Main content area

The Role of Mixing Temperature on Microstructure and Rheological Properties of Butter Blends

Buldo, Patrizia, Wiking, Lars
journal of the American Oil Chemists' Society 2012 v.89 no.5 pp. 787-795
butter, lipid content, microstructure, temperature, confocal laser scanning microscopy, mixing, rapeseed oil, firmness, rheological properties, melting point, milk fat, melting, heat treatment, water distribution
The present study demonstrated that the rheological properties of butter blends can be modified by the applied mixing temperature. Blends were prepared by mixing 10 or 25% of rapeseed oil (RO) with butter, at three different temperatures (13, 18 and 23 °C). Afterwards the blends were stored at 5 °C until analyzed. Microstructure, rheological properties, melting behavior and solid fat content (SFC) of the blends were examined. The viscoelastic properties of the blends were measured by rheological oscillation analysis. Mixing at 23 °C always resulted in the softest products, hence the lowest firmness, independently of the content of rapeseed oil. By increasing the percentage of RO and the mixing temperature, a decrease in melting point (Mp) and in SFC was observed in the blends. The microstructure of the blends was analyzed with confocal laser scanning microscopy (CLSM), which explains the effect on the rheological behavior. The microstructure analysis showed that a high content of RO and high processing temperatures produce a less dense crystal network and a change in protein/water distribution. Furthermore, this study shows that the addition of RO to butter and the high mixing temperature solubilize some of the milk fat triacylglycerides (TAG), which are not able to re-crystallize fully. A high mixing temperature is shown to inhibit the ability to rebuild the rigidity of the crystal network in butter blends.