Appendices
Appendix A
Quick Reference: Key Numbers, Temperatures, and Times
This appendix collects the temperatures, times, and concentrations that appear in the chapters of this book. Learn each number together with its conditions. "−20°C" on its own is of no use in the kitchen. It becomes useful only when you remember it as "24 hours or more after the center of the fish reaches −20°C."
Each section first gives a table of the numbers to learn for Grade 2. A table of the numbers to learn for Grade 1 follows. The Grade 1 tables carry the Grade 1 mark.
At the end of the "Meaning" column, a label in square brackets shows what kind of number it is. [Standard] means a number based on laws, national standards, guidelines, or official advice. The thinking behind it also applies outside Japan. [Science] means something that is known scientifically. [Rule of thumb] means a guide drawn from chefs' experience, or a guide given as a range. It changes with the size of the fish, its fat, the season, and the way each restaurant works. Do not just memorize a [Rule of thumb] number. Instead, check why it is that number in the chapters listed in the "Chapters" column.
A.1 Temperature
The temperatures are listed from coldest to warmest. Picture four zones as marks on a single thermometer: freezing, refrigeration, the temperature danger zone, and cooking. This makes them easier to remember.
| Number | Meaning | Memory tip | Chapters |
|---|---|---|---|
| −60°C or below | Ultra-low-temperature freezing. This is the temperature used to freeze tuna caught in distant waters on board the ship and keep it for a long time. Fat oxidation and color change (browning, or metmyoglobin formation) almost stop, and parasites die. [Science] | It is more than 40°C colder than an ordinary freezer (−18°C). Think of it as "the tuna boat temperature." | Chapters 12 and 14 |
| −20°C for 24 hours or more | The freezing condition that kills Anisakis. It is advice from Japan's Ministry of Health, Labour and Welfare (MHLW), not a legal duty. To be sure, count from when the center of the fish reaches −20°C. [Standard] | "Minus 20 for one full day." Vinegar, salt, wasabi, and soy sauce do not kill it. For standards outside Japan, see A.4. | Chapters 3 and 12 |
| −20°C or below for 2 weeks or more | Storing retained food samples (small portions of the dishes served and their ingredients). Seal about 50 g of each dish and each ingredient. This applies the rule for large-scale cooking facilities to small restaurants as well. [Standard] | If food poisoning is suspected, the samples help find the cause. | Chapter 26 |
| −18°C or below | The standard temperature of home freezers and ordinary commercial freezers. Bacteria do not grow, but they do not die. Fat slowly oxidizes, and freezer burn occurs. [Science] | "−18°C and −20°C are not the same." Many ordinary freezers cannot reach the −20°C needed against Anisakis. | Chapters 5 and 12 |
| −5 to −1°C | The zone of maximum ice crystal formation. In this range, the water in the flesh turns to ice. If the fish passes through it slowly, large ice crystals break the cells. Then, when the fish is thawed, drip (juices that carry umami) comes out. [Science] | "A zone to pass through quickly." Quick freezing and quick thawing are meant to get through this zone in a short time. | Chapter 12 |
| 0 to 1°C | The water temperature for thawing in ice water. Put the fish in a bag, press out the air, and sink it in ice water. This is many times faster than thawing in the refrigerator, and the surface stays near 0°C. [Rule of thumb] | "Cold water, fast, and gentle." | Chapter 12 |
| 0 to 4°C | The temperature for refrigeration and aging. It is also the range in which cooked rice (starch) hardens fastest. [Science] | "Good for fish, bad for shari." This is why shari does not go in the refrigerator. | Chapters 9 and 10 |
