I have been adding fat to each jar of canned legumes to prevent frothing during processing (pressure canning). The fat looks unappetizing in the final product, especially if the beans are used cold such as in a salad. I have tried oils and solid fats and do not like the results in both.

Is there anything other than fat that I can put into the beans to prevent frothing during processing?

  • 1
    Have you tried onion? Adding raw onion when pre-soaking dried beans is supposed to help break down oligosaccharides that cause flatulence, and I believe the same compounds cause the frothing.
    – csk
    Commented Jun 12, 2021 at 3:45
  • I will try that in the batch I am soaking now.
    – Bookaholic
    Commented Jun 12, 2021 at 18:47
  • Please let us know if that helps; if it does, go ahead and write an answer. I'm sure other people with the same problem will appreciate it.
    – csk
    Commented Jun 15, 2021 at 15:19
  • Onions did not help. I tried 2T, 4T & 6T of chopped raw onions. I was sure the 6T jar would stop the foaming, but it did not. 6T was 25% onion , 75% legumes by weight. If it takes more onion than that it would be too much onion in the final product.
    – Bookaholic
    Commented Jun 17, 2021 at 13:58
  • Interesting, and also disappointing. Thank you for experimenting and sharing the results. Now I wonder if onions actually reduce the gas-producing components. I've only ever heard that by word-of-mouth, but I've never seen a science-based source say so. Of course, there's a big difference in time and temperature between an overnight soak and a canning bath.
    – csk
    Commented Jun 17, 2021 at 15:54

1 Answer 1


I have finally found a solution to the frothing issue in the USDA recommendations for canning legumes.

In addition to soaking the beans (they add salt to the soak water), par-boil them in plain water for about 15 minutes. Drain the water, then add fresh water to the jars.

I am not sure if it is the fact that they add salt to the soak water or the par-boiling, or both. But the beans did not froth during canning using their method without adding any fat at all.

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