Ikejime: The Japanese Way to Butcher Fish

Discover the traditional Japanese ikejime fish butchering method and its impact on umami flavor in Japanese cuisine. Learn from chef Toshio Suzuki's insightful presentation and the maturation process that turns a live fish into sublime food. Find out about the transcendent sushi experience at Sushi Zen restaurant with Suzuki-san.

At a workshop at Saveur, I taxied over a live fish for Chef Sono to butcher the traditional way, a method called ikejime. Why share a cab with a flopping fish? I've been fascinated by this killing process since I first witnessed it in Japan, and Sono-san was kind enough to demonstrate it and explain the technique. This week I learned even more, thanks to an outstanding presentation featuring the revered chef Toshio Suzuki.

So, you ask, what is ikejime and what makes it so special?

Ikejime, as Suzuki-san explained, is the precision Japanese method to butcher a fish, developed some 350 years ago. We in the audience watched Suzuki-san kill two fish this way, a fluke and a local black fish (can't remember the name, alas). After Suzuki-san pulled the first fish, the fluke, out of water, he placed it on a cutting board. In a swift move, he drove the knife into the back of the head, then made a incision at the tail. He bent the fish and dunked it in salt water (mimic sea water) to let it bleed out. The cut at the back of the head, for you fish biologists out there, severs the medulla oblongata and the main artery. The cut at the root of the tail helps drain the blood. Once the blood was out, Suzuki-san did something incredible: He forced a thin, metal skewer into the nerve canal that sits above the fish's spine, and pushed it all the way in, crushing the spinal cord. Afterwards, he scaled and gutted the fish and filleted it. The fillets he wrapped carefully and stuck in the fridge to mature (we'll get into maturation in a minute).

Okay, I know what you're thinking. Why didn't he just bop that sucker in the head with a mallet and be done with it? Why the elaborate kill? Here's where it gets fascinating, and why Japanese cuisine is so endlessly mind blowing (at least to me):

What Suzuki-san explained, is that you kill a fish ikejime-style to develop its umami. Umami, as you may know, is one of the taste sensations we experience; in a nutshell, it's the sense of savoriness that develops especially when foods cure, ferment or ripen -- as foods break down umami flavor compounds develop. You get this sense of umami when you bite into a hunk of parmesan, a slice of prosciutto or a perfectly ripe tomato. It's even quite present in mother's milk (wonder why babies don't get sick of drinking it?!) But while umami is found in foods everywhere, I believe in Japan it became the intrinsic and fundamental sensibility of the cuisine because the cooking there evolved without using animal fats and butter as the primary flavoring agents (think European or Chinese cooking). So the umami flavor is central to Japanese cooking.

With this umami digression in mind, what Suzuki-san explained is this: By killing the fish with the ikejime method, you essentially cut the brain signal to the fish's body, so the fish doesn't know it's dead. Yes, incredible. Doing this slows down and extends the process of rigor mortis. Why is this important? Because it's during rigor mortis, Suzuki-san told us, that a certain compound in the fish's muscle tissue breaks down (adenosine 5 triphosphate (ATP), to be exact), creating an umami compound called inosinic acid in the process. The slower the rigor mortis, the more umami created. Body temperature, fatigue and violence of death also effect this transformation. I was amazed how gently Suzuki-san handled the fish as he butchered it -- the creature was calm until the end, not flopping violently. (So no tissue burn -- that is, blood spots in the flesh -- the flesh was totally perfect and translucent, evidence of a peaceful end.) Also fascinating was watching the gills and mouth of the fish move, even though the spine had been severed -- the brain was still producing signals to the head for a while after butchering. But not just the head. I got to touch the flesh of the fish soon after it was filleted and it was still quivering; I could feel the electricity of life in it. The flesh still thought it was alive! This also went on for a while, thanks to this technique.

Now wait, we're not done yet. Once Suzuki-san finishes ikejime and filleting, he told us, he sticks the fillets in the refrigerator for up to three days to mature. Maturation is critical to develop umami, he explained. Here we're delving into what makes Japanese cooking, well, Japanese cooking. For raw fish or delicately steamed fish to have most exquisite flavor, you have to let it mature. So at the finest sushi restaurants, you're not eating absolutely "fresh" fish -- fish just butchered and sliced doesn't have that umami sensibility to it. It's just flesh. What I liked about the presentation is that Suzuki-san gave us three samples of fluke to taste: the flesh he just butchered, fish he butchered the day before and fish he butchered two days before. The difference was stark. The fresh flesh was chewy and didn't have much flavor. The day old flesh was tender and you can sense the savoriness or umami. Now with the two-day old fish, yup, you guessed it, the texture was buttery and flavor deeply savory and delicious. So if you think about all this, what's happening, essentially, is that through deft knife skills, hypersensitivity to the character of the ingredient, and maturation, Suzuki-san has "cooked" the fish -- he has taken a live creature and transformed it into sublime food. Wild, eh? Even more wild is to keep in mind that this all evolved nearly four centuries ago, way before scientists knew about ATP, inosinates or this word, umami. It evolved almost organically way back when because of the singular character and sensibility of Japanese culture and its cuisine. (Also consider this was, of course, before the age of refrigeration -- ikejime suppresses decomposition and spoilage.) This is why I'm so fascinated with this cooking. On the surface it sounds so rudimentary, kill a fish. But this process is so deep, deep, deep -- you can keep drilling into it and still not hit bedrock. I know there are a million things about ikejime that I still don't understand...

Okay, before we go, a word about Suzuki-san and his restaurant: For someone who's such a fan of Japanese cuisine, I actually eat sushi relatively rarely. Sushi is such a profound expression of the chef creating it that I only want to experience it at the transcendent level. One of the places where I go to do this is Sushi Zen. The last time we went my wife and I reserved two seats at the dining counter directly across from Suzuki-san and let him do this thing (omakase, as they say). His thing just blew us away. Suzuki-san is such an erudite, sensitive and gracious soul, and he expresses his very being this through his sushi. In other words, his sushi is so damn good and heavenly and sublime. It's what the art of sushi's all about. Why eat any other kind?