| 4°C or below | The temperature at which Vibrio parahaemolyticus does not grow. The MHLW advises storing seafood for raw consumption at 4°C or below. Chilling does not kill the bacteria. [Standard] | The legal line is 10°C. The line that stops Vibrio parahaemolyticus from growing is 4°C. "Ideally 4°C or below, and at least 10°C or below." | Chapters 3 and 5 |
| 10°C or below | The upper limit for storing seafood for raw consumption (the legal standard). Takeout sushi must also be kept at 10°C or below. [Standard] | The most important number in this book. To leave a margin, many restaurants set their refrigerated topping cases and refrigerators to 5°C or below (a rule of thumb). | Chapters 5 and 26 |
| 10–60°C | The temperature danger zone. Most food poisoning bacteria grow in this range. They grow fastest at around 30–40°C. [Science] | "10 to 60 is the danger zone." Think of a boxed lunch left out in a kitchen in summer. | Chapters 2 and 5 |
| 24–30°C | The temperature at which tuna fat (toro, or fatty tuna) is said to melt. [Rule of thumb] | Cold shari cannot fully melt the fat. This is why toro is paired with shari at body temperature. | Chapter 14 |
| 35–37°C | Shari at "hitohada" (body temperature). It is almost the same as the chef's own body temperature (about 36°C). [Rule of thumb] | Remember it as "my own body temperature." It slows the hardening of the rice and melts the fat of the neta (topping) in the mouth. If you handle the topping too much, this same body heat damages it. | Chapters 9 and 24 |
| About 40°C | The water temperature for thawing in warm salt water (about 3% salt). Thaw only the surface, then move the fish to the refrigerator right away. [Rule of thumb] | Do not soak it for long. Take it out once the surface has thawed. | Chapter 12 |
| About 60°C for 1 hour | The temperature and time for making kombu (kelp) dashi. If you are short on time, use about 70°C for 30 minutes. Boiling brings out sliminess and off-flavors. [Rule of thumb] | "Kombu at 60, never boil." | Chapter 20 |
| 70°C or higher, or 60°C for 1 minute | The heating condition that kills Anisakis. [Standard] | "At 70, right away. At 60, 1 minute." | Chapter 3 |
| 70–80°C | The temperature for simmering abalone (ni-awabi). Hold it at this temperature without boiling for 3–5 hours. The collagen that makes it tough turns into gelatin, and the abalone becomes tender. [Rule of thumb] | "Never boil abalone. Cook it long." | Chapter 18 |
| Core temperature of 75°C for at least 1 minute | The standard for heating the center of food. It kills common food poisoning bacteria. [Standard] | "75 at the core for 1 minute." But it does not work on heat-resistant bacterial shells (spores) or on toxins that heat does not destroy (see the 100°C row). | Chapters 2 and 3 |
| 80°C for at least 5 minutes | Disinfecting knives, cutting boards, and other tools with hot water. [Standard] | Always remove dirt with detergent first. If dirt is left, the heat sets it hard, and it protects the bacteria inside. | Chapter 4 |
| 85–90°C for 1–2 minutes | The temperature and time for making dashi with katsuobushi (dried bonito). Do not simmer it long. Steep it briefly and strain it. [Rule of thumb] | "Katsuobushi at 85 to 90, briefly." It is the same temperature as the heating standard for norovirus, so learn the two as a pair. | Chapter 20 |
| 85–90°C for at least 90 seconds | The heating standard that makes norovirus no longer infectious (core temperature). [Standard] | Norovirus is tough. It needs a higher temperature and a longer time than "75°C for 1 minute." | Chapter 3 |
| 100°C (boiling) | Most bacteria and parasites die. However, the Staphylococcus aureus toxin, histamine, and natural toxins such as pufferfish toxin are not destroyed. The spores of Clostridium perfringens and Bacillus cereus survive. [Science] | "What boiling or grilling cannot remove must never be allowed to form." Prevent it with handwashing, 10°C or below, and time control. | Chapters 2 and 3, Appendix B |
For Grade 1, you will also learn the temperatures below. They cover low-temperature cooking work and more detailed numbers about bacteria and standards.
