Ellen Phiddian
Cosmos science journalist
To make chocolate glossy, producers spend a lot of time and energy tempering it. But the addition of a couple of common chemicals found in our food could do away with the tempering process, according to new research in Nature Communications.
Just like salt and ice, the cocoa butter in chocolate crystallises when it hardens: the molecules settle into a rigid, regular pattern as the liquid cocoa butter cools and becomes a solid. But the cocoa butter can form different crystalline structures, and some make better chocolate than others.
One particular crystal structure, called Form V, is most desired by manufacturers because it makes chocolate with the best texture, gloss, snap and melting profile.
“Attaining this form can be challenging or tedious, often demanding very specific tempering processes that include specific cooling rates, target temperatures, and shear,” write the researchers, who are based at the University of Guelph, Canada, in the paper.
The researchers addressed this by testing a class of chemical called a phospholipid in the chocolate-hardening process.
Phospholipids are molecules made of a phosphate connected to long, fatty ‘lipid’ tails. They’re a major component of cell membranes, and have a huge range of other biological uses. Previous research had suggested that phospholipids might help chocolate crystallise because of their amphipathic properties – the phosphate is attracted to water, while the lipid section repels it.
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The researchers found that adding two particular classes of phospholipid – phosphatidylcholine and phosphatidylethanolamine – allowed the cocoa butter to achieve the hallowed Form V crystal structure, and the right physical properties. The two phospholipids both appear in cell membranes, meaning they’re common throughout nature and the human body. In particular, they’re both found in the lecithin in egg yolks and soybeans.
No complex tempering was required, and just 0.1% of the chocolate mixture (by weight) had to be phospholipids.
The researchers say there’s still plenty to learn about chocolate hardening and tempering, but these results may eventually help manufacturers simplify the chocolate-making process.