SciAntics

The Sweet Smell of Chocolate: Sweat, Cabbage and Beef

The new discipline of “sensomics” is helping find new ways to make chocolate even tastier.

Chocolate may be the most sought-after treat among trick-or-treaters on Halloween, with little hands grasping for all of the milk- and dark-chocolate morsels they can collect, but the details of its taste and aroma profiles have long eluded scientists.

And new science is revealing why coca’s  potent sensual properties have been so difficult to pin down. A recent analysis found that the individual aroma molecules in roasted cacao beans (the primary ingredient of chocolate) can smell of everything from cooked cabbage to human sweat to raw beef fat. Together, more than 600 of these flavor compounds melt together in just the right combination to yield the taste and scent of what we all call chocolate 

Most of the molecules that comprise a food’s aroma are volatile, which means they transform into gases easily at room temperature. These volatile compounds are inhaled along with the air we breathe, bringing them into contact with the 900-plus odorant receptors in the upper half of the nostril.

As a volatile aroma compound latches onto an odorant receptor, it triggers the firing of the olfactory neuron. Complex aromas form when multiple volatile compounds trigger their respective olfactory neurons at the same time. The brain identifies flavor by measuring how frequently the different neurons fire.

Processed foods such as chocolate, beer and tea contain thousands of aroma compounds. This multiplicity of molecules creates a mosaic of odor in the brain as each individual molecule contributes a hint of scent to the final flavor. Just as our brains can often assemble a whole picture from seeing just a sketch of an image, Schieberle and colleagues found that humans can recognize chocolate aroma using only 25 of its 600-plus volatile compounds. Of these, many are also found in much less appetizing items, including cooked cabbage, raw beef fat and human sweat, which are in turn also composed of many different volatile compounds.

Schieberle calls the study of individual aroma and flavor molecules “sensomics,” which sifts through the countless potential aroma compounds for those molecules of particular importance to human taste and smell. Schieberle’s work has identified which aroma compounds from roasted cacao beans could bind to odor receptors in humans. None of them, it turned out, smell anything at all like the sweet, rich scent we identify as chocolate.

What we think of as “chocolate” smell is due in large part to the way in which the food is made—a process that includes both fermentation and roasting. Foods that are processed by fermentation, roasting or grilling such as wine, coffee and steak, respectively, generally contain the most aroma molecules. It is this process’s conversion of otherwise odorless compounds into volatile aroma-bearing ones that helps explain this type of food’s popularity. Natural, raw foods like fruits and vegetables also have an appealing aroma and taste, although their flavor profile is much simpler and usually dominated by one or two major molecules.

Better understanding chocolate’s alluring aroma can also help with tasting technique. Let the chocolate dissolve on your tongue, Schieberle says, so that you can taste the full array of flavor compounds. As the chocolate melts in your mouth and you exhale, some of the volatile molecules will once again pass over your odor receptors, letting you get another whiff before the chocolate melts away.

Read more (Via Scientific American)

Image hosted by Flickr (Via Johnathan Reyes)