Many home chefs know that tempering chocolate to achieve a perfect finish and a satisfying 'snap' is no easy feat. Small variations in the quality of ingredients, temperature, mixing and timing can all set you up to fail, even when you learn from the best.
The results of a new study by food scientists from the University of Guelph in Canada suggest the addition of two common, naturally occurring fats – in the right proportions – might make chocolate tempering less of a gamble.
Pick up just about any block of milk chocolate from your local store, and you'll find it's more or less made out of the same things – cocoa butter for the form, cocoa mass (or chocolate liquor) for that familiar bitter taste, and additives like sugar or vanilla for sweetness and flavor.
Crafting a solid bar of chocolate is a matter of encouraging the right size and distribution of crystals. In chocolate, crystalline forms of cocoa butter triglycerides (TAGs) are what give the food its characteristic shine, smooth texture, brittleness, and melting point.
Not just any crystalline structure will do, either. Of the six distinct configurations of this class of molecule known to exist, Form V is the one that gives us a perfect temper.
Tempering – transforming the diverse mix of molecules into something that resists your bite while feeling heavenly smooth on your tongue – is a culinary process that has been gradually perfected over time, relying on a fine-tuned sequence of heating, mixing, and cooling.
While researchers have investigated the influence TAG composition has on the success of tempering, little is known about how minor components of cocoa butter might make or break the process, including things like free fatty acids and phospholipids.
Given they make up just a few percent of the chemicals in cocoa butter, differences in their origins and refining might significantly alter the make-up of this key ingredient, either by helping the right crystals generate or interfering with their growth.
Previous research hinted at roles certain minor components had in the formation of the 'seed' crystals. For example, having a lot of free fatty acids seems to poison the crystallization process. Phospholipids, on the other hand, appeared to help them grow.
To nail down the precise proportions and chemical nature of these components, the researchers analyzed the exact make-up of a sample of cocoa butter, varying its composition by adding ingredients or bleaching out existing ones.
They then subjected it to a variety of tests to determine how variations in fat content might affect the growth time and proportion of crystal types, as well as things like melting point, surface reflection, micro-structure, and flex.
While the amount of molecules such as free fatty acids had some effect, the real game-changer was the proportion of phospholipids, specifically saturated phosphatidylcholine and phosphatidylethanolamine. Don't let the tongue-twister names fool you, though: these are garden variety biological molecules found in the membranes of living cells.
Both of these molecules in higher concentrations saw to the formation of Form V crystals, giving the cocoa butter the optimal glass, micro-structure, and mechanical properties.
Adding the right amount of each to chocolate just might take the anxiety out of the tempering process, either by simplifying it or even eliminating it altogether.
This won't necessarily turn all of us into home kitchen dessertiers. But for professionals relying on recipes they can count on, knowing a little more about the chemistry of their chocolate creations just might give them the formula they need.
This research was published in Nature Communications.