3. Tuna Canning Process

4. Reasons for Precooking
Reduces fat content to improve flavor
and reduce oxidation problems
Lowers water content so “cook out” does
not occur in the can
Prevents curd formation in the can
Facilitates cleaning
Destroys pathogens and parasites

6. “Typical” Precooking Process for
large Albacore Tuna
55 min

7. Optimum Temperature Range for Proteolytic Enzyme Activity
In Fish:
50-60 ºC

9. Follow Textural Degradation during Precooking
Myosin Degradation
Kramer Shear Testing
Sensory Analysis
Piece/Flake Size
Can Yield

10. Whole Muscle
Bundle
Muscle Fiber (Myofiber)
Myofibril
Thick and Thin Filaments

11. Thick Filament
Myosin Molecule
Myosin Heavy Chain (MHC)

12. Proteolytic Myosin Degradation
Myosin decreases with time
No Myosin Degradation

13. Experimental Design: Dorsal Precook Temperatures Tail
Belly
Dorsal
Tail
Precook Temperatures
(50, 55, 60, and 70 ºC)
7 Time Intervals (30 min)
3 Fish Positions

17. Treatments Chosen for Further Testing

18. Kramer Shear Texture Test

24. Who cares?

25. With the help of NC State Food Engineers
Janet Zhang
Brian Farkas
Prashant Mudgal
Assume the fish is a cylinder
Break it into finite elements
Mathematically model the
temperature of any given
location at any given time in
the cooking process.

26.
Time (Min) 80
100
120 60 40 20
Temperature (C)

29. Followed by Cooling at Designated Temperature
Tuna Dorsal Heated to 60 C
Followed by Cooling at Designated Temperature 80
100 60 40
% Myosin Remaining
Time (Min)

30. Followed by Cooling at Designated Temperature
Tuna Dorsal Heated to 70 C
Followed by Cooling at Designated Temperature 80
100 60 40
% Myosin Remaining
Teal = 65 ºC
Orange = 60 ºC
Brown = 55 ºC
Red = 50 ºC
Blue = 45 ºC
Green = 40 ºC
Pink = 35 ºC
Purple = 30 ºC
Time (Min)

31. Conclusions: Albacore tuna cooked at 70 ºC experiences
very little proteolytic degradation, whereas albacore tuna cooked at 50, 55 or 60 ºC have much greater rates of degradation
The dorsal and tail portions of albacore tuna experience the least amount of proteolytic degradation overall

32. Factors correlated with a high amount of proteolytic degradation include:
Soft texture
Smaller Flake size
Grittiness
Residual left in mouth after swallowing
Lower can yield

33. During the cooling process, albacore tuna meat continues to degrade until the temperature reaches about 30 ºC
Mathematical simulations can be used to predict the time/temperature exposure of different locations of the tuna based on retort conditions.
This data can be combined with myosin degradation rates to predict the total textural degradation that occurs at any given location in the fish during the precooking process.