Vacuum Packing Explained

The deterioration of food is caused by chemical reactions that occur in food which is exposed to air, temperature, moisture, the action of enzymes, the growth of micro- organisms or contamination by insects.

Vacuum packing reduces the absolute pressure of the air inside the bag by removing the oxygen. The oxygen in the air causes food to deteriorate through a process of oxidation, which causes the loss of nutritional values, flavour and all the food’s qualities. Air also promotes the growth of most micro-organisms and when freezing causes the frost burns which occur on frozen food.

Vacuum packing extends the shelf life of many fresh foods, by reducing oxidation and preventing the proliferation of microbes (bacteria and mould). However, many fresh foods contain sufficient moisture to encourage the growth of micro-organisms that can grow with or without air. To prevent the deterioration of such foods, they must be preserved at low temperatures.

Micro-organisms like mould, yeast and bacteria are present everywhere, but they can cause problems only in certain conditions. Refrigeration slows the growth of yeast and freezing blocks it completely.

Clostridium Botulinum is a dangerous type of bacteria which can develop in environments which do not contain acids, are without oxygen and are exposed to temperatures in excess of 4°C for long periods of time.

Foods vulnerable to attack by Clostridium Botulinum are those with low acidity (like red meat, poultry, fish, seafood, olives in brine, eggs, mushrooms and vegetables) and medium acidity foods like virtually all vegetables and many fruits (ripe tomatoes, onions, red pepper, figs and cucumbers). To prevent contamination by this bacteria, it is essential to observe the basic rules of hygiene and to prevent its harmful proliferation in preserved foods, they must be refrigerated for only short periods and/or frozen for long-life preservation. However, such foods must be cooked and eaten immediately after defrosting and heating.

Important: You must consume immediately any food which has been heated while still sealed in Food Preserver bags. Leaving the food to cool slowly at room temperature in the sealed vacuum bag may cause several harmful micro- organisms to multiply, in just a few hours, to values that are health-threatening.

Insect larvae are frequently found in many low water content or dried foods found in the pantry which have not been vacuum packed and they can develop during storage and thus contaminate the food. Some products like flour and grain might contain larvae, but using Food Preserver vacuum packing will stop them developing into insects.