Japan — kuzu cultivation for starch production is documented from at least the Nara period (8th century). The Yoshino area of Nara Prefecture (Yoshino-kuzu, 吉野葛) is Japan's most prestigious kuzu-producing region — the cold mountain climate and specific soil composition produce the highest-quality kuzu starch. Premium Yoshino-kuzu is sold in lumps (the dried, unmixed starch forms irregular white lumps during drying) and commands significantly higher prices than industrially processed kuzu powder.
Kuzu (葛, Pueraria lobata, kudzu/Japanese arrowroot) is a premium natural starch derived from the root of the kudzu vine — the highest-quality thickening agent in Japanese cooking, valued for its superior transparency when cooked (clearer than potato starch or cornstarch), its smooth, non-gummy texture when thickened, and its specific gelatinous quality that is distinct from other starches. Kuzu is primarily used in Japanese cooking and wagashi for: ankake (thickened glaze sauces, where kuzu produces a cleaner transparency than katakuriko); kuzukiri (葛切り, transparent kuzu noodles — made by setting kuzu in a sheet, chilling, then cutting into strips; eaten cold in sweet dashi as a Kyoto summer specialty); goma-dofu (sesame tofu, set with kuzu rather than gelatin); and kuzumochi (葛餅, Kyoto-style mochi set from kuzu rather than pounded glutinous rice).
Kuzu's own flavour is nearly neutral — a very faint, slightly grassy sweetness that is almost imperceptible in seasoned preparations. Its contribution to flavour is textural and visual: the specific transparency and smoothness of kuzu-thickened sauces allows the visual quality of the broth to show through, maintaining the aesthetic refinement prized in kaiseki. In goma-dofu: the kuzu's gelatinous character is the vehicle — the sesame's richness suspended in a matrix that is simultaneously firm and yielding, that melts slowly on the tongue, releasing sesame flavour in a prolonged dissolution rather than an immediate impact.
Kuzu preparation: dissolve in cold water (1:2 kuzu-to-water ratio); add to warm liquid while stirring; bring to temperature while continuing to stir constantly — kuzu thickens at approximately 70°C and must be stirred through this temperature to prevent lumping. Once thickened and translucent, cook for a further 30 seconds to complete gelatinisation. Kuzu produces a slightly different texture than cornstarch or potato starch — slightly more gelatinous, slightly glossier, with a specific smoothness on the tongue. In goma-dofu: kuzu dissolved in water + neri-goma (sesame paste), cooked and stirred constantly until the mixture thickens to a pudding consistency; poured into moulds; chilled until set.
Kuzukiri (葛切り, kuzu noodles) — prepared fresh in premium Kyoto tea houses (Kagizen Yoshifusa has served kuzukiri since the Edo period) — is one of Japanese culinary culture's most refined summer preparations: transparent, cool, slightly gelatinous strips of set kuzu served in cold sweetened dashi (chilled kuromitsu, black sugar syrup) as a dessert. The preparation requires dissolving kuzu in cold water, spreading thin on a warmed plate, steaming briefly until set, then chilling. The result is a translucent, pale amber strip with a specific silky-smooth, almost liquid texture when eaten cold.
Substituting cornstarch for kuzu without acknowledging the texture difference — cornstarch produces a more opaque, slightly gummier result; kuzu produces a transparent, clean-finish texture. Using hot water to dissolve kuzu — kuzu begins gelatinising in warm water; always dissolve in cold water before heating.
Washoku — Elizabeth Andoh; Japanese Cooking: A Simple Art — Shizuo Tsuji