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Generally, saltwater fish grow in seawater, and their bodies naturally contain a certain concentration of salt. Because seawater has a higher salinity than the fish’s internal fluids, the water in their bodies is constantly being drawn out by osmotic pressure<\/a><\/span>. As this water is lost, the internal salt concentration increases. To compensate, saltwater fish actively drink large amounts of seawater and excrete the excess salt through specialized cells in their gills and kidneys. This complex osmoregulation mechanism helps them maintain a balance, which is why their flesh typically contains a high percentage of water.<\/p>\n This high moisture content sometimes gives the impression that the fish is “somehow watery” or lacking in firmness. However, once the fish is cooked\u2014especially through gentle heating\u2014the texture becomes soft and fluffy, enhancing its natural qualities.<\/p>\n Therefore, when preparing fish for cooking, it is often sprinkled with salt approximately 30 minutes to one hour beforehand. This process, commonly practiced by sushi chefs as well, is called Shiojime (\u5869\u7de0\u3081), or salting.<\/p>\n Shiojime serves several purposes. First, it draws out excess moisture through the process of osmosis, which in turn concentrates the fish\u2019s natural umami<\/a><\/span> (savory) flavor.<\/p>\n Additionally, by removing moisture, Shiojime helps eliminate the fishy odor (commonly caused by compounds like trimethylamine), allowing the clean, delicate flavor of the fish to shine through.<\/p>\n Another important benefit of Shiojime<\/em> is that it helps control bacteria. When salt is applied to the fish, it creates a salty (hypertonic) environment that draws water out of the bacteria on the surface. Without enough water, the bacteria can\u2019t survive or grow. In addition, salt lowers the water activity in the fish, which makes it harder for microbes to multiply. This helps keep the fish safe to eat and slows down spoilage, making it last longer.<\/p>\n In traditional sushi preparation, Shiojime is often followed by Sujime (vinegar curing). The amount of vinegar that penetrates the fish depends significantly on the prior conditions established during Shiojime, making it a delicate and finely tuned process that requires experience and attention to detail.<\/p>\n Ultimately, Shiojime is a time-honored technique that delivers numerous benefits\u2014enhancing flavor, improving texture, reducing odors, and increasing safety\u2014while showcasing the depth of Japanese culinary knowledge.<\/p>\n We hope this information will be helpful.<\/p>\n Revision date: June 12, 2025<\/p>\n
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