If you've ever had store bought no-sugar ice cream you may notice it's harder and less creamy than its sugary counterparts. Adding a splash of booze helps keep the ice cream soft and easier to scoop. Because alcohol freezes at a much lower temperature than water, the vodka prevents as many large ice crystals from forming in the ice cream. The result is a homemade sugar free ice cream that stays soft, creamy and scoopable even after days in the freezer.