Nothing says Christmas like a punchbowl filled with creamy eggnog. Although its exact origins remain uncertain, eggnog is almost always prepared using the same ingredients and following the same method. Simply heat milk or cream in a saucepan and slowly add egg yolks whisked with sugar. Of course, an alcoholic beverage, usually rum or brandy, is often added as a special touch. Eggnog is normally chilled before serving, and no batch is complete without a dash of either nutmeg or cinnamon.
Did you know? Vegan eggnog can be made using soy milk. The emulsifier lecithin, found in eggs, can also be found in soybeans. So even if you use a lecithin-free egg substitute, emulsification can still take place.
When it contains alcohol, eggnog is an emulsion. In other words, it’s a mixture of two immiscible liquids, like oil and water or cream and alcohol. Immiscible means that the two liquids cannot be easily mixed because of differences in their chemical properties. To form an emulsion, they need to be mixed vigorously, so that one substance (oil or alcohol) forms tiny droplets interspersed in the other (water or cream).
Unlike an oil and water emulsion, which will separate back into distinct layers over time, the cream and alcohol in eggnog stay emulsified. This is because of the egg yolk, which contains an emulsifier (or emulsifying agent) called lecithin. Emulsifiers are molecules with one end that is hydrophilic, or water-loving, allowing substances like lecithin to hold onto compounds that can dissolve in water. The other end is hydrophobic, or water-hating, allowing the emulsifier to hold onto compounds that do not dissolve in water, like oil. Both ends work together to hold all components of eggnog together merrily.
A sprinkling of nutmeg is often added to eggnog as a final touch. The nutmeg tree is endemic (native) to Indonesia, but can also be found in neighbouring Malaysia. The powdered nutmeg you can buy at the supermarket is produced by grating the seed of the tree’s fruit. In small quantities, nutmeg gives food or drink a distinct spicy yet pleasant taste.
Did you know? Another spice, mace, is derived from the nutmeg tree. It comes from the red webbing, or “aril” covering the nutmeg seed.
In larger quantities, however, nutmeg has the potential to trigger hallucinations, irregular heartbeats, and uncontrollable sweating. This is because of a mind-altering compound called myristicin that is found in nutmeg’s essential oil. But don’t worry about the small dash you put in your eggnog. It would take about two full teaspoons of nutmeg powder to really affect your mind or body.
A more likely source of danger is salmonella poisoning, which can cause fever, diarrhea, and painful abdominal cramps. Since eggnog is prepared at relatively low temperatures, the egg yolks are not always cooked enough to kill all the salmonella bacteria. Although researchers have suggested that the risk of this is very minor, it is still a very good idea to use Grade A or pasteurized eggs in eggnog to help avoid any such unpleasantries during the festive season. Also, try and keep the yolks from coming in contact with the shell when separating them from the egg whites.
So the next time you prepare eggnog, remember the science behind the drink. It will help you avoid food poisoning while amazing your yuletide guests with your knowledge of emulsification and mind-altering substances!
- McKenna A, Nordt SP, Ryan J. 2004. Acute Nutmeg Poisoning. European Journal of Emergency Medicine. 11(4):240-241.