>Why not get rid of the ridiculously complicated (but truly beautiful) barrels, and instead use pieces of kioke wood, maybe from actual kioke barrels, in stainl

>Why not get rid of the ridiculously complicated (but truly beautiful) barrels, and instead use pieces of kioke wood, maybe from actual kioke barrels, in stainless vats? In other words, brew the soy sauce in stainless vats, but seed the cultures using pieces of wood that harbor the microbes. Why does the wood need to take the form of a barrel? I do a lot of beer homebrewing, including long term lambic-style sour beers in barrels, which actually shares a lot of similarities with shoyu brewing. Surface ratio is the big thing here. It affects not only how much of the flavor comes from the wood itself, but also oxygen ingress, etc. With shoyu it's open air, so a bit different compared to beer or wine which is usually aged in a sealed barrel, but it does affect the total amount of oxygen in there, even with an open fermentation. Oxygen will get in through wood, it won't through steel. But in general with chips or rods/spirals, you are imparting the wood flavor very quickly in comparison to a barrel, especially an old one. Depending on the biological interactions taking place, the organisms might not be able to process all of that in the same way they would over a longer period of time - they might have different reactions when some compounds are present in higher numbers, than if it is smaller. With beer brewing, if you are using brettanomyces strains of yeast, they produce entirely different flavors if the brett is used as the primary fermenter when there's tons of sugars available, or secondary/co-pitched fermenters where saccharomyces takes care of most of the sugars. I expect you get different flavors from new kioke barrels as well - many microorganisms can eat the sugars in wood, so you're likely to have a different bioflora profile in something fermenting in a new barrel vs. one where it's all already been digested. And there's other processes that'll bring in flavors from fresh wood vs. old. It's a lot harder to maintain something like chips or even rods or spirals over the multiple decades of use you can get out of barrels. It's not that I don't think all of those variables are possible to account for, in the theoretical sense, but no one has so far. Cantillon, a brewery in Belgium that is quite famous for their lambic beers has a sign in their brewery that translates to "Time does not respect that which is done without it", and in my experience, it's been true so far. (Interestingly enough, there's other parallels with Cantillon here - this story talks about the microflora living in the eaves, etc. When expanding their barrel aging program to a new facility, they went and sprayed the whole thing down with their beer to try and jumpstart the microbes being in the environment.)