The role of partially hydrolysed glyceride compounds (monoglycerides, MG; diglycerides, DG) on the protective effect of a natural antioxidant (citric acid) in a commercial marine oil (cod liver oil) was investigated during the heat treatment. Lipid oxidation development was analysed by fluorescence and browning detections. An inhibitory effect of the antioxidant action was observed at 50ºC for all the concentrations tested (MG: 0.1-5.0%; DG: 0.1-2.0%) that was faster as the hydrolysed lipid was employed in a higher proportion; no inhibitory action of MG and DG was observed at the same concentrations when lower temperatures (15ºC and 30ºC) were tested. MG including four different branched fatty acids (lauric, myristic, palmitic and stearic) were compared; the inhibitory effect on the citric acid action was found faster and higher when the fatty acid chain was longer.Running Title: Partially hydrolysed lipids and inhibited oxidation