Optimisation of conditions for precipitation of collagen from solution using κ-carrageenan. Studies on collagen from the skin of Baltic cod (Gadus morhua)

The effects of the concentration of collagen (0.025-3%), extracted from the skins of Baltic cod (Gadus morhua) and the concentration of κ-carrageenan (0.04-1%), in the presence of NaCl (0-5%), on the yield of precipitated collagen fibrils at 0 °C and at pH 2.2-8 were determined. The yield of precipitated collagen was directly proportional to the ratio, κ-carrageenan to collagen, within the range 0.015-0.4. Collagen dissolved in citric acid could be completely precipitated using κ-carrageenan if the weight ratio of dry reagents was 1:0.4 within a protein concentration of 1.5-0.08%. The maximal yield of precipitated collagen fibrils using κ-carrageenan could be achieved in the pH range 2.2-3. In this range of pH, the presence of NaCl in the system did not affect the efficiency of precipitation of collagen fibrils with κ-carrageenan. The yield of precipitated collagen was lower at 20 °C than at 0 °C.