Gelatin from cod skins as affected by chemical treatments

Concentrations of sodium hydroxide, sulfuric and citric acids used in processing gelatin from cod skins affected both yield and quality. The highest yield of gelatin was obtained when low concentrations [0.1-0.2% (w/v)] of sulfuric acid and sodium hydroxide were applied to the skins followed by treatment with 0.7% (w/v) citric acid. The effects on bloom value, viscosity, odor, clarity, color and pH of the gelatin varied. However, the use of 0.7% (w/v) citric acid in different combinations with sodium hydroxide and sulfuric acid usually gave best results. Freeze-dried gelatin had considerably higher bloom value than air-dried gelatin.