The biggest, most delicious secret is that frozen custard must contain egg yolks. According to the FDA, a real frozen custard has at least 1.4% egg yolk solids by weight. Soft serve, on the other hand, usually skips the eggs entirely, relying on milk solids, sugar, and stabilizers. Why does that tiny addition matter so much?
Egg yolks are nature’s emulsifiers. They bind fat and water together into a silky, unbreakable team. That’s why custard feels denser, richer, and almost velvet-like on your tongue. Soft serve is lighter and fluffier, thanks to air being pumped in—sometimes 50% air or more.
