By taking the rheological changes into consideration, it was possible to discriminate among the samples. The rheological properties of the batter and the final properties of the muffin differed significantly depending on whether oil or butter was used. At room temperature, the greatest predominance of the elastic component is to be found in the butter batter. During heating, however, the viscoelasticity of butter batter is found to decrease significantly between 25 and 38 °C, which is associated with fat melting; over the same temperature range, on the other hand, viscoelasticity increased in the oil batter. These differences in the batter's viscoelastic properties may explain the significantly lower height and the less aerated crumb texture of the butter muffins, as a lower degree of viscoelasticity in the batter during heating is supposed to favour air loss during baking.
Using the cellulose ether emulsion either to reduce total fat or to replace the type of fat induced a very significant decrease in the starch gelatinization temperature in comparison with the oil and butter muffins, which was associated with the higher water content in the emulsion composition. The evolution of the batter's viscoelastic properties during heating was very similar to the oil batter, especially for the cellulose type (K250M) with the highest molecular weight. The appearance of both emulsion muffins was quite similar to the oil muffins, and was characterized by the presence of bubbles of different sizes. The biggest difference between the cellulose emulsion muffins and the oil and butter muffins was found in the parameter of texture, with the emulsion muffins being significantly harder.
The emulsion muffins obtained significantly lower sensory acceptability results, although the differences were only of one point, which is good considering that their fat content is 49% lower than the control muffin.