I looking not to waste time and product experimenting. What are the consequences of leaving the salt / glutimate / etc mixture on kombu when, say, making dashi?

2 Answers 2


The consequences are a relatively trivial loss in flavor-enhancing compounds (the glutamates). There's no reason to waste water removing it.

I vaguely recall some books like Gaku Homma's Japanese Country Cooking suggested you could wipe off the kombu with a wet paper towel if you like, but that's not really necessary, or in my experience, even remotely common.

  • The damp-towel-wiping is the practice that I'm used to, and the Japanese (very much like the French) at times have a "process for process's sake", which may stem more from convention and tradition than pragmatism. Feb 24, 2015 at 23:22
  • Not only is it “not common,” the Japanese just don’t do it, as that white powder is full of flavor. Experiment for yourself, though. Make one pot of dashi with the cleaned kombu, and another with the dusty kombu, make some miso soup and see if there’s a difference.
    – Just Joel
    May 18, 2018 at 9:38
  • @JustJoel I'd hesitate to over-generalize and say "the Japanese" don't do it; Gaku Homma is a Japanese chef, and multiple Japanese sources, including Maki of Just One Cookbook and seaweed manufacturer Kurakon's web site, suggest wiping dry kombu with a damp cloth or wet paper towel. However, they're not necessarily recommend it for the purpose of removing the white powder, but for theoretical other dirt and debris (sand, etc). I don't find it necessary with current manufacturing standards. Our family does not. It's worth noting that culinary folklore drives habits science does not support.
    – JasonTrue
    May 19, 2018 at 11:47

No! Not only is it unnecessary, it's kind of the point of using kombu. You want the glutimates for the umami, right? Don't rinse.

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