Debate: Fresh Tuna vs. Frozen Carbon Monoxide Treated Tuna


From day one we made an explicit decision to only use fresh fish and for good reason - quality and safety. Frankly, we started Coast because we couldn’t find poke that reminded us of what we’ve had in Hawaii. We take great pride in the fact that we use the cleanest sashimi grade fish. It’s delivered to us daily, which allows us to inspect and identify exactly how fresh our fish shipments are by checking the color, clarity, scent, texture and taste.

On June 1st, the FDA posted information about their investigation into the findings of Hepatitis A linked to frozen carbon monoxide (CO) treated tuna. To summarize, in May there were two instances of frozen CO treated fish recalls. On May 18th, Hilo Fish Company recalled product from CA, TX and OK. Luckily, there haven’t been any reports of illness. COAST has not been affected by this recall. We do not use frozen CO treated tuna in any of our stores.

To be clear, Hepatitis A doesn’t naturally occur in tuna. This investigation is happening because of human error and it underscores the importance of sourcing from trustworthy suppliers who handle and process their seafood with strict attention to food safety. But this issue brings to light the importance of a larger issue: fresh vs. CO treated frozen fish. It’s similar to the organic vs. conventional debate, the difference being that consumer awareness of this process is non-existent. So let’s dive in...

The Carbon Monoxide Controversy

A large majority of the frozen tuna cubes imported into the US have been treated with carbon monoxide (CO) which is a color preservative. This process, also known as “gassing”, can turn “chocolate fish” (fish that has naturally turned brown as it oxidizes) back to a dark pink color, to make it look fresh. Once gassed, the fish retains this color for a very long time, even after defrosting. However, gassing fish does not preserve the flavors, textures nor the integrity of the fish.

Frozen gassed cubed tuna is being explicitly produced for use in poke shops. No butchering = reduced labor costs - just defrost and go. It comes as no surprise that so many poke places are using this product. Better margins, yes. But at what cost?

The FDA generally regards this process as safe. Interestingly a number of countries (Australia, Canada, Japan, Singapore and countries in the EU) have banned gassed products. New York Times reporter Julia Moskin, dove into this issue with a balanced story Tuna’s Red Glare, It Could Be Carbon Monoxide. Even though her story was published years ago, the theme of supply and demand for visually appealing products is more relevant than ever.

Critics worry that this process can easily mask spoiled fish, by removing visual queues. They argue that without the right disclosures, altering the appearance of the fish so that it looks fresh is deceiving the customer. Advocates argue that gassing and freezing the fish is a safer for transportation and distribution, can be used when thawed - thus reducing waste, all while retaining a fresh appearance.

For our guests, the bottom line is this: we are committed to the highest quality. Sure our poke may be slightly more expensive than other poke bowl concepts, but the quality of fish in your bowl parallels that of three orders from a discriminating sushi bar. Easily $15-$20 in the Bay Area. We can taste the difference and we know that many of our guests can too. More important, all of our guests can rest assured that we’re vetting our sources carefully and we’d never compromise on the quality of our fish.