Why nowadays’ sushi is not sushi / Prophylactic self-isolation series. Day 225th.

Sushi rolls on a wooden board with tamari sauce aside

Western-style sushi is what we know as commercial “sushi” around the world these days: sticky rice and lots of other ingredients to satisfy any customer’s need and taste, including vegan, vegetarian, meat, hot-served versions and even sweet sushi!

However, if you would ask a Japanese man living hundreds years ago about sushi – he would tell you a different story, and a different concept of the recipe!

The name sushi in Japanese(すし) derives from the word Su(す), which is used to describe the sour taste. In Kanji, another form of Japanese writing, sushi is written as 鮨, which means fermented fish. In older times, sushi was a fermented dish rather than the fresh fish and riceball that we are used to.

Daniel Choi (1)

Sushi began as a way of preserving fish

In the 7th century, the technique of pickling was invented by the mountain people of Southeast Asia. Later, the Japanese acquired the same practice for fish preservation: cleaned fresh fish was pressed between rice and salt by a heavy stone for a few weeks (up to a year) until the fish was considered ready to eat. During the process of fermentation, the rice produces a lactic acid, which in turn caused the pickling of the fish. The finished edible product (naresushi, a sushi made with carp). Only the fish was eaten while rice was discarded because of too sour taste! (2)

Similar traditions in Philippines

Burong isda/dalag is an indigenous fermented food made from fish and rice in the Philippines. Cooked rice, salt and fresh fillet fish (like tilapia) or shrimps are used for the fermentation (3).

Image on the left: fish fillet in salt layers during the preparation of burong isda (3)


A drop of chemistry to explain why fermented rice is different from just cooked rice

Upon the fermentation process, lactic acid bacteria (mostly Lactobacillus plantarum) produces specific enzyme. This enzyme in its turn hydrolyzes starch in rice by breaking down the complex structure into shorter segments (chem. hydrolyzes both α-1,6- and α-1,4-glucosidic linkages) (4).

Lactic acid bacteria is produced upon fermentation. This process facilitates breaking down the complex structure of starch in rice

When the complex molecules of starch in rice are broken down – it facilitates digestion and absorption of nutrients. The process of starch fragmentation in rice is possible only upon fermentation!

Why rice fermentation is important

Rice (white rice) is a well-known food causing constipation. It is a mucus former and makes a perfect paste. According to Prof. A. Ehret, the leprosy illness is prevalent among one-sided rice eaters (5).

Speeding-up of sushi preparation within the centuries has led to the fact that nowadays fermentation step of rice is totally forgotten, and therefore the sushi is not anymore sushi, not anymore 鮨, – a fermented fish.

It is supposed that fermented rice with changed structure of starches is more digestible and do not cause constipation, more so, fermentation in general improves nutritional value of food (6).

Rice without husk – a silent “hijacker”

Those people whose diet is based mainly on white rice (rice where husk, bran and germ are removed) could suffer from thiamine (vitamin B1) deficiency. An acute and chronic forms of illness beriberi may affect cardiovascular and nervous system (external link): How Killer Rice Crippled Tokyo and the Japanese Navy (7).

If beriberi illness was a huge problem in 19th century, these days its face masked.

It is known that alcohol consumption (alcoholism) leads to the deficiency of vitamin B1. In other words:

sushi + alcohol = brain damage

Image on the left: Brain regions affected by thiamine deficiency (8)

sushi + alcohol = brain damage

Of course, one time is not enough to damage the brain, but some people are making their attempts persistently and constantly, especially on weekends!

What to do if after reading this article I still want sushi?:)

Make your sushi by yourself, at home! The main points:

  • use whole grain rice with husk. Wild rice or red rice are preferred, because it gives much better taste than brown rice
  • tamari or soy sauce contain a small amount of alcohol (around 2%), you may dilute it with water
  • no additional alcohol “in bottles” needed!

I have not yet made fermented sushi version to improve nowadays recipe even more, but the recipe of delicious sushi with wild and red rice is already discovered by me a few weeks ago! Here is the recipe:

Wild black sushi with whole rice! / Prophylactic self-isolation series. Day 209th.

References:

  1. How Sushi was Invented by Daniel Choi, available online on https://medium.com/history-of-yesterday/how-sushi-was-invented-43f946427af7
  2. The Tale of Sushi: History and Regulations by Cindy Hsin-I Feng. Vol.11, 2012 Comprehensive Reviews in Food Science and Food Safety, doi: 10.1111/j.1541-4337.2011.00180.x
  3. Recipe of Burong isda on AmiableFoods, available online: https://amiablefoods.com/burong-isda/
  4. Characterization of starch-hydrolyzing lactic acid bacteria isolated from a fermented fish and rice food, “burong isda”, and its amylolytic enzyme. Minerva Olympia et al. Journal of Fermentation and Bioengineering, Volume 80, Issue 2, 1995, Pages 124-130, https://doi.org/10.1016/0922-338X(95)93206-Y
  5. Mucusless Diet Healing System / A Scientific Method of Eating Your Way to Health, 2013. Ehret Literature Publishing Company, Summertown, Tennessee. The book by Professor Arnold Ehret (1866-1922). 1st edition was published before 1922
  6. Importance of lactic acid bacteria in Asian fermented foods by Sook Jong Rhee et al. Microb Cell Fact. 2011; 10(Suppl 1): S5. Published online 2011 Aug 30. doi: 10.1186/1475-2859-10-S1-S5: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3231931/
  7. How Killer Rice Crippled Tokyo and the Japanese Navy by Anne Ewbank, available online: https://www.atlasobscura.com/articles/rice-disease-mystery-edo-tokyo-navy-beriberi
  8. The Role of Thiamine Deficiency in Alcoholic Brain Disease by Peter R. Martin et. al. Alcohol Research & Health, Vol. 27, No. 2, 2003. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6668887/pdf/134-142.pdf

Further reading

Cover image and text © Dr. A. Palatronis / www.z-antenna.com

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