@NullNowhere Wheat apparantly does quite well in hydroponics, and at least here in Scadinavia hops is a rather new thing, first appearing in the 6th century, and only dominating from the 14th century onwards.

Beer with hops hold up to tramsportation much better.

So dwarves must have been drinking wheat beer with bog myrtle or alewort as bittering agents all this time.

@Nyborg You'd generally still want barley when you make beer (even wheat beer) for diastatic power, especially if you're working with ye-olde malt. Sparging with pure wheat would also be a right pain because it gets stuck so easily. So, they'd still have to either grow it or trade for it. Trade would be fine for dwarves near lowland settlements, but a pain for dwarves in an "underdark" setting. But maybe they just magic a growing cave? It'd be a stretch for them to spend that much energy creating something like that.

It's unlikely that they'd trade for beer directly. Beer is kinda a pain in the ass as an ancient trade good. It's a lot of water (heavy), somewhat delicate, and as you mentioned, before hops and modern container vessels, it didn't ship all that well. Whiskey and other distilled spirits actually filled this role a lot more nicely historically, so if the dwarves were importing drink it'd probably be whiskey.

On that note, the "foamy beer" is also rather newer development in beer as well like hops, as you mentioned. It would be more like "real ale" which is fizzy, but only slightly. bog myrtle, alewort or other gruits (what we call these kind of beers) would be possible. For sealed barreling like this, they'd also need good source of pine for brewer's pitch. Possible for your mountain dwarves, painful for your underground dwarves.

What it boils down to is that if you were world building, and you wanted your dwarves to have "logical" beer, your mountain dwarves would have to have some strange mountain agriculture, and your deep dwarves would have to just have a completely different fermentable - some kind of fermentable tuber or mushroom. Or just handwave it with magic.

@NullNowhere Speaking of fermentable tubers; there is such a thing as banana beer. Made from banana corm (tubers, sort of).

So Cave Banana Beer?

@NullNowhere On an entirely unrelated note "Cave" in Latin translates to "Beware" in English.

@Nyborg Beware Banana beer...

I suppose the latin makes sense. You can layer a map of missing peoples over a map of caves and old mines and ... find a dressing correlation. I grew up near a bunch of old coal mines and at least once a year someone fell into a coal hole they missed while wandering the woods and died.

mubisi is something I'd like to make but unfortunately it's kinda impossible to get African Highland Bananas here ​​ I do like the dwarves growing weird bananas instead of like, weird sugar beets.