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Frozen foods

According to the regulations, quickly frozen foods are foods that have been frozen using a quick freezing method where the crystallisation zone is passed as fast as possible until the product reaches and maintains a temperature of -18 °C or less. Ice cream and ice intended for consumption are not considered as frozen foods according to the regulations for frozen foods.

It is necessary that only fresh ingredients are used in production of frozen foods and that the transport route from the field to the freezing facility is as short as possible. Only faultless foods without visible signs of microbial deterioration can be frozen. Fruits and vegetables should not have any visible signs of decay or mechanical damage. Prepared dishes (for instance bakery products, flour based foods – dumplings and rolls, partially fried foods – breaded meat, baked potatoes…) are also made from fresh and high-quality ingredients. After the thermal process is completed, the dishes are cooled down as fast as possible using shock cooling chambers, where the temperature drops from the temperature of the thermal process to +4 °C in only minutes. Immediately after cooling, the process continues with quick-freezing where the temperature reaches -18 ° C or lower.

The preparation and quick freezing have to be carried out as fast as possible using appropriate equipment which ensures that any possible chemical, biochemical and microbiological changes of the foods are kept to the minimum. This means that the freezing process has to ensure that the sensitive zone of maximum crystallisation between 1 ° C and -8 ° C is passed as fast as possible. When this transition is rapid, which is only possible using industrial freezers (sadly, not chest freezers and freezer compartments at home), we prevent the formation of large water crystals in the foods. Those crystals damage the cell structure and during thawing the cell liquid, containing the most nutrients (vitamins and minerals) leaks out.

Air, nitrogen and carbon dioxide are used during industrial freezing today. As a point of interest: quick-freezing is also one of the methods used in modern gastronomy, called molecular gastronomy, where the foods are prepared using liquid nitrogen (a tasteless and colourless liquid). Most common foods prepared using this method are ice-creams, creams, foams and sorbets with unusual flavours which are frozen using liquid nitrogen at a temperature lower than -100 °C (the boiling point of liquid nitrogen is at -192 °C) and served immediately. Ice cream prepared using this method has a light and fluffy structure and it retains vitamins and flavour because there was no damage to the cell structure during freezing. This kind of damage is common when freezing a homemade ice-cream in a regular freezer.

 

Andreja Širca Čampa, a Bachelor of Food Technology and Clinical Dietician

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