Measuring the reflectivity from molten chocolate sandwiches

Molten chocolate is a dense suspension of solids (mainly sugar) in oil, to which surfactants have been added to improve the flow properties, either during manufacture or in the consumers mouth ('mouth feel'). To obtain the structural details of the interfacial film of surfactants we have turned to neutron reflectivity. By spin-coating a 50-60 nm thick sucrose film onto silicon we have been able to learn that the lecithin component forms into a lamellar-like structure. When we can use an oil with a sufficiently high deuterium content we have also been able to determine the comb polymer (PGPR) distribution. We could do this in a flow cell for the medium chain triglyceride that is a model for the shorter fractions of cocoa butter, but for the majority component we have to use expensive deuterated triolein. Here we will use micron-thick films of surfactant containing deuterated triolein.