An Easier Way to Temper Chocolate

(Inside Science) – For a chocolate lover, one of the great joys in life is breaking off a bite-sized piece from a good-quality bar and letting it slowly melt in your mouth. The roughly 600 aroma compounds that make up the intoxicating scent of cocoa -- some of which smell individually like potato chips, cooked meat and other unexpected foods -- are released at once, like a symphony on your palate.

Key to creating that experience is tempering the chocolate, a complex process involving precise heating and cooling to attain a particular texture. Manufacturers typically use bulky, expensive machines that run melted chocolate through a series of stages to get a tempered batch that can then be molded into bars.

“What tempering achieves is the right gloss, hardness and snap in the chocolate,” said Alejandro Marangoni, a food scientist at the University of Guelph in Canada. “It also makes sure the chocolate has the correct melting point, so that it melts in the temperature of your mouth but not in your hand.”

While Marangoni and his colleagues were investigating the chemical components of cocoa butter, which makes up almost 30% of chocolate, they discovered a much simpler way to temper chocolate. By adding more of a fatlike molecule naturally found in cocoa butter to melted chocolate, they quickly and easily produced a batch with the ideal hardness, gloss and texture -- indistinguishable from chocolate tempered the old-fashioned way, the researchers say. The study was published Tuesday in the journal Nature Communications.

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The texture of a finished piece of chocolate largely depends on how the molecules that make up cocoa butter have arranged themselves. This crystalline structure can take on six different forms, but only one -- known as Form V -- offers the texture, gloss, snap and melting profile that chocolate aficionados know and love. Traditional tempering leads to the creation of Form V crystals, but the technique is far from foolproof. Performed even slightly incorrectly, it can produce one of the other crystalline structures, leading to a waxy or crumbly product.

Marangoni and his colleagues took an unconventional approach to tempering by adding minor components of cocoa butter to the chocolate mixture to see how they changed the overall microstructure. In particular, they found that adding a tiny amount of a fatlike molecule called a phospholipid to melted Lindt chocolate and then rapidly cooling it to 20 degrees Celsius (68 F) promoted Form V crystal growth. The chosen phospholipid was extracted from cocoa butter and originates from cell membranes of the cocoa plant itself.

The researchers ran several experiments comparing their chocolate to the store-bought variety and say the two show equivalent crystal structure and mechanical strength. “And there was no difference in -- we food scientists have this funky name for taste -- the organoleptic properties,” said Marangoni.

The new technique “will allow the small- to medium-sized manufacturer to scale up the tempering, which would mean reducing costs and using less energy,” Marangoni said. “All the companies are trying to get better in terms of carbon footprint, and [our method of tempering] will consume a lot less energy.”