Scientists Just Figured Out a Surprisingly Simple Way to Can Tuna With Less Mercury

An estimated 10% of Americans eat canned tuna at least once a week, according to a 2022 Consumer Reports survey. Consumer Reports also found that certain types of canned tuna can have unhealthy levels of mercury, which is particularly harmful for pregnant women. However, researchers from Chalmers University of Technology in Sweden say they’ve developed a new method of packaging that helps reduce mercury levels in each can. 

“Our study shows that there are alternative approaches to addressing mercury contamination in tuna, rather than just limiting consumption. Our goal is to improve food safety and contribute to enhanced human health, as well as to better utilize food that is currently under certain restrictions,” Mehdi Abdollahi, an associate professor at the Department of Life Sciences at Chalmers, shared with SciTechDaily about their new work now published in the journal Global Challenges.

According to the team, they created a new method of packaging that puts the tuna in a water-based solution that contains 1.2% cysteine, an amino acid that draws mercury out of the fish. It tested whole pieces of fresh and canned tuna, minced canned tuna, and steamed tuna, and found the highest value of mercury reduction at 35% when testing canned minced tuna, which it purchased from a standard grocery store. The team added that this was because the minced tuna had greater surface area contact with the solution. “This method has the potential to enable the application of effective active packaging strategies, thereby increasing the safety of fish products for consumption,” the researchers noted in their research. 

They further explained that the method involves treating them in the solution first, then absorbing the mercury onto “powdered, thiolated silica and thiolated polymers,” which could be replicated by using “adsorbent-filled sachets placed within the container.” This would also mean the system is self-contained and does not require any extra steps in the processing of the tuna, and users can simply discard the water solution after opening the package as they typically do.

“The beauty of this type of packaging is that it is active while the product is on the shelf. No additional production steps would be needed if a method like this were used industrially. Przemysław Strachowski, the first author of the study, stated.

In their conclusion, the researchers added, “There is an undeniable need to develop safe and effective tools for reducing mercury levels in fish meat. These tools can complement the industry’s efforts to minimize mercury release into the environment and offer new insights and ideas to enhance the safety of fish consumption.”