A lick of cold, creamy gelato isn't just magic. It's mathematics. "You have to respect the range," emphasizes Gianpaolo Valli, a senior instructor at Carpigiani Gelato University in Bologna, Italy, who has spent decades drilling aspiring gelato chefs on the right ratio of solids to water in any given recipe. (FYI: Solids need to be between 32 and 46 percent.) If your numbers are off, you're likely to end up with a disaster instead of a dessert.

That's particularly true if you skimp on sugar, which is considered critical for achieving a smooth consistency. Too little, and the result is a hard, icy mass. Or, at least, that was what used to happen. In January at Sigep, the annual mega trade show in Rimini dedicated to gelato (and pastry, chocolate and coffee), Carpigiani — the leading manufacturer of gelato machines — unveiled a new technology to "defy the law of balancing."