articles baseIn later stages of oxidation secondary oxidation productswill customarily be present and thus be indicative of a historyof autoxidation. These products section 5. 4 comprisealdehydes, ketones, short chain fatty acid and others, many ofwhich have very unpleasant odours and flavours, and which incombination yield the fishy and off character associated withoxidized fish lipid. Some of the aldehydic secondary oxidationproducts react with thiobarbituric acid, forming a reddishcoloured product that may be determined spectrophotometrically. Using this precept, a measure of thiobarbituric acid reactivesubstances TBA RS can be got. Several method variationsexist; one method for fish lipids is described by Ke and Woyewoda1979, and for fish by Vyncke 1975.