Effects of monoglyceride content, cooling rate and shear on the rheological properties of olive oil/monoglyceride gel networks

Functionality of conventional fat spreads can be achieved without hydrogenation by the formation of stable network structures upon cooling of mixtures of monoglycerides (MGs) and vegetable oils from the melt. Such mixtures are healthy substitutes for margarine and butter. The effects of MG content, cooling rate and shear on the temperature ramp, mechanical spectra and hardness of olive oil/MG gel networks were investigated. A minimum MG volume fraction was necessary for formation of a gelled network, but this concentration was less than that needed for a space-filling network structure. Onset of gel network or structure formation was indicated by a sudden divergence in value of the elastic modulus G'. The temperature at onset of structure formation, T(o), final G' value and network hardness all increased with increase in MG content. High cooling rates led to low final G' values but harder networks, and vice versa. Maximum gel network development occurred when moderate shear (about 300 s-1) was applied at incipient gelation.