Sour taste - what happened?

Greetings, all. Long-time brewer/first-time poster here. Just started sampling my Pumpkin Ale - a recipe I have brewed successfully and to rave reviews for years (extract recipe with some speciality grains - butternut squash as the pumpkin source - no real big tricks). To my horror, I've now sampled two times after 3 and 4 weeks in the bottle, and it's a failure. Very sour taste, with a nose almost like old orange juice. Any ideas what happened here? I'm guessing something airborne found its way in past the airlock, but I pride myself on cleanliness. And, if I knew the answer, I guess I wouldn't be posting. Any ideas about what usually causes this kind of failure? Thanks in advance!

Since you have been brewing a long time and this is a first and assuming you used your usual sanitary process then I'd consider your gear. Some of it is likely old, maybe scratched or grunge where you can't see it well etc. I replace all my tubing every 2-3 years, stopped using buckets for fermentors, dismantle everything I can when I clean or sanitize it and use Star San now as my primary sanitizer, PBW to clean.

GT

** Just noticed I hit 500 posts. Guess I should upgrade huh...

What GT said. In conversation with da boys at LHBS, they all agreed: Bacterial. Some critter found a home and went to town. Like you, I am big on cleaning, Star San, PBW, etc. Not gonna lose a lot of sleep over it.
Like the motto says, "Relax. Have a HB."


Oh, and BTW, GT, you freeloader, YES you should upgrade!!