| Number | Meaning | Notes | Chapters |
|---|---|---|---|
| −35°C or below | The freezing temperature used against parasites outside Japan. The U.S. Food and Drug Administration (FDA) calls for freezing at an air temperature of −35°C or below and holding at −35°C or below for 15 hours (or freezing at −35°C and then holding at −20°C for 24 hours). The EU requires −35°C or below in every part of the product for at least 15 hours. [Standard] | The sources are the FDA Food Code in the United States and EU Regulation 853/2004. Outside Japan, you are required to keep records of the temperature and the number of hours you froze the fish. | Chapters 1 and 12 |
| −1 to 1°C | The chilled range. Thawing in ice water is fast because water carries heat about 20 times better than air. The fish thaws to the core while its surface stays near 0°C. [Science] | It is fast, and the surface does not warm up. As a result, there is less cell damage and less drip. | Chapter 12 |
| Around 10°C (sometimes 5°C) | The lowest temperature at which Vibrio parahaemolyticus can grow. It does not grow at 4°C or below. But even when cold reduces their numbers, the bacteria do not always die out. [Science] | This is why storage at 4°C or below is advised. | Chapter 3 |
| Why about 40°C (thawing in warm salt water) | This temperature moves the surface quickly through the zone of maximum ice crystal formation (−5 to −1°C). 40°C itself is not a temperature that destroys cells. The salt level of about 3% is close to seawater. It lets the flesh take up less water than fresh water does. It is not the same concentration as the fish's body fluids. [Science] | The body fluids of fish are about one-third as concentrated as seawater. 3% is not "isotonic." | Chapter 12 |
| 60–70°C | The temperature for steamed dishes and low-temperature cooking. Proteins begin to set in earnest in this range. [Rule of thumb] | It is also the range in which Anisakis dies: at 60°C in 1 minute, and at once at 70°C or higher. | Chapters 3 and 19 |
| 70–80°C (yubiki) | The water temperature for yubiki (quick blanching) of shirako (milt) and similar items. Only the proteins on the surface set, and then ice water stops the cooking. [Rule of thumb] | Setting the surface film makes it harder to break, while the inside stays close to raw. | Chapter 13 |
| The limits of a core temperature of 75°C for 1 minute | Common food poisoning bacteria die, but spores and heat-resistant toxins are not destroyed. The Staphylococcus aureus toxin survives 100°C for 30 minutes. The emetic toxin of Bacillus cereus survives 126°C for 90 minutes. [Science] | For details, see Appendix B. | Chapter 3, Appendix B |
A.2 Time
Bacteria multiply over time, and both fish and shari change over time. Always think of temperature and time as a pair.
| Number | Meaning | Memory tip | Chapters |
|---|---|---|---|
| About 30 seconds | The time for one handwashing. When your hands are very dirty, such as after using the toilet or touching raw fish, wash them twice. [Standard] | The first wash removes skin oil and dirt. The second wash gets the soap into the creases and under the nails. | Chapter 4 |
| About 10 minutes | The time it takes Vibrio parahaemolyticus to double in number (under the best conditions for growth). [Science] | In 1 hour, the number can grow dozens of times. Do not leave toppings out on the cutting board. | Chapter 3 |
| Summer: 30 minutes to 1 hour; winter: 1–2 hours | A guide for soaking rice (water at about 25°C in summer, 5–10°C in winter). For previous year's rice (komai), soak about 30 minutes longer. [Rule of thumb] | The colder the water, the more slowly the rice absorbs it. If the water does not reach the center, the grains stay hard in the middle. | Chapter 7 |
| 15–30 minutes | A guide for draining the rice in a colander. If it sits too long, the surface of the grains dries and cracks (fissured grains), and the rice turns sticky when cooked. In a dry kitchen, make the time shorter and cover the rice with a damp cloth that has been wrung out tightly. [Rule of thumb] | "Once the rice is in the colander, do not forget about it." | Chapter 7 |
| 2–4 hours | A guide for the maximum time to keep shari warm. Each restaurant sets its own limit within this range and records the time the vinegar was mixed in. Shari past the limit is not used for nigiri. It is thrown away. [Rule of thumb] | Even vinegared rice leaves room for Bacillus cereus to grow as time passes. In kitchens or outdoor spaces above 30°C, use 2 hours as the guide. | Chapters 6 and 9 |
| 3–5 minutes | The time after grating when wasabi is at its most pungent. [Rule of thumb] | After that, the heat fades and bitterness remains. Do not grate a large amount in advance. | Chapter 21 |
| 15–30 minutes | A guide for sprinkled salting of white-fleshed fish such as sea bream and olive flounder (hirame). Use a shorter time for thin fillets. The fattier the fish, the more salt and the longer the time. [Rule of thumb] | The salt draws water out of the flesh and firms it. | Chapters 13 and 15 |
| 2–4 hours for thin, angled slices; half a day to overnight for a saku block | A guide for kobujime (curing between kombu sheets). If left too long, the flesh turns amber and hard, and the kombu aroma overpowers the fish. [Rule of thumb] | The umami of the fish and the umami of the kombu combine, and the umami becomes stronger. | Chapters 13 and 15 |
