Mussels offer a simple, flavorful way to enjoy seafood at home, often requiring only a quick steam or sauté. The success of any mussel dish depends entirely on the quality of the shellfish selected at the market. Unlike fin fish, mussels must be purchased and cooked while they are still alive to ensure both the best flavor and food safety. A dead mussel spoils rapidly, releasing toxins that can cause illness.
What to Look for at the Seafood Counter
The initial inspection begins with the environment where the mussels are displayed. They should be kept on a bed of fresh, melting ice, which maintains the necessary cold temperature to keep them dormant and alive. Look for a tag or label indicating the harvest location and the date, as traceability is a strong indicator of a reputable supplier.
Visually inspect the shells for any signs of damage or dehydration. Healthy mussels have shells that appear wet and shiny. Shell color can vary from deep blue to black or even brown, which depends on the species and environment. Avoid any mussels with cracks or breaks in the shell, as this damage compromises the integrity of the animal inside and likely means it is dead.
A quick sensory check of the air around the display is also informative. Fresh mussels should smell clean, like the ocean, with a distinct briny aroma. Any strong, overtly fishy, or foul odor is a clear sign of spoilage, and the batch should be avoided. Finally, pick up a handful to gauge their density. A good mussel should feel heavy for its size, a sign that it is full of meat and the natural water it holds, rather than being dried out or empty.
The Essential Liveness Check
The single most important step in selecting mussels is confirming their liveness, which is determined by the state of their shells. Mussels that are actively alive will keep their shells tightly closed, protecting the soft tissue inside from the outside environment. This closed state is the ideal condition for purchase.
It is common to find some mussels with shells that are slightly ajar, which does not automatically mean they are dead. This is where the simple “tap test” becomes necessary to confirm viability. Gently tap the shell or apply a light squeeze to the slightly open mussel.
A healthy, living mussel will react to this stimulus by contracting its adductor muscle and closing its shell completely within a minute or two. This muscle is responsible for keeping the shell sealed when the mussel is out of the water, confirming the animal is alive. Any mussel that remains open, or has a gaping shell that does not respond to the tap test, must be immediately discarded. A gaping shell indicates the adductor muscle has relaxed completely, meaning the mussel is dead and has begun to spoil.
Keeping Mussels Fresh Until Cooking
Proper handling after purchase is necessary to maintain the mussel’s liveness until cooking. Mussels are living organisms that require oxygen, so they must never be sealed in an airtight plastic bag or submerged in fresh water. Sealing them will cause the shellfish to suffocate and die quickly.
For transport and storage, use an open container, such as the mesh bag they were purchased in, or a bowl. Place the container in the coldest part of the refrigerator, typically the bottom shelf. To prevent dehydration while allowing them to breathe, cover the mussels loosely with a damp cloth or a moist paper towel. This environment keeps them cool and moist. Mussels are highly perishable, so plan to cook them the day of purchase for the best quality, or within one to two days.
Pre-Cooking Prep and Final Discard
Before cooking, mussels require a final preparation to ensure a clean eating experience. Scrub the shells under cold running water using a stiff brush to remove any external grit or sand. The next step is “debearding,” which involves removing the tough, fibrous byssal threads the mussel uses to anchor itself. To remove them, firmly grasp the beard and pull it sharply toward the hinge of the shell. Discard any mussels that have opened during storage or that appear damaged. After cooking, any mussel that remains tightly closed must also be discarded, as this indicates it was likely dead beforehand.