ginkgo nut
ingredient / ingredient-ginkgo-nut
ぎんなん / Ginkgo biloba
Ginkgo nut is the seed of the ginkgo tree (Ginkgo biloba). The commercially sold kernel has had the fleshy outer seed coat, which causes a bad odor and skin irritation, removed. Cracking the hard white middle seed coat (the so-called shell) reveals endosperm and cotyledons enclosed in an inner seed coat (thin or astringent skin); these are cooked by methods such as boiling in salted water, roasting, or frying. Their slight bitterness is appreciated by some, while others dislike it.
On this page (8 sections)
Reading the bitterness
Ginkgo nuts are sold as kernels with the outer fleshy skin (outer seed coat) removed. Cracking the white, hard shell (middle seed coat) reveals a thin inner seed coat (astringent skin, thin skin) wrapping the kernel, and a cooking-related article states that some people notice bitterness in this skin. The same article writes that the source of the bitterness is a component called an alkaloid, but it does not give a specific compound name or amount. As a preparation step, the same article quotes Nagano producer information describing 「アク抜き」 (in translation: "aku removal"): soaking the kernel, with the thin skin removed, in water for about a day.
There is also a description that frying softens the slight bitterness, but this, too, is from a cooking-related article, without sensory-panel or chemical-analysis corroboration. The same article writes about the taste of ginkgo nuts, 「ほろ苦さの奥にやさしい甘みがある」 (in translation: "there is a gentle sweetness behind the slight bitterness") and 「加熱するとほっくりとした食感とナッツのようなコクが広がる」 (in translation: "when heated, a fluffy texture and nut-like richness spread"), and treats the bitterness as a flavor that divides preference. Both descriptions are based on the writer's personal sensory impression, and there is no record that goes as far as identifying or quantifying the bitter constituent.
Sources for this overview
銀杏(ぎんなん)が苦い理由や苦みを抑える食べ方!食べ過ぎるとどうなる?
Checked for this overview: The part introducing the statement that the source of the bitterness is an alkaloid. / The part introducing the aku-removal process of removing the thin skin and soaking it in water.
銀杏（ぎんなん）はどんな味？苦い？｜美味しい食べ方と下処理・旬・栄養・保存方法
Checked for this overview: The part introducing the description that frying softens the slight bitterness. / The part introducing the writer's personal description of the taste and texture.
Other names: 銀杏 (ja), 内種皮（渋皮・薄皮） (ja)
Hypotheses and recipe candidates for this entry are on the Japanese page.
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (1)
Scope: A web article explaining ginkgo-nut bitterness (Bow!, July 13, 2021).
Note: The article says only 「苦みの正体はアルカロイドという成分」 (in translation: "the source of bitterness is a component called an alkaloid") and provides no identification of particular compounds or quantitative data. Lacking such data, this statement is not connected to a discussion of safety or intake amounts.
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ingredient-ginkgo-nut —has_perceived_bitterness_associated_with→ "Alkaloid components (the article does not identify specific compounds)."Sensory (1)
Scope: A web article explaining the taste of ginkgo nuts (Wagokoro Gohanchō).
Note: The writer's personal sensory description, not a sensory panel.
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ingredient-ginkgo-nut —has_sensory_attribute→ "A distinctive flavor with gentle sweetness behind slight bitterness, developing a fluffy texture and nut-like richness when heated."How processing and cooking change it (2)
Scope: A web article on ways to eat ginkgo nuts (Wagokoro Gohanchō).
Note: A description in a cooking web publication rather than a sensory panel. The same article compares several preparation methods, including microwave heating, boiling water, and dry roasting.
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ingredient-ginkgo-nut —has_perceived_bitterness_suppressed_by→ "Frying in oil as a cooking method."Scope: Nagano producer information quoted by the Bow! article.
Note: A secondary quotation in the b-o-w.jp article; the primary source itself was not checked in this investigation. The step is not explicitly described as aiming to weaken bitterness; the source uses only the term 「アク抜き」 (in translation: "aku removal").
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ingredient-ginkgo-nut —is_prepared_by→ "A preparation step of removing the thin skin (inner seed coat) and soaking the kernel in water for about a day for 「アク抜き」 (in translation: "aku removal"), as quoted from Nagano producer information."