Corn syrup is a liquid sweetener made from the starch of corn and contains varying amounts of sugars: glucose, maltose, and higher oligosaccharides, depending on the grade. It is used in foods to soften texture, add volume, prevent crystallization of sugar, and enhance flavor. Corn syrup is not the same as high-fructose corn syrup (HFCS), which is manufactured from corn syrup by converting a large proportion of its glucose into fructose using the enzyme D-xylose isomerase, thus producing a sweeter substance. Corn syrup serves two purposes in food, including as a sweetener and as a thickening agent. It is used in candies to provide shine and to prevent the crystallization of the sugars, and it also provides moisture to the finished product. Corn syrup is often used in combination with sugar to give a creamier texture to frozen desserts like ice cream and sorbet. It is also used in commercially prepared foods as a thickener, a sweetener, and a humectant (an ingredient that retains moisture and thus maintains a foods freshness) . Some breweries use corn syrup to activate the yeast in their beer.