| Salt: 30 minutes to 1 hour; vinegar: 10–30 minutes | A guide for the salting and vinegar times for kohada (gizzard shad), 7–10 cm long. For shinko (baby kohada), the times are very short: from a few minutes to between ten and twenty minutes in salt, and a few minutes in vinegar. The bigger and fattier the fish, the longer the time. [Rule of thumb] | Even fish in the same box vary in size and fat. Sort them into large, medium, and small, and change the times. | Chapter 16 |
| White-fleshed fish: 2–5 days; amberjacks: 2–4 days; blue-backed fish and squid: same day to next day | A guide for aging (at 0–4°C, and if possible 0–2°C, for fish that were killed by ikejime and bled, then stored whole or as skin-on saku blocks). White-fleshed fish means red sea bream (madai), olive flounder, Japanese sea bass (suzuki), and similar fish. Amberjacks means Japanese amberjack (buri), greater amberjack (kanpachi), and striped jack (shima-aji). Keep shellfish alive, and use them the same day once opened. [Rule of thumb] | The fattier the fish and the faster it spoils, the shorter the time. If a smell like ammonia appears, the fish has spoiled. The time varies greatly with the species and the individual fish. | Chapter 10 |
| 1–3 days after thawing | A guide for how many days to rest frozen tuna at 0–2°C after thawing. The umami increases. [Rule of thumb] | Right after thawing, tuna often has little umami and a flat taste. | Chapters 10 and 14 |
| 2 hours and 1 hour | A guide for takeout sushi. Keep it at 10°C or below, and hand it over with a note saying "eat within X hours" of making it. If it cannot be kept cold, ask the customer to eat it within 2 hours. If the air temperature is above 32°C, ask them to eat it within 1 hour. [Standard] | "2 hours if it can't be kept cold, 1 hour in midsummer." | Chapters 5 and 26 |
| 1 week to 1 month | How long a person who has had norovirus keeps shedding the virus after the symptoms are gone (usually 1 week, and up to 1 month). [Science] | Recovery is not the end. Do not touch food directly until a stool test confirms that the virus is gone. | Chapters 3 and 26 |
| At least once a month | A guide for stool tests. From October to March, adding a norovirus test is recommended. [Standard] | This applies the thinking behind the rules for large-scale cooking facilities to sushi restaurants. | Chapter 26 |
For Grade 1, you will also learn the times below. They cover curing shime-saba, the changes in fish after death, and finer points of the rules on dates.
| Number | Meaning | Notes | Chapters |
|---|---|---|---|
| Salt: 1–3 hours; vinegar: 30 minutes to 1 hour | A guide for the salt and vinegar times for shime-saba (salt-and-vinegar-cured mackerel). Depending on the restaurant's style, the vinegar time may be extended to several hours. The fat repels the salt, so mackerel takes longer than white-fleshed fish. [Rule of thumb] | Curing does not kill Anisakis. If you serve it raw, it must also be frozen. | Chapter 16 |
| Several hours to several days | The time from the start of rigor mortis until it resolves. It varies with the species, the killing method, and the temperature. Ikejime and low temperatures delay the start of rigor. [Science] | However, some fish, such as red sea bream, go into rigor faster if they are chilled to 0°C right after killing. | Chapter 10 |
| Several days to more than 1 week for fresh tuna | A guide for aging fresh (never frozen) tuna. It varies greatly with the cut and the individual fish. [Rule of thumb] | For thawed tuna, it is 1–3 days after thawing (Table A-3). | Chapters 10 and 14 |
| Every piece | How often to moisten your hands with tezu (vinegared hand water). Change the tezu regularly. The vinegar strength and how often to change it depend on the restaurant's style. [Rule of thumb] | It keeps shari from sticking to your hands and keeps bacteria from getting onto the rice. | Chapters 6 and 24 |
| Within 2 hours of leaving refrigeration | The basis for the 2 hours for takeout. The 10°C or below comes from Japan's Hygiene Management Manual for Large-Scale Cooking Facilities. The 2 hours comes from an MHLW notice. The 1 hour when the air temperature is above 32°C (90°F) comes from general guidance by the U.S. Department of Agriculture (USDA). [Standard] | There is no legal duty to label a date on takeout items made and sold in the restaurant. Even so, stating the time clearly is strongly recommended. | Chapters 5 and 26 |
| What gets a use-by date | A use-by date goes on foods whose quality drops quickly and that may become unsafe after the date (Japan's Food Labeling Standards, Consumer Affairs Agency). Sushi, sashimi, and boxed lunches fall into this group. [Standard] | The old idea of separating use-by dates from best-before dates at "roughly 5 days" was dropped in 2008. The Consumer Affairs Agency does not recommend it either. If the date has passed by even 1 day, throw the food away. | Chapters 5 and 26 |
A.3 Concentration and Quantity
This section covers the strength of salt water, disinfectants, vinegar, and sushi vinegar. It also covers how many bacteria or viruses it takes to cause food poisoning.
