Preparation and Physicochemical Attributes of Refined Liver Oil from Deep‐Sea Dogfish

Abstract

The liver oil of deep-sea dogfish, Centrophorus squamosus, was extracted by different physical methods and refined by sequential processes of degumming, neutralization, decolorization, and deodorization. Phosphoric acid effectively eliminated the mucilaginous substances in crude oil to result in triglycerides with permissible contents of peroxides, unesterified fatty acids, volatile compounds, thiobarbituric acid reactive species, and total oxidation values. A synergistic combination of activated charcoal and Fuller's earth could effectively bleach the crude deep-sea dogfish liver oil (CDLO) for greater clarity and acceptable color characteristics. The adverse odors in the crude oil were eliminated by acetic acid treatment and vacuum deodorization. This study shows that the multistep refining process of CDLO significantly enhances the composition of C 20-22 n-3 polyunsaturated fatty acids, with the removal of the components responsible for the undesirable physicochemical characteristics. Keywords Deep-sea dogfish Á Refining Á Refined liver oil Á C 20-22 n-3 polyunsaturated fatty acids Á Degumming Á Decolorization Á Deodorization J Am Oil Chem Soc (2018) 95: 591-605. Abbreviations ANOVA analysis of variance CDLO crude deep-sea dogfish liver oil DHA docosahexaenoic acid EPA eicosapentaenoic acid FAME fatty acid methyl esters FFA unesterified fatty acid IT induction time MUFA monounsaturated fatty acid p-AV para-anisidine value PUFA polyunsaturated fatty acid PV peroxide value SFA saturated fatty acid ST stability time TBARS thiobarbituric acid reactive species TOTOX total oxidation value * Kajal Chakraborty These authors contributed equally to this work. J Am Oil Chem Soc (2018) 95: 591-605Samples and Initial Processing C. squamosus was obtained from the islands situated at the southwest coast of India (9.97 N, 76.28 E) during the monsoon period (July-August), and their livers were collected hygienically after washing with sterile water. The liver 592 J Am Oil Chem Soc J Am Oil Chem Soc (2018) 95: 591-605 J Am Oil Chem Soc J Am Oil Chem Soc (2018) 95: 591-605