If you have ever tried tempering chocolate at home, you will know it is harder than it looks. It turns out that the commercial production process is not much easier! The chocolate we see in the shops undergoes a long multi-step process to achieve that perfect snap and melt in the mouth texture.
It's therefore not surprising that researchers want to know if it is possible to simplify this process. Recent research showed that adding specific phospholipids to chocolate yields a product that is comparable to high quality commercially tempered chocolate by influencing the nano and microstructure of the chocolate. In a recent collaboration, led by the University of Guelph with the Canadian Light Source, Institute Laue-Langevin (ILL), the National Research Institute for Agriculture, Food and the Environment in France and ISIS Neutron and Muon Source, the researchers wanted to know how these phospholipids promote the most desirable form of chocolate without undergoing complex stages of the process such as precise shear and temperature gradients.
Cocoa butter is a major component of chocolate, and to achieve that perfect glossy look and creamy texture, it must crystallize in a specific way, known as a form V polymorph. The cocoa butter polymorph can be influenced by external factors such as temperature, shear, pressure and time (this is what happens when old chocolate begins to turn white). Lipid molecules, which are insoluble in water, also influence the chocolate form. Phospholipids are a class of lipids with an attached phosphate group that make up most of a cell membrane. Previous research from the University of Guelph demonstrated that specific phospholipids can promote the formation of the form V polymorph of cocoa butter crystals in chocolate without the need for complex tempering procedures.
In this recent study, researchers aimed to learn more about the mechanism of this impact by analysing the structure of a phospholipid called 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) in chocolate and cocoa butter. Using a variety of techniques, including small angle neutron scattering on Sans2d and at the ILL, and specific temperature measurements, they gained information on the structure of DMPC in chocolate and confirmed that it meets the criteria for an ideal templating agent in the chocolate making process.
However, they also observed some side effects of DMPC on chocolate. Their synchrotron microcomputed tomography and small angle X-ray scattering measurements showed increased cracking in chocolate at the sub-mm range when tempered solely with DMPC relative to the traditional tempering method. The team concluded that the DMPC phase separates from the cocoa butter phase, creating a large crystalline imperfection, or large microstrains, which then grow into a macroscopic crack.
“Unfortunately, the observed cracks means that DMPC does not perfectly simplify the chocolate tempering process," says Alejandro Marangoni, from the University of Guelph. He adds; “although it is a promising compound for tempering chocolate, more recent work suggests that a similar phospholipid molecule to DMPC can actually temper chocolate without leading to crack formation, as it incorporates better within the cocoa butter crystalline lattice. Another visit to ISIS is warranted!"
Read the full paper at DOI: 10.1021/acs.cgd.3c01130
