January 15, 2020

Koji Kimura (Kimura Sushi, Tokyo), Japan’s master of fish ageing, presented the qualities of fish aged in salt at Reale Seguros Madrid Fusión 2020, in particular his favourite product, swordfish.

“Hello, I am the Andrés Iniesta of sushi”. That is how the chef Koji Kimura (Sushi Kimura, Tokyo) made his entrance and introduced himself to the audience in the Madrid Fusión auditorium. Japan’s leading expert on ageing fish (up to 60 days) showed, with a live tasting for five members of the public, the process of ageing fish “to create more tasty sushi”.

“Using the technique of ageing in salt, I am able to soften the meat, which I complete in the sushi with al dente rice”, he explained. As a result, his sushi, predictably, is made up of a hard part and a soft part. “The contrast is spectacular”, he concluded.

For the ageing process, Kimura discards the fish’s tail and bleeds it himself by blowing water on it. “Removing the blood also eliminates the bad smell”, he explained. After this process, the real ageing begins, when the fish is immersed in salt for four days so that no humidity enters. After filleting it, it is salted again and kept there for up to 60 days, “depending on the type of fish and its size”.

Throughout the process, Kimura removes pieces to remove salt and moisture from them, and to remove the oxidised parts with a knife. “I do this process every other day, and I use what’s left over to make soup”, he went on. Sustainability. In the end, the product is not salty, he assured us.

With this process the fish “gains in taste and umami, because fresh fish doesn’t have much”, he added. And it also gains in colour, as “the intensity grows”. These virtues were demonstrated by Kimura through a selection of pieces of swordfish, “my star ingredient”. He cut several portions and made nigiris with both fresh pieces and those aged for 40 days. “The taste in the second one is more fully incorporated. The fresh piece doesn’t taste as much”, observers asserted. You will have to check it out. The debate is on.