Publicité
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 pro-
liferation 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 tem-
peratures.
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 mois-
ture 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 bac-
teria 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.
HOW TO PRESERVE FOOD IN MAGIC VAC® BAGS
Vacuum packing for the freezer
First of all, use the freshest possible food. The MAGIC
VAC
system will allow you to retain all the freshness
®
of the food only if it is properly preserved. Some foods
have a soft consistency which could be damaged by
vacuum packing the product when fresh. To prepare
delicate foods like meat, fish, berries, bread, etc., it is
advisable to pre-freeze them first. In the first twenty-
four hours there is no risk of freezer burns, so you can
vacuum pack the products frozen the previous day in
MAGIC VAC
bags, and then keep them in the freezer
®
for long periods so as to preserve all the nutritional
values and flavour of the product you have packed.
When vacuum packing soups, stews or other liquid
food, pre-freeze it in a pan or high-strength dish. When
the food becomes solid, vacuum pack it, add a label
and replace in your freezer.
To vacuum pack vegetables, peel them and then
blanche them briefly in boiling water or a microwave
oven until they are warm but still firm. Then vacuum
pack them in convenient portions.
If the food is not pre-frozen, leave an extra 5 cm in
ABOUT VACUUM PACKING
Foodstuffs vulnerable to attack by Clostridium
Botulinum are those with low acidity (like red meat,
poultry, fish, seafood, olives in brine, eggs, mush-
rooms 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
temperature in the sealed vacuum bag may cause sev-
eral 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, tem-
perature 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 preser-
vation and thus contaminate the food. Some products
like flour and grain might contain larvae, but using
MAGIC VAC
ing into insects.
the length of the bag to allow for expansion due to
freezing. With regard to meat and fish, it is advisable
to place the food on a paper towel and vacuum pack
it with the towel in the bag. This will absorb any mois-
ture in the food.
To preserve food like focaccia, crêpes and small ham-
burgers, stack them on top of each other, placing
greaseproof paper or film between each piece. This
will make it easier to remove some of the food, repack-
age the rest and replace it immediately in the freezer.
Vacuum packing for the fridge
For busy households, food can be prepared in
advance, then vacuum packed and kept in the fridge
for use at different times, ready to be heated as and
when necessary.
Vacuum packing for the larder
Even foods that can keep at room temperature (like,
for example, coffee, flour, pasta, sugar, etc.) can benefit
from vacuum packing. If these products are to remain
unused for several days, such as when you go away on
holiday, it is advisable to protect all foods by vacuum
24
bags. Leaving the food to cool slowly at room
®
vacuum packing will stop them develop-
®
Publicité
