Relationship between muscle pH and flesh color of Atlantic halibut

After 7 d of ice storage, the muscle pH and flesh color (CIE L*, a*, b*) was measured in 118 Atlantic halibut (Hippoglossus hippoglossus) slaughtered at different times of the year. All fish originated from the same stock and the fish were farmed under natural and continuous light and slaughtered fed or starved, representing a wide distribution of fish undergoing different stages of growth, maturation, and sizes (1.5 to 5.9 kg). Results show a considerable variation of end pH ranging from 5.7 to 6.8. The color correlated significantly with muscle pH with R = -0.63, 0.61, and -0.57 for L*, a*, and b*, respectively, while fillet weight and sampling position on the fillet had less influence on color. We conclude that the end pH of the muscle is an important factor for the visual quality of fish, and in particular for Atlantic halibut. Therefore, measures should be taken to avoid high glycogen levels at death, as this will have a large impact on the muscle pH, with negative consequences for flesh color.