Process Drying Confectionery
Many products in the confectionery industry are coated with either sugar or a sugar substitute, usually applied as a water-based suspension. This is typically sprayed into the centre of a rotating pan, with air blown on or through the product to evaporate the moisture. This whole process is repeated until the desired thickness of coating is achieved. Many of these processes are thermally sensitive and high temperatures are to be avoided.
The coating process is largely taken up by the drying of the product in sequential cycles, something that can amount to up to 90% of total coating time. Clearly, a constant flow of dry air is crucial in order to maximise production capacity. A uniform process drying time is preferable throughout the year, with no seasonal variations. The best system for these specific requirements is one that produces dry air through adsorption dehumidification, combined with refrigeration and heating.
This combination of processes filters, cools and dehumidifies the ambient air, reducing its moisture content. In the summer months this pre-cooling is essential as it enables the system to reach the low dewpoints necessary. After dehumidification, the air is cooled or reheated to obtain the desired process temperature.
Such a combined air handling system has the following advantages:
- Clean filtered air
- Use of ambient air gives an energy saving for the factory's air conditioning plant
- No seasonal variations means predictable production times
- Total process time is reduced by up to 35%, because the low moisture level of the air allows an increase in production capacity and a better quality product
- Payback time for initial investment is typically between 10-12 months.
Other areas within the confectionery (and food) production processes where dehumidification and the control of ambient humidities can be of benefit includes:
- Prevention of clogging of materials in the packing process
- Reduction of drying time in starch deposited gum type product
- Reduction in the drying time of the starch itself between batches (and with deeper drying)
- Prevention of blooming on chocolate enrobing machinery
- Long term storage of chocolate product (Easter eggs for example)
- Reduced cleaning of machinery