Glucose syrup (confectioner's or liquid glucose) is a thick, clear, almost flavourless syrup made by breaking starch — usually corn, wheat or potato — down into glucose and shorter sugar chains with acid or enzymes. Its defining trick is not flavour but function: it interferes with sugar crystallising, so pastry chefs, chocolatiers and ice-cream makers rely on it to keep caramels, fondant, ganache and sorbets smooth, glossy and non-grainy.