Narezushi: fish, rice and regional fermentation

One Shiga-style funazushi method begins with prepared whole fish preserved in salt. After washing and draining, the fish enter a rice-pickling stage, arranged with cooked rice between and around them. Rice covers the upper layer, and a lid supports the weight above it.

Lactic fermentation

Lactic-acid bacteria use available nutrients and produce lactic acid, changing acidity and flavour. Fish, salt, rice and additional ingredients help form the fermentation environment. Different materials and microbial communities yield different flavours. This differs from preparing vinegared rice and assembling a quick sushi dish for immediate eating.

A study of Toyama ayu narezushi

A 2020 study of Toyama ayu narezushi makes one pathway concrete. In the preparation with rice koji, saccharification breaks rice starch into sugars that lactic-acid bacteria can use. The researchers observed increasing lactic acid and falling pH. Rice thus contributes to fermentation rather than merely accompanying the fish. This koji-assisted example should not be treated as the method used by every regional preparation.

Mie preparations use fish including ayu, saury and mackerel, with local additions such as yuzu, ginger or koji. A mackerel preparation in Obama, Fukui, starts from heshiko fish already preserved in salted rice bran before desalting and rice-pickling. Even apparently similar whole-fish forms can therefore have different preliminary stages.

Early names and local methods

Nara-period wooden records include names such as funazushi, but do not provide a complete production sequence. Researchers including Terutoshi Hibino and Michinori Hashimoto have reconsidered the idea that today’s Shiga funazushi survives unchanged from antiquity. Their work stresses early modern regional development and variation across time, rather than one simple progression from discarding rice to eating it.

Coexisting forms of sushi

Fermented sushi also coexisted with later forms. Muromachi-period namanare used shorter fermentation and included eating the rice with the fish. By the eighteenth century, vinegar-based hayazushi offered acidity without waiting for fermentation. Yet court and warrior households and some established shops continued to serve fermented forms. New preparations did not replace every regional narezushi at once.

Some preparations emphasise the fish; others include eating fermented rice with it or using the rice in other ways. Narezushi also belongs to New Year meals, shrine offerings and local gatherings. In 2023, the production techniques of Omi narezushi were registered as a Japanese Intangible Folk Cultural Property.