The Delicious Chemistry of Sushi

Long before Pokemon, magical girls, and Los
Angeles Dodgers pitcher Kenta Maeda, the Japanese gave us one of the world’s most perfect
foods. Sushi is sublime. Just fresh fish and seasoned rice in its simplest
form, or rolled up with some veggies in a seaweed wrapper. But while the ingredients are straightforward,
making perfect sushi isn’t. Japanese sushi chefs can spend seven years
learning the art. While some of you were off getting your Ph.D.,
sushi chefs studied the blade. Er, the chef’s knife. Let’s get into the chemistry that creates
the subtle interplay of flavors in your tuna nigiri. But first, a little history. Sushi started out as a way of preserving fish,
as early as three or four centuries B.C.E. Fish packed with rice would undergo a year-long
process of fermentation. Fermentation occurs when friendly bacteria
munch on carbohydrates like the starches found in rice and convert them to acid. In this case, lactic acid. The buildup of acid makes it more difficult
for harmful bacteria like botulinum to grow. That means they can’t get a foothold to
contaminate or spoil the food. Hey, people had to get creative in the days
before refrigerators. They didn’t even eat the rice in this earliest
form of sushi. They tossed it out, maybe because it was a
year old and full of sour-tasting lactate. But fast forward a few centuries and people
started to acquire a taste for the stuff. Modern sushi rice is seasoned with vinegar
to give it that acidic sharpness. By the bustling Edo period in the 19th century,
sushi had become a popular street food. Lightly cured fish was served over seasoned
rice for on-the-go working folk looking for a quick bite. Now that we have refrigerators, the fish can
be served completely raw, although some kinds like eel and octopus are still served cooked. Two of those years sushi chefs spend studying
is spent just on rice. The rice is seasoned with vinegar and sugar. Some chefs also add a type of seaweed called
kombu–more on that in a second. The rice itself has to be perfect. When cooked, it should just hold together
without being a sticky, mushy mess. A grain of sushi rice contains granules of
sticky starch like amylopectin. When cooking, chefs try not to break open
the individual grains. Doing so would release the starch, which would
cause the grains to stick together too much. Plus, it’s considered aesthetically important
for the grains to maintain their shape. Then there’s the seaweed. The wrappers that hold sushi rolls together
are a kind of seaweed called nori, whereas the kombu sometimes used to season the rice
is a variety of kelp. Seaweeds have a huge variety of flavor compounds
like mannitol that give it sweetness and iodine and bromophenols that contribute a certain
seabreeze-y tang. But there’s one other important ingredient. Early in the 20th century, chemist and professor
Kikunae Ikeda was sitting down to a hot supper. He asked his wife just what was in the soup
that made it so delicious and started studying the kelp she used to add flavor. After years of research, he discovered what
his wife and Japanese cooks like her already knew: Kombu gives foods a savory deliciousness
captured by the Japanese word umami. This was the Fabled “fifth taste” after
salty, sweet, sour and bitter. And he was able to isolate the compound responsible
for umami-ness: glutamate. Glutamate in the form of glutamic acid, is an amino acid,
one of the twenty common building blocks of protein. But our tongues also have a taste receptor
for it, so we perceive it as meaty, cheesy GLORIOUSNESS. Adding a sodium ion, like the kind in table
salt, turns glutamate into MSG. WAIT, don’t close the tab! MSG has gotten plenty of bad press on food
labels and health websites. It’s been blamed for all kinds allergies and headaches. But scientific evidence for those claims just
hasn’t emerged. Anyway, what about the star of the sushi show? You know, the fish? Yeah, of course, there’s plenty going on
there too. Fish itself also contains glutamate, for more
umami goodness. But the flavor of fish is thanks in large
part to the fats it contains, which vary based on the fish’s diet and habitat. Those fats include brain-healthy omega-3 fatty
acids, which are also in seaweed–making sushi a very smart snack. Well, at least if you’re not getting one
of those big mayo-y fried things. Omega-3, by the way, refers to the chemical
structure of the long chains of carbon and hydrogen in fatty acid molecules. Omega refers to the end of the tail, and the
3 means a double bond first appears three carbons inward from the end. Our bodies can’t just throw double bonds
into fatty acid molecules willie-nillie wherever they want. Which means, to get those molecules in our bodies, we have to consume them in our diet. Thanks for looking after our brain and heart
health, sushi! Fish also come in colors from the deep red
of tuna to the whitish hue of flounder. And that depends on the fishy’s lifestyle. Tuna are strong swimmers, and their muscles
need tons of oxygen. That’s delivered by a protein called myoglobin
that turns those muscles red. Lazier fish like this flounder — the couch
potato of the ocean floor — still sometimes need to make a quick dash to escape predators. That kind of quick movement doesn’t depend
on oxygen, so there’s less myoglobin in their muscles and they tend to be lighter
in color. There’s one weird exception. Salmon are also lazy. Well, apart from that time when they swim upstream and all. But they eat crustaceans, whose shells contain a pigment called astaxanthin that turns their muscles pink. Without it in their diet, farmed salmon would
be gray. So aquaculturists add the pigment to salmon
feed rather than offer up gray fish to squeamish shoppers. That’s it for the main ingredients in sushi,
which come together to form a harmonious sweet-sour-umami treat. Next time your friends say they don’t eat
raw fish, you can wow them with the chemistry that makes sushi objectively amazing, or
you can just say “Cool, more for me.” We’d like to thank chef Kaz Okochi of Kaz
Sushi Bistro in Washington, DC, home of the beautiful eats you see in this video. We didn’t have time to go into all the sides
and fixin’s. Like, did you know the little lump of green
stuff in your plastic sushi tray isn’t real wasabi? Lies! Scandalous lies! Sound off in the comments on your favorite
kind of sushi, and thanks for watching!

