Pressure canning a MUST for green beans
I thoroughly enjoy fresh vegetables this time of the year. The most popular Indiana vegetable is sweet corn followed by tomatoes and then green beans. Green beans are one of those foods that must be pressure canned! There are no exceptions to this!
Green beans are earlier like many vegetables and many of you are busy pressure canning them. Green beans, corn, meat, and all other foods classified as low acid must be pressure canned. There is no way that you can add an acid like lemon juice or vinegar to the green or yellow beans for canning. This is the serious science side of food preservation. A deadly form of foodborne poisoning is known as botulism which can occur when low-acid vegetables are canned improperly. The toxin produced by clostridium botulism causes this and it is often fatal. This organism is extremely resistant to heat and it grows without oxygen in low-acid foods.
This deadly toxin may be produced before you see the signs of spoilage. Remember to never taste home canned non-acid foods before boiling them 10 minutes. This gives you a margin of safety in case your pressure canner’s gauge is faulty or you did not follow the pressure canning procedure exactly.
The botulinum spore that produces the toxin is killed at temperatures of 240 degrees and higher. A boiling water bath canner only reaches 212 degrees no matter how long you boil it. The botulinum spore is not killed at that temperature. To destroy the spore, you must use the pressure canner and reach the 240 degree temperature.
Many of you who have called say you have trouble with losing liquid from the jars during pressure canning. There can be several reasons for this. The most likely reason is the food was packed raw or cold in the jars. Hot pack is preferred. To hot pack vegetables, pre-heat the vegetables in water or steam. Once the food is put in the jars, cover with the cooking liquid used during pre-heating or use boiling water. Cooking liquid is recommended because it may contain minerals and vitamins dissolved out of the food. Boiling water is recommended when cooking liquid is dark, gritty, or strong flavored or when there isn’t enough cooking liquid to sufficiently cover the food.
Another cause of liquid loss may be due to the vegetables being packed too lightly if raw packed or the jar was too full. The pressure may have been lowered too rapidly such as opening the petcock before the pressure had actually reached zero. When pressure canning starchy food, the food may have absorbed the liquid or the pressure fluctuated during processing. For fruits, the jars may have been too full or the jars were not covered with boiling water in the boiling water bath.
When you have jars that have lost liquid, besides wanting to know why, you also want to know what you should do with these jars. Check carefully if they are really sealed. If they are sealed properly, do nothing except label and store for future use. Remember, if you open the jar, you must reprocess the food again for the full length of time recommended for that food and I don’t recommend this.
For current research-based food preservation publications visit the Purdue web site at www.extension.purdue.edu/elkhart.