Margarines. A rheological study

SEGURA, J.A; HERRERA M.L.; AÑÓN MC

JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY (JAOCS)

SPRINGER

Lugar: Berlin; Año: 1995 vol. 72 p. 375 - 378

0003-021X

Time-dependent flow properties of both commercialand pilot plant-made margarines were characterized understeady shear. Flow curves were fitted to the kinetic expression= zi + a e-kit+ b e -k2t. A first-order kinetic model did not describethe observed destruction process of the margarine structurein an adequate manner. In the proposed model, two structureswith different destruction rates are postulated. Each structurecontributes to a part of the shear stress necessary to deformthe margarine sample. The parameters "r i a and b are temperature-dependent. Decreasing temperatures produce an exponentialincrease of ~i, a linear increase of b and an increase of a upto a point beyond which it remains constant. A physical interpretationof the model is proposed. The role of the aqueousphase was also studied. Greater hardness was detected at higherwater content. Parameter zi increased, at any selected temperature,with increasing aqueous phase content of the sample. Parameter a increased with decreasing temperatures and higher water content. On the other hand, parameter b was not affected by the amount of aqueous phase. This kinetic model could beemployed to perform studies on the influence of different parameters of margarine formulation on its rheologic behavior