Crystallization behavior of monoglyceride oleogels: A comparison between a fully hydrogenated palm oil and a fully hydrogenated rapeseed oil based monoglycerides

Fat polymorphism plays a crucial role in many fat-rich food products (e.g., margarine, chocolate). Due to this, polymorphism of triglycerides is widely investigated. During the previous years, the interest of using monoglyceride oleogels to replace margarine is increasing due to its structure, reduced amount of saturated fatty acids, stability and application potential. However, polymorphism of monoglyceride oleogels is less investigated. This research shows the effect of the composition (C18:0 or C18:0 and C16:0), temperature (25°C–20°C–10°C) and production process (static or lab-scale scraped surface heat exchanger) on the crystallization behavior of monoglyceride oleogels (MO) by using differential scanning calorimetry, (synchrotron) X-ray scattering and polarized light microscopy. Based on time-resolved synchrotron WAXS, it was found that the rapeseed oil based MO (MO-C18) occurred in four different polymorphs. During crystallization, transitions from an inverse lamellar phase (Lα) toward sub-α1 and sub-α2 could be established. Upon storage, a polymorphic transition toward β occurred. For the palm oil based MO (MO-C18/C16), only two polymorphs were found during crystallization (Lα, sub-α), followed by a polymorphic transition to β upon storage. By applying high shear and cooling rates during the production of MO-C18 (dynamic production), the polymorphic transition from sub-α2 to β occurred much faster compared to the static production method. When comparing the dynamically produced MO-C18 and MO-C18/C16, the thickness of 1 lamella, the crystal nanoplatelet and the fat crystals were smaller for MO-C18/C16. This research clearly illustrates that the composition and the applied crystallization conditions have an impact on the properties from nano- to microscale.

Practical Application: This research illustrates the importance of engineering monoglycerides oleogels to obtain food products with an improved nutritional balance. Hereby, the manuscript focuses on the crystallization behavior of monoglyceride oleogels by changing the composition and the crystallization procedure. The acquired insights go beyond the state of the art. It was found that applying high cooling rates and high shear rates by using a lab-scale scraped surface heat exchanger affected the crystallization behavior of monoglyceride oleogels. These are crucial experiments to verify the application potential of monoglyceride oleogels in the food industry. Moreover, different polymorphic transitions occurred for the two types of monoglycerides. This is the starting point to investigate the effect of polymorphism on a final food product in order to improve the nutritional balance in fat-rich food products.