stability and the texture customers expect.