The Alleged Toxicity of Free Fatty Acid and Nitrogen in Cod Liver Oil

COD liver oils, sold for feeding purposes, vary in color from lemon yellow to dark red, and, in a few instances, nearly black. The oils rendered by the direct steam process tend to be lighter in color than those rendered by the indirect steam method, whereas those made by the “sun rotting” process are dark red or black in color. However, there is a wide variation in the color of oils rendered by the direct steam process (Branion, 1928). The longer the interval between the time of removal of the livers from the fish and the time of extraction of the oil, the deeper is the pigmentation of the oil. As a general rule, but not always, the deeper the color of the oil the higher is its content of free fatty acid. It should be emphasized that there is, however, no apparent direct relationship between the color of an . . .