Tempering Large Tuna Prior to Thawing to Minimize Histamine Formation

The time and temperature controls for processing canned tuna to control histamine formation were first published in the 1998 edition of the Fish & Fishery Products Hazards & Controls Guide from the U.S. Food and Drug Administration (FDA). The controls have been refined since then with validation studies and FDA warning letters. To control histamine formation, the latest precooking validation study allows a 12-h thawing and butchering time limit, a critical limit of a minimum precooking temperature of 60°C at the backbone of the fish, and a 12-h critical limit from the end of precooking until the inhibitory temperatures is reached in the cold spot in the can in the retort. The largest tuna cannot be thawed within the initial 12-h limit prior to precooking. We propose a tempering phase in ambient air of −3 to −4°C to increase the enthalpy of the still frozen tuna so the thawing time in water can be shortened and the critical limits can be met. The potential for growth of bacteria that form histamine and the formation of histamine at temperatures near 0°C was evaluated based on published data. At the proposed ambient tempering temperatures of −3 to −4°C, there is minimal risk of the growth of histamine-forming bacteria and the formation of histamine.