Burning Issue: Green Beans and Botulism

How can I can my green beans safely?

burning image

Easy to grow in a home garden and delicious year-round, green beans are a popular home-canned food. Just like with any other home-canned food, it is important to always use proper procedures and follow tested recommendations. Yet we have received many concerns about canning green beans this season, including confessions of improper processing. Unfortunately, in multiple situations we’ve had to recommend discarding entire batches due to under-processing, because there is a risk of botulism from under-processed green beans.  Botulism is a potentially deadly food poisoning.

To help you prevent waste, sickness, or worse, here are our responses to the most common questions about canning green beans:

Q: I want to can my green beans in a boiling water bath…is that ok?

No. Green beans are a low-acid food and require the higher temperature from a pressure canning process for a pre-determined length of time in order to destroy the potentially deadly bacterial spores of Clostridium botulinum. The ONLY processing we can support for green beans is under pressure, using the directions and steps found on our website at http://nchfp.uga.edu/how/can_04/beans_snap_italian.html. The correct procedures include the steps for managing the canning process found here:  Using Pressure Canners.

Q: My neighbor gave me green beans that were canned using the oven method…is it safe for me to eat them?

A: No. Using the oven method is NOT a recommended method of canning for green beans or any other food. It is dangerous because dry heat is slow to penetrate into jars (so recommended process times would not be enough), temperatures inside ovens vary (so a standard process time would be indeterminable), and no reliable, research-based safe process times have been developed for oven canning.  There are also stories that jars heated in a dry oven could explode or break more easily than with recommended canning procedures.

Q: Last month I force cooled the pressure canner with my last batch of green beans, but now I think that may not have been a good idea…what should I do?

A: We recommend that the jars of beans be discarded. This is the safest option when home-canned foods are suspected of being spoiled or improperly canned.  The cool-down time of a pressure canning process is calculated into the overall heat treatment required to destroy dangerous bacteria (Clostridium botulinum). So, if you do not let pressure canners cool down naturally and slowly to 0 pounds pressure, the jars did not receive a complete canning process.  These jars are therefore considered to be under-processed, which means it is not safe to store them at room temperature. If it had been less than 24 hours, you could have refrigerated the jars immediately and eaten them within one week or frozen the green beans for longer term storage.  Instructions for discarding suspect jars or detoxifying and cleaning unsealed spoiled jars are available on our website: http://nchfp.uga.edu/how/general/identify_handle_spoiled_canned_food.html .

Q: Last night I pressure canned my green beans using USDA recommendations, but this morning I noticed that 3 of the jars did not seal…can I re-process them?

A: Yes, if the jars received a proper pressure canning process but simply did not vacuum seal, then you can re-process them within 24 hours. Remove the unsealed lids and check the jars for nicks. Replace the jar if needed, and replace the lid with a new, properly prepared lid. Repeat the canning process, using the same processing time for this second process. Another option is to refrigerate the jars and eat the beans within a week, or to freeze the green beans for longer term storage. If more than 24 hours had passed, then we would recommend that you discard the beans.

There are cases of botulism from under-processed home-canned green beans and other vegetables.  These two short reports document that this is hazard to be taken seriously.

August 2014
Kasey Christian, National Center for Home Food Preservation