The solid fat content (SFC) at different temperatures is an important characteristic of fat phases because it correlates to functionality in product applications. Consequently, this characteristic is also used to specify fat compositions in trade. Of three methods applicable, pulsed nuclear magnetic resonance (pMNR) is predominantly applied. Dilatometry and differential scanning calorimetry (DSC) find much less application. Handling with glass vials and high equipment costs make the search for alternatives to pNMR a useful endeavor. Optical refractometry is evaluated with respect to its potential to determine SFC values. Since refractometry is in the first place not suited for suspensions the positive results found are surprising. Applying temperature modulated optical refractometry (TMOR), isothermal optical refractometry with a superimposed temperature undulation yields repeatable results that are highly comparable to pNMR data. For the system studied (palm oil, coconut oil, partially hydrogenated palm oil), TMOR clearly outperforms DSC when pNMR is considered the method of reference. The key finding that refractive index is suitable to determine properties of suspensions is accompanied by the indications that refractometry has the potential to enable competitive methods within the fat technology.
Practical Applications: The observation that refractometry can deliver quantitative data on fat suspensions enables the development of an array of new analytical methods. Next to SFC values and melting point, studies on the characterization of polymorphism can be envisioned. Since the device is robust and affordable, it could be in product development and quality control.