Glucose syrup is a thick, clear syrup made by breaking down starch, usually from corn, wheat, tapioca or potato, with enzymes or acid. Despite the name it is a mixture: glucose, maltose and longer sugar chains. The further the starch is broken down, the sweeter and thinner the syrup, but most types are noticeably less sweet than table sugar.
Confectioners rely on it because it gets in the way of sugar crystals, so sweets stay smooth instead of grainy, and because it holds water, keeping cakes and marshmallows soft. It also adds body and chew. In the Mildy Marshmallow Filled With Lychee it makes up 39% of the recipe, almost as much as sugar, and in the Euro Cake Hokkaido Milk it is second only to egg.
Glucose syrup made from wheat is refined so thoroughly that EU allergen rules exempt it from wheat labelling.
