In order to maintain the quality of tuna, when it is caught in the sea, the ikejime technique is used first, then rapid freezing is used as a matter of course. This means that the quality of the thawing technique is also important. Poor thawing conditions mean that the drip outflow volume will be too high, shrinking the meat and worsening the texture. Here I will explain a thawing method that doesn’t cause drip, uneven thawing, or loss of color.
What exactly is drip anyway?
I’m sure you’ve seen it before in any type of thawing frozen meat, but there is a red liquid that comes out of the tuna when thawing. This is called ‘drip’. This liquid includes the tuna’s umami, and when the fish loses a lot, it naturally detracts from the flavor.
First of all, we will explain the worst thawing methods. Never thaw naturally at room temperature or in the microwave. These are common methods at home, but they are out of the question.
Next we will explain the general method of thawing.
- Mix 30 g of salt with 1000 cc of warm water at 40℃ to create a saltwater mixture.
- Place the frozen block of tuna in this 40℃ saltwater, submerge for one to two minutes and then drain the water.
- Wash any remaining salt off the surface of the block of fish with fresh water and remove moisture from the surface with paper towels.
- Wrap the fish in clean paper towels, wrap with plastic over that and leave it in the refrigerator for about a day to thaw naturally.
- Cut from the block directly before consuming.
Now for the thawing method used by professionals, such as sushi chefs.
The first three steps are the same as the general thawing method above.
- Place block in an air-tight plastic bag. Push out as much air as possible before sealing the bag.
- Prepare ice water in a bowl or container and submerge the plastic bag in the water for one hour. Normally the bag will float, so it must be weighed down with something.
- Remove the thawed tuna from the plastic bag and remove moisture with paper towels.
- Wrap the fish in clean paper towels, wrap with plastic over that and leave it in the refrigerator for about a day to mature.
After thawing, the meat of the tuna may have shrunk. This is called ‘chijire’. The reason for this is, after the tuna is caught, it is frozen before rigor mortis begins, so the rigor mortis process starts once the fish is thawed. Therefore, this is proof of freshness. The meat of tuna for which ‘chijire’ has begun is tough and isn’t yet matured. However, amateurs can’t tell if ‘chijire’ is happening or not. That’s why it’s better to let the fish mature in the refrigerator for half a day to one day. Please use these explanations for your own reference.
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Revision date: October 2, 2020
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However, in 1934, a restaurant in Ginza called Kyubey started a revolution. This restaurant is still synonymous with high-end sushi, but at that time many political and business people went there as well. Then, one night… Apparently, one of the regular customers was tired of eating ordinary sushi and said to the chef, Hisaji Imada, “I want to eat some sushi that is more unusual. Ikura (Salmon roe) sounds like it would make good sushi,” as a joke. Imada, who took these words seriously, thought to himself, “But the roe would fall off if put directly on the shari (vinegar rice),” and racked his brain that night for a solution. Finally, he had an idea and said, “I know, I could just surround shari with seaweed and put salmon roe in it.” This is how the Ikura Gunkanmaki was born.
Next, when that customer came in again and Imada nervously served him his new Ikura sushi concept, it was received much better than expected. Gaining confidence from this reaction, Chef Imada put it on his regular menu. The story goes that rumors of the delicious taste spread and other sushi restaurants started to copy it. Then, the term “ikura gunkan-maki”(salmon roe battleship roll) was coined.
There is only one trick to distinguishing between conveyor belt sushi restaurants (kaiten-zushi), and that is to try eating the tuna as your first dish.
The most commonly used ingredient at kaiten-zushi is tuna. At kaiten-zushi, the tuna is imported and frozen nearly 100% of the time. The most famous is the Southern blue-fin tun, but you’ll also find Boston bluefin tuna, Canadian tuna farmed in fish preserves, inland sea tuna from Turkey and Spain, New Zealand offshore tuna, Atlantic tuna, etc. Also, the season of each type of tuna and the timing of high-volume catch differ, which makes the prices fluctuate greatly.
He gave out his hidden recipe, something that only a sushi chef can think of, and something you don’t see in those classic recipes. First, it might be hard to get at places like a supermarket, but he was telling us that using cane sugar (三温糖) and 
When you make chirashi sushi, don’t push the sushi rice too hard to squeeze in a container. Try to put it in softly as if letting the air in.
It seems kanikama was invented in Japan. In the early 1970s, Sugiyo, a fish paste manufacturer, in a failed attempt to developed artificial jellyfish, ended up with a product that had a texture exactly like crab and shifted development to that instead.
The tiny red balls around the outside of the rice on California rolls are Tobiko (飛び子). Specifically, they have salted roe of flying fish and are known for the plump, crunchy texture. This crunchy texture comes from the skin, which is relatively tough, even compared to other fish eggs. As the roe is made up of small eggs of only 1 to 2 mm, each one bursts as you bite, without leaving the outer skin in your mouth, so you can enjoy a nice texture that you won’t find with any other fish roe. Unlike the orange-colored tobiko sold in stores, natural tobiko has a pale golden color with a sense of transparency. Therefore, some processors have dubbed it “golden caviar”.
On the other hand, an orange-colored tobiko is often seen at conveyor belt sushi restaurants, etc., but this is the roe of a fish called capelin (カペリン), which is similar to shishamo smelt. A salted version of this is used for sushi rolls in the US and other places, where it is called masago. Compared to tobiko, the grains are smaller and the texture is a bit chewier. It is mainly rich in EPA (Omega-3 fatty acids) and collagen.
