what molecules does yeast contain
Simple sugars like glucose also provide flavor to the bread and participate in browning reactions that occur at the crust during baking. Fortunately, the yeast used in bread-making contains the enzyme maltase, which breaks maltose into glucose. When the yeast cell encounters a maltose molecule, it absorbs it. Maltase then bonds to the maltose and breaks it in two. Yeast cells also contain invertase, another enzyme that can break sucrose, like the sucrase described above. This enzyme works on the small percentage of sucrose found in the flour. These two enzymes are responsible for producing much of the glucose needed by the yeast for fermentation. The other major enzyme at work in bread dough is protease. Protease acts on protein chains, breaking the peptide bonds between amino acids.