Cooling and Freezing
Cooling and freezing are important applications in many stages of food production. Compliance with the maximum permitted temperatures is regulated by law. Fruit and vegetables are cooled or frozen both during and after processing to achieve as long a shelf life as possible.
The cooling and freezing of food products occurs at various points in the manufacturing process. Depending on the product and time and space capacities, this can be done continuously or batch wise. The objectives of the cooling process can be varied: for the hardening of product surfaces, for cooling above the freezing point or for the freezing of the product
A high freezing rate of more than 5 cm/h is achieved with liquid nitrogen (LN2) or liquid carbon dioxide (LCO2) as a freezing medium, so that the cell structure of the frozen food is preserved through the fine-crystalline freezing of the water portion. This means that after defrosting no losses in cell liquid content occur. A further advantage is the prevention of dehydration and thus undesirable weight loss during the freezing process through rapid freezing of the product surface.
During the production of many ready-made meals, vegetables or meat are coated with sauce. The products are kept in motion in tumblers while the sauce is added using a nozzle. Dosing of cryogenic gas allows the sauce to be gradually set onto the product.
Rotary freezers continue to be suitable for IQF freezing (IQF: Individually Quick Frozen). The loose products are continuously in motion during freezing so that agglomerate formation is avoided.
In general, a distinction can be made between batch freezers and continuous freezers. One example of batch freezers is freezing cabinets, which are operated with liquid nitrogen or liquid carbon dioxide. Continuous cryogenic frost equipment includes long tunnels, spiral freezers and rotary tube freezers.
- Higher product turnover through short freezing times
- High quality of frozen products
- No dehydration losses
- Fast operation
- Low investment costs
- Takes up little space
- High plant
- Low maintenance and repair costs (simple plant construction)
Messer has an extensive range of different freezer types on offer.