26 comments on “The Delicious Chemistry of Sushi”

  1. Reactions says:

    What's your favorite kind of sushi? And where's your favorite sushi joint? Send us the Yelp review. We're hungry.

  2. Minori Ruba says:

    I still can't believe sushi is made with raw fish!!😮😮😮

  3. Shlok Kumar Pandey says:


  4. Leonardo Celente says:

    Don't really like sushi, but loved the video!

  5. Yugoviandi Mamahit says:

    great video! very educational

  6. Herb Toker says:

    In regards to the comment made at the end of the video, some higher profile restaurants will use freshly grated sawa wasabi.

  7. MrOscarggg says:

    What about heavy metals?

  8. Lamont P says:

    So, what is the green lump of deliciousness on my tray?

  9. Ineed Therapy says:

    Master sushi chefs tend to age their fish thus enhancing the umami flavours of the sushi

  10. Pal Dali says:

    I LOVE Sushi! All Sushi!
    Sashimi, hand rolls, you name it and I'll stuff it in my gully-hole!

  11. Fauler Perfektionist says:

    "Sushi is sublime."
    Oooooooh. 😕 Well that's a matter of opinion.

  12. Stare Wyatt says:

    Commenting for YT algorithm!

  13. Ireallyreally Hategoogle says:

    My favorite kind of sushi is the one that doesn't taste like fish. I don't like fish.

  14. Eu Jin See says:

    This channel is so underrated! It's actually really educational and informative haha! Thanks!

  15. Nathan Hevenstone says:

    I adore MSG. Wish people would stop being afraid of it and start recognizing it's usefulness.

  16. Angel Terri says:

    I don't care what science says. I have MSG and get the shakes, nausea, headache, and more.

  17. Раиса Ершова says:

    (ᵔᴥᵔ) ➤

  18. Jennifer Wilson says:

    Stop saying BCE. It's historically inaccurate, if not blasphemous.

  19. Jacky Liu says:

    What about wasabi???

  20. Ayamedragon1 says:

    Hearing this voiceover makes me cringe as a Japanese American. Like "Edo," "nigiri," and "kombu" are all pronounced wrong. The science might be right, but don't look to them for pronunciation. Also, if you just want raw fish at a Japanese resturant, order sashimi. Sashimi is raw fish, while sushi literally means vinegar rice.

  21. Felipe Viegas says:

    oh, my god, I'm new to sushi, but i already love it.I miss eating it so much 🙁

  22. Nis Style says:

    Too fast….difficult to understand

  23. oldcowbb says:

    90% of the seven years of training are just cleaning the kitchen

  24. Nolan says:

    Good ol colored horseradish + mayo … I mean Wasabi

  25. Alex says:

    I can't wait for the next sushi lunch with my colleagues to overwhelm them with facts!

  26. D F says:

    I've read there's a "chemical test" for sashimi fish quality/freshness used by some buyers. Maybe pH?

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