Pop Quiz Time
What do you get when you combine hydrolyzed collagen polymers containing glycine, proline, and hydroxyproline residues,1,3-dipalmitoyl-2-oleoylglycerol, 1-palmitoyl-2-oleoyl-3-stearoylglycerol, and 1,3-distearoyl-2-oleoylglycerol, theobromine, caffeine, phenylethylamine, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, among other “ingredients” along with “processing” that adds among other things, alkypyrazines, Strecker aldehydes, melanoidins, furan and pyran derivatives?
The true origin of this chemical mixture remains shrouded in mystery. One self-referential source dates the first recipe to a 1927 handbook, Tramping and Trailing with the Girl Scouts. Those ingredients, in the form we find them – the marshmallow, milk chocolate, and graham cracker – have their culinary birth as a mixture celebrated today on National S’mores Day.
The s’more, a contraction of the original recipe's name Some More, not only features three simple ingredients but is a classic lesson in the controlled transfer of heat across distinct material structures.
You say marshmallow, I say aerated hydrocolloid foam.
The marshmallow is dispersed microscopic gas bubbles trapped within a semi-solid sugar-protein matrix; replace the protein that comes from gelatin with protein from flour, and you would have bread. The warm sugar-gelatin mixture is whipped, or air is injected, to create a pillowing matrix that, when cooled and extruded, yields those delightful culinary short-form cylinders.
The chocolate has been tempered, a culinary term for gently heating and cooling it to alter its crystalline structure so it stays solid at room temperature but “melts in your mouth” at body temperature.
The graham cracker’s defining feature is Graham Flour, a whole-wheat flour made by grinding the components, endosperm, germ, and bran separately, then re-proportioning and combining them to create its distinct nuttiness and flaky texture. While the original, a vegan digestive aid, had no other ingredients, today’s version contains a bit of sweetener, oil, and leaveners.
The Conflagration
The S’more is a study of how heat affects our food. We begin, classically, by roasting the marshmallow over an open flame. As heat is applied, the microscopic gas bubbles expand, inflating the outer shell, just as bread experiences “oven spring” as it rapidly expands in the oven. Then the gelatin protein network begins to liquefy, converting the once-firm foam into a soft, nearly flowing liquid. A bit more heat and the sugar molecules “caramelize,” a culinary term for the thermal decomposition that leaves marshmallow sommeliers with “nutty, complex notes.” Of course, too much heat results in ignition and a bitter carbon char.
The now-heated, presumably toasty marshmallow is sandwiched between two layers of chocolate. As the final S’more takes shape, heat conducted from the marshmallow's “molten” interior is transferred to the chocolate, allowing it to melt gently in place. The graham cracker now takes its rightful place, with its baked flour serving as both an effective insulator that protects your fingers and a flavor counterweight that differentiates and accentuates the sugary goodness of the marshmallow and chocolate.
A Prop 65 Warning?
We have no firm data on minimal consumption of S’mores. Its general ingredients include simple sugars, saturated triglycerides, and methylxanthines, including caffeine and theobromine found in chocolate. All are considered safe in moderation, but excess- a not-so-clearly-defined amount- may be associated with insulin resistance, metabolic dysfunction, elevated cardiovascular risk, and cavities.
Processing those ingredients, by which I mean heating and caramelizing the marshmallow, results in the formation of furans, which the International Agency for Research on Cancer (IARC) classifies as possible human carcinogens based on animal evidence. The accidental partial incineration of the marshmallow produces polycyclic aromatic hydrocarbons and acrylamide, both of which are classified as possible carcinogens.
Given all those “possibles,” does the precautionary principle come to mind? Should the S’mores be avoided or labeled on the front of the package with a scarlet D for danger? Or are you willing to believe that the dietary contribution of those possibles is insufficient to arouse concern, even if you accumulate them every summer as you toast up a S’more?
At the end of the day, understanding the chemistry behind the campfire magic only makes the experience sweeter. The true beauty of the S’more is not found just in perfecting a golden toast or eating the glorious sticky mess, but in the glow of a fireside ritual shared with friends and family. Take a moment to celebrate a summer triumph. Enjoy your day, S’mores; you earned it.
Chuck Dinerstein, MD, MBA
Director of Medicine
Dr. Charles Dinerstein, M.D., MBA, FACS is Director of Medicine at the American Council on Science and Health. He has over 25 years of experience as a vascular surgeon.
