With temperatures dropping, it's customary to imagine oneself snuggled indoors, inhaling the scent of froth atop a hot chocolate. Comfort par excellence. But why do we so easily picture foam on the surface of hot chocolate? Does it make it better, or is it simply a byproduct of making it the right way? Delve into the secrets of foam on hot chocolate.

A matter of chemistry

Our senses of taste and smell must be able to detect molecules associated with different aromas. By definition, aromas are volatile molecules. This means the substance evaporates to release these molecules. However, for these molecules to reach our sensory receptors, they must "escape" from the substance. By significantly increasing the surface area between the hot chocolate and the air, foam allows these aromas to escape.

Thus, frothing hot chocolate just before drinking it helps to better reveal its aromas. But, be careful, if the foam on the hot chocolate sits for too long, the aromas will disappear, literally volatilized. This is why hot chocolate should be enjoyed when it has just been prepared.

Chocolate foam, a long tradition

The properties of foam in enhancing aromas seem to be an integral part of cocoa's history. On the one hand, Bernardino de Sahagún, who accompanied Hernán Cortés to Mexico, recounts in his codex that the Aztecs who consumed cocoa as a drink did so in vessels accompanied by a whisking utensil. On the other hand, pre-Columbian artifacts suggest that cocoa preparation involved pouring it from one container to another to aerate it. In addition to its divine virtues, cocoa seems to be associated with various ritual practices. Even today, ceremonial cacao is considered the heir to these traditions.

With the transition from Aztec cacao to European chocolate, sweetened and flavored with other spices, the first compressed cocoa wafers appeared to facilitate its transport and the preparation of the drink. It was also around this time that the Spanish introduced the tradition of whisking hot chocolate with a molinillo (whisk). From the 18th century, this accessory was integrated into most chocolate pots. Serving both to prepare and serve hot chocolate, these utensils had a perforated lid to allow the whisk to pass through and stir without spilling anything.

How to froth your hot chocolate?

While baristas have frothers that inject air into any drink, it is possible to simplify by reconnecting with tradition. Besides the simple option of using a whisk, there are also contemporary molinillos. While manufacturers often favor wood, anything is possible: from porcelain to metal. Choose stainless steel for easy cleaning and to avoid a reaction between the metal and the chocolate, which could alter the latter's taste.

The main challenge is finding a suitable container. Indeed, if the bottom of chocolate pots is wider than the top, it's to allow foam to form without overflowing. Despite this, the lid often proves essential. Thus, the brand Bodum has created a modern glass chocolate pot, with an integrated molinillo and, most importantly, a leak-proof lid.

And you, what's your favorite hot chocolate: with or without foam?

Main image credit: Nica Cn

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