Dashi storage question
I typically purchase instant dashi that comes in individual packets. Often I'll use a bit of the packet and keep whatever is leftover for the next Japanese meal. I am wondering if I should keep the leftover (not sealed) dashi powder in the refrigerator, or whether it's OK to keep it at room temperature.
Buy a small bag of katsuobushi (shaved bonito), niboshi (small dried sardines) and kombu (kelp), which are all dried and shelf-stable (and will maintain flavor if properly sealed). Bring to a boil in water and then let steep for 30 minutes. Strain and toss the solids. Make only as much dashi as you need. Much better than any instant powder.
When will your next Japanese meal be? Assuming these are more or less the same granules you can buy in (recloseable) jars, they're very shelf stable at room temperature, many months if not necessarily years. But if you're not going to use it within a few days, I'd try to seal up the packet pretty tightly or stick it in a small jar so it doesn't absorb too much moisture from the air. It'll clump up and the flavor might start to change if it gets really damp.