Quick bread leavening agents include a weak base, such as baking soda (sodium bicarbonate) plus a weak acid, such as cream of tartar, lemon juice, or cultured buttermilk, to create an acid–base reaction that releases carbon dioxide. (Quick bread leavened specifically with baking soda is often called "soda bread".) Baking powder contains both an acid and a base in dry powdered form, and simply needs a liquid medium in which to react. Other alternative leavening agents are egg whites mechanically beaten to form stiff peaks, as in the case of many waffle recipes, or steam, in the case of cream puffs. Nevertheless,
Welsh cuisine butter. The dough which is mixed with raisins, sultanas and sometimes currants, is similar to shortbread, meaning they can have the consistency of biscuits when cooked on the griddle, and slightly more like a cake when cooked in the oven. Bara brith is a fruit loaf originating from rural Wales, where they used a mortar and pestle to grind the fresh sweet spices. Historically it was made with yeast and butter, though recently it is likely to be made with bicarbonate of soda and margarine. The fruit included would be dried raisins, currants and candied peel, which would be soaked