Ahi tuna, also known as yellowfin tuna, is a popular ingredient in dishes like sushi and poke bowls. While raw fish can pose certain health risks, ahi tuna is generally considered a low risk option when properly handled. Here are some quick answers about the safety of eating raw ahi tuna:
- Raw ahi tuna is safe to eat when it is very fresh and properly stored and handled to prevent bacterial growth.
- Certain people with compromised immune systems are advised to avoid raw fish due to infection risks.
- Purchasing sushi grade ahi from a reputable seller helps minimize risks.
- Proper storage and handling of raw ahi, keeping it refrigerated at all times, reduces bacterial growth.
- Searing or lightly cooking the exterior kills any bacteria present on the surface while leaving the interior raw.
To better understand the nuances around the safety of eating raw ahi tuna, let’s take a deeper look at this popular fish.
About Ahi Tuna
Ahi tuna, sometimes written “ahi,” refers to yellowfin tuna (Thunnus albacares), one of the largest species of tuna. “Ahi” means “yellowfin” in Hawaiian. Ahi tuna is distinguished by its olive green back and silver sides with faint yellow stripes. Its average size ranges from 100 to 200 pounds, though yellowfin tuna can grow up to 400 pounds.
Ahi tuna is an epipelagic fish, meaning it lives in the upper sunlit layer of the open ocean. Yellowfin tuna are found mainly in tropical and subtropical waters. Major commercial fisheries exist off the coasts of Mexico, Hawaii, the U.S. Atlantic and Gulf coasts, Australia, Japan, and the Philippines. The richest sources come from the Western and Central Pacific Ocean.
Nutrition
Ahi tuna is prized as a healthy source of lean protein. A 3-ounce serving of cooked yellowfin tuna contains:
- Calories: 119
- Protein: 24g
- Fat: 1g
It’s an excellent source of omega-3 fatty acids, which have anti-inflammatory effects. Ahi tuna also contains good amounts of vitamins and minerals like niacin, vitamin B6, vitamin B12, magnesium, potassium, selenium and iron.
Due to its nutrition profile, eating ahi tuna provides many health benefits. These include:
- Boosting heart health
- Supporting brain function
- Preventing arthritis and autoimmune diseases
- Aiding weight loss
- Increasing endurance
Is Raw Ahi Tuna Safe to Eat?
Now that we know more about ahi tuna itself, is it safe to eat raw? With any raw fish, there is an inherent risk of exposure to bacteria, parasites, toxins and viruses if certain guidelines are not followed.
According to food safety experts, raw ahi tuna is generally considered low risk when properly handled. Here are some factors that determine the relative safety of consuming raw ahi tuna:
Freshness
Freshness is the number one factor impacting the safety of raw ahi tuna. Like any raw meat, raw fish is susceptible to bacterial growth if left sitting too long. Freshly caught ahi has much lower bacteria levels compared to tuna that is not freshly caught or exported long distances.
It’s ideal to eat raw ahi the same day it was caught. If that’s not possible, the key is keeping it properly refrigerated or flash frozen at ultra-low temperatures throughout handling and storage. High quality sushi restaurants go through tuna quickly for this very reason.
Parasites
Certain ocean fish like salmon and some tuna carry parasitic worms that can infect humans if consumed alive in raw fish. However, yellowfin tuna caught in tropical offshore waters has very low risk of parasites compared to other fish species.
One exception is raw ahi caught locally in Hawaii nearshore, which has seen cases of parasites and thus requires full freezing to kill any worms present. Imported raw ahi, on the other hand, is found to be parasite-free.
Bacteria
No raw animal product is sterile – there are always background bacteria levels present on any meat or fish. Proper food handling and storage is key to prevent these bacteria from multiplying to dangerous levels.
Ahi tuna has relatively low risks of harmful bacteria compared to other fish. Salmonella and Vibrio vulnificus are two foodborne pathogens associated with some raw seafood. But these are rarely found in tuna.
Of greater concern is scombroid poisoning, which occurs when certain fish aren’t kept chilled adequately after catching. The combination of time and warm temperatures allows bacteria on the fish to produce histamine, which causes allergy-like symptoms when ingested by humans. This is prevented by rapid chilling of fresh ahi tuna.
Toxins
Some large marine fish accumulate mercury and other environmental toxins through the food chain. The FDA recommends limiting intake of high mercury fish like swordfish, shark, tilefish and king mackerel.
In comparison, yellowfin tuna is lower on the mercury scale – its smaller size, shorter life span and lower position on the food chain results in less mercury accumulation. The FDA considers light canned tuna one of the best low mercury seafood choices for pregnant women and children.
Viruses
Viruses are not a significant concern with ahi tuna. Foodborne viruses like norovirus and hepatitis A can contaminate certain raw seafood like oysters, but are generally not found in tuna. Proper hygiene when handling any raw fish reduces viral transmission risks.
Populations at Higher Risk
While ahi tuna is considered low risk for most people when fresh and handled properly, some groups have higher vulnerability to foodborne illnesses from raw fish consumption:
- Young children
- Older adults
- Pregnant women
- Those with compromised immune systems
These individuals, and anyone experiencing flu-like symptoms, should avoid raw fish including ahi tuna due to greater susceptibility to infection. Cooked fish is the safer choice.
