[CH] Foodsafety.org
Tantrika (hummer13@earthlink.net)
Thu, 01 Jul 1999 09:32:35 -0700
well I got a canned salsa mix from the USDA which is very much like Nel's
<http://www.foodsafety.org/he/he186.htm>http://www.foodsafety.org/he/he186.htm
and
<http://www.foodsafety.org/he/he182.htm>http://www.foodsafety.org/he/he182.htm
They also say: United States Department of Agriculture Extension Service
Quality: Select only disease-free, preferably vine-ripened, firm fruit for
canning.
Caution: Do not can tomatoes from dead or frost-killed vines. Green tomatoes
are more acidic than ripened fruit and can be canned safely with any of the
following recommendations.
Acidification: To ensure safe acidity in whole, crushed, or juiced tomatoes,
add two tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per
quart of tomatoes. For pints, use one tablespoon bottled lemon juice or 1/4
teaspoon citric acid. Acid can be added directly to the jars before filling
with product. Add sugar to offset acid taste, if desired. Four tablespoons
of a
5 percent acidity vinegar per quart may be used instead of lemon juice or
citric acid. However, vinegar may cause undesirable flavor changes.
Recommendation: Use of a pressure canner will result in higher quality and
more
nutritious canned tomato products. If your pressure canner cannot be operated
above 15 PSI, select a process time at a lower pressure.
about Botulism:
Growth of the bacterium Clostridium botulinum in canned food may cause
botulism--a deadly form of food poisoning. These bacteria exist either as
spores or as vegetative cells. The spores, which are comparable to plant
seeds,
can survive harmlessly in soil and water for many years. When ideal conditions
exist for growth, the spores produce vegetative cells which multiply rapidly
and may produce a deadly toxin within 3 to 4 days of growth in an environment
consisting of:
a moist, low-acid food
a temperature between 40°F and 120°F
less than 2 percent oxygen
Botulinum spores are on most fresh food surfaces. Because they grow only in
the
absence of air, they are harmless on fresh foods.
Most bacteria, yeasts, and molds are difficult to remove from food surfaces.
Washing fresh food reduces their numbers only slightly. Peeling root crops,
underground stem crops, and tomatoes reduces their numbers greatly. Blanching
also helps, but the vital controls are the method of canning and making sure
the recommended research-based process times, found in these guides, are
used.
The processing times in these guides ensure destruction of the largest
expected
number of heat-resistant microorganisms in home-canned foods. Properly
sterilized canned food will be free of spoilage if lids seal and jars are
stored below 95°F. Storing jars at 50°F to 70°F enhances retention of quality.
Food Acidity and Processing Methods
Whether food should be processed in a pressure canner or boiling-water canner
to control botulinum bacteria depends on the acidity in the food (Plate 1).
Acidity may be natural, as in most fruits, or added, as in pickled food.
Low-acid canned foods contain too little acidity to prevent the growth of
these
bacteria. Acid foods contain enough acidity to block their growth, or destroy
them more rapidly when heated The term "pH" is a measure of acidity; the lower
its value, the more acid the food. The acidity level in foods can be increased
by adding lemon juice, citric acid, or vinegar.
Low-acid foods have pH values higher than 4.6. They include red meats,
seafood,
poultry, milk, and all fresh vegetables except for most tomatoes. Most
mixtures
of low-acid and acid foods also have pH values above 4.6 unless their recipes
include enough lemon juice, citric acid, or vinegar to make them acid foods.
Acid foods have a pH of 4.6 or lower. They include fruits, pickles,
sauerkraut,
jams, jellies, marmalades, and fruit butters.
Although tomatoes usually are considered an acid food, some are now known to
have pH values slightly above 4.6. Figs also have pH values slightly above
4.6.
Therefore, if they are to be canned as acid foods, these products must be
acidified to a pH of 4.6 or lower with lemon juice or citric acid. Properly
acidified tomatoes and figs are acid foods and can be safely processed in a
boiling-water canner.
Botulinum spores are very hard to destroy at boiling-water temperatures; the
higher the canner temperature, the more easily they are destroyed. Therefore,
all low-acid foods should be sterilized at temperatures of 240°F to 250°F,
attainable with pressure canners operated at 10 to 15 PSIG. PSIG means pounds
per square inch of pressure as measured by gauge. The more familiar "PSIG"
designation is used hereafter in this publication. At temperatures of 240°F to
250°F, the time needed to destroy bacteria in low-acid canned food ranges from
20 to 100 minutes. The exact time depends on the kind of food being canned,
the
way it is packed into jars, and the size of jars. The time needed to safely
process low-acid foods in a boiling-water canner ranges from 7 to 11 hours;
the
time needed to process acid foods in boiling water varies from 5 to 85
minutes.
Process Adjustments at High Altitudes
Using the process time for canning food at sea level may result in spoilage if
you live at altitudes of 1,000 feet or more (Plate 2). Water boils at lower
temperatures as altitude increases. Lower boiling temperatures are less
effective for killing bacteria. Increasing the process time or canner pressure
compensates for lower boiling temperatures.
Therefore, when following canning directions in this series, select the proper
processing time or canner pressure for the altitude where you live. If you do
not know the altitude, contact your local county Extension agent. An
alternative source of information would be the local district conservationist
with the Soil Conservation Service.
Equipment and Methods Not Recommended
Open-kettle canning and the processing of freshly filled jars in conventional
ovens, microwave ovens, and dishwashers are not recommended, because these
practices do not prevent all risks of spoilage. Steam canners are not
recommended because processing times for use with current models have not been
adequately researched. Because steam canners do not heat foods in the same
manner as boiling-water canners, their use with boiling-water process times
may
result in spoilage. It is not recommended that pressure processes in
excess of
15 PSI be applied when using new pressure canning equipment. So-called canning
powders are useless as preservatives and do not replace the need for proper
heat processing. Jars with wire bails and glass caps make attractive antiques
or storage containers for dry food ingredients but are not recommended for use
in canning. One-piece zinc porcelain-lined caps are also no longer
recommended.
Both glass and zinc caps use flat rubber rings for sealing jars, but too often
fail to seal properly.
And this is a whole page on canners....
<http://www.foodsafety.org/he/he204.htm>http://www.foodsafety.org/he/he204.htm
Hope this helps to clarify! This is what most of the Extension offices rely
upon.
Btw, I would suggest you all check out foodsafety.org for a number of things,
including lots of recipes!