I have to admit to a bit of a problem with my canned butter. Although I have been canning it for a number of years, I have never kept it over the summer on a hot shelf. This year, I had quite a lot of canned butter, and I wasn't going through it as quickly as I have in the past. A few days ago, I opened a jar and sniffed and the butter was STRONG! I was so surprised! I have never had that happen before, but I can only imagine that it had to do with the temperature that I have been storing the butter at. Generally, I can and use the butter in the winter - the storage temperature is very cool. This year I canned in the winter but didn't use the butter. It does not seem to be storing well over the summer.
In the future, I won't be storing canned butter over the summer, unless I have a root cellar, or somewhere equally cool in which to store it!
I hope my oversight hasn't caused a problem for any of you. Please forgive flawed testing methods.