FISH LIVER OIL

Dominion, Volume 37, Issue 284, 28 August 1944, Page 4

FISH LIVER OIL

Production At Island Bay Factory

SHARK, LING AND GROPER

Five thousand: gallons of fish-liver oil from sharks, groper, and ling were prepared at the Karitane Products Society’s factory at Island By, Wellington, during its first year of operation, from March, 1943, to March, 1944. A review of the work is given by M. M. Cunningham and C. Scott, of the society’s laboratory, in an article published in the “New Zealand Journal- of Science and Technology-” , ' . •'At the commencement of the work technical difficulties of various kinds were encountered,” they state, “and inferior grades of oil were sometimes obtained, but it is now possible to say with confidence that oils of excellent quality and high ■ vitamin value can >be produced on a large scale in New Zealand from the livers of locally-caught fish.”

They point out that shark liver oil is a very general term, since the species of shark known in New Zealand waters are numerous, and the livers supplied to the factory by fishermen are entirely unsorted. It is quite obvious that oils from the different species must have very different characteristics. As regards vitamin A content, values of different batches of oil vary from 2000 to 55,000 international units a gram. A few vitamin D estimations have been made, and the content of this vitamin found to be low, usually less than 25 international units a gram. So far the only sorting of livers done at the factory has been a rough division into two types, a small dark coloured 1 type and a larger light coloured type. It is found that oil from the first is much higher in vitamin A content than that from the second. At present it is found most convenient to mix successive batches in 500 gallon lots, so obtaining an oil of uniform yellow colour and vitamin A potency of at least 20,000 international units a gram. The oil from the liver of the New Zealand ling is.easily produced, clear, attractive and unobjectionable. _ It is easily tolerated and contains such amounts of vitamins A and D that only small quantities are required to ensure adequate intake of both vitamins. The vitamin A content of ling liver oils produced at Island Bay has been found to varv from 8000 to 15,000 international units a gram, while the vitamin D content remains fairly constant at approximately 500 international units a gram. Tests show that high concentrations may be fed with safety to rats. Though no controlled evidence. is'yet available on the toleration of ling liver oil by humans, many samples of the oil, distributed to members and friends of th/ staff have been taken, in many cases over long periods, with estimated 1 benefit to health aud without any complaint of intolerGroper oil. as now produced, is light in colour, bland in taste, and free from objectionable smell. The vitamin A content of the oil obtained during the vear has varied from a maximum of 88,600 international units a gram to a minimum of 35,000 international units a gram in some of the inferior oils.. It seems probable that the.re is considerable seasonal variation in vitamin A potency, and it is hoped in time to collect data on this point. Over the year the average vitamin A potency has been 60,000 international units a gram. A few vitamin D estimations have been made, and values obtained range from 2400 to 4000 international units a grain. It seems likely that groper liver oil will provide an excellent natural concentrate of vitamins A and D as well as a very good raw material for further concentration of these vitamins. The oil is well tolerated by rats, and would probably be equally well tolerated in human nutnThe processing ut the livers generally involved mincing and digestion with steam, but in the case of the groper livers it was necessary to employ an acid pepsin digestion followed Iby neutralization. The digested materials were centrifuged to give clear oils.