The role of surfactants in chocolate: structural studies at the sucrose/oil interface

Rheology of molten chocolate plays an important role in its manufacturing and mouth feel. Chocolate is a dense suspension of solids, mainly sucrose, in a continuous fat phase, cocoa butter, stabilised by Lecithin, which predominantly comprises phospholipid, and PGPR, a polymeric surfactant. These two surfactants show a co-operative effect in the rheology of chocolate such that yield stress and viscosity are both reduced for a binary mixture of these two. Understanding the structure formed by the surfactants can give an important insight into their role in the rheology of molten chocolate. Given the compositional complexity of chocolate we model the system into a simpler sucrose in oil suspension with PGPR and Lecithin. I will briefly talk about the model sucrose/oil suspension and its rheology and also develop a model system based on planar (spin-coated) sucrose interface. Further, I will discuss the structural investigation done on the model systems using Tensiometry, QCM-D and Small Angle Neutron Scattering, the challenges of these techniques, their limitations and future structural investigations using Neutron Reflectivity.