Proposal on the usage of conversion factors for fatty acids in fish and shellfish

Different approaches for converting fatty acid (FA) data in fish and shellfish expressed as weight percent of total FA or of total lipid content (TL) to per 100 g edible portion fresh weight (EP) are used. FAO/INFOODS studied on a dataset of 668 fish and shellfish firstly the impact on their FA and TL content per 100 g EP using two fatty acid conversion factors, namely the factors published by Weihrauch et al. (XFAW) and Greenfield and Southgate (XFAGS), and secondly the usefulness of Sheppard factors (ShF), which convert fatty acid methyl esters to fatty acids. The data show that XFAW should be used as they are applicable to fish and shellfish and the resulting FA values are a continuous function of the TL content while applying a minimum TL value of 0.55 g/100 g EP even for lower TL values. This study showed that the use of ShF is not necessary for fish and shellfish as they do not influence fatty acid values significantly.