For the process of purifying collagen from trout skin, supercritical carbon dioxide (SC-CO₂) extraction was investigated as a method for removing lipids. Selected conditions such as extraction pressure, time of exposure and sample moisture content were evaluated in an effort to determine their significance regarding lipid removal. Freeze-drying and increasing extraction pressure and time were found to be effective in improving lipid removal.

The effect of ethanol as an entrainer was also evaluated and found to significantly enhance the lipid yield under all experimental conditions. Collagen extracted from trout skin defatted with SC-CO₂ was not damaged by this treatment.