Shirako (milt) (白子 (精巣))
Shirako is the name of the milt of fish when the milt is used as ingredients in various dishes. Matured milt of cod, angler fish, and pufferfish is tasty, used in vinegared dishes, soup, and nabe dishes, or grilled.
Milt is characterized in that it normally contains 75-82 % water and 1-5 % fat, plenty of strong-basic protein such as protamine (histone) and nucleoprotein, and polyamine. It also contains a high level of deoxyribonucleic acid (DNA).
The pufferfish hoards the lethal poison tetrodotoxin in its flesh and internal organs. Where they hoard the tetrodotoxin differs in each kind, but only a few kinds of pufferfish hoard the tetrodotoxin in their milt, which is mellow; so the milt is used for food.
Salmon milt is mainly used for extracting DNA and protamine, and also used for nucleic acid seasoning, nutrient supplement, preservatives, and industrial material.
Cod milt is called "Tachi (Tatsu) in Hokkaido, "Kiku" in Iwate Prefecture, "Dadami" in Akita Prefecture, Yamagata Prefecture, and Fukui Prefecture, and is processed into Kamaboko (steamed fish paste) within the jurisdiction area of Shiribeshi branch office, Hokkaido. It has been imported from abroad in recent years.
With Ponzu sauce (juice pressed from bitter oranges), for nabe dishes, tempura, saute, broth, and miso soup.