The Science of Sushi
Featuring Dr. Ole Mouritsen and Morihiro Onodera
April 23, 2014
To kick off our 2014 public lecture series, Dr. Ole Mouritsen joined Chef Morihiro Onodera to satisfy our craving for sushi-related science. The duo explained everything from sushi’s early history to the starchy science of sushi rice. Watch the entire lecture or check out some of the shorter highlights below.
Ole Mouritsen on the history of sushi
“The history of sushi is really the history of preservation of food. . . . Throughout Asia, in particular in China and later in Japan, people discovered that you can ferment fish – that is, you can preserve fish – by taking fresh fish and putting it in layers of cooked rice. . . . After some time the fish changes texture, it changes taste, it changes odor, but it’s still edible and it’s nutritious. And maybe after half a year you could then pull out the fish and eat the fish. That is the original sushi.”
Ole Mouritsen on the science of rice
“If you look inside the rice, you have little [starch] granules that are only three to eight microns, or three t0 eight thousandths of a millimeter, big. . . . When you cook the rice, you add some water and the water is absorbed by the rice and [the granules] swell. And the real secret behind the sushi rice is that when they swell, these little grains are not supposed to break.”
Morihiro Onodera on examining the quality of sushi rice
“First what I do is I soak uncooked rice in water. . . . Sometime after 20 minutes it will start to break. . . . I take a sample to check to see if there are any cracks. . . . With good rice, which has less cracks or breaks, you’re able to feel the texture of each of the grains in your mouth, whereas with the lower quality rice you’re just going to get the stickiness [from the starch].”
The audience present at The Science of Sushi asked our guest lecturers some great questions, and quite a few of them! Unfortunately, there wasn’t enough time to answer them all, but Ole G. Mouritsen has been kind enough to answer some of the lingering questions that went unanswered. Below his responses, we have included some additional information to help quench your thirst for knowledge (and sake).
Q: Are parasites within fish common? Are they a passable health problem?
A: Parasites can be common in some species, e.g., cod, mackerel, herring, and wild salmon. If in doubt, always freeze or marinate fish before eating raw.
The FDA provides guidance under their Parasite Destruction Guarantee on the preparation of raw fish. Fish intended to be consumed raw must be “frozen and stored at a temperature of -20°C (-4°F) or below for a minimum of 168 hours (7 days)”. 
Q: What exactly is ‘sashimi/sushi grade’ fish?
A: Fish that can be eaten raw. If in doubt, ask a fishmonger you trust.
In the United States, the term ‘sushi grade’ is unregulated. However, many suppliers have set up their own parameters for their products, often reserving the term for their most fresh fish.
Q: What are your thoughts on using brown rice in sushi?
A: I don’t myself like brown rice in sushi. If you worry about the calories in white rice, don’t eat sushi.
During the milling process, the germ and bran layer of brown rice are left intact, and are not removed as they are in white rice. The only layer removed is the outermost layer, the hull. Some health-conscious people often opt for brown rice because several vitamins and dietary minerals are lost in this removal process and the subsequent polishing.
Q: What’s your thought on cooking rice with ‘bamboo charcoal’?
A: I don’t understand this question. In principle the source of heating does not matter (except if the cooking pot is open and takes taste from the burning material).
Q: Sake: does it add, hide, or subtract?
A: It is a matter of taste. An old Japanese proverb says that one should not drink sake with rice (too much of a good thing). So drink sake before the sushi meal, or after.
Sake, the alcoholic rice beverage officially known as “Seishu” is defined as one of the following:
- Fermented from rice, rice-koji (the mold used to convert the starch in rice into fermentable sugars), and water.
- Fermented from rice, water, Sake-Kasu (the lees that remain after pressing Sake; these can still contain fermentable elements), rice-koji, and anything else accepted by law.
- Sake to which Kasu has been added.
After any of these processes, the liquid is then strained through a mesh to produce a clear beverage. 
- “FDA Food Code 2009 – Chapter 3 – Food.” Fda.gov. N.p., n.d. Web. 28 Apr. 2014.
- Ransom, Warren. “Sushi Grade Fish.” The Sushi FAQ. N.p., n.d. Web. 28 Apr. 2014. <http://www.sushifaq.com/sushi-sashimi-info/sushi-grade-fish/>.
- “Sake.com: Sake Making.” Sake.com: Sake Making. N.p., n.d. Web. 28 Apr. 2014.
Chef Morihiro Onodera trained as a sushi chef in Tokyo, and at seminal Los Angeles restaurants including Katsu, R-23, Matsuhisa, and Takao as well as Hatsuhana in NY. By the time he opened his first restaurant, Mori Sushi in Los Angeles, he was preparing many of the same handmade ingredients, harvesting his own locally grown rice and creating handmade pottery to be used in the restaurant. After selling Mori Sushi in 2011, Mori began creating handmade pottery for several Michelin Guide restaurants in Los Angeles and established a partnership with rice farmer, Ichiro Tamaki. Tamaki farms in Uruguay will harvest its first crop in May of 2013 and will be available for distribution world-wide.
- What hooked you on cooking?
- The desire to want to eat and taste delicious food.
- The coolest example of science in your food?
- My basic approach to cooking is to think about the natural ingredients and the climate (seasons) of its origin, ingredients that are kind to the body and to earth—a very simple-minded attempt with natural science at its core.
- The food you find most fascinating?
- I’m always seeking the true flavor of a given ingredient—that’s what fascinates me.
- What scientific concept–food related or otherwise–do you find most fascinating?
- Natural science.
- Your best example of a food that is better because of science?
- Konbu and natural salt.
- How do you think science will impact your world of food in the next 5 years?
- It will be interesting to see how the true flavors of ingredients change over time—how natural science will affect that change. Simultaneously, I will continue my studies in discovering and knowing what’s kind for the human body and our earth.
- One kitchen tool you could not live without?
- Rice cooker, including donabe (Japanese clay pot).
- Five things most likely to be found in your fridge?
- Fresh local vegetables, miso, umeboshi (pickled plum), homemade yuzu kosho (pepper), and leftover cooked brown rice. Outside of the fridge: dry goods, salted bran (used for pickling), rice, oil (sesame and olive), salt, konbu.
- Your all-time favorite ingredient?
- Favorite cookbook?
- Book series by Rosanjin (Kitaoji Rosanjin, Japanese artist and epicure).
- Your standard breakfast?
- Black tea (straight). Seasonal, local fruits. Bread or hot rice cereal. Sometimes eggs (steamed) cooked with sautéed spinach.