Why tasting is never a botulism safety test for home canned low-acid food

What to take away

The rule, stated plainly

The National Center for Home Food Preservation's page for safety's sake puts it in one sentence. If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a poisonous toxin. Even a taste of food containing this toxin can be fatal.

That is the whole argument against tasting to check. Every other food fault in this subject announces itself through the senses. This one does not, and the dose that matters is smaller than a mouthful.

What the same page says about boiling

The guidance describes a boiling step and frames it carefully. Boiling food 10 minutes at elevations below 1,000 feet should destroy the toxin when it is present, adding 1 minute per additional 1,000 feet. Here boiling means large foamy bubbles breaking all over the surface.

To prevent botulism risk, low-acid and tomato foods not canned according to the USDA Complete Guide to Home Canning or other USDA-endorsed recommendations should be boiled that way before consuming, even with no signs of spoilage.

Two qualifications matter more than the step. This is not a recommendation to eat food known to be significantly under-processed, and it is not a guarantee that boiling overcomes all possible defects.

The page notes that since July 2013, the CDC has recommended discarding any home canned food that might contain botulism toxin.

Read the whole passage rather than the boiling time. It is a description of last-resort handling for a jar someone already made, not a technique that makes an untested process acceptable.

What tasting is actually for

Where beginners get caught

The pressure canner. The National Center's page states that pressure canning is the only recommended method for canning meat, poultry, seafood, and vegetables, and that using boiling water canners for these foods poses a real risk of botulism poisoning.

The University of Alaska Fairbanks Extension guide to canning low-acid vegetables adds the raw-material side that beginners underestimate. Vegetables for canning should be young, tender, and freshly gathered. Delay lets nutrients dissipate and gives bacteria in the food an opportunity to multiply.

Tough, overmature vegetables give a poor finished product. Frostbitten vegetables may be canned, best processed as soon as possible after frost, though texture is generally poor once vegetables freeze. Tomatoes may not be canned after freezing because freezing changes their pH.

Build the habit early

Taste for pleasure, decide safety on the process. Our pillar on the documented cases covers what the record shows, and the guide to off flavors and what they mean covers the faults that tasting genuinely diagnoses.

Common questions