> Most of the soy sauce you encounter in the US has wheat, while in Japan (and seemingly South Korea) there's no wheat added.
This is incorrect with regards to Japan. Shoyu is made with wheat. Tamari is not. Their production process is different.
Kikkoman is the most popular brand in the West AND in Japan, which is a koikuchi shoyu, which is the "standard" shoyu type in Japan. It is made with wheat.
For me I always have Kikkoman in the fridge (especially because thats what wife grew up with) as the staple soy sauce. I like to dabble in having 1-2 other variants in the fridge at once, but they can tend to have too strong a flavor for some peoples taste. Or certain variants are best with certain dishes, etc.
I have feeling that I should do it. The difference between open bottle that have stayed outside and fresh bottle is pretty clear. Refrigeration would slow down any reactions and thus keep taste better longer.
I keep sweet soy like kecap manis and 醬油膏 in the fridge because occasionally it can catch mold otherwise. I do the same with sweet vinegar like balsamic. However I think this depends a lot on how hot and humid your environment is. In cool and dry climates it's probably not necessary.
This is incorrect with regards to Japan. Shoyu is made with wheat. Tamari is not. Their production process is different.
Kikkoman is the most popular brand in the West AND in Japan, which is a koikuchi shoyu, which is the "standard" shoyu type in Japan. It is made with wheat.