Why can you marinate raw fish for 3 days, but you’re supposed to cook it in a day or two after buying it from the grocery store?


I’ve been reviewing recipes for a Japanese black cod recipe. It’s very poopular. Every video I watch has Japanese chefs confidently stating that you need to marinate it in a mixture of sake, mirin, and miso for 3 days before baking it. When you do bake it, it’s for about 20 minutes.

How do people not get sick from this process? Does the sake somehow kill bacteria or something?


In: 3

You need about 70% alcohol by volume to reliably kill bacteria, so the marinade won’t decontaminate your fish, but it will inhibit bacterial growth. Basically it extends that 1-2 day cooking window by at least slowing bacterial growth. It may even kill the bugs, but don’t rely on it. Cooking mostly does that.

So a few things at play here.

First, freshness of the fish matters. If you are watching japanese chefs cook a locally sourced expensive fish…chances are very good that the fish was caught very recently compared to when it is being prepared. In many cases, it may have been alive and swimming around the same day it is being prepared.

If you get that same fish in the US, it was possibly caught up i alaska (and died), then shipped to a hub city before getting on a truck to your hometown. Finally it sat in the grocery store for 2-3 days before being purchased by you.

Now, for a lot of that time, the fish might have been frozen, but ultimately it will not be super fresh by the time you get it. Shelf life starts tikking as soon as you kill the animal, not when you buy it.

The second answer is, alcohol kills everything. Sake and Mirin are both alcoholic drinks, and so will be generally good at killing bacteria. Will fish eventually still go bad while submerged in alcohol, yes, probably. Will it be a lot slower? Yes, definately.

Remember, ethanol, or ethyl alcohol, is actually used in the scientific community as a means of preserving samples and specimans. Now preserving a speciman for study is a different process, high concentrations of ethanol will absolutely help preserve things.