A process for the manufacture of a leavened foodstuff, comprising at least: A) treating an ingredient composition comprising food structurant selected from the group comprising protein, polymeric carbohydrate and hydrocolloid, water and a leavening agent, said ingredient composition being a dough or batter, with ultrasound from an ultrasound source to modify the gas cell structure developing in the ingredient composition during at least a part of a leavening step to provide a leavened ingredient composition as the leavened foodstuff, wherein said ultrasound has a frequency in the range of from 20 kHz to 200 kHz and a power in the range of greater than 50 W to 1 kW and wherein when the leavening agent is a biological leavening agent, the leavening step further comprises the step of controlling the relative humidity of the environment surrounding the ingredient composition such that it is greater than 30%, and/or B) i) treating an ingredient composition comprising food structurant selected from the group comprising protein, polymeric carbohydrate and hydrocolloid, water and a leavening agent, said ingredient composition being a dough or batter or ii) a leavened ingredient composition having a gas cell structure and comprising a food structurant selected from the group comprising protein, polymeric carbohydrate and hydrocolloid and water, said leavened ingredient composition being a dough or batter with ultrasound from an ultrasound source to modify the gas cell structure developing in the ingredient composition or to modify the gas cell structure of the leavened ingredient composition during at least a part of a heat treating step to provide a heat treated leavened foodstuff, wherein said ultrasound has a frequency in the range of from 20 kHz to 200 kHz and a power in the range of greater than 50 W to 1 kW. A) treating an ingredient composition comprising food structurant selected from the group comprising protein, polymeric carbohydrate and hydrocolloid, water and a leavening agent, said ingredient composition being a dough or batter, with ultrasound from an ultrasound source to modify the gas cell structure developing in the ingredient composition during at least a part of a leavening step to provide a leavened ingredient composition as the leavened foodstuff, wherein said ultrasound has a frequency in the range of from 20 kHz to 200 kHz and a power in the range of greater than 50 W to 1 kW and wherein when the leavening agent is a biological leavening agent, the leavening step further comprises the step of controlling the relative humidity of the environment surrounding the ingredient composition such that it is greater than 30%, and/or B) i) treating an ingredient composition comprising food structurant selected from the group comprising protein, polymeric carbohydrate and hydrocolloid, water and a leavening agent, said ingredient composition being a dough or batter or ii) a leavened ingredient composition having a gas cell structure and comprising a food structurant selected from the group comprising protein, polymeric carbohydrate and hydrocolloid and water, said leavened ingredient composition being a dough or batter with ultrasound from an ultrasound source to modify the gas cell structure developing in the ingredient composition or to modify the gas cell structure of the leavened ingredient composition during at least a part of a heat treating step to provide a heat treated leavened foodstuff, wherein said ultrasound has a frequency in the range of from 20 kHz to 200 kHz and a power in the range of greater than 50 W to 1 kW.