The highly refined heroin had an estimated street value of over 50 million euros (about USD 65 million) and would be enough for 1.3 million individual doses, they said.
The amount of heroin seized in the truck in Essen in the western state of North Rhine-Westphalia was more than the total confiscated last year by German police, around 270 kilograms.
The opiate was hidden in a 23-tonne food shipment of the pickled foodstuffs on a truck that was intercepted on September 22.
The Federal Criminal Police office said its investigation of a Syrian-Iraqi drug ring, suspected of having shipped heroin to Europe for years, had also led to the arrest and extradition to Germany last month of a Dutch national living in Belgium.