Page 11 - The Lost Book Preserving Food Naturally
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The Lost Book of Preserving Food Naturally
solution on both sides of that membrane. So, water will move from a low-concentration
area, across the semi-permeable membrane, to a high-concentration area, until the
concentration is the same on both sides.
For the purpose of food preservation, the concentration we are referring to come from
either salt or sugar. If there is more salt on one side of a membrane, than there is on the
other side, water will move through the membrane to equalize the levels. Since cell walls
are semi-permeable membranes, this works with all vegetables, fruit and meats. It also
works with bacteria.
You can see the results of this by doing a simple experiment. Take a piece of raw meat
and put it on a plate, drying the surface with a paper towel. Then sprinkle a liberal coating
of salt onto the meat, allowing it to sit. Within a few minutes, the salt will be wet, having
drawn water out of the meat.
Bacteria are single-cell organisms. As such, they are also surrounded by semi-permeable
membranes. The space between the various parts of the cells, just like the cells in our
bodies, is filled with water. So, when salt comes into contact with bacteria, it draws water
out of the bacteria, just like it draws it out of meat or any other food. When it draws
enough water out of the bacteria, the bacteria dies.
While the main idea behind osmosis is that the water passes across the membrane, salt
will pass across the membrane in the opposite direction, increasing the salt level in the
cells of the food. This is an important part of the preservation process, as that protects
the food from further infestations of bacteria. As long as the level of salt in the food is
high enough to draw water out of any bacteria that comes into contact with the food, it
will kill the bacteria.
This is why so many preserved foods are salty. While modern food processing plants use
chemical preservatives, they also use salt. It is the salt, more than the chemicals, which
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