AbstractMargarine and butter have a certain yield value which is mainly determined by the fact that the fat crystals do not move in respect of each other but are fixed in a tridimensional network. The permanent network greatly contributes to the total hardness (60舑80%). This contribution can be determined by kneading the sample isothermally and by measuring the hardness before and after kneading. The decrease in hardness is called the 舠structural hardness舡 and the relative decrease the 舠worksoftening.舡 These values give a certain impression of the plasticity of the product at a certain hardness, while the Spreadability Index, which can be calculated from the structural hardness and the worksoftening, is a good measure for spreadability.