[Red Badger]

My wife has near constant heartburn, and especially after eating oily and greasy foods.

The problem may be you have Acid-reflux disease:

http://www.medigus.com/healthcare-professional/clinical-presentations/273-anti-reflux-barrier-how-does-your-body-prevent-acid-reflux

[treetopsandroofs]

Ah, one of over 50 of Dr. Cooper’s sphincters.

[Boogieman]

Yeah, I was going to say this sounds more like acid reflux than food going “rancid”. Packaged, processed foods usually take waaaaaaay longer than the “sell by” date to actually go bad.

[TigerHawk]

You need to have your Gall Bladder checked out. I’d make book on it.