Quick breads are breads leavened with carbon dioxide gas from chemical leaveners rather than yeast. They include foods like banana bread, muffins, and biscuits. Quick breads use little or no gluten development and require only brief mixing. There are two main types of dough/batters - soft doughs for biscuits and pour/drop batters for muffins and pancakes. Over-mixing can lead to toughness and tunneling. Different mixing methods are used depending on the type of quick bread.