CreditVictoria Roberts
Q. How does frozen salmon lose its pinkish color?
A. What you are observing may be temporary color loss because of light scattering by ice crystals.
Researchers in Norway have used microscopy to study the size of ice crystals in frozen salmon at varying temperatures. The study measured the size of the voids in cell tissue left by the ice crystals.
The freezing temperatures thought best to insure quality, between -40 degrees and -75 degrees Fahrenheit, caused a substantial loss in color, the researchers found.
The temperatures left many small ice crystals in the flesh of the fish, which increased the scattering of light and the absorption of visible wavelengths.
Most of the coloration in pinkish fish comes from astaxanthin, a red, fat-soluble carotenoid. Normal levels were still present in properly frozen fish, the scientists found. The color loss is temporary.
