Three ways have been undertaken to modify solid fat content of butter oil: (i) interesterification, (ii) adjunction of high-melting glycerides and (iii) joint effect of adjunction of high-melting glycerides and interesterification. A solvent-free interesterification, carried out with 1,3-specific lipase from Mucor miehei, resulted in an increase of the solid fat content (SFC) by shout 114% after 48 h of interesterification. The changes in triglyceride composition induced by this method were followed by quantitative determination of triglycerides of different equivalent carbon number (ECN) and different theoretical carbon number. The major changes in the triglyceride composition occurred mainly in the concentration of three groups of triglycerides with the same ECN (ECN = 38). Adding high-melting glycerides trimyristin (MMM) and tripalmitin (PPP) led to an increase of the SFC measured at 20 degrees C as these proportions increased in the mixture, The joint effect of the addition of MMM or PPP and interesterification was quite significant, mainly for triglycerides that in eluded myristic and palmitic acids. As far as the increase of SFC is concerned, the effect of interesterification decreases when both substrate amounts increase.