How to can and know that
your home canning recipes are safe.
The first question many
individuals ask when embarking on the process of canning food is: What exactly do I need? Before you fill your first jar, or use your home canning recipes from your great grandmother, it is important to understand the science of what you are doing.
Learning these fundamentals will help answer many future questions, as well as the initial question of 'What do I need'?
The Science: Chemical Changes and Microorganisms
When home preserving foods, you should be aware of two types of spoilage; Chemical changes and microorganisms.
* Enzymes cause the process of decomposition in foods. This starts as
soon as food is picked Enzymes are why it is important to use fresh
* Oxidation occurs when
fruit is exposed to air, this causes browning in fruits like
apples or pears. If you’re not careful, it may cause your
to look very unattractive.
* Yeast, the main cause of fermentation and bubbling.
* Mold, this is the green fuzzy stuff that we’re all familiar
with. It grows in a wide range of foods and conditions.
* Bacteria is what causes
is a very serious type of food poisoning. It thrives in low acid and oxygen free environments. This
bacteria will only be killed in very high temperatures of over 240
degrees F. These temperatures are achievable under pressure,
NOT in a water bath canner.
Repeat: Canning food in a pressure
canner stops botulism, a boiling water bath does
not. Botulism is a serious, but avoidable risk in canning low acid food.
How Processing Stops Spoilage in Your Foods.
During processing, as the contents boil, food
spoilers are stopped and oxygen is expelled from the jar. As the jar
cools after processing, its contents shrink and the lid is pulled down
flat to form a seal. This prevents further contamination of the freshly
sterilized foods inside the jar.
canning food in a boiling water bath will NOT prevent
botulism. However, it will – prevent yeasts and molds from forming, oxidation from occurring and stops
enzyme action in high acid foods.
All fruits are high acid foods. Pie fillings, jams, jellies
and fruit spreads (such as apple butter) are all included in this
Pickled products have acid added during preparation, usually in the
form of vinegar or lemon juice. Salsa, some condiments including
ketchup and barbecue sauce, as well as the dill pickle are included in
this group. Because the acid is added during the cooking process, these
are also considered high acid foods.
When processing jars in a boiling water bath, the heat
achieved is about 212 degrees F. This temperature is
sufficient to stop any yeast or molds from forming as well as halting
Pressure Canning – prevents
yeasts, mold, oxidation and stops enzyme action ; most importantly, it
Vegetables and meats are low acid foods. Botulism thrives in
low acid, low oxygen environments. In order to safely
acid foods, pressure is necessary.
As in a hot water bath, the process involves heating the foods in order
to sterilize them and stop any spoiling factors. Once the
jars are removed from the heat, the food cools and shrinks. As the food
cools it pulls down on the lid, forming a seal. Your food is
then protected from further contamination.
The difference between the two processing methods is the amount of heat
produced. A pressure canner produces a much higher level of
heat. And remember, Botulism can only be
very high temperatures.
Self Check :
Think about this statement... "My
grandmother used a boiling water bath and boiled her veggies and meats
for a very long time, this made them safe to eat.".
True or False? Why?
Answer to yourself, then scroll down to find what my answer is.
False - All vegetables and meats are at risk of
botulism. Canning food in a pressure canner is the only way
to assure that botulism
is stopped. The higher heat will stop botulism. The
produced in a boiling water bath will not.
Articles that restate or further explain canning food safety.
~ a special case of changing acidity
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Canning Books by Sharon
I have attempted to share safe preserving methods. However, I make no promises. You alone are responsible for your health. Be aware of current safety recommendations.
See my Full Disclaimer here.