Buying Quality Ahi for Raw Consumption
To maximize food safety, start with purchasing high quality tuna from reputable sellers. Here’s what to look for when sourcing raw ahi tuna:
Sushi Grade
Seek out ahi labeled as “sushi grade” or “sashimi grade.” This denotes that the tuna meets standards for use raw in Japanese cuisine, including prompt chilling, proper storage and transport temperatures, and testing for parasites.
While the term is not formally regulated, suppliers labeling tuna this way understand the product will be eaten raw and therefore take necessary quality assurance steps.
Color
The ideal color of raw ahi is a deep ruby red. Dull or brownish hues indicate oxidation of the tuna’s pigments and lipids, signaling lower freshness. Bright red flesh with a sheen is the goal. Discoloration may also suggest improper storage temperatures.
Smell
Take a whiff of the tuna – it should have a fresh, clean ocean smell without any fishy or ammonia odors. Off-putting smells mean the tuna is past its prime.
Texture
Use your finger to gently poke the flesh – it should bounce back and feel firm yet yield slightly. Soft or mushy spots demonstrate cell degradation.
Packaging Date
Raw tuna meant for sashimi should show a packaging date, which indicates when it was processed and frozen. More recently packaged tuna ensures greater freshness.
Storage Temperature
The seafood counter should keep sushi grade tuna well iced or in a cold display case, ideally at 40°F or below. Warm temperatures accelerate bacteria growth and enzymatic breakdown of the meat.
Reputable Seller
Purchase ahi from a trusted fishmonger or seafood counter with high turnover of fresh fish. Supermarkets, Japanese markets and sushi restaurants often provide reliably fresh options. Avoid sellers with lackluster storage conditions.
Proper Handling of Raw Ahi Tuna
Once you’ve sourced high-quality fresh or frozen tuna, maintaining optimal storage conditions prevents bacterial growth. Follow these raw ahi tuna handling tips:
Keep Chilled
Whether at the market, during transport or once home, always keep fresh or thawed ahi well iced or refrigerated below 40°F. Use freezer packs and insulated bags for travel if eating away from home.
Avoid Temperature Abuse
Prevent the tuna from warming up then cooling again, which creates ideal bacterial growth conditions. Don’t let it sit out on the counter. Refrigerate promptly.
Practice Proper Hygiene
Always wash hands with soap and water before working with raw seafood. Avoid cross contamination by keeping tuna and its juices away from other foods, and thoroughly cleaning surfaces and utensils after contact.
Use Promptly
Prepare the tuna for sushi, sashimi, poke or other recipes as soon as possible after purchasing. Consume leftover raw ahi within 1-2 days for maximum freshness and safety. The outer inch or two exposed to air will degrade quickly.
Freeze for Long-Term Storage
Raw tuna can be frozen at 0°F for 2-3 months before appreciable quality loss occurs. Use air-tight freezer bags or wrap in plastic to prevent freezer burn. Thaw in the refrigerator just prior to use.
Is Lightly Cooked Ahi Tuna Safer?
While food safety experts consider high quality raw ahi relatively low risk, lightly cooking the exterior offers an extra layer of protection against bacterial presence on the surface while keeping the interior raw. Here are some tips:
Quick Sear
A very brief sear of 30 seconds to 1 minute on each side of the tuna steak or piece will kill surface pathogens without cooking the interior past rare. Use high heat and oil.
Light Pickling
A quick 5-10 minute soak in an acidic mixture like vinegar, citrus juice or wine kills some bacteria. Rinse and pat dry before serving as tartare or in sushi.
Partial Curing
A brief cure of 5-10 minutes in a marinade with some salt, sugar, alcohol and citrus juice reduces bacterial levels through osmosis. Rinse and pat dry before eating raw.
Torching
Running a cooking torch briefly over the exterior kills surface bacteria. This technique is often used in restaurants serving seared rare tuna.
Safety Tips for Consuming Raw Ahi
Here are some final food safety recommendations when eating raw ahi tuna at home or in restaurants:
- Always inspect the tuna first and check for bright coloration, firm texture and fresh smell.
- Avoid raw tuna with discoloration, dull hue, soft texture and fishy odor.
- Only eat raw fish at reputable establishments with high turnover and cold holding conditions.
- Inspect the restaurant’s cold holding area, tables, plates and utensils for cleanliness.
- At home, always wash work surfaces, knives, dishes and hands thoroughly before and after handling.
- Refrigerate leftover raw ahi within 2 hours and consume within 1-2 days.
- If in doubt, cook tuna thoroughly to 145°F minimum internal temperature.
- Immuno-compromised individuals should avoid raw fish.
The Bottom Line
Fresh, properly handled ahi tuna is generally considered low risk for consumption raw or rare. For added safety, lightly sear the exterior while keeping the center rare, and follow strict storage and hygiene practices. Certain individuals are better off avoiding raw fish. Use common sense when sourcing quality tuna and handling it properly to make for an enjoyable eating experience.
