Sushi-grade is an unregulated term used to identify fish deemed safe for raw consumption. The term is used by vendors to indicate the freshest and highest-quality product, which is treated with extra care to limit the risk of food-borne disease. In many cases, this means that fish has been flash-frozen before selling it.
There is no official standard for sushi grade fish and the term is not a guarantee of safety.
The US FDA does have regulations for the proper handling of fish meant for raw consumption, which are not required to be followed to claim "sushi grade". These guidelines, called the "Parasite Destruction Guarantee", are:
- Freezing and storing at an ambient temperature of -4°F (-20°C) or below for 7 days (total time)
- Freezing at an ambient temperature of -31°F (-35°C) or below until solid and storing at an ambient temperature of -4°F (-20°C) or below for 24 hours
- Freezing at an ambient temperature of -31°F (-35°C) or below until solid and storing at an ambient temperature of -31°F (-35°C) or below for 15 hours
The low temperatures kill the parasites that may live in the fish when it's caught. However, this process needs to begin as soon as the fish is on the boat. They must be caught fast, bled and gutted upon capture, and frozen in a flash freezer within 8 hours of leaving the water.