Host: "Morning, bakers. Very exciting news this morning. We've got a new category of bread ... quick breads. Quick breads, of course, are just very speedy breads made without yeast. Paul and Mary would like you to make two of these, any flavour you like, but they have to be free form. That is not in a tin. "

Paul Hollywood: "Now, a quick bread is a bread risen without yeast, so the only thing they're going to be able to use to rise is bicarb or baking powder. You throw your bicarb in, which is your alkali, and then you throw your buttermilk in, which is essentially acid. The reaction between the two creates a gas and grows your bread. If they use too much bicarbonate baking powder, it's very bitter and the moment you eat into it, you know it."