A Taste of Culture – AKU NUKI

Food Elizabeth Andoh
A Taste of Culture  ©

Dear friends, colleagues and those who have expressed an interest in the FOOD & CULTURE of Japan:

Kogomi (fiddlehead ferns) and other sansai (mountain vegetables) are foraged from woodland areas in Japan just as snow begins to melt and the promise of spring is in the air. Bitter foods such as sansai play an important role in Japanese cookery. For many the culinary allure lies in the ability of bitter foods to awaken winter-dormant taste buds and reinvigorate a hibernating metabolism.

But, as much as the Japanese appreciate how bitterness can stimulate appetite and improve digestibility, the expression hodo hodo (“just so much…”) also applies. And that is why many Japanese recipes will instruct the cook to perform what is called AKU NUKI, literally “bitterness removal.”

© Copyright late January 2021. All rights reserved by Elizabeth Andoh.

The word aku is written with calligraphy for ASH 灰 and BROTH 汁 and it accurately describes the ancient procedure of mixing alkaline ashes left in the hearth with water, then using this solution to tame enzymes that would otherwise make some foods inedible.

The Jomon peoples, a hunting/gathering society that lived in Japan during the Neolithic Period, performed aku nuki to render acorns and other nuts, seeds and many shrubs edible. They soaked them in various solutions including yaki myōban 焼みょうばん, or alum.

Alum is short for “aluminum potassium sulfate” and it has been used for millennia worldwide: the ancients Egyptians used it to fix dye to fabric and in ceramic glazes. In ancient China and Europe alum was used in various elixirs and medicinal brews. A hundred years ago alum was a pantry staple in households where home pickling and preserving was common practice — used to neutralize enzymes that occur naturally in many plants (fiddlehead ferns being one). Without performing aku nuki those plants would taste especially bitter, turn black and become slimy when boiled.

Kogomi prepared with yaki myōban (or baking soda — bicarbonate of soda — that has a similar neutralizing effect) renders the fronds vibrant with just a hint of bitter taste. Fiddleheads are an excellent source of vitamins A and C and are rich in niacin, magnesium, iron, potassium, and phosphorus. They are also rich in anti-oxidants and bio-flavonoids, which are plant chemicals that help protect against disease. I do hope you can source them near where you live. Then make some Fiddlehead Ferns in Tōfu Sauce using my KITCHEN CULTURE blog post to guide you in your kitchen.

Looking for recipes & resources? Explore KITCHEN CULTURE

Posts archived from June 2019 includes a guide to displaying hina ningyō dolls.

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Elizabeth Andoh

A Taste of Culture

Culinary Arts Program

Setagaya-ku, Tokyo 158-0095, Japan


  1. paul hand says:

    thankyou for your help i will aku nuki some home gtown fuki tomorrow

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