Not sure if you have high or low acidic foods? Is the way to can them different? What does it all mean? Here are some helpful tips to determine the acidity level and what foods are what.
First off, foods have a pH – thats the acidity level. What the pH is determines if they should be processed in a pressure canner or a boiling water canner. If a pH is low then the food is more acidic. To give you an idea these foods are low acidic:
- dairy products
- all vegetables
But these foods are high acidic:
- properly pickled vegetables
- ripe pimientos
Acidic foods have pH values below 4.6. These foods include pickles, most fruits, and jams and jellies made from fruit. (In pickling, the acid level is increased by adding lemon juice, citric acid, or vinegar.) Acidic foods contain enough acidity either to stop the growth of botulinum bacteria or destroy the bacteria more rapidly when heated. Acidic foods may be safely canned in a boiling water canner.
Low-acid foods include red meats, seafood, poultry, milk, all fresh vegetables and some tomatoes*. Low-acid foods have pH values higher than 4.6. They do not contain enough acid to prevent the growth of botulinum bacteria. These foods are processed at temperatures of 240 degrees F to 250 degrees F, attainable with pressure canners operated at 10 to 15 pounds per square inch (psi) of pressure. The exact time depends on the kind of food being canned, the way it is packed in jars, and the size of jars.
However, tomato is an exception. Some tomatoes have a pH above 4.6 so you can them add some lemon juice or citric acid – 2 tablespoons of bottled lemon juice or 1/2 tsp of citric acid per quart of tomatoes.
For pints, use 1 tablespoon of bottled lemon juice or 1/4 teaspoon citric acid. Acid can be added directly to the jars before filling. If the flavor is too acid to suit your taste, add a little sugar to offset the acid taste. Do not reduce the amount of acid.
Figs are also a food that has a pH value close to 4.6 so add some acid to them also.
When you mix low-acid and high-acid foods, assume the mixture remains low-acid and process in a pressure canner.
Please note the importance of this:
Non-Acid foods must be processed in a steam pressure canner, also known as a pressure cooker, at 10-15 pounds of steam. This ensures a heat of 240ºF to 250ºF which is sufficient enough to kill all micro-organisms and bacteria in non-acidic foods. It is impossible to do this at lower degrees of heat.
The addition of lemon juice, vinegar or any other acidic additive does not change the acidity of the food enough to permit processing by any method other than the pressure canner/cooker. The exception is when food is pickled in vinegar, which may be processed with the hot water method.
Please click through for more important information that you must know as a safe canner. Also what you must know about pumpkins and squash which may surprise you…