Dong dong ju - does it go bad?

[samiamsl]

I made a batch of makgeolli maybe a year or two ago and decided to experiment and fill two beer bottles with undiluted makgeolli (I think it's dong dong ju in that case). They were put in the basement and forgotten about until recently. I'm guessing they're waaay past their expiration but has anyone else had experience with this? Could dong dong ju in beer bottles still be okay after 1-2 years?