Listeria Risks in Seafood

Listeria monocytogenes is a type of bacteria that can cause serious food poisoning. It is especially concerning in foods that are ready to eat and stored in the fridge. Researchers in Japan looked at how common this bacteria is in certain types of seafood products. They tested 500 samples of cod roe, seasoned cod roe, salmon roe, smoked salmon, and minced tuna.

The results showed that minced tuna had the highest amount of L. monocytogenes, with 23% of samples testing positive. Salmon roe had 9% positive samples, while seasoned cod roe, cod roe, and smoked salmon had 4%, 2%, and 2% positive samples respectively. Luckily, the levels of contamination were generally low.

But here's the thing: most of these seafood products can support the growth of L. monocytogenes during storage. This is because of their pH and water activity levels. The researchers also looked at the genetic makeup of 40 isolates of L. monocytogenes. They found that these bacteria are quite diverse, with 14 different groups and 27 subtypes.

Some of these bacteria had genes that help them survive stress, tolerate disinfectants, and invade cells. When tested, some isolates were able to invade epithelial cells more easily than others. This varied depending on the type of bacteria and some specific genetic traits.

The study suggests that the risk of L. monocytogenes in seafood products in Japan varies widely. This means that some products may be safer than others. More research is needed to understand the risks and how to prevent food poisoning.