IR heaters help keep chocolate in shape

Edited by the Engineeringtalk editorial team Apr 13, 2005

Four carbon medium-wave infra-red heating systems are helping Magna Speciality Confectioners to achieve better control over the quality of its filled chocolate products.

Four carbon medium-wave infra-red heating systems from Heraeus Noblelight are helping Magna Speciality Confectioners to achieve better control over the quality of its filled chocolate products, as well as saving energy and space when compared with the previous chocolate heating system.

Magna Speciality Confectioners makes a wide range of chocolates, under contract, for most of the well-known chocolate manufacturers.

The company has particular expertise in filled products, such as filled chocolate bars and filled chocolate eggs, where the application of heat is an important process step.

For example, in the manufacture of chocolate filled eggs, molten chocolate is poured into moulds on a so-called book moulding line to form the two halves of the finished product.

The chocolate is then chilled so that it solidifies.

The moulds are then filled and are eventually brought together, rather like the pages of a book, so that they can form the complete eggs.

Obviously before this joining can take place, it is necessary to heat the egg rims, so that the two halves in the two moulds can fuse together.

Previously this had been carried out by using hot air blowers; but the temperature profile proved difficult to control with the result that the chocolate was sometimes not at the right consistency, or temper.

This caused quality control problems and could also cause problems at the subsequent chilling and wrapping stages.

It is also important to heat the moulds before the chocolate is poured in.

If the moulds are too warm, then the chocolate can detemper as it is poured in and if they are too cold, then it can chill.

This heating task had previously been carried out by hot air blowers and the inability to guarantee temperature profiles again caused quality control problems.

In an effort to solve these problems, and a similar quality control problem encountered when manufacturing filled chocolate bars, Magna decided to investigate alternative heating methods.

As the company had successfully used infra-red heaters on a similar production line, it contacted Heraeus to see if infra-red could provide the solution.

As a result of successful tests carried out at Heraeus's Neston Applications Centre, it was decided to install four 8.4kW, pyrometer-controlled, carbon medium-wave infra-red systems on the Magna production lines.

The pyrometer on the mould heating section of the line measures the temperature of the plastic moulds just before the infra-red station.

This temperature then dictates the length of time that the heaters are switched on when the moulds under the infra-red heater.

A pyrometer after the heating station then ensures that the correct mould temperature has been achieved to allow chocolate to be deposited.

Deflector plates at the front and back of the heating module ensure that only one module at a time is heated.

Typical dwell times are 3 to 4s for line speeds of around 16 to 20 modules per minute, and temperatures can be controlled at 29C +/-1C.

On the book moulding section of the line, the pyrometer measures the chocolate temperature before the heater station and controls the infra-red heaters to ensure that the chocolate temperature is raised to around 30C to ensure that the two halves are satisfactorily fused together.

Apart from the quality improvements and the more consistent presentation of the finished product, the new infra-red heating system has also provided significant savings in space and energy over the previous system.

For example, each heating station previously required three 9kW hot air blowers, compared with the 8.4kW of the infra-red system.

In addition, the virtually instantaneous response of the carbon heaters means that they can be switched off instantly in the event of unexpected production line stoppage, ensuring that product spoilage is kept to a minimum.