A research team from Germany discovered that what causes the white film in chocolate is a blooming process. This discovery can help scientists develop a way of preventing chocolate from turning dusty white.
The study was conducted by researchers from the Hamburg University of Technology, Deutsches Elektronen-Synchrotron national research center and was funded by Nestlé. Powerful X-ray was used to discover what this process looks like at a microscopic level.
It seems that what seems to be a white dust cover is fat which has bloomed. Although it is not dangerous for your health, it makes chocolate unappetizing. The cocoa butter from the chocolate can form up to six different shapes of crystal structures. Fat blooms when the specific crystal structure of the chocolate is changed. When this happens fat goes to the surface of the chocolate. For instance a crystal shape which makes chocolate look glossy and smooth can be obtained when chocolate is heated and cooled in a specific manner, a process which is known as tempering. What causes fat to bloom is an improper tempering process.
The lead author of the study Svenja Reinke of the Hamburg University of Technology said that although fat blooming is not harmful for health it leads to the taxing of food industry because customers reject such products or complain about them.
Using DESY’s PETRA III, a very powerful X-ray machine, researchers were able to observe the process of chocolate blooming in real time. The x-ray machine offered an insight at the scale of just a few nanometers. So the scientists observed how liquid fats migrated to the surface of the chocolate where they formed crystals. Reinke remarked:
“This can happen when liquid chocolate cools down in an uncontrolled manner and unstable crystals form. But even at room temperature, a quarter of the lipids contained in chocolate are already in a liquid state.”
The researchers also wanted to find out the nature of various mixes of the chocolate component such as cocoa, milk powder, cocoa butter and sugar. They grounded the chocolate and turned it into a fine powder and observed how powdering accelerates the blooming process.
The speed of the fat migration process was increased when they placed a few drops of sunflower on each sample. When the chocolate combined with the oil the chocolate’s internal structure was altered. After a couple of hours the lipid structures of the chocolate were dissolved by the liquid fat. That’s how the researcher obtained a chocolate with a softer structure. This could help the food industry solve the problem of chocolate blooming.