lye; alkaline water
Specifically the alkaline liquid extracted from ashes, used in traditional cooking or processing.
昔は灰汁を使ってこんにゃくを作った。
In the past, they used lye to make konjac.
You pre-boil bamboo shoots to remove their harsh taste before cooking them.
harsh taste; bitterness; astringency
Refers to the unpleasant, sharp, or alkaline taste found in certain vegetables (e.g., bamboo shoots, bracken) or poorly prepared food.
たけのこは灰汁が強いので、米ぬかで茹でる。
Bamboo shoots have a strong harsh taste, so you boil them with rice bran.
The froth or impurities that rise to the surface when boiling meat, fish, or vegetables; often skimmed off.
鍋の灰汁を丁寧にすくい取る。
Carefully skim off the scum from the pot.
strong personality; idiosyncrasy; self-assertiveness
Metaphorical extension: a person's rough edges, strong individuality, or excessive self-assertion. Often used in phrases like アクが強い (to have a strong personality) or アクが抜ける (to become mellow). Sometimes incorrectly written as 悪.
See also: アクが強い
彼はアクが強いから、人によって好き嫌いが分かれる。
He has a strong personality, so people either like him or dislike him.
年を取って、だいぶアクが抜けたね。
He's mellowed a lot with age.
スープを煮ているときは、こまめにアクを取ってください。
While simmering the soup, skim off the scum frequently.
As he's gotten older, he's mellowed out.
渋み is astringency, such as in unripe persimmons or strong tea, while アク often carries a harsher, alkaline quality beyond simple astringency.
悪 (あく, evil/bad) is a completely different word that shares the same pronunciation as アク and is sometimes mistakenly written in place of it when describing a strong personality.
yellowish gray; scum color
akumaki; glutinous rice cake wrapped in bamboo leaf and soaked in lye
scouring; washing vegetables in lye
Usually written in kana; katakana is common for this word.
Hiragana spelling, also common.
Kanji spelling is rare and may not be recognized by all readers; the reading is a gikun/jukujikun.
The origin is uncertain. The kanji 灰汁 literally mean 'ash liquid', reflecting the traditional method of making lye from wood ash. The reading あく is a jukujikun (special kanji reading) assigned to this word.