About Vacuum Packing - Magic Vac Jumbo Operating Manual

ABOUT VACUUM PACKING

The deterioration of food is caused by chemical reactions that occur in food which is exposed to the 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 package or container, by removing the oxygen and
eliminating volatile compounds. The oxygen in the air causes food to deteriorate, firstly through a process of oxidation,
causing the loss of nutritional values, flavour and all the food's qualities. Air also promotes the growth of most micro-
organisms and 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.
For example, mould will not grow in environments with a low oxygen content, or in the absence of moisture or humidity.
To grow, yeast requires moisture, sugar and a moderate temperature, but it can grow in the presence or absence of
air. Refrigeration slows the growth of yeast and freezing blocks it completely. Bacteria can multiply with or without air,
depending on their type.
Clostridium Botulinum is a very 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.
Foodstuffs 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 bacterium, it is essential to
observe the basic rules of hygiene and, to prevent its harmful proliferation in preserved foods, they must be refrigerated
for short periods and/or frozen for long-life preservation. However, such foods must be eaten immediately after heating.
Important: you must consume immediately any food which has been heated while still sealed in MAGIC VAC®
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.
Several enzymes found in foods cause increasingly noticeable changes in colour, structure and flavour; such changes
depend on the preservation time, temperature and, above all, the presence of air. To halt the action of enzymes, vegetables
must be blanched briefly using steam or a microwave oven. Food which contains a high percentage of acidity, like most
fruits, do not require blanching. The absence of air created by the vacuum will in any case slow down or prevent the action
of these enzymes.
Insect larvae are frequently found in many low water content or dried foods which have not been vacuum packed or frozen,
and they can develop during preservation and thus contaminate the food. Some products like flour and grain might contain
larvae, but using MAGIC VAC vacuum packing will stop them developing into insects.
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