Fermentation of bakery products
Adding sugar/syrup to a savoury dough nourishes the yeast.
The sugar is transformed into carbon dioxide and thus accelerates the rising process.
The more sugar/syrup, the more the loaf rises (to a certain point).
The yeast enzymes generally split up sugar into glucose and fructose, while most of the sugar in syrup is already split up.
The yeast primarily uses glucose to create carbon dioxide, but fructose can also be used. The yeast also splits the maltose in flour into glucose.