When processing flour products including breads, additives, called leavening agents, are used to soften the texture and to improve tastes and chewing feelings. When kneading flour, net-shaped gluten is formed and gases are entered into these net shapes to make the dough rise and to give unique, soft sponge-like structures. These gas-producing agents are called leavening agents, and there are natural type (yeast) and synthetic type. The natural type, which is mainly used in breads, produces more gas and tastes good, but has longer fermentation time and is difficult to use. Synthetic types (sodium bicarbonate, ammonium bicarbonate) are easy to use, but have weak leavening activity and disadvantages such as discoloration or bad aftertaste. To complement these disadvantages, acidifying agents are mixed with synthetic agents to make baking powder.