After doing a LOT of research, I believe there is a SAFE way to can butter for long term use. There is much information on the internet about canning butter in your oven. DO NOT buy into it as it will only keep for about 6 months and it is not safe. Various home canners have reported to me that they have tried that method and within 6 months, a thin layer of black mold begins to grow on the butter. Others have tried a BOILING WATER BATH with only a slight improvement in the product.
Butter is a LOW ACID food; therefore, it will only get hot enough to kill all bacteria in a pressure canner. I found a few people who have said they found satisfactory results with canned butter that was dated 1999, however it WAS pressure canned.
I experimented with three methods of preparation. All methods require vigorous shaking of the butter as it cools to keep it from separating.
First, I did one jar by simply filling it with soft butter. That jar (it was brand new) broke in the canner. Perhaps I didn’t leave enough headspace. I don’t know . . .
Second, I melted the butter and stirred it well before filling the jars. This appears to be a satisfactory method, although I wouldn’t be surprised if the texture is not as smooth as the third method.
Third, and preferably, I melted the butter and brought it to a boil in a large pan. Allow enough room for it to foam up within the pan. I continued cooking it at a slow boil for a minimum of 5 minutes, stirring frequently to prevent scorching. The last thing we want is a burnt butter flavor.
Fill the jars leaving standard headspace. Be sure to stir the butter well and scoop up from the bottom of the pan. Wipe the rims and place the lids and rings on tightly. Pressure can for 10 minutes at 10 pounds of pressure for ½ pints or pints.
After you remove the jars from the canner, allow them seal and to cool a bit before shaking them. Shake about every half hour until the butter begins to congeal. You may sit them in the refrigerator to speed up the process.
I assumed that I would need ½ pound of butter for each half pint, however, it required a bit less than that. I ended up with two pints more than I had planned and still had an extra pound of butter left over. I had purchased 12 pounds of butter with the intention of ending up with 24 ½ pints.
Butter was on sale at a good price ($1.99 per pound). Though I store butter in the freezer, I wanted some shelf stable butter as well. It’s great to take camping with you!
The next time I can butter, I plan to make some garlic butter and perhaps experiment with a few other herbs and spices as well.