FISH-LIVER OILS 507 



in Mexico, Central and South America, Africa, Europe, Japan, and the Caribbean 

 Islands. Many of the livers produced in these areas are shipped to the United 

 States for final processing. 



The purchasers of salted livers have set out a series of instructions for use by 

 those who produce them in more or less remote areas. To preserve the livers 

 adequately they must be thoroughly cleaned, with removal of the gall bladder, and 

 promptly packed in a tight container. They are required to be cut into pieces not 

 more than 3 inches thick and evenly salted with 10 per cent salt by weight. The 

 containers should have tight covers and be packed as full of livers as possible so 

 that there will be a minimum of enclosed air. If proper care is used in handling 

 livers in this manner, they may be stored at air temperature over periods of several 

 months without serious loss of vitamin A potency. 



According to some reports, it has been found that salted livers require a larger 

 amount of alkali for digestion. Whereas fresh livers require 2 to 3 per cent alkali 

 for digestion, salted ones require 8 per cent. This increase in alkali leads to exces- 

 sive formation of soap, which in turn is diflBcult to remove from the oil. In the 

 pepsin digestion process similar difficulty is experienced, but it is not so pro- 

 nounced. 



Formalin as a Liver Preservative. Formalin has been used as a preservative for 

 all types of livers. If the percentage of this chemical is in excess of 0.25 per cent 

 by weight, the livers become hardened to such an extent that it is impossible 

 to extract the vitamin A. Formalin causes the formation of small hard lumps which 

 are resistant to all known methods of extraction. In the case of shark livers this 

 applies to the patented compound "Aquacide," and its use on these livers is not 

 recommended. In the case of shark and other high-potency livers a preservative 

 in the powdered form is suggested. 



Another preservative which can be used for ground shark livers is composed of 

 9 parts sodium carbonate, 1 part sodium nitrate, and 10 parts water by volume. 

 This solution is used in the proportion of 5 per cent by weight of the ground 

 livers. Since the sodium carbonate has a mild alkaline reaction, it does not increase 

 the difficulties of extraction when the alkali process is used. 



Factors Controlling Quality of Vitamin A Liver Oil 



Some vitamin A liver oils are classed as medicinal products. The quality is 

 regulated by strict government inspection and tests. Only that oil meeting the 

 requirements is permitted to be sold for medicinal uses. These regulations apply 

 not only to the oil used in human nutrition, but also to that going into the markets 

 for use in animal diets. The requirements of the U. S. Pharmacopoeia XIII are that 

 cod and halibut livers used in the preparation of medicinal grades of oil be fresh 

 or suitably preserved. The liver oil industries of Canada, Newfoundland, Iceland, 

 and Norway have very rigid standards and are under strict governmental super- 

 vision and inspection. 



Oils which contain more than 0.3 per cent moisture and 0.03 per cent sediment, 

 other than stearin or waxes, require further refining. Moisture in the oil always 

 carries some protein which will decompose and impart a putrid odor. The moisture 

 and protein mixture is also an excellent medium for the growth of bacteria, which 

 will extend into the oil and cause serious deterioration. 



Light and atmosphere are to be avoided, as far as possible, since both hasten 



