Q.What is kakinoha-zushi, and why is it wrapped in persimmon leaves?

A feast born in mountains far from the sea

Its origin lies in the mid-Edo period. Fishermen from Kishu (Wakayama) salt-cured summer mackerel caught in the Kumano Sea, then carried it over the mountain passes to sell in villages along the Yoshino River. In these mountains, far from the sea where seafood was precious, this salted mackerel became a treat eaten at summer festivals. Nara's official tourism site notes that households in Gojo — a persimmon-growing area — and along the Yoshino River have enjoyed it since at least the mid-Edo period, though the exact origin is unknown.

Why persimmon leaves? Wisdom for keeping it fresh

The persimmon leaf is there for preservation. Astringent persimmon leaves are rich in tannins (polyphenols) with anti-spoilage, anti-bacterial properties. Combined with the germicidal power of the rice vinegar, they keep the mackerel fresh and lend a distinctive aroma. The leaves were also close at hand, and being thick and large, ideal for wrapping. In preparation, the pieces are packed in a box, weighted, and rested overnight to several days; this presses out excess air and lets the leaf's fragrance and the mackerel's flavor settle into the rice — making it a true preserved food.

Not just mackerel — salmon too, and seasonal fish

Salt-cured mackerel is the classic topping, but salmon has also been used since long ago, and today there are many kakinoha-zushi made with seasonal fish. The table below lists the representative fillings confirmed in our research. Taking salt-preserved fish that was easy to obtain in the mountains and turning it into something that keeps, by means of the persimmon leaf and vinegared rice — that is the idea at the heart of the dish.

The leaf's power, backed by science — and Nara is Japan's No.2 for persimmons

The anti-viral effect of persimmon tannin has been confirmed scientifically. In September 2020, researchers at Nara Medical University (Professors Toshihiro Ito and Hisakazu Yano and colleagues) reported that high-purity persimmon tannin reduced the infectivity of the novel coronavirus to one ten-thousandth or less (as of 2020). For context, Nara is a leading persimmon producer — second in Japan for harvest volume (Wakayama is first; 2024 crop year), with about 1,800 ha under cultivation and roughly 25,000 tons shipped. That fits neatly with persimmon leaves being close at hand in every household.

Datasets behind this article

• Traditional Foods of Japan: Miwa Sōmen (MAFF)農林水産省
• Nara's Nationally Designated Traditional Crafts奈良県