Hi Old Fixer, I'm wondering ... would you have a general idea to share of what my expiration date might be? Some years ago, while travelling to the Maritimes with my children, something less than teenagers at the time, after a day's travel when we stopped for supper and pulled milk from the cooler ... it poured slightly chunkily. I tasted it and it tasted O.K ... but my offspring weren't going to touch that idea with a ten foot pole! I said, "What's the matter - the only thing out of the ordinary is texture" ... but my parental suggestion rolled like the proverbial water off of a duck's back, with them. That story still provokes some merriment when we get together. I have a suspicion, backed by a small bit of evidence ... that they've not changed that choice, still (and the younger hits the round number of age 50, later this year). ole joyfuelled ... with some fuelling help regularly from milk - occasionally chunky

This is a pretty old story, printed in Dear Abby in 2003. There was a medical journal article in 2001 about anaphylaxis (a very severe, potentially fatal allergic reaction) in an individual who ate some foul-tasting pancakes made from old moldy pancake mix. The individual had a history of multiple allergies, including pets, mold, and penicillin. The researchers called it an "unusual case," so let's not get too carried away here.

If you read carefully, it usually says 'best by' on canned items. That is not an expiration date, but signifies that taste/texture may be less than ideal. Canned items do tend to last for quite some time. http://99percentinvisible.org/episode/best-enjoyed-by/ "...Over the years we’ve lost track of what these labels meant in the first place. We’ve come to associate the dates with safety, when in fact, they’ve always been about freshness. As much as we might want them to, the dates on our food are not going to tell us if we’ll get salmonella or e-coli. Most date labels are arrived at by conducting taste tests. Does a product still taste good on day 4? Day 5? And yet today, according to a report that Emily Broad-Leib co-authored, a majority of consumers believe that eating food past it’s sell-by or use-by date is a risk to their health. And as many as 90% of Americans throw out food based on date labels at least occasionally...."

I know this is an old thread but as a buttermilk lover I wanted to offer some comments. I pay little attention to expiration dates on buttermilk. I usually keep a culture going but do restart with purchased buttermilk after a few months. Right now I am using a purchased gallon with a date of May 30 and it is still fine. It sat unused for a while while my wife was in the hospital and we weren't home to use it. Some argue for a difference in cultured and churned buttermilk and there may be a difference in the bacteria culture but taste is essentially the same. Home churned buttermilk was made from the natural culture of bacteria present in the raw milk. Pasteurization kills these bacteria thus supermarket milk on its own will not make good buttermilk. I purchase whole milk by the gallon and if not used by a reasonable time after the expiration date has passed I add a cupful or more of purchased buttermilk or my culture. I often push milk well past the expiration date by shaking the jug at every use. I was raised on raw milk. My mother always kept a Jersey cow and had a crock of milk clabbering in a warm corner at least once per milk. I was used to butter extracted from clabbered milk and it took me a long time to develop a taste for sweet cream butter, though I know some farm women had crank butter churns to make butter from cream. Mother churned with a dasher in the crock, usually flipping pages in the Sears or Wards catalog as she churned. When the butter came she centrifuged it by twirling the dasher handle (probably fashioned from a broomstick) between her palms. The whey was squeezed from the butter and it was washed several several times with water before being chilled enough for molding. The buttermilk was refrigerated, fairly thin to begin with and getting thicker with age. When it was deemed too thick it went out to a trough for the chickens. This is where the cultures may differ, purchased buttermilk doesn't thicken so quickly and the whey doesn't separate as much.