Viewpoint: advanced valve control vital to future food preservation

Our ability to preserve food has a long history, with more recent developments being directed by the desire to maintain nutritional value in addition to the food’s original taste and texture.

Indeed, research in this field within the UK is helping to develop new techniques that can be applied on an industrial scale.

Take ohmic heating, for example. This process involves applying an electrical current directly through a product to be heated and it is the electrical resistance of the product which causes the increase in temperature.

It is also a well advanced application, with some play throughout industry. Via ohmic heating, the whole product acts as the conductor, so energy is released throughout the product rather than at its surface, making it extremely efficient.

In fact, modern production facilities claim up to 95% efficiency for this process. In addition, this method of heating greatly reduces the thermal shock to the product compared to traditional methods, which improves the retention of taste and colour within the food.

Clearly, the control of the temperature, pressure and flow of the product needs to be carefully maintained in order to offer a consistent, high quality, final product for the consumer

From a control perspective, accurate temperature measurement is essential as well as precise flow control of the product to ensure a continuous and consistent production rate.

Flow control of the food product can be achieved to a high level of precision thanks to a range of intelligent control valves supported by process controllers. These can also be used to manage Clean-In-Place (CIP) processes which require the use of automated control valves. These valves are integrated with the main production control system and designed to withstand the high temperatures and aggressive cleaning media.

High pressure processing

High pressure processing, meanwhile, is essentially a cold pasteurisation technique that uses cold water at extremely high pressure to kill vegetative bacteria. This process can maintain the original flavour and consistency of the food and provides an extended shelf life without the use of heating or preservatives, which makes it well-suited for preserving the ‘fresh’ characteristics of a food.

The control of this process requires a number of valves and controllers to supply the cold water and to evacuate the vessel after each batch has been processed.

However, for such a high pressure application, some of these will be specialist pieces of equipment, while the remainder can be specified to suit both the application and to allow integration into the control infrastructure of the processing plant.

Pulsed light processing

Finally, pulsed light processing, which is still undergoing development for use within the food industry, can be applied to liquid products that are pumped through a pulsed electric field at mildly elevated temperatures and then cooled rapidly.

This process kills bacteria, yeasts and moulds while retaining the freshness, taste, vitamins and colour of the food product.

Clearly, the control of the temperature, pressure and flow of the product needs to be carefully maintained in order to offer a consistent, high quality, final product for the consumer.

So as food preservation technology advances, the process control infrastructure needs to keep pace and continue to deliver improvements in hygiene and efficiency.

• Mark Lilley is a field segment manager for Bürkert Fluid Control Systems