Studies in fish liver oils Part I. Seasonal variation in (a) vitamin A content, (b) some of the physical and chemical constants of some fish liver oils

Abstract

With a view to finding out whether there exists any relationship among the colour of the oil and its different physical and chemical constants and vitamin A content, liver oils were obtained from six varieties of fish available in the Bombay coastal waters. These fish yielded a large amount of oil with high vitamin A content. The oil was extracted and analysed month by month and the different physical and chemical constants of the oil along with vitamin A content were investigated. It is found from the table that (1) there is no relation between the colour of the oil and its different constants. (2) An increase in vitamin A content is followed by (a) an increase in the saponification value, in non-saponifiable matter and in acetyl value, (b) no marked change in specific gravity and in acid values and (c) decrease in iodine number. When these results were treated statistically, only the alterations in acid values of Waghbeer and Surmai were found statistically not significant. An attempt to obtain an expression to correlate the vitamin A content in B.U. and the logarithm of the physical and chemical constants of the liver oils studied has been made. The expression obtained being: Vitamin A (in Blue Units per gm. of oil) = K log P + C, where K and C are constants and P is the physical or the chemical constant. Values for K and C are different for the different oils studied.