filled equally well by products from other 

 fishes or synthetic processes, there would be 

 no assurance that the dogfish products would 

 be used; rather, some other generally avail- 

 able product might be used and the dogfish 

 product might be ignored. 



Characteristics and Properties of 

 Dogfish Oils 



Oils occur in the dogfish in both body tissues 

 and liver. The chemical nature of the oils 

 from these two sources differs. Those in the 

 tissues are chemically different from those in 

 the liver. The possibility exists that oils from 

 each source might have entirely different 

 applications. 



Dogfish body oils : — Dogfish body oils are 

 similar to most other fish oils (table 3). They 

 consist predominantly of glycerides of fatty 

 acids, which may be looked upon as combina- 

 tions of glycerin with fatty acids that, in 

 fish oils, have long-chain carbon molecules — 

 usually containing 16, 18, 20, or 22 carbon 

 atoms. Further, fish oil fatty acids are 

 often highly unsaturated, i.e., double bonds 

 exist between many of the carbons in the 

 molecules. The remaining small pro- 

 portion of the body oils consists of "un- 

 saponifiables" — substances that are not 

 affected by alkalies and that are in- 

 soluble in water. The unsaponifiable mate- 

 rial in fish oils (including dogfish body 

 oils) usually constitutes less than 1 percent 

 of the total. 



It is the variation in the proportions of 

 fatty acids of different chain lengths and in 

 degrees of saturation that makes each specific 

 fish oil a little different from all others. Not 

 much is known, specif ically, about dogfish body 

 oils. Their compositions indicate that they 

 are probably fairly similar to other fish oils 

 in chemical properties. But, if a technological 

 project on dogfish should be started, an im- 

 portant project phase should be devoted to 

 determining the exact characteristics of the 

 body oils. Relatively simple research would 

 suffice to show whether or not dogfish oils 

 behave chemically as most other fish oils 

 do. 



Dogfish liver oils; — The oils taken from 

 dogfish livers seem to hold more promise in 

 the development of unique uses for dogfish 

 products than do body oils. Unsaponifiables 

 are present in the liver oil in far greater pro- 

 portion (about 15 percent compared with about 

 1 percent in body oils) than they are in body oils. 

 The definite possibility exists that something 

 is present in the unsaponifiables that is unique 

 and that has a high potential for some indus- 

 trial application. Just what this something 

 might be cannot be surmised at present. 



Glyceryl ethers occur in fish oils in the 

 form of an alkoxydiglyceride. This type of 

 compound differs from the ordinary fish oil 

 (triglyceride) by having one of the fatty acid 

 esters replaced by an ether- linked fatty alcohol. 

 These ethers, representing about one-half of 

 the unsaponifiables, represent one promising 

 point of attack in the search for dogfish prod- 

 ucts with unique industrial uses. One firm in 

 Vancouver, British Columbia, is already ex- 

 tracting and marketing the glyceryl ethers from 

 dogfish liver oil. Moreover, a search of patents 

 indicates that the glyceryl ethers are valuable 

 intermediates of compounds that include in- 

 gredients of textile treatment media, perfume 

 fixatives, dye additives, emulsifiers, insecti- 

 cides, disinfectants, and foaming agents. 



Use of glyceryl ethers as vehicles for food 

 antioxidants is another promising lead. Some 

 work has been done toward development of this 

 use at the Hormel Institute of the University 

 of Minnesota, but the work was discontinued 

 before completion. The dogfish glyceryl ethers 

 are particularly promising in this regard be- 

 cause (1) they can be used to provide sub- 

 stances that mix well with both oil and aqueous 

 phases of foodstuffs and (2) they are natural 

 substances that have been accepted in medi- 

 cines, so that the U.S. Food and Drug Adminis- 

 tration would be abletopasson their suitability 

 in much shorter time than would be the case 

 with most synthetic substances. 



In addition to the oil, dogfish livers also 

 contain vitamin A. Extraction of vitamin A 

 from dogfish livers is, at best, a marginally 

 economic operation at the present time. If, 

 however, several other substances could be 

 used for products of high value, such extrac- 

 tion might become profitable. 



14 



