“Dilly beans” are green beans pickled with dill and garlic. In canning books they’re vinegar pickles, processed in a water bath; the fermented version uses only a salt brine and lets the beans’ own lactic acid bacteria sour them over about a week. They stay crunchy, taste tangy and garlicky rather than sharp, and contain live bacteria as long as they’re not heated.
What Ferments Green Beans
Green beans carry their own fermenting bacteria. In an Italian study, raw French beans yielded Leuconostoc mesenteroides, Lactiplantibacillus plantarum, Pediococcus pentosaceus and others. When beans were fermented with a starter made from their own bacteria, the pH fell below 4.5 quickly, unwanted Enterobacteriaceae and yeasts were held back, and the beans stayed firmer than beans left to ferment on their own (Di Cagno et al., 2008). At home, the closest equivalent is a few spoonfuls of brine from a previous good batch of fermented vegetables – optional, but it helps a slow start.
Choosing and Preparing the Beans
- Use the freshest beans you can find – firm, bright, snapping cleanly. Limp beans ferment limp.
- Green, yellow wax and purple beans all work; thin haricots verts ferment a little faster.
- Trim the stem ends and cut the beans to stand upright in the jar with about 3 cm to spare.
Fermented vs Canned Dilly Beans
Canned dilly beans are acidified with vinegar and must follow a tested recipe to be shelf-stable (NCHFP). Fermented beans get their acidity from lactic acid instead; once properly sour, their brine is well below pH 4.6, the line US regulations use for acidified foods (21 CFR 114), but they aren’t processed, so they live in the fridge. If you want the vinegar kind without canning, see our quick refrigerator pickles; for cucumbers fermented the same way, see fermented dill pickles.
Flavour Ideas
- Spicy: add a sliced fresh chilli or ½ tsp chilli flakes.
- Horseradish: a few slices of fresh horseradish root, which also adds bite.
- Ginger and Sichuan pepper: instead of dill, for an Asian-style bean.
For other vegetables and their salt and timing, see the best vegetables to ferment. For films, softness and off smells, see the NCHFP’s problems with fermented pickles and our troubleshooting guide.