| Number | Meaning | Memory tip | Chapters |
|---|---|---|---|
| About 3% (30 g of salt in 1 L of water) | Tate-jio, a salt-water brine. Its strength is close to seawater (about 3.4%). Unlike fresh water, it washes off dirt and blood without letting the flesh take up water. [Rule of thumb] | Remember it as "about the same as seawater." It is not the same concentration as the fish's body fluids (the body fluids of fish are about one-third as concentrated as seawater). | Chapters 13 and 16 |
| About 70% (effective range 60–90%) | The strength of alcohol sanitizer (ethanol). [Science] | Stronger is not always better. A little water is needed to break down the proteins of bacteria. It does not work on wet surfaces. It works poorly against norovirus. | Chapter 4 |
| 200 ppm (0.02%) and 1,000 ppm (0.1%) | Concentrations of sodium hypochlorite. Use 200 ppm for soaking cutting boards and cleaning cloths and for work surfaces. Use 1,000 ppm for cleaning up vomit or feces. [Standard] | "200 for tools, 1,000 for vomit." It rusts metal, so rinse with water afterward. Never mix it with acidic cleaners. | Chapters 3 and 4 |
| pH 4.6 or below, or 4.2 or below (actual vinegared rice is roughly 4.0–4.5) | The standard and the guide for the acidity of vinegared rice. Depending on the region, the standard is either 4.6 or below or 4.2 or below. [Science] | 4.6 is the line for Clostridium botulinum. Bacteria such as Staphylococcus aureus can grow at an even lower pH. So do not rely on acid alone. Also control time and temperature. | Chapters 6 and 8 |
| Acidity of 4.2–4.5% | The acidity of rice vinegar and grain vinegar sold in Japan. Acidity is the weight of acid (in grams) in 100 mL of vinegar. Some vinegar for restaurant use has an acidity of 10–15%. [Science] | When you switch vinegars, check the acidity and recalculate so the amount of acid stays the same. | Chapter 8 |
| 180–220 mL of vinegar for 1 sho of rice (about 1.5 kg) | A starting point for mixing sushi vinegar (awasezu). For Kanto-style white vinegar (180 mL of rice vinegar), use 30–35 g of salt and 30–60 g of sugar. For Edomae (Edo-style) akazu (red vinegar made from sake lees) (180–220 mL), use 35–45 g of salt and no sugar. For Kansai-style oshi-zushi (pressed sushi) (180–200 mL of rice vinegar), use 30–40 g of salt and 80–120 g of sugar. [Rule of thumb] | Start from "about 1 go (180 mL) of vinegar for 1 sho of rice." Kansai uses more sugar, and with akazu, sugar is sometimes left out. It varies greatly with each restaurant's style. | Chapter 8 |
| 7–8 times | How strong the umami is when you taste the umami of kombu (glutamic acid) together with the umami of fish or katsuobushi (inosinic acid). The value is compared with tasting either one alone. [Science] | This is umami synergy. It is the reason for kobujime and for dashi made from both kombu and katsuobushi. | Chapters 13 and 20 |
| 10–100 particles | The number of norovirus particles said to be enough to cause infection. [Science] | An amount too small to see can infect you. Prevent it with handwashing, cooking, and sodium hypochlorite. | Chapter 3 |
| About 80 g per serving, no more than once a week | A guide for how much Pacific bluefin tuna, bigeye tuna, splendid alfonsino (kinmedai), swordfish, and similar fish a pregnant woman should eat. The MHLW gives this as a caution about methylmercury (a form of mercury). [Standard] | "80 g, up to once a week." It does not mean these fish must not be eaten. It is an upper limit on the amount. | Chapters 14 and 26 |
For Grade 1, you will also learn the numbers below. They include legal specifications, the basis for standards, and how many bacteria it takes to cause illness.
