astringent inner skin of a chestnut
Refers specifically to the thin, bitter brown skin directly covering the chestnut kernel, distinct from the hard outer shell (鬼皮). Commonly encountered in cooking contexts.
It's difficult to peel the astringent inner skin of a chestnut cleanly.
渋皮煮は、栗の渋皮を残して甘く煮た料理です。
Shibukawa-ni is a dish where chestnuts are sweetly simmered with their inner skins left on.
Compound of 渋 (shibu, 'astringent') and 皮 (kawa, 'skin'). The derivation is straightforward; the word literally describes the astringent skin of chestnuts.