Invert sugar is a liquid sugar that contains the simple individual sugar molecules (glucose and fructose) that sucrose (granulated sugar) is made out of. When there are lots of these simple sugars floating around, it’s harder for sucrose molecules to build up on themselves and crystallize. Corn syrup also contains larger sugar molecules (called oligosaccharides) which can physically interfere with sucrose molecules and prevent them from coming together and clumping.