The weather outside is frightful. As you look ahead to 2018, enjoy this hot cup of science!

After a long and busy year of blogging we decided to end the year with a nice, steaming cup of hot chocolate.  But first, a cup of science. The use of chocolate dates back more than 2,000 years when the Mayans apparently used cocoa in food preparations. Today, chocolate can be found everywhere—from those ubiquitous chocolate bars to chocolate-covered bacon and even chocolate-covered potato chips.

Chocolate contains small amounts of the chemical tryptophan, which the brain uses to make serotonin, the neurotransmitter that produces feelings of ecstasy is found in chocolate. Small amounts of phenylethylalanine, which promotes feelings of attraction, excitement, giddiness and apprehension, has also been isolated in chocolate, and theobromine – a weak stimulant found in chocolate – in concert with other chemicals such as caffeine, may be responsible for the characteristic ‘buzz’ experienced when eating chocolate.

Why we love the taste of chocolate is an interesting question, says Lucas Armstrong, PhD, the Associate Director of Cell & Molecular Biology at Charles River Laboratories’ site in Cleveland, Ohio who recently blogged about taste receptors for Eureka. Chocolate and a few other ingredients, such as coffee, are essentially bitter. Why those bitter substances become pleasurable when mixed with sweet substances is unclear, though perhaps bitter and sweet taste receptors synergistically activate a pleasure signal.

As you ponder the chemistry of chocolate try this hot chocolate recipe from Crista King, Internal Communications Specialist at Charles River.


½ cup cocoa powder

½ cup granulated sugar

3 ounces chopped up semi or bittersweet chocolate

¼ teaspoon vanilla extract

1/8 teaspoon sea salt

1 tablespoon cornstarch (which helps dissolve the sea salt perfectly)

Combine all ingredients in a food processor and blend until powder-y. Recipe yields almost 10 cups. To make a single cup of cocoa, mix 2-3 tablespoons of the mixture into a mug full of scalding liquid milk or water. Top your cup with marshmallows or whipped cream, and mix in cinnamon or a pinch of cayenne pepper for a different flavor. This also pairs well with Bailey’s, Kahlúa or espresso vodka.  

Enjoy! Happy New Year! Thanks for tuning in to Eureka.

(This Eureka blog post originally appeared in 2016.)