Why you should care
Because many of us eat sushi all the time — and know absolutely nothing about what we’re eating.
Sushi: Seems everyone’s eating it, and it’s popping up everywhere, from Whole Foods to the ballpark.
But whether you are a sashimi purist or prefer hand rolls, how much do you really know about your sushi? What’s the wasabi on your plate really made of, and why is fatty tuna that glorious shade of red?
For answers to these questions and others you didn’t even know you had, read on…
It ain’t wasabi
That spicy green paste served at your favorite sushi bar is not the real deal. You’re probably ingesting ground horseradish mixed with a binder, maybe some mustard, and green food coloring. Real wasabi — Wasabia japonica, to be precise — is a touchy plant that grows best in semi-marsh-like areas with running water. As one food scientist notes, “Real wasabi is expensive and rare outside of Japan.” And even if chefs elsewhere could get their hands on the gnarled plant, you really want to consume the wasabi within 15 minutes after it’s been ground, for the most kick. Should you ever get the chance to sample genuine wasabi, we’re assured you’ll instantly taste the difference — it delivers a fresh, almost herbal spiciness, compared to the harsher horseradish version.
That tender sliver of fresh sushi on your plate is actually pure muscle. So how can sushi stay so supple when other muscular dishes, like steak and chicken, get tough? Consider the human beer belly versus a six-pack of abs: The more muscles work, the harder they become. Land-based animals — think cows or fowl — strain every day against the pull of gravity, which toughens their tissue. Fish are suspended in water, so they stay flabby. And delicious.
What we call sushi today started more than 1,000 years ago as a way to preserve fish before refrigeration. Back then, salt and acid were used to ferment fresh fish, which was layered with rice, according to Ole Mouritsen, a biophysicist at the University of Southern Denmark who has devoted 30-plus years to making, eating and studying sushi. A thousand years ago, sweetened rice balanced out the salty, acidic flavors, and today, sushi rice is prepared with vinegar and sugar.
Eventually, it happens to all living creatures, including fish: the release of protein ions that cause muscle fibers to harden after death. Which is why fresh-from-the-sea sushi tastes far better than anything you’ll find packaged at your local grocer, because the rigor hasn’t had time to set in. Freezing fish immediately after it’s been caught can slow the process a bit, but it’s always smart to ask the sushi chef for the freshest catch of the day.
Red fish, white fish
They call it a rainbow roll for a reason. The colors are simply gorgeous — and here’s some simple science by way of explanation. The rich, deep red color of tuna is the result of myoglobins, the carrier molecules that bring oxygen to the fish’s muscles used for constant swimming — these are known as slow muscles. When you see white-fleshed sashimi, that comes from a fish that moves even faster (think flapping fins versus a slow swim) whose muscles don’t receive as much oxygen. As for orange and pink fish, like wild salmon, the reason for their hue is the same as that for shellfish and flamingos: They are what they eat — tiny bits of ocean plankton that contain enough color to turn crab and lobster shells orange, or fish pink.
Now that you’ve gotten the lowdown on what’s really in your sushi sampler, eat up — and make sure to enlighten your dinner companions, who probably think the green stuff on their plate is actually wasabi…