According to Ethnic Spoon, Vietnamese egg coffee is strong French roast coffee festooned with a foamy blend of egg yolks and sweetened condensed milk. Interestingly, the concoction wasn’t crafted for its richness, but born out of necessity. Atlas Obscura explains that egg coffee was invented in Hanoi in 1946, during the French War. At that time, a milk shortage made it impossible to create what Hanoi coffee drinkers cherished most – robust coffee with a generous amount of sweetened milk. In an effort to create a similar beverage, bartender Nguyen Van Giang of the Sofitel Hotel whisked egg into the coffee instead. The coffee was such a profound success, Giang opened his own café where his son still serves the signature brew.
Are egg coffees safe to drink? Regarding Swedish egg coffee, certified food safety professional Janilyn Hutchings explained to HuffPost that the egg may contain salmonella, especially if only “lightly cooked.” She asserted that the water used for coffee brewing typically doesn’t reach the boiling point, the temperature needed to kill bacteria. While some studies show that coffee grounds may have antibacterial properties, Hutchings suggested using fresh pasteurized eggs to ensure safety. Note that many recipes, including one from Food.com, suggest boiling the egg-coffee mixture for at least three minutes.
For the Vietnamese version, Instructables states that only yolks are used and are often protected from bacteria by the egg whites and several other membranes. That said, only use fresh, quality yolks that are free of imperfections.