Finally, we’ll let you in on a not-so-pleasant secret. Flying fish and capelin roe is actually a light yellow or beige color. However, you’ll find it in bright red, orange, yellow and lately even green or black. Of course, these are colored by either natural pigments or synthetic coloring. Furthermore, tobiko is sometimes mixed with the cheaper capelin or herring roe. Unfortunately, food fraud is common in seafood products that are consumed in high quantities.
Ikezukuri means to take a fish that’s swimming in a tank at the restaurant, and immediately making sashimi after killing it, while the meat is still super fresh. In this state, there is no Inosinic acid, but there is quite a show with movement still in the fish and this preparation method gives the best-tasting texture.
Nojime* means using a massive amount of ice to suddenly reduce the temperature, resulting in the death of the fish, either at the fishing site or at the local market. This method is used for small, cheaper mass-market fish that are caught in large amounts. Nojime starts with a reverse calculation for flavor from the day after fishing, but if the process isn’t thorough or there are any deficiencies, the fish won’t stay as fresh, so detailed care must be taken in temperature management.
Ikejime is used so that the peak flavor will be reached during afternoon and evening business hours. The spinal cord of the live fish is cut and spinal fluid drained at the early morning market. This result is a firmness from the remaining ATP, and delicious flavor from the Inosinic acid that is generated as time passes. After some time has passed, even fish for which Ikejime is applied, can reach the same state as Hamajime if used after being refrigerated for one to two days, in order to maximize the Inosinic acid generated. Of course, sushi chefs find their own balance of firmness in meat or added flavor, and incorporate this balance for the optimum combination with their shari in each piece of sushi.
The fish used in sushi is generally salted or soaked in vinegar then matured for several days while the umami Inosinic acid component increases. This is called “Jukusei” (aging). Sushi made with toppings that have been aged in this way is called “Jukusei sushi”. The aging period depends on the type, individual size and origin of each fish, and some are even aged for over four weeks. However, the preparations are not only difficult and time-consuming, but the discolored parts and inedible parts must also be trimmed, so these toppings tend to be expensive. If gone too far, the Inosinic acid converts to hypoxanthine and rots. The ability to make this judgment is important. In the end, Jukusei is an evolved version of the culture of “maturing toppings” which existed in Edo-style Sushi.
In order to mature seafood, after completing advance preparations (removing the head and internal organs then washing thoroughly; all blood must be removed), more than adequate considerations must be made for the fat content of the fish and management of the bodily fluids. Specifically, this includes processes like dry-aging at a low temperature, removing moisture using salt, utilizing enzymes and fermentation, wet aging by putting the item in a vacuum pack, and wrapping in aging sheets, which were developed thanks to 
Once tuna caught in the open sea is processed by draining its blood on the ship, it is flash-frozen at ultra-low temperatures (-60℃). Ultra-low temperatures stops the enzymatic hydrolosis of protein, oxidation of fat and cultivation of microorganisms so it can be stored over a long period of time. The process can prevent discoloration for over two years and maintain a freshness worthy of being served as sashimi. Therefore, skillful sushi restaurants mature the thawed tuna in the refrigerator for about one week to attain the perfect balance of umami and change in color.
In the United States and other countries, “
As an aside, three cousins (closely related species) of buri are often used as sushi toppings in sushi restaurants. In the Fish Name Dictionary, the translations of these cousins are Goldstriped amberjack (
I’m sure you’re interested in the price, and while the price of the seasonal winter buri varies, it is generally around $10-20 per kilogram. Since there is very little distribution of hiramasa, the price is said to be about double that of buri. The price of 
Why is only tuna brought into certain ports high-priced, even though all of the tuna is caught in the seas near Japan? This is because the level of stress caused to the fish when it is caught has a huge impact on the quality, including taste, color and texture. In other words, the same fish may be delicious or taste unpleasant depending on how the fisher handles the fish directly after catching it. Naturally, everyone ends up wanting the fish from the ports with fisherman who are skilled in this practice*. Furthermore, it is individuals who process the fish. The quality changes drastically depending on who caught it.
Even Japanese people can be overwhelmed by the somehow special atmosphere when they sit down at the sushi counter. This continues even when starting to eat. Other customers are concentrating on eating, quietly. You kind of get the feeling that if you utter anything, you will be asked to leave. If you don’t end up mustering up the courage, you just end up paying the high price for your meal and going home without much more to say of the evening.
The customer ends up not remembering which fish they ate. For example there are very few people who can name the order of the 15-piece Omakase course they ate. You may be sure you ate tuna. But where was it caught? Was it the belly side or the back side? How long had the fish been matured? To be a bit more frank, how much did it cost? If you ask the chef these questions, next time you visit, you’ll be able to compare different taste based on the fishing location. Knowing the difference in taste based on the part of the fish, and difference in flavor depending on where it was procured, and different taste depending on the preparations will certainly improve your sushi literacy remarkably. It will also lead to a better awareness of your own taste preferences.
However, sushi chefs will remove the topping from the refrigerator and leave it standing out for a while (in the case of tuna, the fat will melt at around 23℃). They do this because if the topping is cold, it becomes difficult to taste the essential nature of the fish. The temperature of the shari is best at human skin temperature (around 36℃) to maximize the taste and sweetness of the rice. However, the ideal temperature differs very slightly depending on the topping.
For example, conger eel which is often lightly grilled or prepared in another, similar way, should have a slightly higher temperature (around 42℃) than the shari, and kuruma prawn, which are boiled, should be the same temperature as the shari.