AGRICULTURAL EXTENSION SERVICE

September 10, 1957

Mrs. Ottie Rhoads
Route 2, Chalybeate
Edmonson County, Kentucky

Dear Mrs. Rhoads:

Your letter of the 5th reached me Saturday and I am answering it myself because Louise is at the fair in Bowling Green through Thursday and I would rather you had this now than had it neatly done next week.

First, the three jars. Put them out. Do not taste them, do not smell them, do not wipe the rims and re-seal them, and do not can them over. A lid that has let go has let air into the jar and once air is in it there is nothing further you or I can reason about it — the whole basis of the thing is that the jar is sealed and airless, and it is not. Carry them to the hogs or empty them in the ditch, wash the jars, and use them again Thursday. That is the whole of it, and now I want to spend the rest of this letter on why it happened, because that is what will keep it from happening in November.

Second, the mechanics, numbered so you can find them again.

1. What kind of a problem beans are. There is exactly one number that divides all canning into two halves, and it is a pH of 4.6. Above that figure — beans, corn, greens, hominy, meat, anything low in acid — the spores of Clostridium botulinum can wake up and grow inside a sealed airless jar. Below it — tomatoes as we grew them, pickles, all the fruit — they simply cannot, and the acid does the work for you. Tomatoes and beans are not two versions of the same job. They are two different jobs, and the one you do with a kettle of boiling water will not do the other one at all.
2. Why the pressure is there. Water boils at 212° at the sea, and the spores will sit in 212° water for hours and be perfectly well when you come back. At 240° they are finished in a few minutes. The onlyonly way anybody has of getting 240° in a kitchen is to put the water under pressure so it will boil hotter. So the canner is not there to hurry the beans along; it is there to raise the temperature. Ten pounds and five pounds are not "nearly the same." Five pounds is a different temperature, and it is a useless one.
3. The cold spot, and why quarts take longer than pints. The middle of the jar is the last part of it to get hot, and it lags the canner by a real number of minutes that you could measure if you had the wire for it. A quart takes longer than a pint not because it holds more beans but because the heat has further to walk to get to the middle. And this is where the pack comes in, and I want you to read this part twice: a loosely filled jar has liquid moving in it, and moving liquid carries heat quickly. A jar stuffed tight has no room to move and the heat has to creep from bean to bean. That is enormously slower. "I packed them good and full" is the most dangerous sentence I hear in this county, and I hear it every August.
4. Elevation and what your gauge does about it. Water boils about a degree cooler for every five hundred feet you go up. Your place is around 1,140 feet, so a weighted gauge rocking at 10 pounds is not delivering what 10 pounds delivers at the coast, and you must run the weight at 15. A dial gauge does not correct itself for anything, and its spring tires with age and begins to flatter you. Bring the dial in each spring and we will test it against the master gauge here in the office; a weighted gauge only wants its vent pipe run out with a wire. I do not know what your gauge reads at weight, and neither do you, which is the whole of the trouble.
5. Venting, which is not a ritual. Let the steam come out the open vent in a steady column for ten full minutes before the weight goes on. If air is left shut up in that canner with the steam, the needle or the weight is reporting a pressure that is partly air, and air does not carry the temperature that steam does. You get a canner that says 10 pounds and is honestly at 232°, and you will never know it from the outside. I believe this one error accounts for more failures than every other cause put together.

Now two more that I thought of while I was typing and will not renumber.

Your loose lids are almost certainly siphoning. If the pressure comes down fast — the weight off early, or a wet towel, or the canner shifted onto a cool eye — the liquid in the jars boils violently, and it pushes bits of bean and broth out under the sealing compound as it goes. The lid then seals against that film. It holds overnight. It lets go on the cellar shelf a week later, which is precisely what yours did. Too little headspace does the same thing, and so does a nick in the jar rim you can only find by running your finger around it, and so does a lid that has been used once already. Let the canner come down on its own and do not lift the weight to hurry it.

Flat sour is a separate matter and will not show at all. That is a heat-loving bacterium that sours the beans without making gas, so the jar stays perfectly sealed and looks right and the food is spoiled anyway. It comes from hot filled jars standing around waiting on the canner. Fill and load and get the lid on.

I will say plainly what I said at Chalybeate club in July: there is a mimeographed sheet going about this county, put out by a seed dealer here in Brownsville, that gives boiling-water-bath times for green beans. Those times are not adequate for a low-acid vegetable and I have written to them about it. If that sheet is in your kitchen, take it out. I am told it is on a good many walls.

And here is the arithmetic, which is short. Green beans, hot pack, quarts: vent ten minutes, weight at 15 pounds for your elevation, thirty minutes at weight; pints, twenty-five. Let the pressure fall of itself. And whatever the jar looks like when you open it in February, empty it into an open pan and boil it hard for ten full minutes before a fork goes near it — every jar, every time, no exceptions, and that is not a sign of distrust in your canner, it is simply free insurance.

(I apologise for the length of this. I began meaning to write half a page.)

I am glad you noticed those lids and wrote instead of pressing them down and letting them be. Most people don't look. Send word by Ratliff's boy if the gauge wants testing and I will come out — I am at Rocky Hill Monday and can come on afterward, Mrs. Rhoads.