A blast chiller (in Italian, abbattitore) is a piece of equipment that cools or freezes food very quickly. An event caterer has one in its kitchen and, when the venue lacks a suitable kitchen, inside the field kitchen, next to fridges and ovens.
It matters above all for raw fish. European rules require fish to be served raw to be blast-frozen, that is brought to very low temperatures for a set time: the guides on sushi and food safety and on the raw seafood station give the reference values. Blast-frozen does not mean fresh, though: origin and freshness are separate questions.
What to ask the caterer
If the menu includes raw fish, tartare or sushi, ask where the fish is blast-frozen and who does it. For an outdoor event or large numbers, ask whether it brings mobile blast chillers and fridges and how it manages the cold chain up to service.
