Shiokara natto (hama natto, tera natto)

Overview

Shiokara natto is a family of salted, dark, non-stringy soybean foods from Japan. Its name combines shiokara, salted, with natto, the soybean food. The name is used as a category term in the food literature. It is not the unrelated seafood dish called shiokara.

The family is not the sticky natto familiar in Japan. Sticky natto is made with Bacillus subtilis var. natto and forms viscous threads. Salted natto uses whole soybeans, toasted grain and salt water, then a long maturation and drying, and it is usually made with a koji-associated or mould-associated stage. Do not carry sticky-natto culture or incubation advice into this family.

History and region

Hama-natto is the best-documented member of the family. A 1974 microbiology study places its production around Lake Hamana in Shizuoka and compares commercial Yamaya and Horinji samples with naturally fermented Daifukuji samples. A 1976 brewing-journal account describes the temple production at Daifukuji and Horinji and the commercial route at Yamaya, and records a change in the market name from Hamana-natto to Hama-natto.

Kyoto tera-natto is associated with Daitokuji and with the broader Kyoto and Yamashiro area. The Japan Traditional Foods Atlas places it in summer through autumn production. The local and national origin stories, including a Ming-era introduction for Daifukuji natto and a Kamakura-era introduction for tera-natto, are preserved as tradition. The inspected sources do not confirm them against primary historical records.

Ingredients and cultures

The Kyoto descriptions use whole soybeans and toasted barley or wheat flour, the hattai-ko, followed by salt water, maturation and drying. The 2007 Daitokuji batch used Hokkaido Tsuruhime soybeans at 360 kg with 90 kg of roasted-grain powder.

The Hama-natto papers describe at least two production routes. Yamaya and Horinji used deliberate mould inoculation, while Daifukuji relied on organisms resident in its long-used koji room and materials. The 1974 study reported Aspergillus oryzae-type moulds and lactic acid bacteria, which it classified with the phenotype labels Streptococcus-type and Pediococcus-type. Those labels are historical and are not modern strain identifications or recommended inocula.

A 1977 study recovered 26 yeast isolates classified in Saccharomyces, Debaryomyces and Torulopsis. Saccharomyces rouxii was found in several products, and Debaryomyces only in the Daifukuji samples. Those yeasts were tested in laboratory media and do not establish a starter for the home.

How it is made

The best-documented method is the 2007 Zuihō-in batch at Daitokuji. Soybeans were soaked overnight and steamed for about three to four hours, then mixed with roasted grain powder and fermented in a cellar for one week. The cellar stage raised peptides and free amino acids, which the authors attribute to enzymatic protein breakdown. The mixture was then combined with prepared salt water and matured in a barrel under summer sun for about two months, with daily stirring. Finished pieces were stored in a pot at room temperature in that study description.

The 1976 Hama account describes separate factory and temple routes that differ in inoculation, the koji room, maturation and drying. Those routes are kept as separate evidence. The steps above are one batch, not a template for every producer.

Uses

The national atlas describes Kyoto tera-natto as eaten with rice, as a tea snack or with sake, and as a seasoning in Japanese and Western cooking, including sweets. The Shizuoka Prefecture page describes Daifukuji natto as a salty rice accompaniment and sake snack. These are variant-specific descriptions, not evidence that every maker serves it the same way. The sources do not give a standard serving quantity.

Monitoring and safety

The safety guidance that is widely available covers sticky natto, and its controls do not validate salted natto. The historical microbiology describes varied yeast and mould populations among producers, so the product cannot be defined by one organism set. The sources do not give a critical salt concentration, pH, water activity or time-temperature limit for the salted product, and they do not give a shelf life.

A food-specific safety assessment for each salted product and process remains an open task. Sensory checks, a single measurement or the absence of visible mould do not show that a batch is safe. This recipe is not a validated home method.

Limits of the evidence

The 1974, 1976 and 1977 Hama studies are historical and use phenotype labels. The Daitokuji study follows one temple batch and measures composition and activity; it does not show a health benefit. The origin dates rest on local accounts and national traditions that the inspected sources do not verify. Exact origins, the seasonal calendar of present-day producers and a variant-specific safety assessment remain open.