Food that has been processed to powdery from is very popular now-a-days. The main reason behind its rising popularity is its longer shelf life when compared to food items available in its natural state. From milk powder to instant food mixes, many kinds of food items are available in powdered from.
However, in order to preserve the long shelf life of powdery food and to maintain its texture, colour and flavour it is necessary to prevent the attack of moisture while processing, packaging and storage.
Granular or powdered materials are transferred to packaging via high velocity air streams or pneumatic conveying. Highly hygroscopic sugar, flour, starches and beverages and food powders make humidity control a crucial element of materials handling system. In addition, the presence of moisture in the air may interfere with the operation of the processing machines and obstruct the free and easy movement of the foodstuff.
Packaging of milk powder in tins/ containers is carried out in semi-automatic machines. Milk powder being hygroscopic in nature, exhibits affinity for water due to humidity in the surrounding environment. Milk powder sticks to hopper, conveyors and packaging machines creating hygiene problems.
A reputed dairy company was facing the all too familiar humidity problem at their milk processing plant. Though the plant was air conditioned the humidity problem persisted. Due to high humidity, the milk powder would often stick to the hoppers, conveyors and packaging machine, leading to frequent breakdowns in the conveyor drive mechanism.
Since the packing of the milk powder in tins containers is carried out on semi-automatic machines, the tins to be filled keep moving continuously on a chain conveyor. The powder is put into the packing machine hopper from where it flows into the tin as it comes into the right slot.
To ensure free flow of powder and avoid sticking of powder on chain conveyor and other machine parts, RH in the packing hall is maintained at 40 ± 5% and temperature at 22-25°C.
To achieve the desired RH, dry air from the dehumidifier is continuously circulated in the packing hall through a suitable supply and return air system. An air handling unit functioning separately maintains the desired temperature in the packing hall.