Moldy taste appearing months after bottling

Question

I brewed and bottled an English Ale in August, and, after a few weeks in the bottle, promptly drank most of the 5 gallons.

However, I'd heard some advice to leave a few bottles for a few months to see how it evolves over time. Yesterday, I cracked open one of the bottles, and it certainly had evolved, but for the worse.

In fact, this brew had become somewhat cloudy, and had a distinctive taste that I could best describe as dusty and moldy. From what I understand, a moldy malt can yield a moldy brew, but this seems doubtful in my case, since I had plenty of this beer and it was delicious until now.

Was it just an anomaly? Or did something grow over time? Perhaps I capped poorly? Or maybe this bottle just wasn't thoroughly clean?

Answer 1

When a beer becomes cloudy after it is bottled it often means that there is some sort of bacterial infection. This could have been introduced in the bottle or before and it just took time to develop which may be why it wasn't present in the bottles you consumed first. Some people describe oxidation as a dusty or papery flavor so it may have also suffered from oxidation. It could also just be a byproduct of the infection. I would suggest looking at your cleaning and sanitation procedures for bottling to prevent this in the future.