| Number | Meaning | Notes | Chapters |
|---|---|---|---|
| Most probable number of 100/g or less | The specification for Vibrio parahaemolyticus in fresh seafood for raw consumption (standards and specifications under Japan's Food Sanitation Act). The most probable number is a statistical estimate of the number of bacteria. [Standard] | Since this specification was set in 2001, food poisoning from Vibrio parahaemolyticus has fallen sharply. | Chapters 3 and 26 |
| A few dozen to about 100 bacteria | The number of enterohemorrhagic E. coli O157 bacteria that causes illness. [Science] | A tiny amount causes illness, so it is important not to transfer it from meat or raw vegetables. | Chapter 3, Appendix B |
| Around pH 4.0 and around pH 4.4 | Examples of the lowest pH at which bacteria can grow. Staphylococcus aureus and pathogenic E. coli can grow down to about pH 4.0. Listeria can grow down to about pH 4.4. [Science] | This is why the pH of vinegared rice alone cannot keep food safe. Vinegar does not kill bacteria. It makes it harder for them to grow. | Chapters 2 and 6 |
| Acidity of 4.2% or more and 4.5% or more | The minimum acidity under the Japanese Agricultural Standard (JAS) for brewed vinegar. Grain vinegar must have an acidity of 4.2% or more. Fruit vinegar must have 4.5% or more. [Standard] | The higher the acidity of the vinegar, the less sushi vinegar you need. | Chapter 8 |
| A ratio close to 1:1 | The ratio of glutamic acid to inosinic acid at which umami synergy is strongest. This was shown in Yamaguchi Shizuko's experiments (1967). It happens because of the way the tongue senses umami. [Science] | It happens not inside the flesh, but on the tongue when you eat. | Chapter 20 |
| Safety factor for use-by dates (less than 1) | To set the date, multiply the number of days found in testing by a factor of less than 1, or subtract days from it. The factor should be as close to 1 as possible (Consumer Affairs Agency, Guidelines for Setting Food Date Labels, revised March 2025). [Standard] | The old version's "0.8 or more as a guide" has been removed. A labeled date has little margin built in from the start. | Chapter 26 |
| Ethanol near 100% | Alcohol that is nearly water-free kills bacteria less well than alcohol at about 70%. Water is needed to break down the proteins of bacteria. Another explanation is that only the surface sets first, so the alcohol does not soak in. [Science] | The effective range is 60–90% (U.S. CDC). | Chapter 4 |
A.4 Working outside Japan
Thermometers and standards documents outside Japan are sometimes written in Fahrenheit (°F). To get Fahrenheit, multiply the Celsius temperature by 1.8 and add 32. The next table converts the main numbers in this book to Fahrenheit. The values are calculated and rounded to whole numbers. For example, −20°C is −4°F, 10°C is 50°F, and 75°C is 167°F.
| Celsius | Fahrenheit | Meaning in this book |
|---|---|---|
| −35°C | −31°F | Freezing against parasites outside Japan (see the "Outside Japan" box in this section) |
| −20°C | −4°F | Freezing against Anisakis |
| −18°C | 0°F | Standard for an ordinary freezer |
| 4°C | 39°F | Vibrio parahaemolyticus does not grow |
| 5°C | 41°F | Working target for topping cases and refrigerators |
| 10°C | 50°F | Upper limit for storing seafood for raw consumption |
| 32°C | 90°F | Air temperature at which takeout should be eaten within 1 hour |
| 60°C | 140°F | Upper end of the temperature danger zone |
| 75°C | 167°F | Heating standard for core temperature |
| 85–90°C | 185–194°F | Heating standard for norovirus |